Features of Reactions to Stress in Rats with Passive-Defense Behavior after Light Desynchronosis and Physical Activity

An assessment was made of hematological parameters of peripheralblood and structural and functional changes in the adrenal glandsin stress-unresistant rats (passive-defensive type of behavior in theopen field test) after exposure to light deprivation and physicalactivity during the spring equinox. The experiment showed that lightdeprivation for 10 days reduces the total number of leukocytes,the absolute content of monocytes, granulocytes, lymphocytes andthe level of corticosterone in the peripheral blood compared tothe intact group, that was on a natural lighting regime. Histological analysisof the adrenal glands of this group showed, that in the zona fasciculataunder such conditions there was nuclear hypertrophy, an increasein the nuclear-cytoplasmic ratio of adrenocorticocytes and a decreasein the size of the zona glomerulosa of the adrenal cortex of ratsin relation to the intact group. Physical activity in the form offorced swimming until complete fatigue for 5 days in a row in naturallight in stress-unresistant rats did not change the parameters ofthe peripheral blood of animals, however it led to an increase inthe area of the cytoplasm, the nuclear-cytoplasmic ratio, as wellas the formation of nuclear hypertrophy of adrenocorticocytes inthe fascicle adrenal zones, which indicated the preparation of cellsfor increased synthetic activity. Keeping rats for 10 days in completedarkness before forced swimming every day for 5 days, on the onehand, formed a hypoxic state and exhaustion of the adrenal glands,on the other hand, stabilized the leukocyte pool of peripheral bloodcompared to similar indicators in intact rats.