Subchronic intoxication with cadmium induces morphological alterations in rat cerebellum: the protective role of a soybean diet

Abstract

Cadmium (Cd) is an environmental contaminant. The aim of this study was to characterize its toxicity in cerebellumand the potential reversal by a soybean-based diet. The glial fibrillary acid protein (GFAP), indicator for neurotoxiceffects in mature brain, was evaluated. Besides, we performed a morphometric and stereological analysis. FemaleWistar rats (n=12) were fed with casein (Cas) and soybean diets (So) as protein source for 60 days. Simultaneously,half of the animals were administered either 15 ppm of Cd in water or regular tap water as control. The cerebellumswere fixed and processed for immunofluorescence. The samples were visualized by fluorescence microscopy and thepositive fluorescence area for GFAP was quantified by IMAGE J Software. Morphometric analysis includedquantifying the number of granule cell neurons (CGn) and Purkinje cells neurons (Pkn) in serial 20μm-thick sectionsstained with cresyl violet along the different lobules. We performed a three-dimensional volumetric reconstruction ofthe tissue through the use of the software Stereo Investigator. The thicknesses of the molecular and granular layers ofthe cerebellar cortex of lobules I-X were determined on digital images. We found a decrease in the number of CGn inthe CasCd group vs. CasCo group (p<0.05) and SoCd group (p<0.01). On the contrary, the number of Pkn remainedunchanged. In addition, there was a significant reduction in the internal granular layer of CasCd group vs. SoCdgroup, while no effect was observed in the thickness of the molecular layer. The cortical thicknesses of the differentregions of each folium base from cerebellar lobules I-X did not show significant differences between the groups.Overall, these results unmask an irreversible toxic effect of low dose-sub chronic Cd intoxication on cerebellum and identify a protective role of a soy-based diet with potential as a therapeutic strategy for those individuals exposed tothis dangerous environmental contaminant.