Morphological changes of sexually mature rat's pineal gland and cerebellar cortex under long-term exposure to heavy metal salts

Abstract

Pollution with heavy metal salts is an important environmental problem today, having an adverse effect on public health. The endocrine system maintains homeostasis in the body. The purpose of the work is to study the morphological changes of the cerebellar cortex and epiphyses of sexually mature male rats under the condition of long-term exposure to the body of a complex of heavy metal salts. The morphological changes in the cerebellar cortex and epiphysis of sexually mature male rats under the condition of long-term exposure to heavy metal salts was studied. Animals of the experimental group were simulated microelementosis by adding to drinking water a mixture of heavy metal salts for 60 days: zinc (ZnSO4×7H2O) – 5 mg/l, copper (CuSO4×5H2O) – 1 mg/l, iron (FeSO4) – 10 mg/l, manganese (MnSO4×5H2O) – 0.1 mg/l, lead (Pb(NO3)2) – 0.1 mg/l and chromium (K2Cr2O7) – 0.1 mg/l. Morphological, morphometric and statistical research methods were used. Long-term (60-days) intake of heavy metal salts mixture in the body of experimental animals leads to the development of the general adaptation syndrome, the stage of chronic stress “subcompensation” in the pineal gland. Morphological changes in the organs had a nonspecific polymorphic character, such as a sharp violation of hemodynamics, a violation of the morphology of the vascular wall, the state of pinealocytes and Purkinje cells, the development of tissue hypoxia, processes of apoptosis and reactive astrogliosis as a response to the action of a damaging agent. The pineal gland of the experimental animals showed signs of indole production, but the evacuation of hormones (including melatonin) into the vascular bed was hampered due to the violation of the morphology of the vascular wall and the cell membrane of pinealocytes. This led to a deficiency of this hormone in the body of the experimental animals, which negatively affected the adaptive processes in the cerebellar cortex in response to the action of the stress agent. Compensatory and adaptive processes in the pineal gland and cerebellar cortex had signs of functional stress. Adaptive processes were observed both in a small number of pinealocytes and in Purkinje cells, as well as an active adaptive glial reaction in both organs.