脑内多巴胺能神经元的细胞体主要分布在黑质致密部

由此发出黑质纹体束进入同侧尾核、壳核和杏仁核。尾核内多巴胺(DA)浓度增高时

可能有对抗电针镇痛的作用。本文向黑质内微量注射DA

观察当黑质DA能神经元本身的胞体和树突受到高浓度DA的作用时

对电针镇痛作用的影响。方法实验动物为白色家兔

体重2公斤左右

雌雄不拘。实验前

在氨基甲酸乙酯(0.75克/公斤)轻麻下

按Sawyer氏图谱

向两侧黑质埋植不锈钢管(P_5、H_(-5)、L、R_4)。套The dopaminergic neurons in the brain are mainly distributed in the pars compacta of the substantia nigra and send up the nigrostriatal bundle to ipsilateral caudate

putamen and amygdalae nucleus. The increase of concentration of dopamine in the caudate appears to have an electroacupun- cture analgesic effect. In the present study we injected dopamine (7.5μg/μl) 2 μl into the bilateral substantia nigra through the chronic implanted stainless steel cannulae in order to observe the effect of dopamine in the substantia nigra on the electroacupuncture analgesia. The pain threshold was determined by the latency of withdrawal of head when the radiant heat was applied on the nose tip of rabbits. The results showed that injection of dopamine into bilateral substantia nigra increased the pain threshold and the analgesic effect by electroacu- puncture in "Zu San Ii" Was also increased. The dopamine in the substan- tia nigra might play a negative feedback inhibition effect on the cell bodies and dentrities of the dopaminergic neurons

and therefore the dopamin discharge from their axon terminals was reduced.