Physical exercise promotes memory function in diabetes mellitus rats: a look at glucagon like peptide-1 and glucagon like peptide-1 receptor

Diabetes mellitus (DM) is a metabolic disorder associated with declining of memory function. Glucagon like peptide-1 (GLP-1) has a role on memory function; binding of GLP-1 and GLP-1 receptor (GLP-1R) can enhance synaptic plasticity. Physical exercise has effect in increasing GLP-1 levels mediated by interleukin (IL)-6 in plasma. However, the effect of physical exercise on GLP-1 and GLP-1R in hippocampus is still unclear. Therefore, we investigated the effect of continuous and interval training on memory function through GLP-1/GLP-1R and its relation to hippocampal IL-6 of DM rats. This was an experimental study using 8-week-old Wistar rats, divided into four groups: normal control (Con); DM control (ConDM); DM with continuous training (DM-CT); and DM with interval training (DM-IT). DM-CT and DM-IT rats were trained six times a week for six weeks. All rats performed the forced alteration Y-maze test to verify spatial memory function. We analysed GLP-1 and IL-6 level by ELISA and GLP-1R by RT-PCR. We found decreased spatial memory function in DM rats accompanied by decreased hippocampal GLP-1 and GLP-1R. Physical exercise promote memory function in DM rats associated with restoration of hippocampal GLP-1 or GLP-1R level. The GLP-1 level is associated with hippocampal IL-6 level. Continuous training slightly increases GLP-1 level while interval training can maintain expression of hippocampal GLP-1R in DM rats. Our findings suggest that physical exercise may promote memory function by slightly increase the level of hippocampal GLP-1 and maintaining expression hippocampal GLP-1R.