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5-1994
The General Adaptation Syndrome in GerbillusBridget L. Moore
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Recommended CitationMoore, Bridget L., "The General Adaptation Syndrome in Gerbillus" (1994). McCabe Thesis Collection. Paper 10.
The Edwin P. McCabe Honors Program
Senior Thesis
"The General Adaptation Syndrome in Gerbillus"
Bridget L. Moore
May 1994
Langston University Langston, Oklahoma
M. B. Tolson Black Heritage Center Langston University Langston, Oklahoma
THE GENERAL ADAPTATION SYNDROME
IN GERBILLUS
By
Bridget Moore
Biology Major
Department of Natural Sciences
School of Arts and Sciences ... Langston Un~versity
Langston, Oklahoma
Submitted in partial fulfillment of the requirements of the E.P.McCabe Honors Program
May 1995
'rBE GENERAL ADAPTATION SYNDROME
IN GERBILLUS
Thesis Approved:
'Ihesis eo!illittee ~ ~ . :
·~~~~ Thesis Ccmnittee .Memh=>..r
/(tt(/L
]!>fr~ of the Honors Program
ii
ACKNOWLEDGMENTS
The author wishes to express deep appreciation and profound
gratitude to Dr. Reuben Manning, Thesis Committee Chairman,
and to Committee members Dr. Sarah Thomas and Dr. Zola Drain.
Their advice, counsel, personal time, and consent to use
facilities and resources in the Biology Department made this
project a success.
Special thanks are also extended to the Laboratory Staff
and the Logan County Hospital for assistance in analyzing blood
samples including the use of facilities and instruments.
Dr. Joy Flasch, Director of the Honors Program at Langston
University is mostly responsible_ for all achievements made by
the author. Her guidance, motivation_ and encouragement have
been the wind beneath my wings. For this and other support,
I am eternally grateful.
iii
TABLE OF CONTENTS
CHAPTER PAGE
I. INTRODUCTION •••••••.•••.•.•.••••.••••••.••.•...•.•.. 1
The General Adaptation Syndrome Purpose .and Objectives
II. REVIEW OF . RELATED LITERATURE ••••••••••••••••••••.•••• 3 ·
Biological Attributes of Gerbils Physiological Stress
III. MATERIALS AND METHODS •..••...•.••.••......••.....•.. 7
Experimental Animals Induced Stress Blood, Extraction, and Analysis
IV. RESULTS AND DISCUSSION ••••••••••••••••.•••••.••••.•. 8
V. SUMMARY AND CONCLUSION •..••.•••••.••••••••••••.•••• 16
BIBLIOGRAPHY •...•.•..••••...•. • • ; ••••.••.•••••..••.••.•••. 1 8 ..
iv
LIST OF TABLES
TABLE PAGE
TABLE I ••••••.•.•.•••.•....•...•...•.•....•......•.••.•.• 1 2 Blood Data from Controls and Experimental Animals
TABLE I I •••••••••••••••••••••••••••••••.••••••••••••••••• 1 3 Lymphocyte and Eosinophil Count in Animals Deprived of Food
TABLE III ••••.••.••.•..•••••..•••..•..•...••••.•..••••••• 14 Lymphocyte and Eosinophil Count in Animals Deprived of Water
TABLE IV ••••••••••••••..••.•..••...•...••..•••.•••••••••• 1 5 Lymphocyte and Eosinophil Count in Animals Exposed to Heat
TABLE V •••••••••••••••••••••••••••••••••••••••••••••••••• 1 5 Lymphocyte and Eosinophil Count in Animals Exposed to Low Temperatures
v
CHAPTER I
INTRODUCTION
The General Adaptation Syndrome or the G.A.S. is the term
applied to collective responses to physiological stres·s. It
is initiated by any disturbance in the normal balance of the
body functions. These responses affect humans, monkeys, and
other animals. The three main physiological changes which occur
as a result of stress are enlarged adrenals, shrunken lymphatic
organs, and bleeding gastrointestinal ulcers. There are also
concomitant changes in the hematocrit and the formed elements
of blood. In particular, there is usually a decrease in
lymphocytes and eosinophils accompanied by the increase in
neutrophils and platelets. ~
Stress is defined as pressure, or the sum of the biological
reaction, to any adverse stimulus. According to Miller, "These
stimuli can be physical, mental, or emotional, internal or
external, that tend to disturb the homeostasis of an organism"
(5). The human body and mind are normally able to adapt to
the stressors of new situations. This ability has definite
limits "beyond which continued stress may cause a breakdown,
although this limit varies from person to person" (5). Stressors
are any factors that disturb homeostasis, producing stress.
