Motion activity is an important property of animals and humans, it is one of the conditions of their normal existence and development, which depends on the illumination level. Limitation of motion activity (hypokinesia, or immobilization) is a powerful stressor factor that causes various pathological processes.

The hypothalamus, as the highest subcortical center of the autonomic (vegetative) nervous system, has a powerful regulatory effect on all vital functions of the body, including, and on maintaining the homeostatic balance of a living system, which is disturbed as a result of the activity of stressors, in particular immobilization. Due to the important role of the large-cellular supervisory nuclei of the hypothalamus in the implementation of the adaptive capabilities of the organism, it is relevant to study the nature of their response at immobilization stress influence on the organism of experimental animals.

The aim of the study. To study changes in the morphometric parameters of large-cellular neurons of the supervisory nucleus of the hypothalamus of rats during immobilization stress.

Material and methods. The experiments were conducted on non-linear male white rats, weighing 200–220 g. Immobilization stress was simulated by keeping the rats in special plastic cage-pencil-boxes for 1 hour daily for 7 days. The animals were divided into 2 series of studies, in each of which biomaterial was collected at 14.00 and 02.00 using morphometric and statistical research methods.