Effect of testosterone on memory and BDNF levels of hippocampus in gonadectomized diabetic rats

Abstract

The prevalence of cognitive impairment in diabetic patients is more than in non-diabetic ones. BDNF and sex hormones levels play important roles in learning and memory. In this study, the effect of testosterone on BDNF expression and memory was investigated in 60 male Wistar rats were randomly divided into 6 groups (n=10): control (C), Diabetic (Dia), Diabetic-Sham (Sh), Diabetic-Gonadectomized (Dia-Gdx), Diabetic-Testosterone (Dia-T), and Diabetic-Gonadectomized-Testosterone (Dia-Gdx-T). Diabetes was induced by STZ (60mg/Kg). Testosterone (2mg/kg/day) was administered intraperitoneally for 6 weeks. The BDNF levels in the hippocampus were assessed by ELISA kit. Novel object recognition (NOR) test was performed for the investigation of recognition memory. Induction of diabetes did not significantly change the BDNF levels of hippocampus, where as Gonadectomy or testosterone administration in diabetic animal's significantly reduced BDNF levels. Short-term memory significantly was reduced in Dia-Gdx, Dia-T, and Dia-Gdx-T groups compared to the control group; however, Gonadectomy or testosterone therapy had no significant effects on it in diabetic rats. BDNF levels and short-term memory decreased in diabetic groups that received or were depleted from testosterone. It is possible that decrease of BDNF gene expression in the hippocampus caused a short-term memory disturbance.