Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
http://www.actaps.com.cn
401
Brief Review
Neural mechanism of rapid eye movement sleep generation: Cessation of
locus coeruleus neurons is a necessity
Dinesh Pal, Vibha Madan, Birendra Nath Mallick*
School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
Abstract: Two types of neurons are involved in the regulation of rapid eye movement (REM) sleep, the REM-ON and the REM-OFF
neurons. As the name suggests, the REM-OFF neurons cease firing during REM sleep and they are norepinephrinergic. It has been
shown that cessation of these neurons is a pre-requisite for the generation of REM sleep and GABA shuts them off. Further, if these
neurons do not shut off, there is increased levels of norepinephrine in the brain and loss of REM sleep. The REM sleep deprivation
induced increase in norepinephrine is responsible for mediating at least REM sleep loss induced increase in Na+-K+ ATPase activity,
which is likely to be the primary factor for causing REM sleep deprivation induced effects.
Key words: GABA; locus coeruleus; Na-K ATPase; norepinephrine; REM sleep generating mechanism; REM sleep loss
快速眼动睡眠产生的神经机制：蓝斑核神经元停止发放是一个必要的条件
Dinesh Pal, Vibha Madan, Birendra Nath Mallick*
Jawaharlal Nehru 大学生命科学学院，新德里 110067，印度
摘 要：两种类型的神经元参与了快速眼动(rapid eye movement, REM)睡眠的调节：快速眼动 - 发放(REM-ON)神经元和快速
眼动 - 沉寂神经元(REM-OFF)。快速眼动 - 沉寂神经元属去甲肾上腺素能神经元，正如名字表示的那样——在快速眼动睡眠期
间停止发放。已有研究表明，这些神经元放电活动的停止是导致快速眼动睡眠的前提条件，γ- 氨基丁酸(γ-aminobutyric acid,
GABA)可使它们停止发放。如果这些神经元不停止发放，脑中的去甲肾上腺素水平将升高，不出现快速眼动睡眠。剥夺快
速眼动睡眠所引起的去甲肾上腺素增加，至少是快速眼动睡眠丧失引起 Na + -K + ATP 酶活性增加的原因，而这可能是导致快
速眼动睡眠剥夺所引发的各种效应的主要因素。
关键词：γ - 氨基丁酸；蓝斑核；N a + -K + AT P 酶；去甲肾上腺素；快速眼动睡眠产生机制；快速眼动睡眠的丧失
中图分类号：Q 42 6 ；R 3 38 . 4
Introduction
Sleep and wakefulness are spontaneous cyclic changes in
behavior and associated levels of consciousness in higher
living beings. To avoid subjective bias, electrophysiological signals from the brain, the electroencephalogram (EEG),
the muscles, the electromyogram (EMG) and the eye
movements, the electrooculogram (EOG) have been used
for classification and quantification of sleep and wakefulness objectively in higher species including humans. While
analyzing sleep using the electrophysiological parameters,
Received 2005-01-25
Aserinsky and Kleitman [1] observed that electrophysiologically sleep was not a homogenous state. After a minimum
time was spent in deep sleep, the EEG and EOG expressed
signs apparently resembling wakefulness, although the EMG
did not show signs associated to wakefulness. Since that
appeared to be a paradox, i.e. presence of signs of wakefulness in EEG and EOG during a phase of sleep, it was
termed as paradoxical sleep. Also, since it appeared to be
an active state of the brain with desynchronization of the
EEG within sleep, it was termed as active sleep or
desynchronized sleep. Since dreams are associated with
Accepted 2005-07-01
This work was supported by Fund from CSIR, DBT, DST, ICMR and UGC, India.
*
Corresponding author. Tel: +91-11-26704522; Fax: +91-11-26717586; E-mail: remsbnm@yahoo.com
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this state of sleep, it has been termed as dream sleep.
Additionally, as rapid eye movements during sleep formed
a characteristic feature of this state, this state has also been
termed as rapid eye movement (REM) sleep. The sleep
state was thus classified into non-REM sleep and REM
sleep.
The REM sleep is present in species higher in the evolutionary ladder, viz. birds and mammals, and has been classically identified by the simultaneous presence of
desynchronization (low voltage high frequency waves) of
the EEG, frequent eye movements, muscle atonia and hippocampal theta rhythm. Several other characteristic
features, e.g. ponto-geniculo-occipital waves, irregular respiration as well as heart rate, body temperature fluctuation,
etc. also are associated with this state. Though all the REM
sleep signs may not be present in all the species, some of
these signs may be expressed in some lower species suggesting that REM sleep-like state may be present in lower
species as well[2-4]. Hence, it is debatable if REM sleep
evolved in lower species or it is of relatively later origin in
evolution. REM sleep loss affects several physiological
processes necessary for normal routine behavior[5-7] and it
is also essential for life to the extent that accumulated effect of its loss may be fatal[8]. REM sleep is regulated by
the brainstem though other brain areas may modulate it as
well. The role of specific area(s) and group of neurons in
the brainstem that play key role in the regulation of REM
sleep would be discussed. Briefly, the neurons in the locus
coeruleus (LC) cease firing during REM sleep and if an
experimental animal was not allowed to have REM sleep,
these neurons in the LC continued firing incessantly leading to disturbance or loss of REM sleep. Alternatively, if
these neurons were not allowed to cease firing either by
continuous electrical stimulation[9] or by applying antagonist of the neurotransmitter that keep these neurons inhibited[10,11], REM sleep did not continue resulting in its
reduction. Thus, the neurons in the LC must cease firing
(as if it is a pre-requisite) for the generation of REM sleep
and non-cessation of these neurons caused reduction of
REM sleep associated with increased levels of norepinephrine (NE) in the brain which ultimately induces the effects
associated to REM sleep deprivation/loss.
Localization of area(s) in brainstem responsible for
the regulation of REM sleep
Initial studies to localize anatomical structure(s) in the brain
responsible for the regulation of REM sleep generation
started with transection and lesion experiments. The
Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
premise behind such studies is that if any normal
manifestation, behavioral or otherwise, of a living organism continues to be expressed even after the destruction
of certain brain area(s), the damaged area of the brain is
possibly not essential for normal manifestation of the function under consideration. Work on cats with spinal transection and in humans with spinal injury showed that the spinal cord makes no essential contribution to the brainstem
signs of REM sleep. The transection studies suggested that
structures caudal to the midbrain and rostral to the spinal
cord are necessary for REM sleep regulation. Further, when
the pons was connected to midbrain and forebrain
structures, most of the defining signs of REM sleep were
seen in the rostral structures, whereas, if the pons was
connected to the medulla and spinal cord, most of the identifying signs of REM sleep were seen in caudal structures.
A transection through the middle of the pontine region abolished the major defining characteristic signs of REM sleep.
Thus, based on the results of transection studies it was
concluded that the pontine region in the brainstem is both
necessary and sufficient to generate the basic phenomenon of REM sleep[12,13].
Pontine region and regulation of REM sleep
The pontine region contains noradrenergic, cholinergic as
well as GABA-ergic neurons. The noradrenergic neurons
are clustered in the LC, which is the primary site for supplying NE in the brain. The functional characteristic of
these NE-ergic neurons in the LC is that they cease firing
during REM sleep[14,15] and hence they have been termed as
REM-OFF neurons. On the other hand, the cholinergic
neurons in the laterodorsal tegmentum (LDT) and
pedunculo pontine tegmentum (PPT) in the brainstem increase firing during REM sleep and they have been termed
as REM-ON neurons[16]. The present knowledge indicates
that interactions between the neurons located in these nuclei in the pontine region are responsible for the generation
and regulation of REM sleep.
