Anti-Neuropathic Pain Activity of Epigallocatechin Gallate in an Experimental Diabetic Neuropathic Pain Via Inhibition of TRPV1 and iNOS

INTRODUCTION: Diabetic neuropathic pain (DNP) is an important complication of diabetes. EGCG is known to have antioxidant, anti-inflammatory, and antidiabetic effects. TRPV1 channel and iNOS are pain-related pathways. Our study aimed to investigate the effects of EGCG on the sciatic nerve and the role of the TRPV1 channel and İNOS in the experimental DNP.
METHODS: Animals were divided into 4 groups (n=7): Control, EGCG, DNP, DNP+EGCG. Throughout the study (days 0, 3, 8, 14, 17), the average weight change of the groups, average blood sugar levels, hot plate, and tail dipping tests were performed. Sciatic nerve samples were examined with stereological, histopathological, and immunohistochemical methods.
RESULTS: According to the findings of the study, the hot plate and tail dipping times were significantly shortened in the DNP group. The hot plate, tail dipping times were longer in the DNP+EGCG group. Axonal degeneration was detected in the DNP group. DNP+EGCG was found to have less deterioration in axons compared to DNP. While intense TRPV1 and INOS expression was observed in the DNP group, low TRPV1 and İNOS expression was observed in the Control, EGCG, and DNP+EGCG groups. No significant difference was observed between the groups in terms of sciatic nerve area. While the number of axons significantly decreased in the DNP group, EGCG treatment prevented the decrease in axons.
DISCUSSION AND CONCLUSION: The results of this study showed that EGCG treatment can modulate pain tolerance by reducing TRPV1 and İNOS expressions, blood glucose levels, alleviating sciatic nerve deterioration, and modulating the hot plate and tail dipping times.

Keywords: diabetic neuropathic pain, epigallocatechin gallate, inducible nitric oxide synthase, rat, sciatic nerve, transient receptor potential vanilloid 1