It was reported by Seyle in 1936 that a variety of noxious
stimuli elicit a generalized syndrome consisting of the
1
2
hypotrophy and hyperfunction of the adrenal cortex, the
involution of the thymus and the lymph nodes, and ulcerations
in the stomach and intestines; this syndrome is a nonspecific
response of the body to intense demand and has been named the
General Adaptation Syndrome (G.A.S.) or the Biological Stress
Syndrome (6). It is the hypotrophy of the adrenal cortex, and
thymus that causes the decrease in the number of lymphocytes
and eosinophils (1). There have been many attempts to understand
the complex intricacies of stress.
The present study was undertaken in order to generate
indicators of stress reactio~s in the .genus *Gerbillus, and
to determine blood changes in response to induced stress. The
results should elucidate the pattern of physiological adaptations
in these animals and help to explain principles and processes
of blood biochemistry. The data showed also provide further
insight and information regarding the biology of gerbils and
their close relatives.
* The term Meriones is also frequently given as the Genus for gerbils.
CHAPTER II
BACKGROUND AND SIGNIFICANCE OF THE STUDY
(REVIEW OF RELATED LITERATURE)
The gerbil is a member of the order Rodentia and family
Muridae. Many characteristics of gerbils distinguish rodents
from other mammals. Rodents are distinguished by having teeth
that allow them to gnaw (3). Gerbils dwell in hot, arid, almost
desertlike areas (3). These areas are characterized by hot,
dry days and often cold nights. Water and food are scarce;
therefore, gerbils have developed a plethora of adaptations
that allow them to cope with limitations (3).
The Mongolian gerbil Meriones unguiculatus is a clean rodent
that is normally free from di.sease. This gerbil originated
in the desert regions of Mongolia and' northeastern China (4).
Gerbils are active burrowing animals who have intermittent
periods of activity and rest during the day and night. Their
elaborate burrows contain multiple entrances, nesting rooms,
and food chambers for storing seeds during the winter (4).
The agouti or mixed brown Mongolian gerbil is the variety
commonly sold as pets or research animals (4). Black and white
gerbils are also common as well as mutations such as dove, ,
piebald, cinnamon color, and hairless (4). Gerbil studies have
helped in the development of live polio vaccines and birth
control pills (8). One of the earliest contributions gerbils
3
4
made as laboratory animals occurred in the study of a disease
called bilharziasis or schistosomiasis that affects about 200
million people (8). About 110,000 gerbils are used annually
· in the United States for studies of cerebral ischemia and stroke,
epilepsy, dental disease, endocrinology, and lipid metabolism
(4). Gerbils have been used in studying parasitic diseases
such as leptospirosis and tapeworm and in studying bacterial
diseases such as tuberculosis, anthrax, and leprosy (8).
Researchers, utilizing gerbils, are also gaining insight into
the role of cholesterol and fats in heart disease (8). Gerbils
develop unusually high levels-of cholesterol in their blood,
even on a normal diet; the difference is that people develop
thick deposits of fatty substances in their arteries, but gerbils
do not (8).
Gerbil blood has several characteristics not seen in the
blood of other rodents. Male gerbils have higher packed red-cell
volumes, hemoglobin levels, total leukocyte counts, and
circulating lymphocyte counts than do females (4).
The response to physiological stress includes increased
secretions of the glucocorticoids and adrenalin, accelerated
heart rate, increased liver glycogenolysis, catecholamines,
epinephrine in blood, blood glucose, and increase in systolic
blood pressure (1). Disturbances also decrease the number of
lymphocytes and eosinophils, affect immunity and digestion,
5
and cause a constriction of vessels in blood reservoirs such
as the skin, kidneys, and most viscera (1). According to
Catherine Anthony, author of Anatomy and Physiology, in the
alarm reaction stage all of the above responses are produced,
and in the stage of resistance, the changes that take place
in the alarm stage as a result of increased corticoid secretion
disappear (1). It is normal for people to go through stages
one and two of the G.A.S., but the stage of exhaustion develops
only when stress is severe. At this stage there is a loss of
resistance to the stressor and may result in death.