Locus coeruleus: An anatomical description
The LC is a small cluster of neurons situated in the pontine
region near the wall of the fourth ventricle and is one of the
few pigmented structures in the brain. Depending on the
size of the cells and their organization, the LC has further
been subdivided into LC-principal, LC-α, peri-LC-α and
sub-coeruleus by some sleep researchers[17]. The LC or its
analage, projecting to the forebrain is not found until reptiles[18] and avians[19], though some catecholaminergic neu-
Dinesh Pal et al: Neural Mechanism of Rapid Eye Movement Sleep Generation: Cessation of Locus Coeruleus Neurons
rons projecting to the cerebellum and nearby tegmentum
has been reported in teleosts and amphibian[20]. Therefore,
it was proposed that the development of LC is in tandem
with the appearance of its cortical target areas[19,20]. The
number of neurons in LC increases from 200 in parakeet
to 1 600 in rats and 20 000 in humans[21]. Projections from
these neurons divide into ascending and descending
branches and innervate almost all the areas in the brain,
spinal cord[22,23] and brainstem[24]. The LC receives cholinergic[25,26] as well as GABA-ergic projections[27,28] from other
parts of the brain and it also has GABA-ergic interneurons
[29]
. Galanin-ergic and GABA-ergic neurons from ventrolateral preoptic area also project to the LC[30,31].
Locus coeruleus and REM sleep
There is ample evidence that the brain noradrenergic system plays a significant role in the regulation of REM sleep.
Several techniques including electrical as well as chemical
lesion, stimulation and microinjection have been extensively
used to explore the role of LC in regulating REM sleep.
Although these studies gathered a large volume of
knowledge, much remains to be known in terms of the
relationship of neurons in LC with other nuclei in the brain
and the exact role that it plays in the generation and regulation of REM sleep. Electrical destruction of the dorsal part
of LC did not suppress the occurrence of REM sleep[32].
Similarly, destruction of ventral part of the LC (LCα and
peri-LCα), was followed by irreversible disappearance of
REM sleep atonia[33]. However, destruction of LCp and
LCα along with peri-LCα suppressed REM sleep completely during the two post-lesion months[34]. Electrolytic
lesions of the dorsal noradrenergic bundle that ascends
from the LCp[35] resulted in increase in both non-REM sleep
and REM sleep[36]. The firing rate of the neurons in the
LCp is maximum during wakefulness, decreases during
non-REM sleep and almost ceases during REM sleep[14,15,37],
while that of the neurons located ventrally increase their
firing rate (almost exclusively) during REM sleep[17,37]. The
activity of the NE-ergic neurons in the LC has been positively correlated with activation of the sympathetic nervous system[38]. Sympathetic activation is normally accompanied by EEG desynchronization and according to Reiner,
the activity of the LC-NE-ergic neurons increases with an
increase in discharge in the sympathetic nervous system.
Reversible inactivation of the LCp by localized cooling
(+10ºC ) induced non-REM sleep followed by REM
sleep[39]. On the other hand, it was found that continuous
activation of the LC neurons inhibited REM sleep by re-
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ducing the frequency of generation of REM sleep although
the duration per episode remained unaffected[9]. Thus, the
results suggested that activation of LC neurons did not
allow REM sleep occurrence while inactivation of those
neurons allowed REM sleep to continue.
Norepinephrine in REM sleep
The concentration of NE increased in the brain[40] after
REM sleep deprivation. An increase in NE concentration in
serum was also reported after REM sleep deprivation[41].
There was an increase in the activity of tyrosine
hydroxylase, the enzyme involved in the first rate limiting
step of synthesis of NE[42] and mRNA levels[43] of tyrosine
hydroxylase, whereas there was a decrease in the activity
of the NE degrading enzyme, monoamine oxidase-A[44] after REM sleep deprivation. The above findings may be
supported by a recent study that there was increased tyrosine hydroxylase activity within the neurons located in
the LC[45]. These results suggested that there would be
increased NE in the brain after REM sleep deprivation. An
inhibitory role of NE on REM sleep may be supported by
the fact that NE levels decreased during REM sleep[46].
Since most of the supply of NE in the brain comes from
the neurons in LC, it is likely that the activity of those
neurons must be getting modulated during normal REM
sleep and/or upon REM sleep deprivation. This view may
be confirmed by the fact that the REM-OFF neurons in
the LC cease firing during REM sleep[14,15], and they continue firing incessantly during REM sleep deprivation[47].
Also, their activation by electrical stimulation[9] or disinhibition by GABA-antagonist, picrotoxin[10] did not allow REM
sleep to continue whereas GABA in LC caused an increase
in REM sleep[48]. A comparative effect on the REM sleep
upon electrical stimulation of LC neurons and microinjections of GABA as well as picrotoxin in LC are shown in
Fig.1A~E.
The studies mentioned above support the involvement
of LC in the regulation of REM sleep. Those studies also
suggest that continuous activity of the neurons in the LC
possibly prevented generation of REM sleep and cessation
of activity of those neurons induced REM sleep possibly
through withdrawal of inhibition. However, the mechanism of cessation of activities of the LC neurons was not
known. The presence of adrenergic receptors in the brain
was shown long ago[49,50]. Since the LC neurons are
noradrenergic, agonists and antagonists of NE were used
to study the role and mechanism of action of NE released
by the LC-neurons in REM sleep regulation. REM sleep
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Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
Fig. 1. Percent changes in REM sleep under various experimental conditions. The original reference is shown beneath each pie diagram. The
numbers in parenthesis show respective references in the reference list. The pie chart shows sleep-wakefulness recordings (8 h except where
mentioned otherwise) under the following conditions: A: Without any treatment (control study). B: Single bilateral microinjection (250 nl) of
normal saline into LC (control study). C: Low frequency, low amplitude electrical stimulation of bilateral LC for 8 h. D: Single bilateral
microinjection (250 nl) of picrotoxin into LC. E: Single bilateral microinjection (250 nl) of GABA into LC. F: Continous low frequency, low
amplitude electrical stimulation of bilateral PrH. G: Continuous low frequency, low amplitude electrical stimulation of bilateral PrH in
presence of single injection of picrotoxin into LC. H: Repeated intermittent microinjections (250 nl) of picrotoxin into bilateral LC for 48 h at
an interval of 6 h. The sleep-wakefulness recording was also done for 48 h continuously.
was facilitated by systemic injection of drugs that stimula ted β-a drenoceptors [51,52] and by blocking α 1 -
adrenoceptors[53-55]. On the other hand, REM sleep was
inhibited by blocking β-adrenoceptors[51,52] and stimulation
Dinesh Pal et al: Neural Mechanism of Rapid Eye Movement Sleep Generation: Cessation of Locus Coeruleus Neurons
of α1-adrenoceptors[56]. Oral administration of prazosin in
rats was found to shorten quiet waking and REM sleep
while it increased active waking and slow wave sleep[55].
α-2 agonist, clonidine, when injected intraperitoneally, reduced REM sleep in rats and cats[57,58]. A similar decrease
in REM sleep was observed in man with a dose roughly
five times smaller than that used in the rat[59]. Yohimbine,
α-2-antagonist, increased active wakefulness immediately
after administration but did not affect REM sleep. Though
systemic injections advanced our understanding of the LC
mediated regulation of REM sleep, localized injections of
adrenergic agonist and antagonist provided a more robust
evidence for the role of LC in the regulation of REM sleep.
