Effect of fluoride on rat cerebellar cortex: light and electron microscopic studies

ABSTRACT

Fluoride accumulation in the brain of experimental animals was particularly observed in the hippocampus. It caused altered neuronal and cerebrovascular integrity, abnormal behavioral patterns and metabolic brain lesions. Fluoride affected indeed the cerebellar development in mice but its effect on adult rat cerebellar cortex is something awaits further investigation. Is to define the effects of fluorosis on the histological structure of adult rat cerebellar cortex. A total number of 40 adult female albino rats were used. They were divided into two groups [20 animals each]. Group I Was kept as control group, received distilled water orally daily by gastric tube for 2 months. Group II Received sodium fluoride orally [dissolved in distilled water] at a dose of 12 mg/Kg body weight for two months. Samples from cerebella were taken and processed for light and electron microscopic investigation. After fluoride treatment, features of neurodegeneration were observed. The Purkinje cells appeared shrunken, deeply stained, with multilayer disposition, which was confirmed by morphometric evaluation of the Purkinje cell layer thickness. Ultrastructurally, increased infolding of nuclear envelope, mitochondrial alterations, dilated Rough endoplamic reticulum cisternae and clusters of vesicles near the Golgi bodies were observed. Apoptotic granule cells accumulated in a clumping manner, Bergmann astrocytes with features of increased activity, dilated and congested blood capillaries were noticed. GFAP positive cells were more abundant and appeared larger in the three cortical layers of treated animals associated with positive reaction for inducible nitric oxide synthase [iNOS] compared to negative reaction in control animals. The cerebellar cortex was particularly susceptible to sodium fluoride- induced oxidative stress and could contribute to the development of neurodegenerative diseases