Sample Lab Report:
April 1, 2000
Serious Student
Bio 296c
"The Effects of Cuddling on Body Temperature and Cyclic Nucleotides Levels in
Cerebrospinal Fluid of the cat"
Introduction:
The association of humans and cats has been a long one. As early as 3500 BC, Egyptians were
domesticating wildcats from Africa (Nip & Scratch, 1980). What cats got out of the association seems
obvious: a warm place by the fire and a bowl of milk. In those early days what humans received in return
also seems obvious; they got a pest control service. However by the end of the 20th century most of the
domesticated cats aren't needed for pest control but they still serve a useful role as pets. Indeed, we know
that there is therapeutic value for humans in cuddling (petting, gentile stroking, foundling) a cat (Pen &
Quil, 1985). The question arose, what does the cat get out of cuddling? In order to address this question
we decided to test the hypothesis that cuddling a cat has a direct effect on the physiology of the cat.
Methods:
The studies were performed on six adult cats, three females and three males. Under aseptic conditions a
stainless steel cannula was implanted with stereotaxic techniques in the 3rd ventricle for intraventricular
cerebrospinal fluid (CSF) sampling. The animals were allowed to recover from the surgery for at least one
week before undergoing the experimental procedures. Human `cuddlers' were selected at random from
various classes of people. Each was assigned a `cuddle value' based upon a 5-point assessment of cat
handling and petting ability (see Table I ). Experiments were conducted at the same time each day and
each animal was used at intervals of not less the 72 hours.
Body temperature of the cat was measured with a thermistor probe applied to the skin and held in position
with adhesive tape and was monitored continuously on a Grass multichannel recorder during experiments.
Control temperatures were set as the value which remained constant for at least 30 min after allowing l
hour for equilibration of the probe after attachment. Control CSF samples were taken at this point. All
experiments were carried out at room temperature with all glassware and equipment in contact with the
subjects sterile and pyrogen free. Five minutes after cuddling CSF samples were collected and stored at
-80° until assayed for cyclic nucleotide content by radioimmunoassay (Steiner et al., 1972). This technique
employs a double antibody procedure to separate the bound and free fraction of the cyclic nucleotides.
Chemicals and materials needed for this assay were purchased from New England Nuclear or
Schwarz/Mann.
Results:
The cuddlers exhibited a wide range of cuddling ability (Table 1). This was probably due to a waxing and
waning of interest by the cuddlers and cuddlees. Nine out of the 10 cuddlers has a considerable effect on
the body temperature of the cuddlees. There is a direct relationship between the cuddling efficiency of the
cuddler and the body temperature of the cuddlee (Table 1). Cats cuddled by proficient cuddlers (++ or
higher) had a significant increase in body temperature which with slow decline over time. Cats cuddled by
poor cuddlers (+ or less) displayed a decrease in body temperature as compared to control levels.
In control conditions cAMP and cGMP tended remained relatively constant from cat to cat, averaging
around 5 picomoles/mg of CSF (Figure 1). When the cats were cuddled, these levels changed. In those
cats cuddled by proficient cuddlers, cAMP levels rose while cGMP levels dropped. The reverse was true
in cats cuddled by poor cuddlers, under these conditions, cGMP levels rose and cAMP levels dropped
(Figure 1).
Table 1. Effects of cuddling on the body temperature of the cat. Values of the table (means and standard
errors) are based on the average of six observations
Cuddle' Proficiency
age and of
sex
cuddling'
Control
5 min
10 min
15 min
20 min
A ( 6, M)
B (11, M)
C (I8, F)
D (19, M)
E (21, F)
F (21, M)
G (32, F)
H (41, F)
1 (42, M)
J (50, F)
37.1±0.3
37.3±0.2
36.9±0.4
37.5±0.3
37.3±0.3
37.7±0 4
36.8±0.4
37.6±0.4
37.0±0.3
37.6±0.3
38.2±0.5°
37.1±0.3
39.1±0.4`
34.1±0.6`
36.6±0.5°
34.5±0.4`
39.4±0.6`
41.0±0.5`
35.3±0.6`
38.8±0.T
37.7±0.6a
37.5+0.5
38.4±0.3°
34.0±0.5`
37.0±0.6
34.9±0.4`
38.5±0.4`
40.9±0.6`
35.9±0.6°
37.7±0.5
38.0±0.4'
37.4+0.4
37.8±0.4'
34.3±0.5`
37.1±0.4
34.9±0.3`
38.0±0.4°
39.8±0.4`
34.8±0.7`
37.6±0.4
37.2±0.4
37.3±0.5
38.1±0.3'
34.1±0.5
37.2±0.3
35.0±0.2
37.7±0.3
39.7±0.3
35.9±0.4`
37.5±0.4
+
+
++
-----+++
+++++
++
Cuddlee's body temperature during cuddling
Indicated P value: a < 0.01, ° < 0.005. ` < 0.001 " based on the following five points: (+, 0. -): (1) Willingness to fondle specifically, (2) Willingness
to fondle generally, (3) Willingness to stand for long periods over over preparation, (4) Evenness of petting, (5) No allergic response to cat
(sniffling, sneezing, itching, blotching. etc.)
