Role of astroglial glutamate-glutamine shuttle in the development of neuropathic pain in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the role of astroglial glutamate-glutamine shuttle in the development of neuropathic pain (NP) in rats. Methods Forty-eight adult male SD rats weighing 200-230 g were randomly divided into 8 groups (n =6 each) Ⅰ control group (group C);Ⅱ sham operation group (group S);group ⅢNP;Ⅳ-Ⅶ 0.01, 0.03, 0.05 and 0.10 mmol/L methionine sulfoximine (MSO, an inhibitor of glutamine synthetase (GS)) group (group M1-4 );Ⅷ MSO + glutaminate group (group MG). In group C no operation was performed. In group S the sciatic nerve was only exposed but not ligated. NP was induced by ligation of the tibial nerve and commom peroneal nerve according to the technique described by Dixon. After the establishment of the model, intrathecal PBS 50 μl was injected in group NP, IT 0.01, 0.03, 0.05 and 0.10 mmol/L MSO 50 μl was injected intrathecally in group M1-4, and 0.05 mmol/L MSO 50 μl was injected intrathecally and then 0.25 mmol/L glutamine 50 μl was injected intrathecally 15 min later in group MG. Mechanical pain threshold was measured 1 week before ligation (T0 , baseline), 1 week after ligation (T1) and 15, 30, 45 and 60 min after injection of MSO (T2-5). Then rats were killed and the lumbar segment of the spinal cord was removed for determination of the expression of glial fibrillary acidic protein (GFAP) and GS and the co-expression (GFAP/GS) in the dorsal horn.Results Mechanical pain threshold was significantly lower at T1-5 in group MG and NP and at T2-4 in group M3.4 ,and the expression of GFAP, GS and GFAP/GS was significantly higher in group MG,NP and M3 than in group S and C ( P ＜ 0.05) .Conclusion Astroglial glutamate-glutamine shuttle in the spinal cord is involved in the development of neuropathic pain in rats.