Lect E2 - Endocrine pituitary & hypo
What we cover today – Glands
Endocrine System
Summary
Lect # 2
Pituitary & Hypothalamic hormones
Prof Kumlesh K. Dev
D
Department
off Physiology
Ph i l
Chapter 4 Principles of Neural and Hormonal Communication
Human Physiology by Lauralee Sherwood ©2007 Brooks/Cole-Thomson Learning
What we cover today – Hormones
Summary
Posterior Pituitary
1. Oxytocin
2. Vasopressin
(Antidiuretic
hormone, ADH)
Hypothlamus
9. Thyrotropin-Releasing hormone (TRH)
10 Corticotropin-Releasing hormone (CRH)
10.
11. Gonadotropin-releasing hormone (GnRH)
12. Prolactin-releasing hormone (PRH)
13. Prolactin-inhibiting hormone (PIH)
(dopamine)
14. Growth-hormone releasing hormone
(GHRH)
15. Growth-hormone inhibiting hormone (GHIH)
(somatostatin) (SS)
Anterior Pituitary
3. Growth hormone (GH)
4. Thyroid stimulating hormone
(TSH)
5. Adreno-corticotropic
hormone (ACTH)
6. Lutenising hormone (LH)
7. Follicle-stimulating hormone
(FSH)
8. Prolactin
•
Melanocyte stimulating hormone
(MSH)
Neuroendocrine System
Hypo/Pituitary
¾ Many physiological functions are co-regulated
by the nervous system and the endocrine
system
¾ Study of this relationship is the focus of
neuroendocrinology
¾ Neuroendocrinology primarily concerns the
way the brain regulates pituitary hormone
secretion
1
Lect E2 - Endocrine pituitary & hypo
Hypothalamus and Pituitary
Hypothalamus and Pituitary
Hypo/Pituitary
•
•
•
•
•
•
hypothalamus-pituitary: major unit of endocrine system
integrates nervous and endocrine systems
pituitary
i i
f
function
i depends
d
d on hypothalamus
h
h l
pituitary (1 cm) lies at base of brain below hypothalamus
it is connected by nerve fibers and blood vessels
regulates function of
–
–
–
–
–
–
thyroid
adrenal
reproductive glands
somatic growth
lactation
water metabolism
Hypo/Pituitary
¾ hypothalamus lies at base of
brain
¾ pituitary connects to base of
brain by infundibular stalk
¾ anterior pituitary: epithelial
structure develops from
Rathke’s pouch
¾ posterior pituitary: neural
structure develops from floor of
midbrain, consists of nerve fibers
that run from hypothalamus to
anterior pituitary
9 Major Pituitary Hormones: Summary
Posterior Pituitary
Pituitary
Site of Production
Posterior lobe
Anterior Lobe
Intermediate lobe
Hormone
Function
Vasopressin (anti-diruetic hormone ADH)
Promotes water retention
Oxytocin
Stimulates milk ejection
Growth Hormone (GH)
Stimulates growth
Adrenocorticotropic hormone (ACTH)
Stimulates adrenal cortex
Thyroid stimulating hormone (TSH)
Stimulates thyroid gland
Prolactin (Prl)
Stimulates lactation
Luteinizing hormone (LH)
Stimulates gonads
Follicle stimulating hormone (FSH)
Stimulates gonads
Melanocyte stimulating hormone (MSH)
Darkens skin
Pituitary
• along with hypothalamus
forms neuroendocrine system
• an outgrowth
g
of hypothalamus
yp
composed of neural tissue
(non-myelinated axons)
• hypothalamic neurons pass
through neural stalk and end
in posterior pituitary
• stores two peptide hormones
in axonal ends
• release controlled by nervous
system (neurosecretion)
• release Oxytocin and
Vasopressin (Antidiuretic
hormone, ADH or APV)
2
Lect E2 - Endocrine pituitary & hypo
Production of Vasopressin & Oxytocin
Oxytocin (1)
Pituitary
¾ differs from other hormones
¾ nerve cells in region of
hypothalamus (supraoptic and
paraventricular nucleus)
produce vasopressin or
oxytocin in their cell bodies
¾ peptides are packaged into
vesicular granules
Vasopressin
Oxytocin
¾ granules transported down
axons through infundibular
stalk into posterior lobe
¾ peptide is released from
terminal (similar to
neurotransmitter release)
Vasopressin/ADH (2)
Pituitary
• Fetus produces oxytocin,
oxytocin contracts uterus
• During
g Birth,, Estrogen
g rises Uterus produces more
oxytocin receptors
• Synthetic oxytocin is given to
induce labour
• Also has weak antidiuretic
action resulting in water
retention (unwanted effect
