Effects of Ethanol Leaf Extract of Chromolaena odorata on the Hippocampus of Alloxan-induced Diabetic Wistar Rats Exposed to Mercuric Chloride

Diabetes mellitus and mercury toxicity are associated with oxidative stress and neuronal degeneration, particularly in the hippocampus. The study assessed histological and immunohistochemical effects of ethanol leaf extract of Chromolaena odorata on the hippocampus of alloxan-induced diabetic Wistar albino rats exposed to mercuric chloride. Thirty-six adult Wistar rats were randomly assigned to six groups. Diabetes was induced using alloxan monohydrate (150mg/kg), while mercury toxicity was induced using mercuric chloride (3mg/kg). Treatment groups received graded doses of Chromolaena odorata extract at 200, 400, and 600 mg/kg and metformin (standard drug). Biochemical assays for oxidative stress markers, including malondialdehyde, superoxide dismutase, glutathione peroxidase, histological evaluation, and immunohistochemical analyses (GFAP and p53) were carried out. Significant elevation in malondialdehyde level (910.59±32.73) and reduction in antioxidant enzymes (SOD: 21.04±2.30; GPx: 37.78±6.20) were observed in untreated diabetic rats exposed to mercury compared to controls. Treatment with Chromolaena odorata extract significantly reduced MDA level and restored antioxidant enzyme activity. Histological findings showed neuronal degeneration in CA1, CA3, and dentate gyrus regions in untreated rats, while treated groups showed preserved neuronal architecture. Immunohistochemistry revealed increased GFAP and p53 expression in untreated groups, which were reduced following treatment. Ethanol leaf extract of Chromolaena odorata exhibits significant neuroprotective and antioxidant effects against diabetes and mercury-induced hippocampal damage.

Key Words: Chromolaena odorata, hippocampus, diabetes mellitus, mercuric chloride, GFAP, p53, oxidative stress