Intrathecal [6]-gingerol administration alleviates peripherally induced neuropathic pain in male Sprague-Dawley rats.

[6]-Gingerol, a structural analog of capsaicin, is an agonist of the transient receptor potential vanilloid 1 channel, which is known to have therapeutic properties for the treatment of pain and inflammation. The main objective of this study was to determine the central effect of [6]-gingerol on neuropathic pain when injected intrathecally at the level of the lumbar spinal cord. [6]-Gingerol distribution was evaluated following a 40 mg/kg intraperitoneal injection, and the brain-to-plasma and spinal cord-to-plasma ratios (0.73 and 1.7, respectively) suggest that [6]-gingerol penetrates well the central nervous system of rats. Induction of pain was performed using the sciatic nerve ligation model on rats, and a 10-µg intrathecal injections of [6]-gingerol was performed to evaluate its central effect. The results suggest a significant decrease of secondary mechanical allodynia after 30 min, 2 h and 4 h (p < 0.05, p < 0.01 and p < 0.001) and thermal hyperalgesia after 30 min, 2 h and 4 h (p < 0.05, p < 0.01 and p < 0.01). These promising results illustrate that [6]-gingerol could alleviate neuropathic pain by acting centrally at the level of the spinal cord.