Antioxidant Enzymes Activity and Hormonal Changes Following Administration of Ethanolic Leaves Extracts of Nauclea latifolia and Gongronema latifolium in Streptozotocin Induced-Diabetic Rats

Abstract

Aim of the Study: To evaluate the effects of ethanolic leaf extracts of Gongronema latifolium (G.L) and Nauclea latifolia (N.L) on antioxidant enzymes activity (GPx, SOD and CAT) and hormonal status (T3, T4, Insulin, c-peptide) in streptozotocin-induced diabetic Wistar rats. Material and Methods: Thirty six (36) albino Wistar rats of both sexes weighing 150-250g were divided into 6 groups of 6 rats each. Groups 1, 2 and 3 received 400mg/kg body weight (b.w) of G.L, N.L and 200mg/kg b.w each of G.L and N.L respectively while group 4 received 5 iu/kg b.w of insulin subcutaneously daily for 21 days, Groups 5 and 6 served as controls (diabetic and Normal) and received placebo. Fasting blood glucose was determined at the start of the experiment and thereafter at 72 hours interval and at the end of experimental period. The animals were sacrificed and sera preparations were used for antioxidant enzymes and hormonal assays. Results: Blood glucose in diabetic animals decreased significantly (P=.05) by 66.34%, 18.12%, 67.73% and 86.62% of initial values upon treatment with G.l, N.l, G.I plus N.I and insulin respectively. There was only a 24.44% decrease in the diabetic control. A significant decrease (P=.05) in insulin and T3 levels was observed in the diabetes-induced rats (65 and 85% respectively) compared to NC. The levels of the hormones where however significantly increased (P=.05) on treatment of the diabetic animals with G.l, N.l, G.I plus N.I and insulin.  Whereas a significant decrease (P=.05)  was observed in T4 level of DC rats compared to the NC, treatment with the leaf extracts and insulin did not result in any elevation of the hormone relative to DC. The C-peptide levels for all groups were much lower than the corresponding insulin levels, suggesting a type 1 diabetes in the diabetes-induced rats. A significant decrease (P=.05) in activity was observed for GPx and SOD in the DC group relative to NC. A combination of G.l and N.l gave a much higher reversal in activity (P<.01) when compared to treatments with individual leaf extracts. There was a significant increase (P=.05) in CAT activity in the DC animals relative to NC. This was potentiated in all treatment groups with the combination group showing a synergy in its potentiating effect. Conclusion: There was a reversal in the level of the hormones and the activity of the antioxidant enzymes towards normal control, and comparable to the reversals by treatment with insulin, on treatment of the diabetic animals with the leaves extracts especially in combination. The results taken together indicate a synergy that makes the combination of the two plants extracts a potent antidiabetic remedy.