J Anat. Soc. India 49(2) 165-167 (2000)
Stress And Serum Cholesterol Levels-An Experimental Study
Jain, S.K. *Pandey, S.N. *Srivastava, R.K. Ghosh, S.K. Department of Anatomy, D.R.P.G. Medical College, Kangra at Tanda. * Department of Anatomy, G.S.V. Medical College, Kanpur.
Abstract : With the Urbanization & Westernisation of our society, stress is increasing day by day. The result of which is an increased incidence of psychosomatic & psychiatric disorders. In the present study by applying immobilization (restraint) stress we compared the serum cholesterol levels between control & experimental group animals by calorimetry & concluded that :
1. Serum cholesterol levels of males were higher as compared to that of females in both the groups i.e. control & experimental group animals.
2. Serum cholesterol levels of stress group animals were higher as compared to that of control group animals of either sex and moreover these higher values were statistically significant. (P < 0.001).
So this study shows that serum cholesterol levels can be used as a possible indicator of stress.
Keywords : Immobilization, Stress, Serum Cholesterol, Calorimetry.
Introduction :
Stress induced psychiatric problems, psychosomatic disorders, hypertension and heart diseases are on the rise across the globe. Stress has become an important etiological factor in the development of gastric ulcers (Das, Bhattacharjee and Banerjee, 1997).
Stress is defined as a �gNon specific result of any demand upon the body�h (Selye, 1980). Any adverse condition during different experimental procedures causes stress (Piere and Michal, 1998). Brodie, Harley and Henson, (1960) found rats highly susceptible to restraint stress (86%) and noted ulceration of gastric mucosa. They concluded that stress was the causative factor. Bharihoke, Gupta and Gohil (2000) subjected their experimental animals to stress of immobilization and cold, in a plexiglass container for 2 hrs for five days. Sanchez, Castro, Alonso and Gaudioso (1996) studied fifteen blood parameters in control and experimental group of bovines under various types of stress including restraint stress and noted a rise in thirteen out of fifteen blood parameters. Cortisol level was significantly higher. Francis (1979) tried to establish the serum cholesterol level as an index of stress.
Aim of this study is to establish serum cholesterol levels as a definite diagnostic tool in the management of stress induced disorders.
Material and Methods :
The study was conducted on forty albino rats of both sexes (20 males & 20 females), weighing between 130-150gms. The animals were kept in separate cages under usual laboratory conditions, with food & water ad-libitum. These were divided into two groups of 20 each (10 males & 10 females) as control A group & experimental (stress) B group. Group B animals were subjected to immobilization (restraint) stress for 4 hrs a day for a period of 3 months. Immobilization was done by restraining the rats in small transparent plastic devices. Blood samples were collected from the rats after ether anaesthesia by intracardiac aspiration and were subjected to estimation of serum cholesterol levels by calorimetric method.
The following reagents were used :?
Absolute alcohol
Stock ferric chloride Sol-20gm ferric chloride in 100ml of orthophosphoric acid (85% A.R.)
Color reagent : 8ml stock sol. of ferric chloride mixed with 92ml of sulphuric acid (Sp Gr. 1.84) Standard cholesterol sol. 200mg%.
Calculation of serum cholesterol level was done by the following formula.
Total cholesterol level in mg% = where T,S,B are optical densities of Test, Standard and Blank respectively.
After the blood samples were taken, animals were sacrificed with overdose of ether. Laparotomy of animals were done by midline incision to take out the stomach. Stomachs were opened along the lesser survature and studied for macroscopic breach in gastric mucosa by Fluorescein staining (Strip method).
Results :
Gross Appearance : Fluorescein staining of gastric mucosa of experimental group of animals showed multiple ulcerated areas as compared to normal mucosa of control group animals. The ulcers were scattered over the whole surface of gastric mucosa, predominantly over the fundic region and sparing the cardiac region. Size of the ulcers varied from pin head to 3 mm in diameter. Some bleeding spots were also seen in the region of ulcers.