The REM sleep was decreased when methoxamine, α1-agonist, was injected into the dorsal pontine tegmentum
of cats. The decrease in total REM sleep was found to be
due to both, an increased REM sleep latency and a reduced
number as well as duration of REM sleep episodes[60]. Bilateral injection of α-2-agonist, clonidine, in the dorsal pontine tegmentum of cat produced an almost complete suppression of REM sleep[61]. β-agonist isoproterenol almost
suppressed REM sleep, while β-antagonist propranolol
consistently enhanced it, mainly through an increase in the
number of REM sleep episodes[62]. Microinjection of βagonist isoproterenol into medial septal region of basal forebrain significantly increased the time spent awake and a
near complete suppression of REM sleep[63]. Norepinephrine in peri-LC-α caused a dose-dependent inhibition of
REM sleep and induction of REM sleep without atonia.
These effects were also produced by clonidine, an alpha2-agonist, whereas alpha-2-antagonists were found to block
the effect of norepinephrine. When co-applied with carbachol into the caudal peri-LC-α, clonidine completely blocked
the marked REM sleep inducing effect of carbachol[64].
Thus, the interaction of various networks of neurons having different adrenoceptors plays a crucial role for the generation and regulation of REM sleep. Although systemic
and local injection studies advanced the knowledge about
the role of NE in REM sleep regulation, they were unable
to elucidate the role of NE released from the LC in such
regulation. Based on our earlier studies[65] and the results
obtained in a recent study where LC stimulation was carried out in presence of adrenergic agonists and antagonists,
we have proposed a model showing the possible mechanism of action of NE release from the LC-neurons and its
role in REM sleep regulation[66].
The studies mentioned above suggest that although some
NE may be needed, excess NE is inhibitory for the genera-
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tion of REM sleep. The brain receives most of NE from
the LC-neurons, which cease firing during REM sleep and
they continue firing during REM sleep deprivation. Thus,
cessation of firing of the LC-neurons is likely to be at least
one of the key factors for the generation of REM sleep.
Further, increased NE in the brain during REM sleep deprivation due to non-cessation of firing of the LC-neurons
is likely to be the primary factor for REM sleep deprivation
induced effects.
How are the LC neurons kept active through wakefulness
Normally REM sleep does not appear during wakefulness
or immediately after going to sleep. It appears after certain
period of non-rapid eye movement (NREM) sleep. At least
in humans, the duration and number of REM sleep episodes increase with progress and depth of sleep through
the night. Although it was known that the REM sleep cannot be initiated as long as the LC noradrenergic REM-OFF
neurons continue firing[9,47], the cellular mechanism(s) of
sleep-wake state dependent changes in the LC neuronal
firing from highly active state during wakefulness to slowing down during NREM sleep and finally cessation of
firing during REM sleep was not known. Mallick’s group
proposed that the wakefulness inducing area, the midbrain
reticular formation (MRF), possibly exerted opposite
influence on REM-OFF and REM-ON neurons and
hypothesized that the MRF would excite REM-OFF and
inhibit REM-ON neurons during wakefulness. In a combined single unit recording and MRF stimulation study
carried out in freely moving normally behaving cats it was
observed that a majority of the neurons whose firing rate
increased during spontaneous wakefulness, including the
REM-OFF neurons, were excited, while the REM-ON
neurons were inhibited[67] by the MRF wakefulness
inducing area. These results supported our hypothesis and
suggested that the wake active neurons in MRF continuously excite the NE-ergic REM-OFF neurons in the LC
and inhibit the REM-ON neurons throughout the waking
period[67,68]. This view may also be supported by the fact
that activation of the REM-OFF neurons is reported to
prevent REM sleep[9] and is likely to increase the level of
NE in the brain causing cortical activation and
desynchronization of the EEG[5,69-71]. Therefore, it is likely
that continuous activation of the noradrenergic REM-OFF
neurons contributes to EEG desynchronization associated
with wakefulness, but not with that of REM sleep when
the effect of cholinergic REM-ON neurons is pronounced.
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This view may be supported by the power spectrum analysis
study in the freely moving cats that the adrenergic and
cholinergic antagonists affected different higher frequency
bands of the desynchronized EEG. Additionally, as mentioned above, MRF wakefulness-inducing area inhibited the
REM-ON neurons and this may be the cause for non-activation of the REM-ON neurons during waking period. It
may be supported by the fact that activation of the area
containing the REM-ON neurons increases REM sleep[72].
It has also been reported that activation of the REM-ON
neurons in the peri-LC during REM sleep is responsible for
muscle atonia during REM sleep[73,74]. All these results considered together provide possible explanation for neural
mechanism as to why does muscle atonia, associated with
REM sleep, not appear during wakefulness although the
EEG is desynchronized during both those stages. Moreover,
logical extrapolation of these observations is that in case of
narcolepsy possibly there occurs an error in this neural
pathway resulting in appearance of muscle atonia during
wakefulness.
Thus, the following is likely to be the working model of
neuronal mechanism of REM sleep generation. The wake
active neurons in the MRF are active during wakefulness.
Activity of these neurons keeps activating the REM-OFF
neurons and inhibiting the REM-ON neurons, which do
not allow REM sleep signs to appear during wakefulness.
Experimentally, we found that the REM-OFF neurons are
normally active during all the stages except during REM
sleep, while the REM-ON neurons behave in an opposite
manner. As a mechanism of action one or more of the
following possibilities may exist. One, that MRF neurons
exert independent excitatory and inhibitory effects on the
REM-OFF and the REM-ON neurons, respectively; two,
that the MRF neurons exert an excitatory effect on the
REM-OFF neurons that in turn (may be through GABAergic
neurons) inhibit the REM-ON neurons[68]; and three, that
the MRF neurons exert an inhibitory effect on the REMON neurons and that in turn (may be through withdrawal
of GABAergic inhibition) exert an excitatory effect on the
REM-OFF neurons[48]. It was known that neurons in the
wake (MRF) and sleep (caudal brainstem) areas are mutually inhibitory to each other[75,76] and at the onset of sleep
the activity of the wake active neurons in the MRF is significantly reduced[77]. This reduction in the activity of wake
active neurons in MRF gradually withdraws the excitatory
and the inhibitory effects from the REM-OFF and the REMON neurons, respectively[67]. Gradually NREM sleep sets
in when the sleep inducing neurons in the caudal brain-
Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
stem[75,78] and basal forebrain further increase firing[79-81].
At some point when certain (yet unknown) conditions are
satisfied, the sleep active neurons stimulate the REM-ON
neurons which in turn actively inhibit and cease firing of
the REM-OFF neurons (directly or indirectly) and initiate
REM sleep[67,68]. Also, recently it was reported from our
laboratory that picrotoxin, a GABA-A antagonist, in PPT,
site of REM-ON neurons decreases REM sleep[82]. We
expect that GABA from interneurons within the PPT[83] or
from sleep area (caudal brainstem) dis-facilitates the inhibitory influence of NE-ergic inputs from LC onto PPT
neurons resulting in an increase in REM sleep. These findings have been summarized in Fig.2.
How do the LC neurons cease firing during REM
sleep
Reciprocal interaction model
The reciprocal interaction model was proposed by Hobson
et al[37]. The model hypothesized that the REM-OFF neurons are inhibitory to REM-ON neurons and to themselves,
but the latter are excitatory to the former and to themselves.
