Effects of glycowithanolides from Withania somnifera on an animal model of Alzheimer's disease and perturbed central cholinergic markers of cognition in rats

Abstract

Abstract The active principles of Withania somnifera (WS, 20–50 mg/kg, p.o.), consisting of equimolar amounts of sitoindosides. VII–X and withaferin A, were investigated for putative nootropic activity in an experimentally validated Alzheimer's disease (AD) model. The syndrome was induced by ibotenic acid (IA) lesioning of the nucleus basalis magnocellularis (NBM) in rats. Cognitive deficits induced in NMB‐lesioned rats were assessed by attenuation of a learned active avoidance task and a decrease in frontal cortical and hippocampal acetylcholine (ACh) concentrations, choline acetyltransferase (ChAT) activity and muscarinic cholinergic receptor (MCR) binding. IA‐induced NBM lesioning in rats caused a marked cognitive deficit, as evidenced by severe reduction of the learned task, and was accompanied by a significant decrease in frontal cortex and hippocampal ACh levels, ChAT activity and MCR binding. WS (50 mg/kg) significantly reversed both IA‐induced cognitive deficit and the reduction in cholinergic markers after 2 weeks of treatment. The findings validate the medharasayan (promoter of learning and memory) effect of W. somnifera, as has been reported in Ayurveda.