Effect of short and long term restraint stress on some physiological and biochemical parameters in rats

The effect of short-term (7 days) and long-term (15 and 30 days) restraint stress on the body weight; weight of the brain, liver and adrenal glands; leucocyte, eosinophil and lymphocyte numbers; electrocardiogram; and on the blood sugar, serum cholesterol and transaminase levels were studied in Wister strain adult male albino rats. The animals showed decrease in body weight after 7 days of stress which was reversed when the period of stress was prolonged for 15 and 30 days. There was increase in the weight of the brain, liver and adrenal glands. A significant decrease in the leucocyte, eosinophil and lymphocyte numbers was observed. Biochemical changes observed were severe hypoglycaemia, hypocholesterolaemia and increase in the serum transaminase levels. No change was observed in the electrocardiogram. The biochemical changes persisted even when the stress period was prolonged for 30 days. In the body weight, organ weights and haematological parameters an increased stress response was seen up to 7 days and there was a gradual decrease in the animals' response to stress after 15 and 30 days. The decreased response could be due to the depletion of biochemical substances due to repeated stress which might have reduced the physiological function. It could be also due to partial adaptation of the hypothalamo-pituitary adrenal axis when the same stress was repeated for a long time.