MORPHOLOGICAL GROUNDS OF USING THE CERVICAL FOLD SUSPENSION MODEL OF IMMOBILIZATION STRESS IN RATS

Abstract

The study of the mechanisms of the acute stress, the search for novel ways to increase resistance to it, prevention and treatment of pathological processes caused by stress reactions, remain relevant areas of medical and biological research. The study of the problem of stress is impossible without performing experimental studies using the different stress models. The purpose of the study was to prove the effectiveness of the experimental model of acute immobilization stress simulation in rats by atraumatic cervical fold suspension for 6 hours on the basis of morphological studies of target organs. The study involved 8-10 month old 20 albino male rats, weighing 240-260 g. Group I (control) involved intact animals, which were housed in vivarium standard conditions and were not involved in any experiments or tests. Group II (experimental) involved rats, exposed to acute immobilization stress. The animals were sacrificed by decapitation under intraperitoneal anesthesia. After the chest and abdomen dissection, the internal organs were examined with the removal of target organs: thymus, adrenal glands and stomach. The findings show that immobilization of rats by atraumatic cervical fold suspension for 6 hours causes manifestations of the Selye’s triad of stress: acute involution of the thymus, hypertrophy of the adrenal glands, as well as hyperemia of the gastric mucosa. In animals of the experimental group intact areas were interspersed with hyperemic swollen foci, which gave the mucous membrane a colorful mosaic appearance; numerous polymorphic hemorrhages and single erosions were noted; no ulcers were detected. Visually, the thymus in rats, exposed to immobilization stress was smaller, and no other changes were detected. The mass of the thymus in animals of the experimental group, compared to intact animals, decreased by 44.5% from 306.5 ± 17.62 to 166.8 ± 41.69 mg. The differences between the adrenal glands in rats of the control and experimental groups were in the increase in their weight and size in those animals that were exposed to stress. In the experimental group the enlargement of the adrenal gland from 38.8 ± 4.34 to 65.1 ± 9.13 mg, i.e., by 67.8%, was noted. The present study demonstrates the effectiveness of the experimental model of acute immobilization stress in rats by atraumatic cervical fold suspension for 6 hours, since it causes manifestations of the Selye’s triad of stress: acute involution of the thymus, adrenal hypertrophy, and hyperemia of the gastric mucosa.

Keywords

• acute stress
• rats
• cervical fold suspension.