The role of T-type calcium channel in the pathogenesis of neuropathic pain in rats / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of intrathecal(IT)mibefradil on the mechanical and thermal hyperalgesia following chronic compression of dorsal mot ganglion(CCD)in rats,trying to elucidate the role of T-type calcium channels in the nociceptive signal transmission at spinal level.Methods Forty-eight male SD rats weighing 230-250 g were randomly divided into 6 groups(n=8 each)group Ⅰ sham operation;group Ⅱ CCD;group Ⅲ CCD+normal saline(N.S.)and group Ⅳ,Ⅴ,Ⅵ CCD+mibefradil 50 ?g(Ⅳ),100 ?g (Ⅴ),200 ?g(Ⅵ).The animals were anesthetized with intraperitoneal(IP)1% pentobarbital 40 mg?kg~(-1). Intrathecal catheter was placed according to the technique described by Yaksh et al.Five days after IT catheter placement L_4 and I_5 dorsal root ganglion(DRG)compression(CCD)was performed in group Ⅱ-Ⅵ.In sham operation group(Ⅰ)only L_(4-5) transverse processes and intervertebral foramina were exposed but DRGs were not compressed.In group Ⅳ,Ⅴ,and Ⅵ 5 days after CCD model was established a bolus of mibefradil 50,100 and 200 ?g in 10 ?l NS was given IT.In group Ⅲ NS 10 ?l was given IT instead of mibefradil.Mechanical withdrawal threshold(MWT)using Von Frey filament and thermal withdrawal latency(TWL)using radiant heat applied to the plantar surface were measured before CCD(baseline)and 1,3,5,7,14 and 21 days after CCD in group Ⅰ and Ⅱ and before and 30,60,120,240 and 480 min after IT mibefradil in group Ⅲ-Ⅵ.Results The animals in group Ⅱ(CCD group)developed mechanical and thermal hyperalgesia from the 1st day after operation to the end of the experiment.IT mibefradil 50,100 and 200 ?g can all attenuate both mechanical and thermal hyperalgesia induced by CCD.Conclusion Spinal T-type calcium channel may play an important role in the pathogenesis of neuropathic pain.