Beneficial effects of rutin in diabetes-induced deficits in acquisition learning, retention memory and pain perception in rats

Abstract

Objectives: Cognitive impairment and hyperalgesia are among the common manifestations of diabetes. Hyperglycemia may contribute to their developments but the exact pathophysiology underlying these complications is not fully understood. Flavonoids from plants original have beneficial effects on diabetes by improving glycemic control. Rutin (RUT) is a bioflavonoid found in many plants and foods with many biological activities including neuroprotective and antidiabetic effects. In this study, we hypothesized that administration of RUT (10, 25 and 50 mg/kg, i.g.) for 30 days in rats would affect on hyperglycemia, cognitive dysfunction and hyperalgesia, which are common complications of diabetes type I. Methods: Diabetes was induced by streptozotocin (STZ) injection which destroys β-cells and induces clinical features in animals that resemble those in diabetes type I in humans. Therefore, STZ-treated animals are used for the evaluation of novel antidiabetic drugs. The animals received vehicle or RUT (10, 25 and 50 mg/kg, i.g., once daily) at the onset of hyperglycemia for 30 days. Learning and memory was assessed by passive avoidance learning and memory test in streptozocin-induced diabetic and non-diabetic rats. Chemical hyperalgesia was evaluated by the formalin test. Results: Diabetes-induced deficits in acquisition and retrieval processes. RUT (25 and 50 mg/kg) reversed learning and memory deficits in diabetic rats. These doses of RUT reversed chemical hyperalgesia during both phases of the formalin test in diabetic rats and induced antinociceptive effects in healthy animals. RUT 10 mg/kg did not alter behaviors in control and diabetic groups. RUT 50 mg/kg induced significant hypoglycemic effects in both diabetic and non-diabetic rats. Discussion: Prolonged oral administration of RUT (25 and 50 mg/kg) induced cognitive enhancing and antinociceptive effects in both control and diabetic rats. Therefore, it may represent a potential therapeutic option against diabetic neurological disorders which deserves consideration and further examination.