Role of saphenous nerve in the behavioral responses of neuropathic pain – due to chronic constriction injury in rats

Introduction: The chronic constriction injury (CCI) was introduced by Bennett and Xie in 1988 as an animal model of peripheral mononeuropathy. In this model, serious sensitivity to the thermal and mechanical allodynia and hyperalgesia is increased the areas in which sciatic nerve innervated. The spread of receptive fields of the saphenous nerve which innervates the medial part of the foot. In this study, we have examined the behavioral effects of the section of saphenous nerve at the time of applying CCI. Material and Methods: Adult male Sprague – Dawley strain, with the weight 200 – 300 grs, used for experiments. Animals divided into four groups: sham operated, CCI group, cut of saphenous nerve (saph.) and CCI + saph. Two weeks after post operation, animals tested for behavioral responses: thermal allodynia (acetone blob and immersion of hind paw in 10°C water) thermal hyperalgesia (immersion of hind paw in 42°C water) mechanical allodynia (Von Frey), mechanical hyperalgesia (Pin Prick) and usage of damage paw. Results: All symptoms of the neuropathic pains were appeared among all animals which went under CCI. CCI + Saph group showed analgesia, thermal allodynia and hyperalgesia, mechanical hyperalgesia and also usage of damage paw, except in mechanical allodynia. Conclusion: Results indicated that saphenous nerve may affect on behavioral responses of neuropathic pain related CCI. Saphenous nerve (as a neighboring with sciatic nerve) may affecte on behavioral responses of neuropathic pain, probably by making collateral branches which may penetrate into the damage area.