Evaluation of electrodermal activity in diabetic rats treated with vildagliptin and metformin

Electrodermal activity (EDA) is the measurement of the electrical conductivity of skin, which indicates the activation of sympathetically innervated eccrine sweat glands. Thus, sympathetic system activity that innervates eccrine sweat glands. In our study, it was aimed to evaluate electrodermal activity and thus changes in sympathetic activity in diabetic rats treated with vildagliptin, metformin and metformin+vildagliptin combination. 50 male rats were used in this study. Rats were divided into control (n=10) and experimental groups (n=40). Fourty animals in experimental group were injected with 45 mg/kg streptozotocin as a single dose intraperitoneally. After 3 days, animals whose blood glucose level exceeded 250 mg/dl were considered as diabetic. Rats were divided into 4 groups as diabetes, vildagliptin, metformin and metformin+vildagliptin. Vildagliptin (50 mg/kg), metformin (500 mg/kg) and 500 mg/kg metformin+50 mg/kg vildagliptin were administered by gavage for 15 days. After measuring blood glucose again at the end of the 15 days and seeing that diabetes continues, tonic activity was recorded before sound stimulus, and phasic skin conductivity level (SCR) was recorded in response to the auditory stimulus by using Biopac MP35 device. Differences between groups were determined by one-way Anova test. Tukey test was used to determine the significance between the groups. P<0.05 was considered significant. Both tonic SCL and phasic SCR were higher (p<0.001) in diabetic groups than the control group. Thease findings might explain the increase in the sympathetic activity in diabetic groups. In additiona, the blood glucose levels of the metformin and vildagliptin groups were lower than the diabetic group. Intrestingly, the metformin+vildagliptin group had a lower tonic SCL than the other experimental groups, whereas the metformin group had a less phasic SCR than the diabetes group (p <0.0001). Peak number of vildagliptin and metformin+vildagliptin groups decreased in tonic recording compared to diabetic group (p<0.0001, p<0.01 respectively). Our study, the fact that diabetic drugs caused a decrease in SCL indicates that these drugs may reduce eccrine sweat gland and sympathetic activity affecting these sweat glands. Further studies are needed on whether a decrease in sympathetic activity will have a positive effect on diabetes.