Electrophysiologically it has been shown that presumably
noradrenergic LC neurons and serotonergic raphe neurons
are REM-OFF while the cholinergic FTG neurons are REMON. Thus, according to the hypothesis, inactivation of
putative monoaminergic REM-OFF neurons plays a critical role in the generation and maintenance of REM sleep.
Mutual inhibitory model
The mutual inhibitory model between the NE-ergic REMOFF and cholinergic REM-ON neurons was proposed by
Sakai[84]. It was based on the hypothesis that cessation of
firing of the REM-OFF neurons excites the REM-ON neurons by disinhibition while the excitation of the REM-ON
neurons inhibits the REM-OFF neurons. Therefore, REM
sleep can appear either by excitation of the REM-ON neurons or by inhibition of the REM-OFF neurons. This hypothesis seems to imply that for the generation of REM
sleep, cholinergic neurons directly inhibit NE-ergic REMOFF neurons.
Lacuna in the above mentioned models
The two hypotheses mentioned above did not consider the
type and role of neurotransmitters involved in mediating
such actions. As mentioned earlier, during REM sleep the
cholinergic REM-ON neurons increased firing, the REMOFF neurons in the LC ceased firing and continuous activation of the LC neurons by electrical or by chemical means
prevented generation of REM sleep. Since NE inhibits cholinergic tegmental neurons[85], it is reasonable to understand
Dinesh Pal et al: Neural Mechanism of Rapid Eye Movement Sleep Generation: Cessation of Locus Coeruleus Neurons
407
Fig. 2. Schematic diagram of a model for REM sleep regulation. The numbers in parenthesis represent the reference number. Abb: PrH,
Prepositus hypoglossus.
that projections from the monoaminergic REM-OFF neurons in LC would tonically inhibit the cholinergic REMON neurons during waking and NREM sleep states.
However, since acetylcholine is reported to depolarise and
excite the noradrenergic neurons in LC[86], it is not possible
that the increased activity of the cholinergic REM-ON
neurons, by releasing acetylcholine, would inhibit the REMOFF neurons in the LC for the generation and regulation of
REM sleep. These facts taken together strongly suggest
presence of an inhibitory input that would transduce the
cholinergic input from the REM-ON neurons on the REMOFF neurons into an inhibitory one. Therefore, Mallick
and his group hypothesised that an intervening inhibitory
interneuron, possibly GABA-ergic, could be converting the
excitatory cholinergic effect into an inhibitory effect on
the REM-OFF neurons for the regulation of REM
sleep[87,88].
GABA-ergic interneuron based model
The possibility of a role of GABA in LC for the regulation
of REM sleep was supported by the facts that GABA-ergic
interneurons and terminals are present in LC[29], GABA receptors are present on the neurons in LC[89,90] and GABA
levels increase in LC during REM sleep[91]. Therefore,
GABA-blocker, picrotoxin, was microinjected into the LC
and the effects on REM sleep evaluated in freely moving
rats. It was observed that picrotoxin injection into the LC
significantly reduced REM sleep[10] and thus supported our
hypothesis[87]. It was also reported that cholinergic stimu-
lation of the dorsolateral pontine area including LC increased
REM sleep[92,93]. However, it was not known how the excitatory cholinergic input from REM-ON neurons to the
REM-OFF neurons in LC would get translated into an inhibitory one, thereby inhibiting REM-OFF neurons. It was
also not known whether the cholinergic and the GABAergic inputs to the LC had different roles to play for initiation and maintenance of REM sleep. Therefore, as mentioned above we proposed that in LC the input from the
cholinergic REM-ON neurons possibly acted on GABAergic neurons and converted the excitation to an inhibition
for the regulation of REM sleep. To prove such microconnections and its pharmaco-physio-behavioral role one
must not only study in isolation using anatomical,
histological, neuropharmacological or behavioral
approaches, rather all these had to be combined to get information simultaneously on micro-neuro-anatomopharmaco-physio-behavior and the study had to be conducted in freely moving normally behaving animal model.
The working model of the proposed hypothesis was that
if the cholinergic input (presumably from the REM-ON
neurons) on the REM-OFF neurons in the LC was mediated through the GABA-ergic neurons, the agonist of the
former in presence of the antagonist of the latter would be
ineffective, while the agonist of the latter in presence of
antagonist of the former would be effective. Therefore,
experiments in chronically prepared freely moving rats were
conducted where cholinergic and GABA-ergic agonist and
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antagonist were micro-injected into the LC bilaterally either individually or in sequence one after the other in selected combinations. The microinjection study revealed that
individual injection of the cholinergic agonist and antagonist,
carbachol and scopolamine, respectively, affected the frequency of REM sleep; the agonist increased while the antagonist decreased the frequency of generation of REM
sleep. On the other hand, GABA and picrotoxin individually affected the mean duration of REM sleep per episode;
the former increased while the latter decreased the duration of REM sleep. These results suggested that
GABA-ergic input to the LC modulated the duration of
REM sleep per episode, while that of the cholinergic input
modulated the frequency of generation of REM sleep. These
results also indicated that GABA acted after the cholinergic
system had initiated the action because maintenance of any
process would be required only after the process had
initiated. Thus, individual injection studies confirmed the
role of cholinergic as well as GABA-ergic inputs into the
LC for the regulation of REM sleep; however, the sequence
of connections between those neurons could not be understood from those results.
To confirm, LC was microinjected with any of the following three combinations (a) GABA-ergic antagonist,
picrotoxin, followed by cholinergic agonist, carbachol or
(b) cholinergic antagonist, scopolamine, followed by GABA
or (c) cholinergic antagonist, scopolamine, followed by
GABA-ergic antagonist, picrotoxin. These microinjections
were done with the assumption that if cholinergic input
acted on the GABA-ergic neurons, carbachol in presence
of picrotoxin would induce an effect similar to that of picrotoxin alone, while GABA in presence of scopolamine
would show an effect similar to that of the GABA alone.
The results from the combination injection studies showed
that picrotoxin followed by carbachol microinjection caused
significant reduction in REM sleep by decreasing mean
REM sleep duration per episode, whereas scopolamine
followed by GABA microinjection significantly increased
REM sleep by increasing mean REM sleep duration per
episode. Thus, when cholinergic and GABA-ergic agonist
or antagonist (as the case may be) were injected into the
LC in any combination, the effect of the GABAergic agonist/antagonist prevailed over that of the cholinergic. The
most likely explanation for such a result is that the cholinergic input in the LC was acting on the GABA-ergic neurons to mediate its effects[48]. Thus, the observation supported our hypothesis that cholinergic influence in LC is
mediated through GABA[87,88] and that acetylcholine-sensi-
Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
tive GABA-ergic neurons are present in and immediately
around the LC[94].
In the above mentioned studies a complete suppression
of REM sleep was not observed after blocking either the
cholinergic or the GABA-ergic receptor. However, there
was an almost complete suppression of REM sleep when
scopolamine and picrotoxin were injected together. This
supports mutually permissive and co-operative role between
cholinergic and GABA-ergic systems in LC. Nevertheless,
since cholinergic antagonist alone into the LC could not
completely prevent occurrence of REM sleep, possibility
of additional GABA-ergic input to LC from any other source
that was triggered by the cholinergic REM-ON neurons,
could not be ruled out. Since it was known that there was
GABA-ergic input to the LC from the prepositus hypoglossus (PrH)[27] and that the latter receives input from
PPT [95], the site of REM-ON neurons, it was hypothesized
that the cholinergic REM-ON neurons could also inhibit
the REM-OFF neurons in the LC by triggering the GABAergic neurons in PrH. To confirm the hypothesis, a combined study involving electrical stimulation of PrH neurons
along with simultaneous picrotoxin microinjection in LC in
freely moving normally behaving rats was carried out (Fig.
