Effects of aminoguanidin on the neuropathic behavioral responses of chronic constriction injury model in rat

Introduction: Previous studies have shown that different mechanisms are involved in neuropathicpain. Increasing nitric oxide (NO) in the location of injury may be an effective factor in neuropathicpain which, in turn, acts through increasing membrane permeability. The aim of this study was toexamine the effects of aminoguanidin, a specific inhibitor of inducible nitric oxide synthetase (iNOS)on neuropathic pain behaviors.Materials and Methods: Male Wistar rats (200-300 gram) were used. Chronic constriction injury(CCI) in the rats were produced by four loosely ligation that the distance between them is 1 millimeterbefore the triple branching of sciatic nerve. Two weeks later, the animals were tested for thermalhyperalgesia and mechanical allodynia. Aminoguanidine were injected (I.P) 60 min before test indoses of 75, 150 and 300 mg/kg.Results: Our studies showed CCI induced neuropathic pain in all rats. All doses of aminoguanidin(75, 150, 300 mg/kg) significantly reduced mechanical allodynia and thermal hyperalgesia incompared with CCI group. Moreover, the effect of aminoguanidin on thermal hyperalgesia at dose of300 mg/kg was significantly higher than two lower doses.Conclusion: According to findings of this and other studies, aminoguanidin has an importantinfluence in reducing neuropathic pain. This effect, at least in part, is mediated through inhibition ofiNOS. Additionally, an inhibition of di-aminoxidase or anti oxidative effects may be contributed toinhibitory effects of aminoguanidin on neuropathic pain. Thus, further investigations can determinethe mechanism of aminoguanidin effects in neuropathic Pain. Findings of this study open a newwindow for synthesis of new drugs for management of neuropathic pain in clinic.