Ameliorative Effects of Vernonia amygdalina and Moringa oleifera Extracts on Cognitive Impairment in Diabetic Wistar Rats

Abstract

This study investigated the ameliorative effects of Vernonia amygdalina and Moringa oleifera on cogni-tive impairment in alloxan-induced diabetes mellitus in male Wistar rats. The animals were allotted into eight groups of five. Group 1 were not induced nor treated. Diabetes was induced with alloxan (135 mg/kg body weight) in groups 2-8. Group 2 which served as diabetic control received distilled water (10 mL/kg). Groups 3-8 were administered ethanol extracts of V. amygdalina (200 mg), M. oleifera (500 mg), V. amygdalina (400 mg), M. oleifera (1,500 mg), V. amygdalina (300 mg) + M. oleifera (1,000) mg, and Metformin (14.29 mg) per kg body weights respectively, for 28 days starting 72 h post induction of diabetes. Novel object recognition, T-maze simple alternation, transfer latency and neurohistology were assessed. Rats in diabetic control had negative discrimination ratio and scored less than 50% in simple alternation. These memory deficits were reversed in the treated groups. The nootropic effect was higher in M. oleifera 1,500 mg/kg than any other group. Severe neuronal degeneration, shrinkage and clumping observed in the diabetic group were ameliorated with administration of V. amygdalina and M. oleifera extracts individually and in combination. Histological findings showed decreased glial fibrillary acidic protein expression. V. amygdalina (400 mg/kg) and M. oleifera (500 mg/kg) were the most effective in ameliorating neuronal damage. The neuroprotective effects of both plants are attributed to their constituent antioxidants, and appear not to be synergistic.