3). It was shown that PrH stimulation increased REM sleep.
However, if the PrH stimulation was carried along with
simultaneously blocking GABA-ergic transmission using
picrotoxin in LC, the increased REM sleep was prevented
(Fig.1F~G). The results showed that in addition to the
local GABA-ergic input in LC, GABA-ergic input from PrH
to LC may also modulate REM sleep[96]. Thus, the cholinergic REM-ON neurons may excite the GABA-ergic neurons either in PrH or locally in the LC, which in turn inhibit
the REM-OFF neurons in the LC for the generation of
REM sleep (Fig. 2).
Functional implications
The studies reviewed above show that the NE-ergic REMOFF neurons in the LC must cease firing for the generation of REM sleep and if those neurons do not cease firing,
REM sleep is significantly reduced. Alternatively, if REM
sleep is not allowed to express, those neurons do not cease
firing and they continue to remain active. Further, if those
NE-ergic neurons in the LC continue firing incessantly there
will be increased NE in the brain. The increase in NE levels
in the brain because of incessant firing of LC neurons may
also be indirectly supported by the fact that after increased
waking (i.e. reduced NREM and REM sleep) there was
increased expression of several transcription factors. This
Dinesh Pal et al: Neural Mechanism of Rapid Eye Movement Sleep Generation: Cessation of Locus Coeruleus Neurons
409
Fig. 3. Diagrammatic representation of coronal section through LC and PrH of rat showing bilaterally implanted cannulae in the LC and
stimulating electrodes in PrH for microinjection and electrical stimulation, of respective sites. Abb: mcp, medial cerebellar peduncle; 4v, fourth
ventricle; DMTg, dorsomedial tegmental area; PnC, pontine reticular nucleus; icp, inferior cerebellar peduncle; Lat, lateral cerebellar nucleus;
Gi, gigantocellular reticular nucleus.
increased expression was found to be regulated by the LC,
the primary site for providing NE in the brain[97].
Furthermore, Cirelli[98] in her recent review put forward
the argument that role of sleep (including REM sleep) is to
interrupt continuous activity of the catecholaminergic system in the brain, which also supports our contention[5].
These results also indirectly suggest that REM sleep deprivation caused increased levels of NE in the brain, which
may be responsible for altered function(s) associated with
REM sleep loss. In order to confirm the same it was
hypothesised that if those neurons in the LC were not allowed to cease firing or kept continuously active, there
would be loss of REM sleep leading to REM sleep deprivation induced changes. Further, these changes would be
prevented by blocking the action of NE.
REM sleep deprivation is associated with reduced
concentration, body weight, memory consolidation and
increased irritability, food intake, aggressiveness,
hypersexuality, etc.[5-7]. At the cellular level it was shown
that after REM sleep deprivation the inhibition of neurons
induced by auditory stimulation was lost[99]. Therefore, it
was proposed by Mallick et al. that one of the functions of
REM sleep is to maintain neuronal excitability[5]; however
the mechanism of action was not known. It was hypothesized that after REM sleep deprivation there might be an
increase in Na-K ATPase activity in neurons in the brain
and that might be responsible for increased neuronal
excitability. To confirm, Na-K ATPase activity was estimated in the normal (control) and REM sleep deprived rat
brains. The results confirmed that there was increased NaK ATPase activity after REM sleep deprivation while the
enzyme was not significantly affected in the control animals[100]. Further, it was confirmed by in vivo and in vitro
studies using various adrenoceptor agonist and antagonist
that the increased Na-K ATPase activity after REM sleep
deprivation was due to increased levels of NE acting
through α-1 adrenoceptors[101]. The role and mechanism
of action of NE on Na-K ATPase activity was later studied
in detail. Such studies revealed that NE acted on α-1A
adrenoceptor that activated phospholipase C pathway. In
addition, NE released membrane bound calcium, activated
calmodulin and dephosphorylated Na-K ATPase resulting
in an increase in its activity[102-104]. Thus, so far it has been
shown that LC-neurons must stop firing for the generation
of REM sleep and if they do not cease firing, there would
be decrease or loss of REM sleep. Furthermore, during
Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
410
REM sleep deprivation there is increased Na-K ATPase
activity and this increase is due to increased NE in the
brain.
Finally, it needed to be confirmed whether the REM sleep
deprivation induced increase in NE level in the brain was
due to non-cessation of the LC-neurons and that this increase in NE, as a result of non-cessation of LC-neurons,
was accompanied with a simultaneous increase in Na-K
ATPase activity in the brain. In order to do so, rats were
surgically implanted with bilateral chemitrodes in the LC
for microinjection and other electrodes for recording EEG,
EOG and EMG. The rats were recovered with adequate
post-operative care. It was shown earlier that the LC neurons ceased firing due to presence of GABA. Hence, after
recovery from the surgical trauma, the LC of the normally
behaving freely moving rats were infused with GABA-A
antagonist, picrotoxin, every 6 h for 48 h and sleep-wakefulness was recorded continuously. At the end of the study,
the brain was removed after decapitation and Na-K ATPase activity estimated. The sleep-wakefulness was also
scored. The results showed that picrotoxin significantly
reduced REM sleep in the rats (Fig.1H) and there was
significant increase in Na-K ATPase activity in the brain,
which was comparable to that of REM sleep deprived
rats[11]. Thus, it may be said with certainty that GABA is
responsible for cessation of the noradrenergic REM-OFF
neurons in the LC for generation of REM sleep. If those
neurons do not cease firing there is loss of REM sleep and
vice versa. Non-cessation of those neurons during REM
sleep deprivation increases levels of NE in the brain and
that is at least one of the primary factors for REM sleep
deprivation induced behavioral and other effects[65].
Summary and conclusion
The primary site in the brain where there is maximum concentration of NE-ergic neurons is the LC. The neurons in
the LC cease firing during REM sleep and hence are called
as REM-OFF neurons. During REM sleep REM-OFF neurons are inhibited through GABA. These neurons fire incessantly during REM sleep deprivation and conversely, if
they continue firing incessantly, REM sleep will not appear.
Continuous activity of these neurons results in increased
levels of NE in the brain. This increased level of NE is one
of the major factors for mediating REM sleep deprivation
induced effects.
REFERENCES
1
Aserinsky E, Kleitman N. Regularly occurring periods of eye
2
motility and concomitant phenomena during sleep. Science 1953;
118: 273-274.
Siegel JM, Manger PR, Nienhuis R, Fahringer HM, Pettigrew
JD. The echidna Tachyglossus aculeatus combines REM and
non-REM aspects in a single sleep state: implications for the
3
4
5
evolution of sleep. J Neurosci 1996; 16: 3500-3506.
Siegel JM, Manger PR, Nienhuis R, Fahringer HM, Pettigrew
JD. The platypus has REM sleep. Sleep Res 1997; 26: 177.
Frank MG. Phylogeny and evolution of rapid eye movement
(REM) sleep. In: Mallick BN, Inoue S. eds. Rapid Eye Movement Sleep. New York: Marcel and Dekker Inc., 1999, 17-38.