Stress can be caused by many factors, which can be taken
to a variety of extremes ranging from· extreme heat to cold
stress. Incidentally, in cold stress there is "an increased
secretion of norepinephrine'' (9). Stress can also "enhance
the acquisition of discrete conditioned responses," as has been
proved by exposing rats to tail shock and observing their
reactions. This test shows that unexpectedly stressed rats
exhibit significantly more conditioned eyeblink responses and
the magnitude. of their individual responses is also enhanced
(7). Stress produces various effects in different animals and
also in humans.
The changes that make up the General Adaptation Syndrome
occur over a period of time in three stages: alarm reaction,
resistance or adaptation, and exhaustion. The research described
6
in this thesis reveals physiological responses of gerbils to
induced stress. The stress factors included food and water
deprivation and exposure to low and high temperatures.
CHAPTER III
MATERIALS AND METHODS
Male and female gerbils of approximately the same age were
used in the experiments. They were exposed to hot and cold
temperatures and deprived of food and water for varying periods
of time. Some were subjected to cage crowdedness.
The gerbils were anesthetized by being placed under a
bell-shaped jar with a wad of cotton saturated with ether.
The animal was immediately removed and blood extracted from
the heart utilizing a 23-gauge one-inch needle and a Sec syringe.
The blood was then immediately injected into a vacuum-packed
test tube with an anticoagulant. The samples were transported
to the medical laboratory of the Logan County Hospital where
they were placed on a shaker for mixing. A small quantity of
each blood sample was then placed into a Sysmex K-1000 blood
analyzing machine. A complete blood count (CBC) was made.
Stained blood smears were made, and utilizing a light microscope,
differential leukocyte counts were carried out. Blood samples
were taken from animals not subjected to stress and analyzed.
These were the controls. Most of the gerbils died immediately
or shortly after the blood was extracted. A total of eleven
animals were successfully subjected to stress followed by blood
extraction and analysis.
7
CHAPTER IV
RESULTS AND DISCUSSION
Prolonged exposure to adverse environmental conditions brings
about physiological stress. This stress is manifested in many
ways. Three major changes are the enlargement of the adrenal
glands, hypotrophy of lymphatic organs· and gastrointestinal
bleeding. There are also changes in the level of hemoglobin
and corticosteroids, the hematocrit, and the number of blood
cells. All of these changes are collectively referred to as
the General Adaptation Syndrome (1).
The data in Table I gives the normality for hemoglobin,
the hematocrit, platelets and l~ukocyte count in gerbils. The
experimental animals are indicated by capital letters. They
include those subjected to food and water deprivation and to
high and low temperatures.
As can be seen in Table I, the hematocrit and hemoglobin
level were not appreciably affected by the induced stress.
Although more than half of the experimental animals showed below
normal ranges for hemoglobin, the lowest level is 8.5 exhibited
by animal B which was exposed to a temperature of 41°C for forty
minutes. It . is also noted that the lowest hematocrit is shown
by animal B. Longer periods of exposure and higher temperatures
would most likely produce different results.
The leukocyte and platelet counts for normality and in the
experimental animals are also given in Table I. Most of
8
9
the experimental animals showed abnormally high platelet counts.
Animals D and E were in the normal range of platelets. They
were deprived of food for forty-eight hours. Most animals showed
a rather significant increase in the total leukocyte count
compared to normality. This is expected since stress and injury
bring about increased leukocytes for defensive purposes. The
lowest leukocyte count was found in animals H (3.1) and I (2.6).
Animal I was exposed to heat stress. The specific lymphocyte
counts in the experimental animals were below normal.
