Features of reactions to stress in rats with passive-defense behavior after light desynchronosis and physical activity

Abstract

An assessment was made of hematological parameters of peripheral blood and structural and functional changes in the adrenal glands in stress-unresistant rats (passive-defensive type of behavior in the open field test) after exposure to light deprivation and physical activity during the spring equinox. The experiment showed that light deprivation for 10 days reduces the total number of leukocytes, the absolute content of monocytes, granulocytes, lymphocytes and the level of corticosterone in the peripheral blood compared to the intact group, that was on a natural lighting regime. Histological analysis of the adrenal glands of this group showed, that in the zona fasciculata under such conditions there was nuclear hypertrophy, an increase in the nuclear-cytoplasmic ratio of adrenocorticocytes and a decrease in the size of the zona glomerulosa of the adrenal cortex of rats in relation to the intact group. Physical activity in the form of forced swimming until complete fatigue for 5 days in a row in natural light in stress-unresistant rats did not change the parameters of the peripheral blood of animals, however it led to an increase in the area of the cytoplasm, the nuclear-cytoplasmic ratio, as well as the formation of hypertrophy of the nuclei of adrenocorticocytes in the fascicle adrenal zones, which indicated the preparation of cells for increased synthetic activity. Keeping rats for 10 days in complete darkness before forced swimming every day for 5 days, on the one hand, formed a hypoxic state and exhaustion of the adrenal glands, on the other hand, stabilized the leukocyte pool of peripheral blood compared to similar indicators in intact rats.