Evaluation of the effect of costus igneus on learning and memory in normal and diabetic rats using passive avoidance task

Objective: To evaluate the effect of Costusigneus on learning and memory in normal and diabetic rats using passive avoidance test. Methods: Wistar rats were divided into 6 groups namely control, diabetic control Costusigneus(CI) alcoholic extract treated normal, and diabetic groups(250&500mg/kg). For induction of diabetes, a single dose of streptozotocin was injected (35 mg/kg i.p). After 30 days of oral administration of respective drug to different groups, blood glucose and body weight were measured and rats were assessed for learning and memory using passive avoidance test. Entrance latency to the dark compartment and time spent in the dark compartment was analysed using ANOVA, followed by Tukey's post hoc test. Results: Diabetic rats showed impairment in acquisition trial of passive avoidance test. Diabetic rats treated with C.igneus showed significant reduction in the entrance latency and increased the time spent in the dark compartment during acquisition trial retaining their normal behaviour. During the post-shock retention testing at 24 and 48 hours, treatment with C.igneus showed significant increase in the entrance latency and decrease in the time spent in the dark room. The blood glucose of these rats was reduced to normal levels. The treated normal rats showed similar behaviour as the saline control. Conclusion: C.igneus prevents learning and memory deficit which is otherwise impaired in diabetic rats. Hypoglycaemic activity of C.igneus is largely accountable for this protective effect on cognition.