Effect of intrathecal dexmedetomidine on expression of GIRK1 in dorsal root ganglia of rats with diabetic neuropathic pain / 中华麻醉学杂志

ABSTRACT

Objective To evaluate the effect of intrathecal dexmedetomidine on the expression of G-protein-coupled inwardly rectifying K+ channel 1 (GIRK1) in dorsal root ganglia of rats with diabetic neuropathic pain (DNP).Methods A total of 144 healthy adult male SPF Sprague-Dawley rats,aged 8-10 weeks,weighing 200-220 g,were randomly divided into 4 groups (n =36 each) using a random number tablecontrol group (group C),dexmedetomidine group (group D),group DNP,and DNP + dexmedetomidine group (group DD).DNP model was established by single intraperitoneal injection of streptozotocin (STZ) 60 mg/kg.In D and DD groups,dexmedetomidine 1.5 μg/kg was injected intrathecally at 14 days after citrate buffer or STZ injection,while the equal volume of normal saline was given in group C.The mechanical pain threshold was measured before STZ injection (T0),at 14 days after STZ injection (T1),and at 2,4 and 6 h after intrathecal injection (T2-4).After measurement of the mechanical pain threshold at T2-4,the rats were sacrificed,and the dorsal root ganglia of the lumbar segment (L4-6) were removed for determination of the number of GIRK1 positive cells and expression of GIRK1 protein by immunofluorescence and Western blot,respectively.Results Compared with group DNP,the mechanical pain threshold was significantly increased,the number of GIRK1 positive cells in dorsal root ganglia was significantly increased,and the expression of GIRK1 was significantly up-regulated at T2-4 in group DD (P＜0.05).Compared with group D,the number of GIRK1 positive cells in dorsal root ganglia was significantly increased,and the expression of GIRK1 was significantly up-regulated at T2-4 in group DD (P＜0.05).Compared with group C,the mechanical pain threshold was significantly decreased at T1-4 in group DNP (P＜0.05).Conclusion Intrathecal dexmedetomidine attenuates DNP through up-regulating the expression of GIRK1 in dorsal root ganglia of rats.