The role of ?1-adrenergic antagonists in an experimental model of neuropathy: chronic constriction injury (CCI) and CCI along with saphenoctomy

In this study the behavioral effects of sectioning the saphenous nerve at the time of application of the loose ligature and the effect of a selective ?1-adrenergic antagonist for two weeks after tying ligatures was examined. Male Sprague-Dawley rats were used in this study. Animals were divided into six groups: Sham-operated, sciatic nerve ligation (CCI), saphenous nerve section (Saph), CCI + Saph, CCI with IP injection of prazocin (CCI+Pra) and CCI + Saph with IP injection of prazocin (CCI+Saph+Pra). Two weeks after induction of neuropathy, animals tested for thermal allodynia, mechanical allodynia, thermal hyperalgesia, and mechanical hyperalgesia. Animals that underwent CCI all had signs of the neuropathic pain. The group CCI + saphenoctomy showed analgesia except in mechanical allodynia. Injection of prazocin in CCI group relieved thermal allodynia and mechanical hyperalgesia, but had no effect on mechanical allodynia and thermal hyperalgesia. Injection of prazosin to CCI+Saph group only relieved mechanical allodynia as compare to CCI+Saph. Meanwhile, comparison between CCI+Saph+Pra with CCI+Pra showed a significant increase in thermal allodynia and mechanical hyperalgesia and CCI group showed a relief in mechanical allodynia and hyperalgesia and thermal allodynia. It may be hypothesized that the hyperesthesia of the sciatic territory, as induced by ?1-adrenergic antagonists, could mediate saphenous collateral sprouts that invade a partially-denervated territory.