Histomorphological Evaluation of the Protective Role of Vitamin D3 Against Cadmium-Induced Neurotoxicity in Albino...

Background Cadmium (Cd) is one of the toxic metals found naturally in the environment and is used in industrial settings. In uncontaminated soils and freshwater, its levels are generally low. However, industrial activities, mining, phosphate fertilizers, and waste disposal can markedly increase environmental Cd concentrations, leading to chronic exposure in humans and animals. Exposure to high levels of Cd may induce harmful effects on nervous tissue. Experimental studies have demonstrated that Cd accumulates in various brain regions, including the olfactory bulb, after crossing the blood-brain barrier. This work was conducted to study the effect of Cd on the olfactory bulb of adult albino rats and the possible protective role of vitamin D3 (VD3). Methods A two-year experimental study was conducted in the Department of Anatomy, Jawaharlal Nehru Medical College, Aligarh Muslim University, Aligarh, after approval from the IAEC, from November 28, 2020, to November 30, 2022 (24 months). A total of 36 adult albino rats of either sex were included in the study and divided into three groups. Group I served as the control group and received normal saline. Group II served as the exposure group and received Cd chloride at a dose of 5 mg/kg/day administered subcutaneously. Group III served as the treatment group and received VD3 at a dose of 1000 IU/kg orally every two days, along with Cd chloride, for a period of four weeks. At the end of the experimental period, specimens of the olfactory bulb from all groups were collected, processed, and stained with H&E for light microscopic examination. Results Among the three groups, the control group showed normal architecture. The Cd chloride group showed loosening of the olfactory nerve layer, distortion of glomeruli with detached periglomerular cells occasionally interspersed with cell clusters, and vacuolar spaces in the neuropil of the external plexiform layer (EPL). Mitral cells showed morphological alterations and pericellular spaces. In the protective group, glomeruli were arranged closely, similar to those in the control group. Vacuolar spaces were negligible in the neuropil of the EPL. Conclusions Cd exposure causes morphological alterations in the olfactory bulb, while concurrent VD3 administration appears to reduce these changes, suggesting a neuroprotective role.