Luteolin reduces sciatic nerve damage and modulates TRPV1 and TRPM2 expression in diabetic rats

BACKGROUND: Hyperglycemia drives peripheral nerve damage through oxidative stress, inflammation, and apoptosis, yet the role of redox-sensitive ion channels in linking these processes remains poorly understood. OBJECTIVE: This study investigates the neuroprotective effects of luteolin (LUT) on streptozotocin (STZ)-induced peripheral nerve damage, with particular focus on TRPV1 and TRPM2 channels. METHODS: Diabetes mellitus (DM) was induced in Wistar rats by a single dose of STZ (45 mg/kg). Animals were divided into four groups: control, LUT, DM, and DM+LUT. LUT (100 mg/kg/day) was administered intragastrically for 21 days, followed by biochemical, histopathological, and immunohistochemical analyzes of the sciatic nerve. RESULTS: Hyperglycemia significantly elevated oxidative stress markers (MDA, ROS), pro-inflammatory cytokines (IL-1β, IL-6, TNF-α), neuropeptides (CGRP, Substance P), and apoptotic markers (caspase-3, caspase-9, Bax), while reducing antioxidant defenses and BDNF levels. These changes were accompanied by upregulated TRPV1 and TRPM2 expression and marked histopathological deterioration. LUT treatment significantly reversed these parameters and preserved sciatic nerve tissue morphology. CONCLUSIONS: LUT attenuates diabetes-associated sciatic nerve damage and modulates TRPV1 and TRPM2 expression. To our knowledge, this is the first study to examine luteolin's effects on redox-sensitive TRP channels simultaneously in an STZ-induced sciatic nerve model.