Elevated hippocampal mGlut2 receptors in rats with metabolic syndrome-induced-memory impairment, possible protection by vitamin D

Abstract

Background: Metabolic syndrome patients are commonly prone to major health problems as cardiovascular diseases, diabetes mellitus, chronic kidney disease, cancer and neuropsychological complications including dementia. Objectives: This research investigates mechanisms linking metabolic syndrome to cognitive impairment and possible impact of vitamin D supplementation. Methods: Forty male Wistar rats were divided into 4 groups. Control, metabolic syndrome (20% fructose solution in drinking water for 12 weeks, vitamin D supplemented (500 IU/kg/day)) and metabolic syndrome supplemented with vitamin D. Animals were assessed for spatial memory, hippocampal expression of SNAP 25, VAMP and mGlut2 receptor and hippocampus histological examination. Animals with metabolic syndrome showed prolonged acquisition and retention latencies in morris water maze, decreased hippocampal expression of SNAP 25 and VAMP and increased mGlut2 expression. Histologically CA1, CA3 regions and dentate nucleus revealed increase in degenerated neurons and glia cells with decreased pyramidal cell layer thickness. Vitamin D supplementation mitigated alterations induced by metabolic syndrome. Conclusions: Metabolic syndrome decreased hippocampal synaptic proteins and altered glutamatergic transmission and increased hippocampal neuronal degeneration. Vitamin D supplementation offered neuroprotective effects.