多巴胺对大鼠背角WDR神经元的抑制不被酚妥拉明和纳洛酮所拮抗

INHIBITION OF DOPAMINE ON WDR NEURONS OF DORSAL HORN NOT ANTAGONIZED BY PHENTOLAMINE AND NALOXONE IN RATS

本实验用微电极细胞外记录方法研究了脊髓局部应用多巴胺对大鼠背角WDR神经元的抑制作用。实验在43只SD大鼠上共记录到54个WDR神经元。多巴胺的剂量从0.26×10^(-6)mol/kg-1.58×10^(-6)mol/kg逐步增加,其对伤害性经皮电刺激诱发的背角神经元后串放电的抑制作用也随之加强;0.52×10^(-6)mol/kg多巴胺的作用在给药后5min即出现,15min达高峰并在此后的25min基本维持在同一水平,这个作用可被静注多巴胺能受体拮抗剂氟哌啶(0.66×10^(-6)mol/kg)完全翻转,而不受静注酚妥拉明(2.65×10^(-6)mol/kg)和纳洛酮(1.37×10^(-6)mol/kg)影响。上述结果表明,多巴胺可能是参与脊髓水平伤害性信息传递调控的另一单胺类神经递质。

The inhibitory effects of dopamine (DA) applied spinally on the wide dynamicrange(WDR) neurons of dorsal horn in rats were studied with extracellular record-ing technique. 54 WDR units were tested from 43 rats. With a dosage of DAfrom 0.26×10^(-6) to 1.58×10^(-6) mol/kg, the inhibitory effect of the neurotransmit-ter on the responses of dorsal horn neurons to noxious transcutaneous electricalstimulation exhibited a gradual increase. After DA (0.52×10^(-6) mol/kg) admini-stration, the inhibitory effect of DA began to appear in 5 min and reach to maxim-um in 15 min, whereupon the maximum level could be maintained for about 25min. This effect of DA could be reversed completely by dopaminergic receptorantagonist, droperidol (0.66×10^(-6) mol/kg) but not by 2.65×10^(-6) mol/kg ph-entolamine or 1.37×10^(-6) mol/kg naloxone. The results of the present investil-gation suggest that DA may be involved in the modulation of nociception at thespinal level as an independent neurotransmitter.