Xu X J, Zhang X, Hökfelt T, Wiesenfeld-Hallin Z
Department of Medical Laboratory Sciences and Technology, Huddinge University Hospital, Sweden.
Brain Res. 1995 Jan 30;670(2):342-6. doi: 10.1016/0006-8993(94)01360-t.
We have examined and compared the effects of systemically applied MK-801, an NMDA receptor/channel blocker, on the wind-up and facilitation of the flexor reflex during and after conditioning stimulation (CS) of C-afferents in rats with intact sciatic nerves or 13-16 days after axotomy. In rats with intact sciatic nerves, intravenous MK-801 (0.5 mg/kg) partially reduced wind-up and totally blocked reflex facilitation following C-fiber CS to the sural nerve. In contrast, 13-16 days after unilateral section of the sciatic nerve, the same dose of MK-801 failed to reduce the wind-up and reflex facilitation following C-fiber CS to the axotomized sural nerve, although the duration of reflex facilitation was significantly shortened. These findings indicate that the involvement of NMDA receptors in mediating activity-dependent spinal hyperexcitability is substantially reduced after peripheral nerve section, possibly reflecting a reduced release of glutamate by primary sensory afferents.
我们研究并比较了全身应用NMDA受体/通道阻滞剂MK-801，对完整坐骨神经大鼠或轴突切断术后13 - 16天大鼠，在C类传入纤维条件刺激（CS）期间及之后屈肌反射的时间总和及易化作用的影响。在完整坐骨神经的大鼠中，静脉注射MK-801（0.5mg/kg）可部分降低时间总和，并完全阻断腓肠神经C纤维CS后的反射易化。相反，在单侧坐骨神经切断术后13 - 16天，相同剂量的MK-801未能降低对切断坐骨神经的腓肠神经进行C纤维CS后的时间总和及反射易化，尽管反射易化的持续时间显著缩短。这些发现表明，在周围神经切断后，NMDA受体介导活动依赖性脊髓兴奋性过高的作用显著降低，这可能反映了初级感觉传入纤维谷氨酸释放的减少。
