Protective effects of the traditional herbal formulation on oxidative stress, learning and memory in the animal model of type 2 diabetes

Introduction: Diabetes mellitus (DM) is one of the most frequent metabolic diseases that affect various body systems. Cognitive impairment caused by diabetes is gaining more acceptance and attention. In this study, we have investigated the effects of a traditionally herbal formulation (THF) on oxidative stress (OS) and cognitive deficits in type 2 diabetic rats. Methods: Thirty-six male Wistar rats were divided into six groups: control group, diabetic group, diabetic+100, 200 or 300mg/kg THF, diabetic+glibenclamide (G) 5mg/kg. Streptozotocin-nicotinamide was used to induce type-II diabetes mellitus. Spatial and passive avoidance learning and memory function were evaluated by Morris Water Maze (MWM), novel object recognition test (NORT) and open field test (OFT). The OS biomarkers were also analyzed. The THF was standardized using RP-HPLC according to phenolic and flavonoids compounds. Results: Indicated that in the diabetic treated (300mg/kg THF and G) vs. diabetic groups, body weight and insulin were significantly increased and the levels of fasting blood glucose significantly reduced. OS was improved in the treated (300mg/kg THF) groups. Furthermore, we noticed that diabetic treated groups (300mg/kg THF) vs. diabetes caused in significant decreases of the travelled distance and escape latency to find the hidden platform, also increased in the time spent and travelled distance in the target quadrant in MWM test, exploration time in NORT and total distance moved in OFT. Conclusion: These findings suggest that THF ameliorated learning and memory deficits in type 2 diabetic rats via reducing OS. THF can be used with a caution against human DM.