电刺激猫中脑导水管周围灰质和中缝大核对脊髓背角神经元伤害性感受反应的抑制

1.在氯醛糖麻醉的猫上,观察了电刺激中脑导水管周围灰质(PAG)和中缝大核(NRM)对脊髓腰段背角神经元传入活动的影响。2.按照对刺激的反应型式,在背角记录到非伤害性低阈值传入、广动力范围、伤害性热敏以及高阈值传入诱发的自发放电抑制等四类神经元。3.刺激 PAG和 NRM对记录到的多数背角神经元皮肤传入反应有明显抑制效应,而对自发放电抑制性神经元产生去抑制。4.比较刺激两脑区的抑制效应:NRM 作用较PAG 强;PAG 活动对背角伤害性反应抑制的选择性较 NRM强;阿片肽拮抗剂-纳洛酮拮抗NRM刺激的抑制。5.这些结果提示PAG和NRM对脊髓的下行抑制,可能有一部分是通过不同神经机制实现的。

INHIBITORY EFFECTS OF STIMULATION OF PERIAQUE-DUCTAL GREY AND RAPHE NUCLEUS MAGNUS ON NOCICEPTIVE RESPONSES IN CAT'S SPINAL DORSAL HORN NEURONS

1. Inhibitory effects of conditioning stimuli applied to the periaqueductalgrey (PAG) and nucleus raphe magnus (NRM) on the nociceptive and non-noci-ceptive responses of spinal dorsal horn neurones was studied in chloralose-anaes-thetized cats. 2. Single dorsal horn neurone was recorded extracellularly in the lumbarspinal cord. According to the pattern of their responses to stimuli, the neuroneswere classified as non-nociceptive low-threshold, wide dynamic range (WDR),nociceptive heat sensitive and inhibition of spontaneous discharges elicited bystimulation of high-threshold afferents. 3. The majority of dorsal horn neurones tested were markedly inhibitedby PAG and NRM stimuli. 4. NRM-induced inhibition was more powerful than PAG-induced one andwas antagonized by naloxone (i.v.). Nociceptive response was preferentiallyinhibited by PAG stimulation and both the nociceptive and non-nociceptive res-ponse were inhibited by NRM stimulation. 5. The results suggest the involvement of the different neural machnismsin inhibitory effects of PAG and NRM descending on the activity of spinal dorsalhorn.