Land Caltrop (Tribulus terrestris) Fruit Extract Improves Learning, Memory and Cognitiveflexibility in Streptozotocin-Nicotinamide induced Diabetes Animal Model

T. terrestris commonly known as Gokshura, Gokharu or Puncture vine belongs to the family Zygophyllaceae, widely distributed throughout India and traditionally it is used for treatment of many infectious diseases. Present study was designed to evaluate the effect of T. terrestris dry fruit extract in diabetes induced cognitive dysfunction. Diabetes was induced by Streptozotocin & Nicotinamide (STZ-NA, i.p. route). Animals were divided into 7 groups for comparing the activity of T. terrestris (150 & 300mg) against standard (Glibenclamide) & control groups. Blood glucose was measured by glucometer. Learning & memory was tested using Morris water maze. Time taken to reach the platform (escape latencies) by animals was noted from day 1 to 8. Probe trial was conducted on day 9 to record the time spent in the different quadrants. Glucose levels were significantly reduced in test and standard groups when compared to diabetic controls. T.terrestris and glibenclamide treated groups had decreased escape latencies in learning phase. During probe trial, test and standard treated groups spent significantly more time in the target quadrant with less entries into other quadrants on day 9 compared to untreated diabetic controls. Our findings confirmed that learning and memory was impaired in diabetic controls. This displays the link between hyperglycemia and cognitive deficit. T.terrestris treatment (150 & 300mg) along with having hypoglycemic effects in diabetic rats, revealed improvement in learning & memory. Glibenclamide treated group also showed equal improvement in learning and memory as it was observed by their performance during task. Hence, controlling the blood glucose levels in diabetes can delay cognitive impairment.