Biochemical Observations :?
Table 1 shows the levels of serum cholesterol of individual rats of both control and stressed group in mg%. Serum cholesterol level of male rats of the control group ranged between 100-120 mg% with mean value of 110.6, while that of females between 90-106mg% with mean value of 98. the difference in serum level between males & females was not statistically significant.
Serum cholesterol levels of stressed group of animals of both sexes showed much higher values as compared to that of control group. Males had a serum cholesterol level of 130-180 mg% with a mean value of 157 mg%, while that of females varied between 100-170 mg% with a mean value of 142.2 mg%.
Table-1
Levels of Serum Cholesterol in Control & Stressed group of animals in mg%
| S.No. | Control Rats | Stressed Rats |
| | Male | Female | Male | Female |
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
Mean
Value
S.D. | 114
110
100
120
116
100
114
120
100
112
110.6
7.96 | 96
100
98
100
90
98
96
106
94
102
98
4.42 | 176
144
156
140
180
156
140
170
178
130
157
18.19 | 156
140
136
120
160
160
120
160
170
100
142.2
22.91 |
Though the males of stressed groups had higher range of serum cholesterol as compared to that of females, the difference is not statistically significant. While comparing the values between control group and experimental group the differences were found to be statistically significant in both sexes. (P < .001).
Discussion :
Use of temporary immobilisation (restraint stress) in small plastic devices as stress inducer in rats has been commonly employed by other workers (Coscum, Alican, Yegen 1995; Brodie et al, 1960; Brennan et al 1996; and Bharihoke et al 2000) as also employed in the present study. This stress was sufficient enough, as evidenced by production of gastric ulcers. (Brodie et al, 1960).
Current experimental design of using two different sets of animals for estimation of serum cholesterol and other blood parameters has also been followed by earlier workers, like Sanchez et al (1996), in their study on cattle & Brennan et al (1996) on rats.
The steep rise of serum cholesterol, subsequent to stress in both male and female rats in the present experimental work compares well with the observations of Brennan et al (1996) in stressed rats, and Mattiason et al (1990) in stressed human beings.
It was also observed that the male rats in general had higher srum cholesterol level than that of the females of both experimental and control group respectively. These findings were not corroborated in rats by other workers. However these were comparable to studies in human beings. Varley et al (1992) reported higher values of serum cholesterol in men as compared to that of women. Vyas et al, (1992), noted a rise of 20% of serum cholesterol level in pregnant women as compared to that of non pregnant women. Our values of serum cholesterol level showed a rise of 42-45% in stressed group of animals. These higher levels of serum cholesterol in our study is possibly due to the fact that the immobilization caused more agony in these animals than that caused by pregnancy in human being. since pregnancy was an acceptable phenomenon, hence degree of stress was less. Various theories have been propounded to explain this rise of serum cholesterol. Patterson et al (1993) are of the view that it is due to hypovolemia, while Koob (1985) associated stress response with release of corticosteroids. Other workers associated the rise with hyperinsulinemia and increased cholesterol synthesis, (Alveraz et al, 1989, and Meyer 1988). All these factors may be applicable to our study resulting in significant rise of serum cholesterol.
Conclusion :
Stress of (restraint type) immobilisation for short periods, causes release of corticosteroids, induces hyperinsulinemia resulting in increased synthesis of cholesterol.
Extrapolating this finding in rats to human beings, one can conjecture that diet and exercise alone can not control serum cholesterol but reduction of any kind of stress would be essential to prevent rise of serum cholesterol.
Acknowledgement :
Authors wish to acknowledge Dr. (Mrs.) C. Anand, present Head of Department of Anatomy of Dr. R.P. Govt. Medical College, Kangra at Tanda HP for encouragement, critical evaluation and constructive suggestions.
Authors wish to acknowledge Mr. Amir Chand for computerized typing of this manuscript without whom this manuscript would not have taken its present form.
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