2. Clinical Pathology Department, Faculty of Medicine, Zagazig University, Egypt.
Heat stress leads clinically to manifestations of central nervous system dysfunction. Heat shock proteins (HSPs) function as molecular chaperones protecting the cells from damage. Melatonin has therapeutic and prophylactic effects on heatstroke-induced multiple organ dysfunction. The present work aimed to investigate the protective effect of melatonin against heat stress-induced histological and HSP60 immunoexpression alterations of cerebral cortex in adult male albino rats. Forty adult male albino rats were used and divided into three groups; I (control) II (3 days heat stressed) and III (3 days heat stressed with melatonin treatment). Cerebral cortex specimens were processed to prepare sections for light microscope examination and blood samples were obtained for oxidative stress and antioxidant analysis. Hematoxylin and eosin stained sections showed degenerative changes in cerebral cortex of rats exposed to heat for 3 days in the form of apoptotic neurons and swelling of astrocytes processes. Neuropil edema, subarachnoid hemorrhage and congested blood vessels were also observed with accompanied increase in serum oxidative stress markers and decrease in antioxidant marker. Melatonin treatment with heat stress showed more preserved nervous tissue with accompanied increase in serum antioxidant marker. HSP60 immunoexpression was weak cytoplasmic in control group which significantly increased and became strong cytoplasmic after 3 days of heat exposure. With melatonin treatment with heat stress nuclear, HSP60 immunoexpression was moderate nuclear in some neurons and strong cyoplasmic in others. In conclusion, melatonin ameliorates heat exposure induced degenerative changes in cerebral cortex of adult male albino rats most probably through antioxidant effect with modulation in HSP60 immunoexpression pattern. Hence, more attention should be thrown to melatonin as a protective treatment to avoid heat stress degenerative effect on cerebral cortex.
Keywords: Microscope, Albino rat, HSP60, Melatonin