Insulin-sensitizing and antioxidant effects of Ethulia conyzoïdes aqueous extract in dexamethasone-induced insulin resistant rats

Abstract

Rising the prevalence of type 2 diabetes mellitus in sub-saharian Africa has necessitated surveys of antidiabetic medicinal plants. Ethulia conyzoïdes is a plant widely used in traditional medicine to treat diabetes. However, the different mechanisms by which it exerts its antidiabetic effects remain unknown. Thus, this study aimed to investigate the effect of Ethulia conyzoïdes aqueoux extract on dexamethasone-induced insulin resistance in Wistar rats. Insulin resistance was induced by intraperitoneal injection of dexamethasone (1mg/kg) for 8 days and the animals received simultaneously, orally, distilled water (insulin resistant control group) and, metformin (100 mg/kg) or Ethulia conyzoïdes aqueoux extract at doses of 133 and 266 mg/kg. Normal control rats received NaCl 0.9% (intraperitoneal by injection) and distilled water orally. Insulin sensitivity, total cholesterol, triglycerides, transaminases activity and redox status were evaluated. Results showed a significant reduction of insulin tolerance (p<0.001), a drastic increased of transaminase activity (p<0.05), hyperlipidemia, and a great potentiation of liver antioxidant enzymes (GSH, SOD and catalase) in insulin resistant control group. Ethulia conyzoïdes aqueoux extract markedly improved insulin sensitivity and reversed all the modified parameters. This study demonstrated the efficacy of Ethulia conyzoïdes aqueoux extract to improve insulin sensitivity and manage biochemical disorders induced by insulin resistance. Short term administration of dexamethasone appears to stimulate the first line antioxidant defense in order to counteract oxidative stress, meaning that Ethulia conyzoïdes aqueoux extract inhibited free radicals production.