Role of N-methyl-D-aspartic acid receptor 2B in neuropathic pain induced by spinal nerve ligation in rats / 医学研究生学报

ABSTRACT

Objective Spinal cord injury-induced neuropathic pain(NP)does not respond well to any existing therapies clinically.This study aimed to explore the molecular metabolisms neuropathic pain by observing the expressions of the N -methyl-D-as-partic acid receptor 2B(NR2B),tumor necrosis factor-alpha(TNF-α)and brain-derived neurotrophic factor(BDNF)in different sta-ges of the condition in SD rats. Methods Thirty-six adult SD rats were randomly divided into a control,a sham operation and an NP model group.The NP model was established by spinal nerve ligation. At 5 and 14 days after modeling,the hindlimb motor function and paw withdrawal threshold(PWT)of the rats were evaluated by the open-field test and the expressions of NR 2B,TNF-αand BDNF in the dor-sal root ganglia of the L4-6 spinal cord were determined by Western blot. Results At 5 days after modeling,the open-field test showed a significantly shorter total distance of movement in the sham operation group than in the control([14 927.93 ±560.87]vs [18 225.15±371.76]mm,P<0.05)and even shorter in the NP model group([3 224.92±89.64]vs[18 225.15±371.76]mm, P<0.01).The time of activity was markedly decreased in the NP model group as compared with that in the control([203.48±19.94]vs [745.95±13.48]s,P<0.01),but with no statistically significant difference between the sham operation and control groups([727.93± 16.29]vs[745.95±13.48]s,P>0.05).At 14 days after modeling,both the total distance of movement and time of activity were re-markably shorter in the NP model than in the sham operation and control groups([3 395.53±96.12]vs[17 382.26±482.31]and [17 975.40±416.56]mm,P<0.01;[195.53±96.12]vs[739.31±18.36]and[775.20±16.84]s, P<0.01).The PWT showed no statistically significant difference among the three groups of rats before modeling(P>0.05)but markedly decreased in the NP model as compared with the sham operation and control groups(P<0.01),with no significant difference between the latter two(P>0.05).The expressions of NR2B,TNF-αand BDNF were remarkably up-regulated in the NP model group in comparison with the sham operation and control groups at 5 days after modeling(P>0.05)and even more significantly at 14 days(P<0.01). Conclusion NR2B and BDNF may be involved in the development and progression of neuropathic pain in rats.