may cause pre-eclampsia)
• Oxytocin also helps in smooth
muscle contractions which
cause release of milk
• Oxytocin may regulate brain
function…
Vasopressin/ADH (2)
Pituitary
Pituitary
• controls water content
• controls blood volume
• acts on distal nephron and collecting tubules in kidney
• acts on kidney to increase water
reabsorption in distal tubule
• effects mediated by G protein coupled receptors
– V1 (vasoconstriction), V2 (Kidney), V3 (brain)
• promotes insertion of water channels into luminal
membrane to increase water permeability
• in Diabetes - failure of ADH secretion or reduced sensitivity
off kidney
kid
to ADH ((antidiuretic
idi
i hormone)
h
) may occur
• Analogues for clinical use
– Vasopressin; desmopressin (nasal spray, enuresis);
terlipressin (control of bleeding); felypressin (adjunct to
local anaesthetic)
• increased blood volume
– sensed by stretch receptors in heart
atrium
– signal to hypothalamus
Hypothalamus
+ ve
- ve
Vasopressin
Osmo
Receptor
Stretch
Receptor
– decreased vasopressin production
- ve
• decreased blood osmolarity
– reduced activity of hypothalamic
osmoreceptors
+ ve
increased
blood vol
– reduces vasospressin secretion
3
Lect E2 - Endocrine pituitary & hypo
9 Major Pituitary Hormones: Summary
Anterior Pituitary
Pituitary
Site of Production
Posterior lobe
Anterior Lobe
Intermediate lobe
Hormone
Function
Vasopressin (anti-diruetic hormone ADH)
Promotes water retention
Oxytocin
Stimulates milk ejection
Growth Hormone (GH)
Stimulates growth
Adrenocorticotropic hormone (ACTH)
Stimulates adrenal cortex
Thyroid stimulating hormone (TSH)
Stimulates thyroid gland
Prolactin (Prl)
Stimulates lactation
Luteinizing hormone (LH)
Stimulates gonads
Follicle stimulating hormone (FSH)
Stimulates gonads
Melanocyte stimulating hormone (MSH)
Darkens skin
Anterior Pituitary Cell Types
Pituitary
• epithelia-derived upgrowth
from roof of oral cavity
(Rathke’s
(Rathke
s pouch)
• secretes tropic and direct
hormones that regulate
release of glucocorticoids,
thyroid hormones, sex
hormones.
• regulate ovulation &
spermatogenesis & mammary
gland function
• anterior pituitary hormones are
regulated by hypothalamic
releasing factors and feedback
influences
Six Anterior Pituitary Hormones (3-8)
Pituitary
Pituitary
Hypothalamus
¾ cells producing these hormones are specialized
¾ generally each cell type produces mainly one hormone
¾ cells named according to hormone they produce
¾ somatotrophs make growth hormone (somatotrophin)
¾ lactotrophs (mammotrophs) make prolactin
Anterior Pituitary
Growth
Hormone (GH)
Thyroid
stimulating
hormone (TSH)
Adreno-Adreno
corticotropic
(ACTH)
many target
organs
Thyroid gland
Adrenal cortex
growth, anabolic
actions
Thyroid Hormone
(T3.T4)
cortisol
¾ thyrotrophs
h
h make
k TSH
¾ corticotrophs make ACTH (corticotrophin)
Prolactin
(non-tropic)
(non-
Luteinising
hormone (LH)
Follicle-Follicle
stimulating
hormone (FSH)
Ovaries/Testes
progesterone &
estrogen
(ovulation &
luteinisation)
estrogen
(development of
ovarian follicles)
testosterone
sperm production
suckling (+ve)
mammary glands
dopamine (-ve)
breast growth,
milk secretion
4
Lect E2 - Endocrine pituitary & hypo
Questions !
what hormone #1 from the
hypothalamus controls the release of
hormone #2 from the anterior pituitary?
which pituitary hormone #2 acts on the
adrenal cortex?
what hormone #3 does the adrenal
cortex release in response to the
pituitary hormone #2?
Answers !
Hypothalamus
Hormone #1
Anterior
Pituitary
Hormone #2
Adrenal
cortex
Hormone #3
what is the function of hormone #3
released from the adrenal cortex?
what hormone #1 from the
hypothalamus controls the release of
hormone #2 from the anterior pituitary?
which pituitary hormone #2 acts on the
adrenal cortex?
what hormone #3 does the adrenal
cortex release in response to the
pituitary hormone #2?
what is the function of hormone #3
released from the adrenal cortex?
