Capsaicin decreases blood glucose, insulin and TRPV1 expression in sensory peripheral neurons in double transgenic diabetes mice

Introduction: Diabetic peripheral neuropathy is a common chronic complic ation of diabetes mellitus. Transient receptor potential (TRP) ion channels are involved in sensing physical and chemical stimuli. TRPV1 is a Ca2+ permeant non-selective cation channel expressed predominantly by unmyelinated C-fibers and thinlymyelinated A-d fibers and plays a major role in inflammatory thermal sensation. Capsaicin is the active component of chili peppers (which are plants belonging to the genus Capsicum) and is the main compound responsible for TRPV1 activation. Purpose: The goal of our study was to evaluate the effect of dietary capsaicin on the diabetic status of the double-transgenic mice. Material: We have used sensory neurons from dorsal root ganglia extracted from double transgenic TCR-HA+/-/Ins-HA+/- diabetic mice and Balb/c mice. Both strains of mice received a supplement in diet of 0.015% capsaicin for 10 weeks and were compared with unsupplemented controls. Method: Whole cell patch-clamp recording and immunofluorescence microscopy have been employed. PCR tests were employed to identify the presence of transgenes. Insulin and glucose were monitored using commercial strips.Results: Larger amplitude and a reduced desensitization of TRPV1 currents were induced by dietary capsaicin in TCR-HA+/-/Ins-HA+/- mice. These data closely resemble changes identified in streptozotocin-induced diabetes in rats upon superfusion of capsaicin in cell culture . Capsaicin treatment reduced the TRPV1 expression in the double-transgenic diabetic mice. Conclusions: In diabetes, the link between abnormal pain sensitivity and hyperglycemia resulting from insulin deficiency is not clear, but our study proves that capsaicin plays a major role in regulating TRPV1 function and expression in diabetes. In addition, dietary capsaicin is able to decrease the glucose and insulin levels, and in principal may reduce the oxidative status induced by hyperglycemia deficiency is not clear, but our study proves that capsaicin plays a major role in regulating TRPV1 function and expression in diabetes. In addition, dietary capsaicin is able to decrease the glucose and insulin levels, and in principal may reduce the oxidative status induced by hyperglycemia conditions. This study was financed by the research grant PNCDI2 41-074/2007