The number of lymphocytes and eosinophils decreased in all
experimental animals. The average lymphocyte count in gerbils
was 60-95% and the eosinophils range from 0-4% of total
leukocytes. Animals deprived of food showed 61% lymphocytes
and about 1% eosinophils (Table II). Animals deprived of water
and exposed to heat also showed decreased lymphocytes and
eosinophils (Table III and IV).
As can be seen in Table V, animals J and K showed a low
eosinophil count and numerous lymphocytes after being exposed
to a low temperature of 32°C for forty minutes.
There have been many stress tests performed on animals.
One such test performed by researcher John Mason and his
colleagues used both humans and Rhesus monkeys. They obtained
measures of many different endocrines and assessed the profile
of response to a variety of physical stressors (6). Physical
10
stressors such as heat, cold, exercise, and fasting were
compared, and a particular effort was made to control any
psychological threats that might have been confounded with these
physical stressors. Any sudden change of temperature was avoided
in the heat and cold situation: in fasting, the psychological
distress a monkey experiences upon seeing a trainer pass him
up while feeding other animals was prevented by using placebos
for the experimental monkeys (6). Mason, using the Rhesus
monkey, also measured both plasma and urinary levels of one
of the metabolites of glucocorticoid hormones. The test sessions
ran for three day cycles. During the three days, there was
an increase in the urinary levels of the hormone and a gradual
decline during the recovery time (2). The plasma levels of
the hormone also increased and rapidly decreased during recovery
( 2) - In animals, exposure to novel environments, electric shock,
frustration, and learned signals of danger can result in
increased plasma levels of corticosteroids; in man, undergoing
surgery, entering the hospital, having a medical exam, or driving
a car can cause the same responses (2).
The findings of stress indicators in gerbils reported here
are consistent with indicators observed in other animals
subjected to adverse environmental conditions (2) and (6).
Harkness and Wagner (4) demonstrated that injury and the
deprivation of food and water in particular bring about both
1 1
internal anatomical and physiological changes in rabbits and
rodents. While blood changes due to stress are more readily
observed, the determination of organ modifications requires
autopsies and histological sectioning.
I
I
SUBJECT HEMOGLOBIN
* NORMAL 14-18 g/dl
A 12.5
B 8.5
c 11.7
D 11.2
E 14.0
F 14.6
G 12.1
H 15.9
I 15.9
J 11.0
K 10.0
TABLE I: BLOOD DATA FROM CONTROL AND EXPERIMENTAL ANIMALS (A-K)
HEMA.TOCRIT COUNT PLATELET
40-54% 150-375
39.9% 1027
27.7% 782
35.4% 758
33.7% 178
38.4% 326 -
45;8% 827 .. 34.4% 786
49.2% 389
48.9% 355
35.0% 1047
33.2% 494
WHITE BLOOD CELL-
4-11
15.8
11.7
- -10.7
4.1
14.2
14.8
10.7
3.1
2.6
33.3
11.2
" The normal range is based on the calibration of the equipment at Logan Hospital and Medical Center.
12
Lymphocyte
&:
Eosinophil
(%}
TABLE II: THE LYMPHOCYTE AND EOSINOPHIL COUNT IN ANIMALS D AND E DEPRIVED OF FOOD FOR 48 HOURS
Key ... lymphocyte
eosinophil
80
60
40
20
SUBJECTS
1 3
TABLE III: THE LYMPHOCYTE AND EOSINOPHIL COUNT IN ANIMALS F AND G DEPRIVED OF WATER FOR 48 HOURS
Key ... lymphocyte
eosinophi1
.. Lymp~ocyte 601--~~~~~~~~~~~~~~~~~~~~~~
&:
(%)
20 1--------
Q._ _____ _
SUBJECTS
14
TABLE IV: LYMPHOCYTE AND EOSINOPHIL COUNT OF ANIMALS EXPOSED TO BEAT (40°C) FOR 40 MINUTES
Key - lymphocyte
eosinophil
LYDJphocyte 60
&
Eesinophil 40
(%)
20
o.__ __ _ A H
TABLE V: LYMPHOCYTE AND EOSINOPHIL COUNT IN ANIMALS J AND K EXPOSED TO LOW TEMPERATURES
Key •I lymphocyte
eosinophil
&
Eosinophil 4Q.,__ _____ _
(%)
20 1--------
OL-------K
15
CHAPTER V
SUMMARY, CONCLUSION, AND RECOMMENDATIONS
Studies on physiological stress were carried out on Gerbillus
of family Cricetidae. The gerbils were first subjected to low
and high temperatures and deprivation of food and water for
varying periods of time. They were then anesthetized and blood
samples were extracted. Analysis of the blood was carried out
determining total leukocyte count, eosinophils, lymphocytes,
platelets, and hematocrits.
