بررسي نقش گيرنده هاي NMDA بر اثرات كورتيكوسترون بر پاسخ هاي رفتاري درد در مدل نوروپاتي CCI در موش سفيد آزمايشگاهي

The role of NMDA receptors in the effects of corticosterone on CCI model neuropathic pain in rats

Introduction: Previous studies have shown that glucocorticoids play an important role in neuropathic pain behaviors, but the underlying mechanisms are not known. The aim of this study was to determine the role of NMDA receptors in the effects of glucocorticoids on neuropathic pain behaviors in CCI model in rats. Materials and Methods: Male adult Wistar rats (200-300 gram) were used in this study. Chronic constriction nerve injury (CCI) rats were produced by loosely ligating a common sciatic nerve. Two weeks after inducing CCI, the effects of corticosterone in the presence or absence of MK-80 I (a blocker of NMDA receptor) were studied. Behavioral pain responses (thermal hyperalgesia and thermal and mechanical anodynia) were studied using standard procedures. Results: Findings indicated that peripheral administration of corticosterone suppressed both hyperalgeisa and anodynia in a dose-dependent manner. MK-80 I (0.3 mglkg) pretreatment attenuated the effects of corticosterone (l5mglkg) on both thermal hyperalgesia and mechanical allodynia. Also MK-801 alone suppressed thermal anodynia, but not thermal hyperalgesia and mechanical anodynia. Conclusion: These findings show that glucocorticoids play an important role in neuropathic pain behaviors. It seems that at least part of glucocorticoids effects on these behaviors may mediate through NMDA receptors suggesting an involvement of non-genomic mechanisms. Our findings suggest a potential role for glucocorticoid receptors agonist in combination of NMDA receptors antagonists in clinical management of neuropathic pain.