Mallick BN, Adya HVA, Thankachan S. REM sleep deprivation
alters factors affecting neuronal excitability: Role of norepinephrine and its possible mechanism of action. In: Mallick BN, Inoue
S. eds. Rapid Eye Movement Sleep. New York: Marcel and
6
Dekker Inc., 1999, 338-354.
Vogel GW. A review of REM sleep deprivation. Arch Gen
7
Psychiat 1975; 32: 749-761.
Gulyani S, Majumdar S, Mallick BN. Rapid eye movement sleep
8
and significance of its deprivation studies? A review. Sleep and
Hypnosis 2000; 2: 49-68.
Rechtschaffen A, Bergmann BM, Everson CA, Kushida CA,
Gilliland MA. Sleep deprivation in the rat: X. Integration and
discussion of the findings. Sleep 2002; 25: 68-87.
9
Singh S, Mallick BN. Mild electrical stimulation of pontine tegmentum around locus coeruleus reduces rapid eye movement
sleep. Neurosci Res 1996; 24: 227-235.
10 Kaur S, Saxena RN, Mallick BN. GABA in locus coeruleus regulates spontaneous rapid eye movement sleep by acting on
GABA-A receptors in freely moving rats. Neurosci Lett 1997;
223: 105-108.
11 Kaur S, Panchal M, Faisal M, Madan V, Nangia P, Mallick BN.
Long term blocking of GABA-A receptor in locus coeruleus by
bilateral microinfusion of picrotoxin reduced rapid eye movement sleep and increased brain Na-K ATPase activity in freely
moving normally behaving rats. Behav Brain Res 2004; 151:
185-190.
12 Siegel JM. Pontomedullary interactions in the generation of REM
sleep. In: McGinty DJ, Drucker-Colin R, Morrison A,
Permeggiani PL. eds. Brain Mechanism of Sleep. New York:
Raven Press, 1985, 157-174.
13 Siegel JM. Brainstem mechanism generating REM sleep. In:
Kryger MH, Roth T, Dement WC. eds. Principles and Practice
of Sleep Medicine. WB Saunders Company, 1989, 104-120.
14 Aston-Jones G, Bloom FE. Activity of norepinephrine containing locus coeruleus neurons in behaving rats anticipates fluctuations in the sleep-waking cycle. J Neurosci 1981; 1: 876-886.
15 Jacobs BL. Single unit activity of locus coeruleus neurons in the
behaving animals. Prog Neurobiol 1986; 27: 183-194.
16 El Mansari M, Sakai M, Jouvet M. Unitary characteristics of
presumptive cholinergic tegmental neurons during sleep-waking
Dinesh Pal et al: Neural Mechanism of Rapid Eye Movement Sleep Generation: Cessation of Locus Coeruleus Neurons
411
cycle in freely moving cats. Exp Brain Res 1989; 76: 519-529.
17 Sakai K, Sastre JP, Kanamori N, Jouvet M. State-specific neurons in the ponto-medullary reticular formation with special
antiserum for demonstration of inhibitory neurons in the rat locus
coeruleus. Am J Anat 1988; 181: 183-194.
30 Sherin JE, Elmquist JK, Torrealba F, Saper CB. Innervation of
reference to the postural atonia during paradoxical sleep in the
cat. In: Pompeiano O, Ajmone V, Marsan C. eds. Brain Mecha-
histaminergic tuberomammillary neurons by GABAergic and
galaninergic neurons in the ventrolateral preoptic nucleus of the
nisms and Percptual Awareness. New York: Raven Press, 1981,
405-429.
rat. J Neurosci 1998; 18: 4705-4721.
31 Steininger TL, Gong H, McGinty D, Szymusiak R. Subregional
18 Parent A, Poitras D. The origin and distribution of catecholaminergic axon terminals in the cerebral cortex of the turtle (Chrysemys
picta). Brain Res 1974; 78: 345-358.
organization of preoptic area/anterior hypothalamic projections
to arousal-related monoaminergic cell groups. J Comp Neurol
2001; 429: 638-653.
19 Tohyama M, Maeda T, Hashimoto J, Shrestha GR, Tamura O.
Comparative anatomy of the locus coeruleus. I. Organisation
32 Jones BE, Harper ST, Halaris AE. Effects of locus coeruleus
lesions upon cerebral monoamine content, sleep wakefulness
and ascending projections of the catecholamine containing neurons in the pontine regions of the bird. J Himforsch 1974b; 15:
319-330.
states and the response to amphetamine in the cat. Brain Res
1977; 124: 473-496
33 Henley K, Morrison AR. A re-evaluation of the effects of lesions
20 Tohyama M, Maeda T, Shimizu N. Comparative anatomy of
the locus coeruleus II. Organization and projection of the cat-
of the pontine tegmentum and locus coeruleus on phenomena of
paradoxical sleep in the cat. Acta Neurobiol Exp (Warsz) 1974;
echolamine containing neurons in the upper rhomboencephalon
of the frog Rana catesbiana. J Himforsch 1976; 16: 81-89.
34: 215-232
34 Sastre JP, Sakai K, Jouvet M. Bilateral lesions of the dorsolateral
21 Singewald N, Philippu A. Release of neurotransmiters in the
locus coeruleus. Prog Neurobiol 1998; 56: 237-267.
22 Bjorklund A, Skagerberg G. Descending monoaminergic projec-
pontine tegmentum. Ⅱ. Effect upon muscle atonia. Sleep Res
1978; 7: 44.
35 Maeda T, Pin C, Salvert D, Ligier M, Jouvet M et. Les neurones
tions to the spinal cord. In: Sjolund B, Bjorland A. eds. Brain
Stem Control of Spinal Mechanism. Amsterdam: Elsevier, 1982,
contenant des catecholamines du tegmentum pontique et leurs
voies de projections chez le chat. Brain Res 1973; 57: 119-152.
55-58.
23 Lyons WE, Fritschy JM, Grazanna R. The noradrenergic neuro-
36 Petitjean F, Sakai K, Blondaux Ch, Jouvet M. Hypersomnie par
lesion isthmique chez le chat. Ⅱ. Etude neurophysiologique et
toxin DSP-4 eliminates the coerulospinal projections but spares
projections of the A5 and A7 groups to the ventral horn of the
spinal cord. J Neurosci 1989; 9: 1481-1489.
pharmacologique. Brain Res 1975; 88: 439-453.
37 Hobson JA, McCarley RW, Wyzinski PW. Sleep cycle
oscillation: Reciprocal discharge by two brainstem neuronal
24 Fritschy JM, Grzanna R. Distribution of locus ceruleous axons
within the rat brainstem demonstrated by Phaseolus vulgaris
groups. Science 1975; 189: 55-58.
38 Reiner PB. Correlational analysis of central noradrenergic neu-
leucoagglutinin anterograde racing in combination with dopamine-β-hydroxylase immunofluorescence. J Comp Neurol 1990;
293: 616-631.
ronal activity and sympathatic tone in behaving cats. Brain Res
1986; 378: 86-96.
39 Cespuglio R, Gomez ME, Faradji H, Jouvet M. Alterations in
25 Luppi PH, Aston-Jones G, Akaoka H, Chouvet G, Jouvet M.
Afferent projections to the rat locus coeruleus demonstrated by
the sleep-waking cycle induced by cooling of the locus coeruleus
area. Electroencephalogr Clin Neurophysiol 1982; 54: 570-578.
retrograde and anterograde tracing with cholera-toxin B subunit
and Phaseolus Vulgaris leucoagglutinin. Neuroscience 1995; 65:
40 Porkka-Heiskanen T, Smith SE, Taira T, Urban JH, Levine JE,
Turek FW, Stenberg D. Noradrenergic activity in rat brain during
119-160.
