Aerobic Exercise Improves Hippocampal Synaptic Plasticity and Learning and Memory via Modulating the Adiponectin Signaling Pathway in Diabetic Rats

Abstract

Abstract Background Changes in synaptic plasticity have been shown to be crucial in the process of cognitive dysfunction in type 2 diabetes (T2D). This study examined the effects of aerobic exercise on learning and memory functions, hippocampal synaptic plasticity, and adiponectin (ADPN) signaling pathway in T2D rats.Methods We established a T2D rats model consisting of three groups: normal control (NC), diabetes control (DC), and diabetes exercise (DE), with DE group receiving an eight-week aerobic exercise. Following the exercise intervention, the Morris water maze was utilized to assess learning and memory functions. Serum indicators were determined, and changes in hippocampal synaptic plasticity were evaluated using Golgi staining. Western blot was used to determine the expressions of ADPN, phosphorylated AMP-activated protein kinase (p-AMPK), glucose transporter type−4 (GLUT4), and synaptic plasticity-related proteins in the hippocampal CA3 region.Results In comparison to NC, DC had a significantly (all P < 0.05) impaired learning and memory functions and hippocampal synaptic plasticity. In T2D rats, eight-week aerobic exercise significantly (all P < 0.05) (1) lowered serum fasting blood glucose, glycosylated hemoglobin, insulin resistance index; (2) shortened escape latency and increased platform crossings; (3) increased insulin, serum ADPN, hippocampal postsynaptic density protein−95, synaptophysin, ADPN, GLUT4; (4) increased the number of dendritic branching and density of dendritic spines in the hippocampal CA3 region.Conclusions In T2D rats, eight-week aerobic exercise improved learning and memory functions. The mechanism could be associated to exercise-induced modulation of the ADPN/AMPK/GLUT4 signaling pathway in the hippocampus, which improved hippocampal synaptic plasticity.