اثر تجویز نخاعی مسدودکننده اتصال‌های منفذدار به همراه آگونیست و آنتاگونیست گابا A بر پاسخ‌های رفتاری به درد شیمیایی در موش صحرایی نر

 Background and Objective: GABAergic inhibitory interneurons are distributed in spinal cord for pain sensation, so that muscimol and bicuculline (GABAA agonist and antagonist) reduces and enhances pain, respectively. Gap junctions (Gj) are membrane contacts for exchanging the signaling agents and small metabolites. Using spinal administration (i.t) of carbenoxolone (Gj blockers), this study tried to understand the Gj and spinal GABAergic system roles on chemical pain sensation.   Materials ad Methods: Male Wistar rats (200-250 g) were divided into 8 groups (n=7). The drugs were injected at 10 μl volume intrathecally including carbenoxolone (1nM), muscimol (0.3 μg) and bicuculline (0.3 and 0.6 μg) individually or as a form of co-treatment. Sub-plantar injection of 0.05 ml of 2.5% formalin was used and pain related behaviors were recorded for 1 hour.   Results: Carbenoxolone and muscimol reduced pain (p<0.01 and p<0.05, respectively), and bicuculline elevated pain (p<0.01) induced by formalin. Carbenoxolone co-treatment with muscimol reduced pain more than each one (p<0.05). Administration of carbenoxolone reduced hyperalgesia induced by bicuculline (p<0.05).    Conclusion: Muscimol analgesic effect elevation and bicuculline hyperalgesic effect alleviation followed by Gjs blockade might be explained when the existence of Gj is considered between a primary inhibitory interneuron effective on a secondary interneuron which inhibits spinal pain projection neurons.