Effect of Epigallocatechin Gallate (EGCG) as an Adjuvant to Paracetamol on Pain Scale and TRPV1 Expression in a Rat Model of Neuropathic Pain

Abstract

Background & Objective: Neuropathic pain remains challenging to treat due to peripheral and central sensitisation involving oxidative stress, neuroinflammation, and dysregulation of ion channels such as transient receptor potential vanilloid 1 (TRPV1). Epigallocatechin gallate (EGCG), the major catechin in green tea, has antioxidant and anti-inflammatory properties that may complement the central analgesic effects of paracetamol. This study examined whether EGCG enhances paracetamol’s analgesic efficacy in a chronic constriction injury (CCI) model of neuropathic pain, by assessing mechanical pain thresholds and TRPV1 expression.

Methods: This experimental study used male Wistar rats (150–200 g, 2–2.5 months old) with neuropathic pain induced by Chronic Constriction Injury (CCI) of the right sciatic nerve. The rats were assigned to three groups: control, paracetamol (200 mg/kgBW), and paracetamol + EGCG (40 mg/kgBW). Pain threshold was assessed using the Electronic Von Frey Test, and TRPV1 levels were measured by ELISA. Data were analyzed with ANOVA and Spearman correlation tests.

Results: The combination of paracetamol and EGCG significantly lowered TRPV1 levels and increased pain threshold compared to other groups (p < 0.05). TRPV1 expression was highest in the control and lowest in the combination group. A strong negative correlation was found between TRPV1 levels and pain intensity (rs = –0.711; p = 0.010), indicating that reduced TRPV1 was associated with less pain.

Conclusions: EGCG enhances the antinociceptive effects of paracetamol by reducing TRPV1 expression and improving nociceptive behaviour. EGCG shows potential as a safe, non-opioid adjuvant for neuropathic pain management.