Protective effects of methanolic extract in a rat model of cadmium chloride-induced neurotoxicity.

Cadmium (Cd) is a common environmental toxicant that has harmful effects on plants, animals, and humans. The present study evaluated the protective effects of methanolic extract (SME) on cadmium chloride (CdCl)-induced neuronal toxicity in rats. Male albino rats were intraperitoneally (i.p) injected with CdCl (6.5 mg/kg) for 5 days with or without the SME (250 mg/kg). We measured the levels of Cd, lipid peroxidation (LPO), nitric oxide, glutathione (GSH), and oxidative enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, and glutathione reductase (GR) in the whole brain homogenate. Compared with the control group, the Cd-intoxicated group showed a marked increase in the brain levels of Cd, LPO, and nitric oxide and a decrease in the levels of GSH and all tested antioxidant enzymes. Compared with Cd-intoxicated rats, the rats pretreated with SME showed restoration of oxidative balance in the brain tissue. While the expression of brain , CAT, glutathione peroxidase 1, and GR was down-regulated in the Cd-treated group, the expression of these enzymes was up-regulated in rats pretreated with SME. In addition, administration of SME before CdCl increased the Bcl-2 expression, but significantly decreased the expression of Bax. Immunohistochemical analysis showed that compared with Cd-intoxicated rats, rats pretreated with SME showed a decrease in the protein expression of tumor necrosis factor α (TNF-α). Our findings indicate that SME protects the brain tissue from Cd-induced neuronal toxicity by improving the antioxidant system and increasing antiapoptotic and anti-inflammatory activities.