Changes in phosphorylation of NMDA receptors in spinal dorsal horns in a rat model of neuropathic pain induced by chronic compression of dorsal root ganglion / 中华麻醉学杂志

ABSTRACT

Objective To investigate the changes in the phosphorylation of N-methyl-D-aspartate (NMDA) receptors in spinal dorsal horns in a rat model of neuropathic pain induced by chronic compression of dorsal root ganglion (CCD).Methods Ninety-six male Sprague-Dawley rats,weighing 200-250 g,were randomly divided into 3 groups (n =32 each) using a random number tablecontrol group (group C),sham operation group (group S) and group CCD.In CCD group,a small stainless steel needle (4 mm in length and 0.8 mm in diameter) was inserted into the L4,5 intervertebral foramen in pentobarbital sodium-anesthetized rats,developing intervertebral foramen stenosis and hence producing a chronic steady compression of the dorsal root ganglion.In group S,the intervertebral foramen was only exposed without inserting the needle.The paw withdrawal latency (PWL) was measured at 1 day before operation and 1,2 and 4 weeks after operation.The rats were then sacrificed after measurement of PWL and the lumbar enlargement segments of the spinal cord were removed for determination of the expression of interleukin-1β (IL-1β) and phosphorylation of NMDA receptor NR1 subunits at serine 896 (pNR1S896) on the injured side by immunohistochemistry and Western blot.Results Compared with group C,the PWL was significantly shortened at each time point after operation,and the expression of IL-1β and pNR1S896 was up-regulated in group CCD,and the PWL was shortened at 1 week after operation,the expression of IL-1β and pNR1S896 was up-regulated,and no significant change was found in PWL and expression of IL-1β and pNR1S896 at the other time points in group S.Compared with group S,the PWL was significantly shortened at each time point after operation,and the expression of IL-1β and pNR1S896 was up-regulated in group CCD,Compared with the baseline value at 1 day before operation,the PWL was slowly shortened starting from 1 week after operation,and decreased to the lowest level at 2 weeks after operation and maintained at this level for 2 weeks,the expression of IL-1β and pNR1S896 was slowly up-regulated starting from 1 week after operation,and increased to the highest level at 2 weeks after operation and maintained at this level for 2 weeks in group CCD,and the PWL was shortened at 1 week after operation,and the expression of IL-1β and pNR1 S896 was up-regulated in group S.Conclusion The development and maintenance of neuropathic pain induced by CCD are related to phosphorylation of NMDA receptors in spinal dorsal horns of rats.