26 Jones B. Immunohistochemical study of choline acetyltransferaseimmunoreactive processes and cells innervating the
rapid eye movement sleep deprivation and rebound sleep. Am J
Physiol 1995; 268: R1456-R1463.
41 Bergmann BM, Everson CA, Kushida CA, Fang VS, Leitch CA,
pontomedullary reticular formation in the rat. J Comp Neurol
1990; 295: 485-514.
Schoeller DA, Rechtshaffen A. Sleep deprivation in the rat: Ⅴ.
Energy use and mediation. Sleep 1989; 12: 31-41.
27 Ennis M, Aston-Jones G. GABA-mediated inhibition of locus
coeruleus from the dorsomedial rostral medulla. J Neurosci 1989;
9: 2973-2981.
42 Sinha AK, Ciaranello RD, Dement WC, Barchas JD. Tyrosine
hydroxylase activity in rat brain following REM sleep
deprivation. J Neurochem 1973; 20: 1289-1290.
28 Aston-Jones G, Shipley MT, Chouvet G, Ennis M, Bockstaele
EV, Pieribone V, Shiekhattar R, Akaoka H, Drolet G, Astier B.
43 Basheer R, Magner M, McCarley RW, Shiromani PJ. REM
sleep deprivation increases the levels of tyrosine hydroxylase
Afferent regulation of locus coeruleus neurons: anatomy, physiology and pharmacology. Prog Brain Res 1991; 88: 47-75.
and norepinephrine transporter mRNA in the locus coeruleus.
Brain Res Mol Brain Res 1998; 57: 235-240.
29 Iijima K, Ohtomo K. Immunohistochemical study using GABA
44 Thakkar M, Mallick BN. Effect of rapid eye movement sleep
Acta Physiologica Sinica, August 25, 2005, 57 (4): 401-413
412
deprivation on rat brain monoamine oxidases. Neuroscience 1993;
55: 677-683.
45 Majumdar S, Mallick BN. Increased levels of tyrosine hydroxy-
alpha-1 adrenergic agonists and antagonists in the dorsal pontine
tegmentum of the cat. Eur J Physiol 1992; 422: 273-279.
61 Tononi G, Pompeiano M, Cirelli C. Effects of local pontine
lase and glutamic acid decarboxylase in locus coeruleus neurons
after rapid eye movement sleep deprivation in rats. Neurosci
injection of noradrenergic agents on desynchronized sleep of the
cat. Prog Brain Res 1991; 88: 545-553.
Lett 2003; 338: 193-196.
46 Shouse MN, Staba RJ, Saquib SF, Farber PR. Monoamines and
62 Tononi G, Pompeiano M, Pompeiano O. Modulation of
desynchronized sleep through microinjection of beta-adrenergic
sleep: microdialysis findings in pons and amygdyla. Brain Res
2000; 860: 181-189.
47 Mallick BN, Siegel JM, Fahringer H. Changes in pontine unit
agonists and antagonists in the dorsolateral pontine tegmentum
of the cat. Pflugers Arch 1989; 415: 142-149.
63 Berridge CW, Foote SL. Enhancement of behavioral and
activity with REM sleep deprivation. Brain Res 1989; 515: 9498.
electroencephalographic indices of waking following stimulation
of noradrenergic beta-receptors within the medial septal region
48 Mallick BN, Kaur S, Saxena RN. Interactions between cholinergic and GABAergic neurotransmitters in and around the locus
coeruleus for the induction and maintenance of rapid eye move-
of the basal forebrain. J Neurosci 1996; 16: 6999-7009.
64 Crochet S, Sakai K. Alpha-2 adrenoceptor mediated paradoxical
(REM) sleep inhibition in the cat. Neuroreport 1999; 10: 2199-
ment sleep in rats. Neuroscience 2001; 104: 467-485.
49 U’Prichard DC, Greenberg DA, Sheehan P, Snyder SH. Regional
2204.
65 Mallick BN, Majumdar S, Faisal M, Yadav V, Madan V, Pal D.
distribution of alpha noradrenergic receptor binding in calf brain.
Brain Res 1977; 138: 151-158.
Role of norepinephrine in the regulation of rapid eye movement
sleep. J Biosci 2002; 27: 539-551.
50 Palacois JM, Kuhar MJ. Beta-adrenergic-receptor localization
by light microscopic autoradiography. Science 1980; 208: 13781380.
66 Mallick BN, Singh S, Pal D. Role of alpha and beta adrenoceptors
in locus coeruleus stimulation-induced reduction in rapid eye
movement sleep in freely moving rats. Behav Brain Res 2005;
51 Hilakivi I. The role of beta and alpha-adrenoceptors in the regulation of the sleep-waking cycle in the cats. Brain Res 1983; 277:
158: 9-21.
67 Thankachan S, Islam F, Mallick BN. Role of wake inducing brain
109-118.
52 Lanfumey L, Dugovic C, Adrien J. Beta 1 and beta 2 adrenergic
stem area on rapid eye movement sleep regulation in freely moving cats. Brain Res Bull 2001; 55: 43-49.
receptors: their role in the regulation of paradoxical sleep in the
rat. Electroencephalogr Clin Neurophysiol 1985; 60: 558-567.
53 Hilakivi I, Leppavuori A, Putkonen PT. Prazosin increases para-
68 Mallick BN, Thankachan S, Kaur S, Pal D. Role of wakefulness
area in the brainstem reticular formation in regulating rapid eye
movement sleep. In: Lader M, Cardinali DP, Pandi-Perumal SR.
doxical sleep. Eur J Pharmacol 1980; 65: 417-420.
54 Pellejero T, Monti JM, Baglietto J, Jouvet M. Effects of meth-
eds. Sleep and Sleep Disorders: A Neuropsychopharmacological
Approach. Landes Bioscience, 2005, 250-256.
oxamine and alpha-adrenoceptor antagonists, prazosin and
yohimbine, on the sleep-waking cycle of the rat. Sleep 1984; 7:
365-372.
69 Huttenlocher PR. Evoked and spontaneous activity in single
units of medial brainstem during natural sleep and waking. J
Neurophysiol 1961; 24: 451-468.
55 Kleinlogel H. Effects of selective alpha1 adrenoceptor blocker
prazosin on EEG sleep and waking stages in the rat.
70 Tanaka DJ. Labeled NA release from rat cerebral cortex following
electrical stimulation of LC. Brain Res 1976; 106: 384-389.
Neuropsychobiology 1989; 21: 100-103.
56 Makela JP, Hilakivi I. Effect of alpha-adrenoceptor blockade on
71 Vanderwolf CH, Baker GB. The role of brain noradrenaline in
cortical activation and behavior: a study of lesions of the locus
sleep and wakefulness in the rat. Pharmacol Biochem Behav
1986; 24: 613-616.
57 Kleinlogel H, Scholtysik G, Sayers V. Effects of clonidine and
coeruleus, medial thalamus and hippocampus-neocortex and of
muscarinic blockade in the rat. Behav Brain Res 1996; 78: 225234.
BS 100-141 on the EEG sleep patterns in rats. Eur J Pharmacol
1975; 33: 159-163.
