Role of glycogen synthase kinase-3β in trafficking of NR1-containing N-methyl-D-aspartate receptor and NR2B-containing N-methyl-D-aspartate receptor in spinal cord in rats with incisional pain and remifentanil-induced hyperalgesia / 中华麻醉学杂志

ABSTRACT

Objective To investigate the role of glycogen synthase kinase-3β (GSK-3β) in the trafficking of NR1-containing N-methyl-D-aspartate receptor (NMDAR) and NR2B-containing NMDAR in the spinal cord in rats with incisional pain (IP) and remifentanil-induced hyperalgesia.Methods Twenty-four male Sprague-Dawley rats,aged 2-3 months,weighing 240-260 g,were randomly divided into 3 groups ( n =8 each)control group (group C),remifentanil group (group R) and GSK-3β inhibitor TDZD-8 group (group TDZD-8).A 1-cm longitudinal incision was made in the plantar surface of the left hindpaw in anesthetized rats.In group C,dimethyl sulfoxide (DMSO) 2 ml/kg was injected and then the normal saline (equal to the volume of remifentanil) was infused for 60 min via the caudal vein.In group R,DMSO 2 ml/kg was injected before IP was made and then remifentanil was infused at a rate of 1.2 μg· kg- 1 ·min- 1 for 60 min.In group TDZD-8,TDZD-8 2 ml/kg was injected before IP was made and then remifentanil was infused at a rate of 1.2 μg·kg-1 ·min-1 for 60 min.Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured 24 h before infusion of normal saline or remifentanil and at 2,6,24 and 48 h after intravenous injection.The rats were sacrificed after the last measurement of the pain threshold and L4-6 segment of the spinal cord was removed to determine the expression of NMDAR NR1 and NR2B subunits in cell membrane (s) and cytoplasm (i) in the spinal cord by Western blot analysis.The ratios of sNR1/iNR1 and sNR2B/iNR2B were calculated.Results Compared with group C,PWT was significantly decreased and PWL was significantly shortened,the expression of sNR1 and sNR2B was up-regulated,the expression of iNR1 and iNR2B was down-regulated,and the ratios of sNR1/iNR1 and sNR2B/iNR2B were significantly increased in groups R and TDZD-8 (P ＜ 0.05).Compared with group R,PWT was significantly increased and PWL was significantly prolonged,the expression of sNR1 and sNR2B was down-regulated,the expression of iNR1 and iNR2B was up-regulated,and the ratios of sNR1/iNR1 and sNR2B/iNR2B were significantly decreased in group TDZD-8 ( P ＜ 0.05).Conclusion GSK-3β is involved in the regulation of trafficking of NR1-containing NMDAR and NR2B-containing NMDAR from cytoplasm to cell membrane in the spinal cord in rats with IP and hyperalgesia induced by remifentanil.