Leptin deficiency is involved in the cognitive impairment of streptozocin-induced diabetic rats undergoing cardiopulmonary bypass

Several lines of evidence have demonstrated that leptin is probably involved in the cognitive impairment which induced by a single injection of streptozocin (STZ). However, there is little literature reporting the relationship between cognitive impairment and cardiopulmonary bypass (CPB). This study aimed to investigate the role of leptin in the cognitive impairment of STZ-induced diabetic rats undergoing CPB. Wistar rats received 2 h of CPB exposure 1 month after a single intraperitoneal injection of 60 mg/kg of STZ or the vehicle. Behavioral results of rats in Morris water maze were recorded. After that, rat hippocampi were harvested for measuring leptin, tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). Besides, we observed intracerebroventricular injection of leptin on the cognitive impairment of diabetic-rats undergoing CPB and measured behavioral performance and hippocampal TNF-α and IL-1β levels. Rats undergoing CPB significantly aggravates STZ-induced an increase of the latency to the platform and a decrease of the proportion of time spent in the target quadrant of rats in Morris water maze test. Additionally, the expression of leptin significantly decreased, while TNF-α and IL-1β levels significantly increased. Moreover, intracerebroventricular injection of leptin has a therapeutic effect for cognitive impairment of diabetic rats undergoing CPB. Leptin deficiency in hippocampus is probably involved in the cognitive impairment of streptozocin-induced diabetic rats undergoing cardiopulmonary bypass.