Role Of Astrogial Glutamate-glutamine Shuttle In The Development Of Neuro-pathic Pain In Rats

Objective:To investigate the role of astroglial glutamate-glutamine shuttle in the formation of neuropathic pain in rats.Methods:Forty eight male SD rats weighing 200-230 g were randomly divided into 8 groups(n=6):groupⅠcontrol (group C); groupⅡsham(group S); groupⅢNP. In group C no operation was performed. In group S the sciatic nerve was exposed but not ligatad. GroupⅢNP was induced by ligating the tibial nerve and commom peroneal nerve according to the technique described by Dixon. After establishing of SNI model, group NP was intrathecal injected 50μl PBS; Group M1-4 was intrathecal injected 0.01,0.03,0.05,0.10 mmol/L MSO(Methionine sulfoximine,50μl each); At 15 minutes after intrathecal injected 50μl 0.05mmol/L MSO, then group MG was intrathecal injected 50μl 0.25 mmol/L glutamine. Mechanical pain threshold was measured before ligating (T0, baseline),7 day after ligating (T1) and 15min(T2),30min(T3),45min(T4),60min(T5) after i.t. injected MSO. Then, rats were killed and the spinal cord of L4-6 were removed and were carried out immunohistochemical staining and observed the change of expression or co-expression of GFAP, GS and GFAP/GS at dorsal horn of spinal cord. Results:Mechanical pain threshold were significantly lower in T1-5 in group MG and group NP than group S and group C. In group MG and group NP, the expression of GFAP, GS, GFAP/GS in spinal cord increase in T5 (P<0.05). These indexes was no significant difference in group MG and group NP(P>0.05).Conclusion:Astroglial glutamate-glutamine shuttle in spinal cord is involved in the formation of neuropathic pain in rats.