Discussion:
The positive value of cuddling has been appreciated by clinicians for many years. In fact many nursing
homes now have resident pets just so their patients can enjoy the comfort of petting a dog or cat. As much
as humans enjoy petting an animal, it appears the pet;; enjoy it as well since many will initiate petting
sessions. The present study shows that cats experience some positive physiological changes when cuddled.
It has been reported that petting produces a `warm feeling' (Dascombe & Milton, 1975). We hypothesized
that this might be caused by an increase in body temperature. Indeed the data support this hypothesis
since, in the test cases, when the cats were cuddled by proficient cuddlers there was a positive increase in
body temperature that gradually declined over time (Table 1). However, being cuddled by a poor cuddled
caused a decrease in body temperature suggesting that the cats did not receive any physiological benefit
from the experience.
The effects of cuddling produced some interesting changes in the CSF levels of the cyclic nucleotides
(Figure 1). In most cases, where the cats' body temperature changes occurred, cuddling apparently
produces a rise in cAMP and a decrease in cGMP the correlated with an increase in body temperature.
When the body temperature decreased that change reversed. Thus there appears to be a direct relationship
between cuddling and cyclic nucleotide changes in the cerebrospinal fluid. ). However it is unclear if the
changes observed in body temperature and cyclic nucleotides are independent (independent variables)
from each other or if these variables might be linked (dependent variables).
It has been proposed that, in cellular systems which mediated bi-directional responses, the intracellular
levels of cAMP and cGMP are inversely correlated. Thus, pyramidal tract neurons in the rat cerebral
cortex have been shown to be inhibited by norepinephrine and cAMP and excited by acetylcholine and
cGMP (Stone et al., 1975). Extending this concept to cyclic nucleotides in CSF, it would be reasonable to
assume that cAMP and cGMP might vary inversely and that these changes could reflect alterations in
neurotransmitter release. However changes that occur in the CSF might not reflect localized changes
that could occur in other areas of the brain. Indeed, since there is a certain emotional component to
cuddling, activation of the limbic system (the emotional system of the brain) should be involved. How
cyclic nucleotides levels change in these structures as compared to that of the CSF is unclear (Cramer et
al, 1973).
References:
Cramer H, LK Ng, and TN Chase (1973) Adensione 3',5'-monophosphate in cerebrospinal fluid.
Effects of drugs and neurologic disease. Arch Neurol 29:197-199.
Nip A and S. Scratch (1980) The association of cats and humans in Egypt. Arch 22:230250.
Pen J and J Quil, (1985) Is there therapeutic value in petting cats? Modern Science 1985:1-10.
Steiner AL, CW Parker, and DM Kipnis (1972) Radioimmunoassay for cyclic nucleotides:
preparation of antibodies and iodinated cyclic nucleotides. J Biolo Chem 247:1106-1113.
Stone TW, DA Taylor and FE Bloom (1975) Cyclic AMP and cyclic GMP may mediate opposite
neuronal responses in the rat cerebral cortex. Science 187:845-847.
Note: This sample lab report is roughly based on the following article. "Effects of Cuddling on the Body
temperature and cyclic nucleotides in CSF of the cat" by KK Sakai, TE Ary, DL Hymson and R Shapiro
published in Exp Brain Res. 34: 279382 (1979)
Some of the methods and references in the sample lab report have been changed. However the table and
figure were taken directly from this article. Also note that not all the references are `real'. Some I made up.