Effect of Vitamin D Supplementation on the Progression of Alzheimer’s Disease in Rats: A Mechanistic Approach

Abstract

Purpose: A multifaceted treatment approach can be effective for Alzheimer's disease (AD). However, currently, it involves only symptomatic treatment with cholinergic drugs. Beneficial effects of high vitamin D levels or its intake in the prevention and treatment of cognitive disorders have been reported. Thus, the present study examined the preventive effect of vitamin D supplementation on AD progression and evaluated its impact on the accumulation or degradation of Aβ plaques. Methods: A single intraperitoneal injection of scopolamine was used to induce AD in rats. Treatment of vitamin D was provided for 21 days after the injection. Various behavioral parameters like learning, spatial memory and exploratory behavior, biochemical alterations in the brain homogenate and histology of the hippocampus were investigated. Results: Our results indicated that scopolamine-induced rats depicted cognitive deficits with high Aβ levels and hyperphosphorylated tau proteins in the brain tissue, while vitamin D supplementation could significantly improve the cognitive status and lower these protein levels. These results were supported by the histopathological and immunohistochemical staining of the hippocampal brain region. Furthermore, mechanistic analysis depicted that vitamin D supplementation improved the Aβ protein clearance by increasing the neprilysin levels. It also reduced the accumulation of Aβ plaques by lowering neuroinflammation as well as oxidative stress. Conclusion: The present findings indicate that vitamin D supplementation can delay AD progression by an increase in Aβ plaques degradation or reducing inflammation and oxidative stress.

The Potential Neuroprotective Effect of Cyperus esculentus L. Extract in Scopolamine-Induced Cognitive Impairment in Rats: Extensive Biological and Metabolomics Approaches

“…In our study, the Scop up-regulated the hippocampal Aβ and β-secretase expression compared with the control group. The administration of donepezil significantly lowered the Aβ1-42 and β-secretase expression, which correlates with the study of Patel and his colleagues [ 62 ]. Interestingly, the Aβ1-42- and β-secretase-lowering effects of TN at the doses of 50–200 mg were nearly comparable with those of the donepezil-treated group, which may suggest a beneficial effect of TN in decreasing the disease burden.…”