多巴胺对正常和吗啡成瘾大鼠疼痛相关电活动的不同作用

目的研究多巴胺对正常大鼠和吗啡成瘾大鼠中枢的伤害性刺激的传递的影响。方法在给予坐骨神经伤害性刺激后,记录中枢痛兴奋神经元的电活动,观察多巴胺对正常大鼠和吗啡成瘾大鼠中枢痛兴奋神经元电活动的影响。结果正常大鼠中,多巴胺使尾核痛兴奋神经元的痛诱发放电潜伏期缩短,说明多巴胺可使正常大鼠尾核痛兴奋神经元的活动增强,多巴胺受体拮抗剂氟哌利多可以阻断这种作用。吗啡大鼠中,多巴胺使尾核痛兴奋神经元的痛诱发放电潜伏期延长,说明多巴胺可使吗啡大鼠尾核痛兴奋神经元的活动减弱。结论脑室注射多巴胺后,正常大鼠和吗啡成瘾大鼠的尾核对痛刺激的反应存在着差异。

Differential effects of dopamine on pain-related electric activities in normal rats and morphinistic rats

Objective To investigate the influence of dopamine (DA) and DA receptor's antagonist on the transmission of noxious information in the central nervous system of normal rats or morphinistic rats. Methods The influence of DA on the electric activity of the pain-excited neuron (PEN) in the caudate nucleus (Cd) of normal rats or morphinistic rats was recorded after the sciatic nerve was noxiously stimulated. Results DA shortened the average latency of the evoked discharge of PEN in the Cd of normal rats, indicating that DA could increase the activity of PEN and pain sensitivity in normal rats. This effect could be inhibited by Droperidol. DA increased the average latency of the evoked discharge of PEN in the Cd of morphinistic rats, indicating that DA could inhibit the activity of PEN and pain sensitivity in morphinistic rats.Conclusion The responses to painful stimulation were completely opposite between normal rats and morphinistic rats after the intracerebroventricular injection of DA.