Wong C L, Chan Y S, Cheung Y M, Hwang J C, Poon P W, Wong T M
Methods Find Exp Clin Pharmacol. 1986 Jun;8(6):351-5.
The effects of superfusion of morphine, met-enkephalin and D-ala2-met5-enkephalinamide on the spontaneous neural discharge rates of units in the spinal trigeminal nucleus and cuneate nucleus of decerebrate cats were studied. The drugs were superfused onto the dorsum of the exposed surface of the caudal medulla overlying these nuclei. Some of these neurons were identified by their response to innocuous mechanical stimuli delivered to the skin. In the caudal spinal trigeminal nucleus, morphine caused a dose-dependent suppression of the spontaneous discharge rate in the majority of the neurons studied. Endogenous opiate peptide, met-enkephalin or its synthetic analogue, D-ala2-met5-enkephalinamide caused an initial reduction, followed by a rebound of the discharge rate to the control value. These depressant effects of morphine and enkephalins were antagonized by concomitant superfusion of the opiate antagonist naloxone. In the main cuneate nucleus, however, similar doses of morphine, met-enkephalin and D-ala2-met5-enkephalinamide have little if any significant effect on the spontaneous activity of the neurons studied. These results provide electrophysiological evidence for the presence of opiate receptors in the caudal spinal trigeminal nucleus and the relative lack of such receptors in the main cuneate nucleus.
研究了吗啡、甲硫氨酸脑啡肽和D-丙氨酸2-甲硫氨酸5-脑啡肽酰胺对去大脑猫三叉神经脊束核和楔束核中单位自发神经放电率的影响。将这些药物灌注到覆盖这些核的延髓尾部暴露表面的背侧。其中一些神经元通过它们对施加于皮肤的无害机械刺激的反应来识别。在三叉神经脊束核尾部，吗啡在大多数研究的神经元中引起剂量依赖性的自发放电率抑制。内源性阿片肽、甲硫氨酸脑啡肽或其合成类似物D-丙氨酸2-甲硫氨酸5-脑啡肽酰胺引起放电率先降低，随后反弹至对照值。吗啡和脑啡肽的这些抑制作用被阿片拮抗剂纳洛酮的同时灌注所拮抗。然而，在楔束核主核中，相似剂量的吗啡、甲硫氨酸脑啡肽和D-丙氨酸2-甲硫氨酸5-脑啡肽酰胺对所研究神经元的自发活动几乎没有显著影响。这些结果为三叉神经脊束核尾部存在阿片受体以及楔束核主核中相对缺乏此类受体提供了电生理证据。