72 Thakkar M, Portas C, McCarley RW. Chronic low-amplitude
electrical stimulation of the laterodorsal tegmental nucleus of
58 Leppavuori A, Putkonenm PTS. Alpha- adrenoceptive influences on the control of the sleep-waking cycle in the cat. Brain
Res 1980; 193: 95-116.
freely moving cats increases REM sleep. Brain Res 1996; 723:
223-227.
73 Morales FR, Engelhardt FK, Soja PJ, Perede AE, Chase MH.
59 Gallard JM, Kafi S. Involvement of pre- and postsynaptic receptors in catecholaminergic control of paradoxical sleep in man.
Motoneuron properties during motor inhibition produced by
microinjection of carbachol into pontine reticular formation of
Eur J Clin Pharmacol 1979; 15: 83-89.
60 Cirelli C, Tononi G, Pompeiano M, Pompeiano O, Gennari A.
the decerebrate cat. J Neurophysiol 1987; 57: 1118-1129.
74 Lai YY, Siegel JM. Muscle tone suppression and stepping pro-
Modulation of desynchronized sleep through microinjection of
duced by stimulation of midbrain and rostral pontine reticular
Dinesh Pal et al: Neural Mechanism of Rapid Eye Movement Sleep Generation: Cessation of Locus Coeruleus Neurons
formation. J Neurosci 1990; 10: 2727-2734.
75 Bonvallet M, Bloch V. Bulbar control of cortical arousal. Science
1961; 133: 1133-1134.
76 Mancia MG, Grantyn NA, Broggi G, Margnelli M. Synaptic
linkages between mesencephalic and bulbopontine reticular struc-
91
92
coeruleus. Eur J Neurosci 1994; 6: 1038-1049.
Nitz D, Siegel JM. GABA release in the locus coeruleus as a
function of sleep/wake state. Neuroscience 1997; 78: 795-801.
Baghdoyan HA, Rodrigo-Angulo ML, McCarley RW, Hobson
JA. Site-specific enhancement and suppression of
desynchronized sleep signs following cholinergic stimulation
of three brainstem regions. Brain Res 1984; 306: 39-52.
tures as revealed by intracellular recording. Brain Res 1971; 33:
491-494.
77 Kasamatsu T. Maintained and evoked unit activity in the
mesecephalic reticular formation of the freely behaving cat. Exp
Neurol 1970; 28: 450-470.
413
93
Gillin JC, Sitaram N, Janowsky D, Risch C, Huey L, Storch FI.
Cholinergic mechanisms in REM sleep. In: Wauquier A, Gaillard
JM, Monti JM, Radulovacki M. eds. Sleep: Neurotransmitters and Neuromodulators. New York: Raven Press, 1985, 153163.
78 Favale E, Loeb C, Rossi GF, Sacco G. EEG synchronization and
behavioral signs of sleep following low frequency stimulation of
the brain stem reticular formation. Arch Ital Biol 1961; 99: 1-22.
79 Mallick BN, Chhina GS, Sundaram KR, Singh B, Kumar VM.
Activity of preoptic neurons during synchronization and
94
Sakai K, Koyama Y. Are there cholinergic and non-cholinergic
paradoxical sleep-on neurones in the pons. Neuroreport 1996;
2449-2453.
desynchronization. Exp Neurol 1983; 81: 586-597.
80 Kaitin KI. Preoptic area unit activity during sleep and wakeful-
95
Higo S, Ito K, Fuchs D, McCarley RW. Anatomical interconnections of the pedunculopontine tegmental nucleus and the
nucleus prepositus hypoglossi in the cat. Brain Res 1990; 536:
79-85.
ness in the cat. Exp Neurol 1984; 83: 347-357.
81 McGinty DJ, Szymusiak R. Neuroanl unit activity patterns in
behaving animals: brain stem and limbic system. Annu Rev
Psychol 1988; 39: 135-168.
82 Pal D, Mallick BN. GABA in pedunculo pontine tegmentum
regulates spontaneous rapid eye movement sleep by acting on
GABA-A receptors in freely moving rats. Neurosci Lett 2004;
96
97
Kaur S, Saxena RN, Mallick BN. GABAergic neurones in
prepositus hypoglossi regulate REM sleep by its action on
locus coeruleus in freely moving rats. Synapse 2001; 42: 141150.
Cirelli C, Pompeiano M, Tononi G. Neuronal gene expression
in the waking state: a role for the locus coeruleus. Science 1996;
274: 1211-1215.
365: 200-204.
83 Ford B, Holmes CJ, Mainville L, Jones BE. GABA-ergic neurons in the rat pontomesencephalic tegmentum: Codistribution
with cholinergic and other tegmental neurons projecting to the
posterior lateral hypothalamus. J Comp Neurol 1995; 363: 177-
98
Cirelli C. How sleep deprivation affects gene expression in the
brain: a review of recent findings. J Appl Physiol 2002; 92:
394-400.
196.
84 Sakai K. Executive mechanisms of paradoxical sleep. Arch Ital
99
Mallick BN, Fahringer HM, Wu MF, Siegel JM. REM sleep
deprivation reduces auditory evoked inhibition of dorsolateral
Biol 1988; 126: 239-257.
85 Williams JA, Reiner PB. Noradrenaline hyperpolarizes identified rat mesopontine cholinergic neurons in vitro. J Neurosci
pontine neurons. Brain Res 1991; 552: 333-337.
100 Gulyani S, Mallick BN. Effect of rapid eye movement sleep
deprivation on rat brain Na-K ATPase activity. J Sleep Res
1993; 13: 3878-3883.
86 Egan TM, North RA. Action of acetylcholine and nicotine on rat
1993; 2: 45-50.
101 Gulyani S, Mallick BN. Possible mechanism of REM sleep
locus coeruleus neurons in vitro. Neuroscience 1986; 19: 565-571.
87 Alam MN, Kumari S, Mallick BN. Role of GABA in acetylcho-
deprivation induced increase in Na-K ATPase activity. Neuroscience 1995; 64: 255-260.
line induced locus coeruleus mediated increase in REM sleep.
Sleep Res 1993; 22: 541.
88 Mallick BN, Kaur S, Jha SK, Siegel JM. Possible role of GABA
102 Mallick BN, Adya HVA. Norepinephrine induced alphaadrenoceptor mediated increase in rat brain Na-K ATPase activity is dependent on calcium ion. Neurochemistry Int 1999;
in the regulation of REM sleep with special reference to REMOFF neurons. In: Mallick BN, Inoue S. eds. Rapid Eye Move-
34: 499-507.
103 Adya HVA, Mallick BN. Uncompetitive stimulation of rat
ment Sleep. Marcel and Dekker Inc., 1999b, 153-166.
89 Olpe HR, Steinmann MW, Hall RG, Brugger F, Pozza MF.
GABA-A and GABA-B receptors in locus coeruleus: effects of
brain Na-K ATPase activity by rapid eye movement sleep
deprivation. Neurochem Int 2000; 36: 249-253.
104 Mallick BN, Adya HVA, Faisal M. Norepinephrine-stimu-
blockers. Eur J Pharmacol 1988; 149: 183-185.
90 Luque JM, Erat R, Kettler R, Prada MD, Richards JG. Radioau-
lated increase in Na+, K+-ATPase activity in the rat brain is
mediated through alpha1A-adrenoceptor possibly by dephos-
tographic evidence that the GABA receptor antagonist SR 95331
is a substrate inhibitor of MAO-A in the rat and human locus
phorylation of the enzyme. J Neurochem 2000; 74: 1574-1578.