Objective:To explore the effects of aerobic exercise on learning and memory functions, hippocampal synaptic plasticity and the ADPN signaling pathway in diabetic rats.Methods:6-week-old male SD rats were randomly divided into a blank control group(NC group)and a high-fat diet group, and a rat model for diabetes was induced by feeding rats in the high-fat diet group with a high-fat diet combined with intraperitoneal instillation of low-dose streptozotocin(STZ)for 5 weeks.Rats in the high-fat diet group were further divided into a diabetic group(DC group)and a diabetic aerobic exercise group(DM group)after successful establishment of the model.Rats in the DM group were subjected to aerobic exercise for eight weeks and then the Morris water maze test was conducted to assess learning and memory functions, relevant serum markers were measured, Golgi staining was used to examine synaptic changes in the hippocampus, and Western blot was carried out to detect hippocampal protein expression levels of adiponectin(ADPN), AMP-activated protein kinase(AMPK), glucose transporter 4(GLUT4), synaptic plasticity-related protein synaptophysin(SYN)and postsynaptic density protein 95(PSD-95)for rats in each group.Results:Serum FBG and HBA1c in diabetic rats were markedly significantly decreased after 8 weeks of aerobic exercise( P<0.01), and serum ADPN and insulin were significantly increased after 8 weeks of aerobic exercise( P<0.05).When test results from the three groups of rats compared, the F value was 69.248 for FBG, 6.740 for INS, 7.017 for HBA1C and 14.315 for serum ADPN.The results of the water maze test and hippocampal Golgi staining showed that the escape latency of diabetic rats was highly significantly decreased after 8 weeks of aerobic exercise( P<0.01).The platform crossing times, the number of dendritic branches and the dendritic spine density in the hippocampal CA3 region of diabetic rats were significantly increased after 8 weeks of aerobic exercise( P<0.05).When results from the three groups of rats were compared, the F value was 13.934 for escape latency, 5.864 for platform crossing times, 9.307 and 6.734 for the number of dendritic branches and the density of dendritic spine in hippocampal CA3 region.Hippocampal PSD-95, SYN, ADPN, p-AMPK, and GLUT4 protein expression levels of diabetic rats were significantly increased( P<0.05)after 8 weeks of aerobic exercise.When results from the three groups of rats were compared, the F value was 15.137 for SYN, 5.415 for PSD-95, 9.687 for ADPN, 27.761 for GLUT4, and 9.298 for p-AMPK. Conclusions:Eight weeks of aerobic exercise can improve the learning and memory functions of diabetic rats, and the mechanisms may be related to exercise-induced hippocampal ADPN/AMPK/GLUT4 signaling activation in rats, leading to enhanced synaptic plasticity in the hippocampus.