For the most part, there was no significant difference in
the blood data from experimental animals compared to that of
the controls. This result most likely reflects the nature of
the natural habitat of gerbi!s, which includes hot days and
cold nights - conditions to which they are well adapted. In
some cases, the lymphocyte count did decrease and the platelets
increased. The hemoglobin was lower in most cases as well as
the hematocrits.
Although these findings are not particularly striking,
they do indicate that gerbils exhibit the general adaptation
syndrome as other mammals do when exposed to adverse
environmental conditions. Changes in the hemoglobin,
lymphocytes, platelets, and hematocrits were brought about by
the food and water deprivation and to some extent by exposure
to low and high temperatures. It is further concluded that
heat and cold conditions produce less physiological stress in
16
17
gerbils as indicated by little change in the total leukocyte
counts. Apparently, gerbils are well adapted to tolerate these
conditions.
This study of the General Adaptation Syndrome in gerbils
has produced the following recommendations:
1. Similar experiments with gerbils should include larger
samples.
2. Exposure and deprivation time should be increased or
made more variable.
3. Exposure to low oxygen s~ould be inc~uded.
4. The effects of increased population density
on the blood system should be included in further
studies.
5. The comparative response and tolerance levels of male
and female gerbils should be determined in further
studies.
6. Instruments for the analysis of blood should be
immediately available for the researcher.
BIBLIOGRAPHY
1. Anthony, Catherine and Gary Thibodeau. Textbook of Anatomy
and Physiology. St. Louis: C.V. Mosby Company, 1983.
2. Archer, John. Animals Under Stress. Baltimore: University
Park Press, 1979.
3. Bradley, Patrick and Heather Pence. A Step by Step Book About
Gerbils. Ontario: T.F.H. Publications, 1988.
4. Harkness, John and Joseph Wagner. The Biology and Medicine
of Rabbits and Rodents, Third edition. Philadelphia:
Lea and Febiger, 1989.
5. Miller, Benjamin and Claire Keane. Encyclopedia and Dictionary
of Medicine, Nursing, and Allied Health. W.B.Saunders
Company: Philadelphi~; 1987.
6. Seyle, Hans, ed. Seyle's Guide to Stress Research. New York:
Van Nostrand Reinhold Company, 1980.
7. Shors, Tracey, Craig Weiss, and Richard Thompson.
"Stress-Induced Facilitation of Classical Conditioning."
Science 24 July 1992:537(3).
8. Silverstein, Alvin and Virginia Silverstein. Gerbils: All
About Them. J.B. Lippincott Company: New York, 1976.
9. Str~nd, Fleur. Physiology: A Regulatory Systems Approach.
London: Collier MacMillian Publishers, 1983.
18
VITA
Bridget LaShunn Moore
Candidate for the Degree of
Bachelor of Science
and
Completion of
E.P.McCabe Honors Program
Thesis: THE GENERAL ADAPTATION SYNDROME IN GERBILLUS
Major: Biology
Biographical Information:
Personal Data: Born in Dallas, Texas, June 6, 1973; Daughter of Rick and Linda Manning. She will complete the requlrements for a Bachelor of Science Degree at Langston University in May 1995, having also completed all requirements in the E.P.McCabe Honors Program.
Honors and Activities: Edwin P. McCabe Honors Program; E.P.McCabe Scholarship; Dean's List; President's Honor Cabinet; Beta Kappa Chi National Honorary Scientific Society; Student Senate; Chairman of the Dormitory House Council; Biology Department's Highest Ranking and Most Outstanding Student, Fall 1994; Secretary, Alpha Chi National Honor Scholarship Society; Who's Who Among American Colleges and University's, Alpha Kappa Alpha Sorority, Inc.