Changes in total and surface N-methyl-D-aspartate receptor NR1, NR2A and NR2B subunits in spinal cord in a rat model of incisional pain-remifentanil-induced hyperalgesia / 中华麻醉学杂志

ABSTRACT

Objective To investigate the changes in total and surface N-methyl-D-aspartate receptor (NMDAR) NR1,NR2A and NR2B subunits in spinal cord in a rat model of incisional pain(IP)-remifentanil-induced hyperalgesia.Methods Thirty-two male SD rate in which caudal vein catheter were successfully placed were randomly divided into 4 groups ( n =8 each)control group(group C),remifentanil group(group R),IP group (group I) and IP + remifentanil group (group R + I).In groups R and C remifentanil 1.2 μg· kg-1 · min-1 or the same volume of normal saline was infused intravenously for60 main.In groups R + I and I,a 1 cm longitudinal incision was made in the plantar surface of left hindpaw and remifentanil 1.2 μg· kg-1 ·min-1 or the same volume of normal saline was infused intravenously for 60 min.Paw withdrawal threshold (PWT) and paw withdrawal latency (PWL) were measured at 24 h before and 2,6,24,48 h after remifentanil or normal saline administration.The animals were sacrificed after last pain threshold measurement.The L4-6 segment of the spinal cord was isolated for determination of the expression of the total and surface NMDAR NR1,NR2A and NR2B subunits in spinal cord by Western blot.The ratio of surface NR2B/NR2A was calculated.Results Compared with group C,PWT was significantly decreased,PWL shortened,the expression of the total and surface NMDAR NR1,NR2A and NR2B subunits up-regulated and the ratio of surface NR2B/NR2A increased in groups 1,R and R + I( P ＜ 0.05).Compared with groups R and I,PWT was significantly decreased,PWL shortened,the expression of the total and surface NMDAR NR1,NR2A and NR2B subunits up-regulated and the ratio of surface NR2B/NR2A increased in group R + I( P ＜ 0.05).There was no significant difference in the total and surface NMDAR NR2A subunits among the four groups( P ＞ 0.05).Conclusion The up-regulation of total and surface NMDAR NR1 and NR2B subunits and the increased percentage of surface NR2B subunits in rats spinal cord may be involved in the development of incisional pain- remifentanil- induced hyperalgesia.