电刺激黑质对脑干伤害性单位放电的影响

THE EFFECTS OF ELECTRICAL STIMULATION OF SUBSTANTIA NIGRA ON NOCICEPTIVE-UNITS DISCHARGE IN BRAINSTEM

本实验采用单细胞外记录神经元单位放电的方法，在Ｗｉｓｔａｒ大鼠上观察到网状巨细胞核。一区伤害性神经元５７个，其中伤害兴奋性神经元（ＮＥＮ）４２个，伤害抑制性神经元（ＮＩＮ）１５个。电刺激黑质对ＮＥＮ（２９）和ＮＩＮ（８的放电呈抑制作用，其反应百分率分别由刺激黑质第１分钟时的１．０±２．１％和－２０．４±６．２％，降到第５分钟时的－８３．６±１２．３％和－６５．４±１０．７％（Ｐ＜０．０１）。刺激黑质对少数ＮＥＮ（１３）和ＮＩＮ（７）的放电有兴奋作用，其值分别由第］分钟时的２０．５±７．３％和１．０±３．４％，升高到第５分钟时的７４．５±１０．７％和２１，５±８．６％（Ｐ＜０．０５）。氟哌啶醇注入ＰＡＧ腹外侧部可阻断刺激黑质的效应，这提示从黑质到网状巨细胞核α－区存在着一条痛调制通路，而且这种通路的递质是多巴胺能的。

Extracellular recordings of the discharges of 57 neurons were made in gigantocellularis pars alpha (NGC a) of Wistar Rat. Two patterns of nociceptive response were classified as 'nociceptively excited neurons' (NEN, n=42) and 'nociceptively inhibited neurons'(NIN, n=15), respectively. Electrical stimulation of the substantia nigra (SNS) suppressed spontaneous discharges in most neurons and enhanced them in a few neurons of NEN and NIN.These effects of SNS were blocked by injection of Haloperidal (Halo) into ventrolateral parts of the periaqueductal gray matter (PAG). The results suggest that there exists a pain modulation pathway from SN to NGC a mediated by dopaminergic transmitter.