Abstract:

Objective To observe the changes of expression of brain-derived neurotrophic factor (BNDF) and glial fibrillary acidic protein (GFAP) in rats with spinal nerve ligation (SNL), and investigate the effects of TrkB/Fc, BDNF inhibitor on expression of GFAP and pain. Methods Eighteen SD rats were randomly divided into blank control group, sham operation group and SNL group (n=6). Values of 50% paw withdrawal threshold (50% PWT) were measured before surgery and on six consecutive days after surgery. Spinal dorsal horn of the spinal enlargement was obtained after last measurement for determination of expression of GFAP and BDNF by Western blotting. Another 18 SD rats were randomly allocated into control group, SNL+placebo group and SNL+TrkB/Fc group (n=6). Rats in control group only underwent intrathecal catheterization, while rats in SNL+placebo group and SNL+TrkB/Fc group received intrathecal injection of either PBS or TrkB/Fc 10 μL once before the operation of SNL catheterization and 6 times after the operation. Values of 50% PWT were measured 1 h before drug administration. Spinal dorsal horn of the spinal enlargement was obtained 1 h after last injection for determination of the expression of GFAP by Western blotting. Results On the first to the sixth days after operation, values of 50% PWT on the ipsilateral hindpaw in SNL group were significantly lower than the baseline value before operation (P<0.01). On the sixth day after operation, the expression of BDNF and GFAP in the ipsilateral dorsal horn in SNL group was significantly higher than that in blank control group (P<0.01). However, the value of 50% PWT in the ipsilateral hindpaw in SNL+TrkB/Fc group was not significantly different from the baseline value (P>0.05), and the expression of GFAP in SNL+TrkB/Fc group was also not significantly different from that in control group (P>0.05). Conclusion BDNF-induced astrocyte activation contributes to the development of neuropathic pain produced by SNL.

Key words: brain-derived neurotrophic factor, glial fibrillary acidic protein, astrocyte, neuropathic pain