Adrenal gland pathology in rats after acute postnatal hypoxia

Aim. To study the histological changes in the adrenal glands of rats with acute postnatal hypoxia and «structural trace» in the adrenal glands during the first month of life. Methods. Wistar rats were used as experimental animals. After calving, the newborn rats (main group, 20 newborn rats, progeny of 5 female rats) were placed in the bell-pressure chamber (simulating altitude of 3.500 meters with an atmospheric pressure of 493 mm Hg) for 5 min. Rats were withdrawn from the experiment by decapitation at the first day (1 hour after the acute postnatal hypoxia modeling, 7 rats), 7 days after (7 rats) and 35 days after (6 rats) the experiment. The same number of intact rats of the control group were examined at the same timepoints. The adrenal glands of rats were examined morphologically using histological, histochemical, immunohistochemical and morphometric methods. Results. It was found that a short episode of mild short hypoxia just after the birth leads to the development of specific adaptive changes in adrenal glands: cortical hyperplasia, increased morpho-functional activity of endocrinocytes in the medullar substance associated with extensive apoptosis, decreasing of morpho-functional activity of endocrinocytes of the glomerular zone and fetal cortex. Cellular regeneration of spongiocytes was observed not only in the cambium layer, but also in the fascicular zone, which presumes not only physiological, but also reparative regeneration. Regeneration of medullar cells, seemingly, only occurs during the first few days after birth by migration of sympathogonia from outside of the adrenal gland to its center. At days 14 th and 35 th, despite the same conditions, histological signs of active functioning of the cortical fascicular zone and medullar substance preserved in animals of the main group compared with the controls. Conclusion. Results of the study prove the need for clinical studies of the adrenal function correction in newborns undergoing postnatal and intranatal acute hypoxia, as well as of consequences for the adrenal gland morpho-functional state after birth for such cases.

adrenal gland, hypoxia, newborns, rats