Aerobic exercise training improves memory function through modulation of brain-derived neurotrophic factor and synaptic proteins in the hippocampus and prefrontal cortex of type 2 diabetic rats.

Abstract

Defective insulin signaling in the brain may disrupt hippocampal neuroplasticity resulting in learning and memory impairments. Thus, this study investigated the effect of aerobic exercise training on cognitive function and synaptic protein markers in diabetic rats. Twenty male Wistar rats (200-250g), were fed on high-fat diet and received a low dose of streptozotocin (35mg/kg, i.p) to induce type 2 diabetes. Then diabetic animals were randomly divided into sedentary and training groups. The exercise training program was treadmill running at 27m/min for 60min/day for 8 weeks. One day after the last training session, Morris Water Maze (MWM) task was performed to evaluate spatial learning and memory. Then, the hippocamp and prefrontal cortex tissues were instantly dissected for immunoblotting assay of BDNF, GSK-3β, p-GSK-3β, P38, p-P38, ERK1/2, p-ERK1/2, heat shock protein-27 (HSP27), SNAP-25, synaptophysin, and PSD-95. Independent t-test analysis and two-way ANOVA was used to determine the differences under significance level of 0.05 using the 26th version of IBM SPSS statistical software. The results showed that aerobic exercise improved memory as assessed in the MWM task. Moreover, aerobic exercise up-regulated HSP27 and BDNF protein levels in the prefrontal cortex, and hippocampus coincided with robust elevations in SNAP25 and PSD-95 levels. Moreover, exercise reduced phosphorylated P38, while increased p-ERK1/2 and p-GSK-3β (p). Our findings suggest that aerobic exercise may debilitate the harmful effects of diabetes on the cognitive function possibly through enhancing synaptic protein markers.