Neurotoxicological effects of Methyl Mercury on developing cerebellum of albino rats: histological and immunohistochemical study

ABSTRACT

Mercury exists in the environment in three major forms organic, inorganic and elemental. Organic methyl mercury is the most widely distributed and toxic form of mercury. It is used extensively in agriculture and industry. It is also bioaccumulated in sea food and fresh water fish. The central nervous system is a critical organ for mercury exposure. The aim of the present work was to study the possible neurotoxicological effects of low- level exposure to methyl mercury on the developing cerebellum of albino rats during the pre- and early postnatal periods. The study was carried out on twenty pregnant female albino rats. Ten pregnant rats constituted the control group. The remaining ten pregnant rats were given methyl mercury orally in a dose of 2 mg/kg body weight daily during late gestational period starting from day 12 and continued for 21 days after birth i.e. until weaning. Control rats were given an equivalent volume [2 ml] of physiological saline orally by gastric gavage for the same experimental duration. Control and methyl mercury-exposed rat pups were sacrificed following weaning [21 postnatal days] by decapitation after ether anesthesia. The cerebellum of each rat pup was prepared for histological study [light microscopic examination using haematoxylin and eosin stain, and electron microscopic examination using the transmission electron microscope], and immunohistochemical study using antibodies against glial fibrillary acidic protein [GFAP]. The present study revealed that there were marked histological and immunohistochemical changes in the neurons and neuroglial cells of the cerebellum of rat pups following exposure of their mothers to low-level of methyl mercury. It was concluded that methyl mercury is a potent neurotoxic substance causing severe damaging changes in the developing cerebellum