The protective effect of Azadirachta excelsa leaves extract and quercetin treatment on the learning and memory impairments in relation with insulin and amylin levels in the brain of streptozotocin-induced diabetic rats

摘要

Azadirachta excelsaincreases the secretion of plasma insulin with subsequent reduction of fasting blood glucose. However, its protective effect towards brain amylin and insulin levels as well as the memory and learning functions remain elusive. Thus, this study aimed to ascertain the effect ofA. excelsaand quercetin consumptions on the brain amylin and insulin concentrations as well as memory and learning abilities of the streptozotocin (STZ)-induced diabetic rats. Diabetic condition was induced in the male Sprague Dawley rats by the intraperitoneal injection of 60?mg/kg body weight (bwt) STZ. The experimental animals were divided into normal control (saline), diabetic control (saline), Metformin-treated diabetic (1000?mg/kg bwt) (positive control),A. excelsa-treated diabetic (250?mg/kg bwt) and Quercetin-treated diabetic (40?mg/kg bwt) rats. All treatments were administered orally by oral gavage once daily throughout the 8?weeks of the treatment period. Amylin and insulin concentrations were determined by using the commercial rat amylin and insulin immunoassay kits, while learning and memory consolidation parameters were conducted using Morris Water Maze (MWM) paradigm. Treatment withA. excelsahad significantly (p?