Hormone #1??
Anterior
Pituitary
ACTH
Adrenal
cortex
cortisol
function??
function
Take home message
Hypothalamus
Hypothalamic regulation of Pituitary
Hypothalamus
don’t pretend to know it…..
….. make sure you really do
know all these feedback loops
• two factors regulate anterior
pituitary hormone secretion
– hypothalamic
yp
hormones
– feedback target-gland hormones
• neurohormones produced by
neurons in hypothalamus
• these neuronal axons secrete
hormones on to capillary bed in
pars tuberalis
• these capillaries join portal veins
which carry hormones into pars
distalis via vascular link where
functions of endocrine cell
hormone production are regulated
5
Lect E2 - Endocrine pituitary & hypo
Characteristics of hypothalamic
releasing hormones
Seven Hypothalamic Hormones (9-15)
Hypothalamus
Hypothalamus
synthesis
• secretion in pulses
• act on specific
ifi membrane
b
receptors (G-protein coupled)
• regulate
– Hyperplasia (cell number):
oxytocin
• Stimulates cell division
• Inhibits apoptosis
ADH
storage & secretion
– Hypertrophy (cell size):
Breast
uterus
• Stimulates protein synthesis
• Inhibits protein breakdown
Kidney
blood
vessels
Hypothalamic
CRH
TRH
PRH
PIH
GnRH
dopamine
(LH releasing
hormome LHRH)
CorticotropinReleasing
hormone
ThyrotropinReleasing
hormone
Prolactinreleasing
hormone
Prolactininhibiting
hormone
Gonadotropinreleasing
hormone
GHRH
GHIH
somatostatin
Growthhormone
inhibiting
hormone
Growthhormone
releasing
hormone
ACTH
TSH
Prolactin
FSH
LH
GH
Adreno-Adreno
corticotropic
hormone
Thyroid
stimulating
hormone
(non--tropic)
(non
Follicle-Follicle
stimulating
hormone
Luteinising
hormone
Growth
Hormone
Adrenal
cortex
Thyroid
gland
mammary
glands
cortisol
Thyroid
Hormone
(T3.T4)
breast
growth, milk
secretion
many
target
organs
Ovaries
/Testes
progesterone
& estrogen
ovulation &
luteinisation
estrogen
(develop
ovarian
follicles)
testosterone
sperm
production
Anterior Pituitary
growth,
anabolic
actions
Posterior Pituitary
Effects of Hypothalamic damage/removal
Hypophysectomy
Hypothalamus-Pituitary Control
Hypothalamus
Anterior Pituitary
Posterior Pituitary
¾ growth
g
stops
p
¾ thyroid hormone deficiency
(Myxoedema)
¾ adrenal cortex atrophy
(decreased production of
cortisol and aldosterone)
¾ loss of sexual characteristics
(beard, pubic hair)
¾ atrophy of gonads
¾ increased insulin sensitivity
¾
¾
¾
¾
¾
dehydration
y
by
y polyuria
p y
Diabetes Insipidus
deficiency of ADH
little effect of oxytocin loss
if damage not extensive then
symptoms can disappear
Summary
Hypothalamus
TRH, CRH, LRH
GnRH, SS,
D
Dopamine
i
Dopamine
Oxytocin
Vasopressin
p
Anterior
Intermediate
Posterior
TSH, ACTH, GH
FSH LH,
FSH,
LH Prl
Pl
MSH
Portal
Vessels
Pituitary
Systemic
Circulation
6
Lect E2 - Endocrine pituitary & hypo
Hypothalamus-Pituitary Overview
What we cover today – Hormones
Summary
Summary
Posterior Pituitary
1. Oxytocin
2. Vasopressin
(Antidiuretic
hormone, ADH)
Hypothlamus
9. Thyrotropin-Releasing hormone (TRH)
10 Corticotropin-Releasing hormone (CRH)
10.
11. Gonadotropin-releasing hormone (GnRH)
12. Prolactin-releasing hormone (PRH)
13. Prolactin-inhibiting hormone (PIH)
(dopamine)
14. Growth-hormone releasing hormone
(GHRH)
15. Growth-hormone inhibiting hormone (GHIH)
(somatostatin) (SS)
Anterior Pituitary
3. Growth hormone (GH)
4. Thyroid stimulating hormone
(TSH)
5. Adreno-corticotropic
hormone (ACTH)
6. Lutenising hormone (LH)
7. Follicle-stimulating hormone
(FSH)
8. Prolactin
•
Melanocyte stimulating hormone
(MSH)
7