The possible protective role of melatonin on the changes in the cerebral cortex and meninges of streptozotocin-induced diabetes in adult male albino rats (histological and immunohistochemical study)

Abstract

Introduction: Diabetes mellitus is a serious common metabolic disease. It causes a variety of functional and structural disorders in the central nervous systems. It induces alterations in the brain glucose metabolism and increase oxidative stress. Melatonin is a potent free radical scavenger and stimulates the major antioxidant enzymes. Aim: This study was aimed to evaluate the possible protective role of melatonin on the histological changes in the cerebral cortex and meninges after induction of diabetes in a rat model. Materials and Methods: In this study, forty adult male albino rats were divided into four groups (ten rats for each): Group I control rats, group II rats received intraperitoneal injection of Streptozotocin (STZ) (60 mg/kg, single dose), group III rats received intraperitoneal injection of melatonin (10 mg/kg/d) for six weeks, group IV received same previous doses of of STZ and melatonin for six weeks. At the end of experiment, the cerebral cortex was dissected and processed for light microscopic examinations and also for glial fibrillary acidic protein (GFAP) to demonstrate the astrocytes. Morphometrical and statistical analyses were carried out. Results: Examination of cerebral cortex of group II showed separation of the pia mater, congestion in the blood vessels and hemorrhage in intermediate lamella. There were multifocal histological changes and depletion of the cellular elements. The neuropil showed vacuolation. There were multiple areas of microinfarction and pericellular halos. Cresyl Violet stained sections showed karyolysis and immunohistochemical study showed significant increase in GFAP positive astrocytes. In contrary, Examination of cerebral cortex of group IV showed apparent improvement in almost all layers. Cresyl Violet stained sections showed darkly stained Nissel’s granules. Immunohistochemical study showed significant decrease in GFAP positive astrocytes. Conclusion: Melatonin can ameliorate the effect of diabetes on the cerebral cortex and meninges through its antioxidant effect.