Dashwood M R, Muddle J R, Spyer K M
Department of Physiology, Royal Free Hospital School of Medicine, London, U.K.
Eur J Pharmacol. 1988 Oct 11;155(1-2):85-92. doi: 10.1016/0014-2999(88)90405-0.
The distribution of mu, delta and kappa opioid receptors in the lower brainstem of the cat has been determined autoradiographically by studying the binding of tritiated [D-Ala2,MePhe4,Glyol5][tyrosyl-3,5-3H]enkephalin (DAGO), [D-Pen2,D-Pen5][tyrosyl-3,5-(n)-3H]enkephalin (DPDPE) and [9-3H]ethylketazocine (EKC), respectively. General opiate receptor binding was established using [3H]naloxone (NX). High densities of [3H]NX and DAGO binding sites were found most prominently in the nucleus tractus solitarii. There was no DPDPE and very weak EKC binding within this nucleus, although both these ligands bound to the cerebellum. The effect of unilateral vagotomy on receptor density was examined. Sectioning the cervical vagus had no effect on the density of mu receptors in the brainstem. Sectioning the vagus, accompanied by nodose ganglion excision, led to a marked depletion of mu receptors which was restricted to dorsal and medial regions of the ipsilateral nucleus tractus solitarii at, and rostral to, the obex. These results suggest that mu opiate receptors are located presynaptically on vagal afferents terminating within a restricted region of the nucleus tractus solitarii.
通过分别研究氚标记的[D - Ala2，MePhe4，Glyol5][酪氨酸 - 3,5 - 3H]脑啡肽（DAGO）、[D - Pen2，D - Pen5][酪氨酸 - 3,5 - (n) - 3H]脑啡肽（DPDPE）和[9 - 3H]乙基酮唑辛（EKC）的结合情况，利用放射自显影术确定了猫脑桥下部μ、δ和κ阿片受体的分布。使用[3H]纳洛酮（NX）建立了一般阿片受体结合情况。发现[3H]NX和DAGO结合位点的高密度最显著地出现在孤束核中。尽管这两种配体都与小脑结合，但在该核内没有DPDPE结合且EKC结合非常弱。研究了单侧迷走神经切断术对受体密度的影响。切断颈迷走神经对脑干中μ受体的密度没有影响。切断迷走神经并伴有切除结节神经节，导致μ受体显著减少，这种减少仅限于闩平面及闩平面上方同侧孤束核的背侧和内侧区域。这些结果表明，μ阿片受体位于终止于孤束核有限区域内的迷走神经传入纤维的突触前部位。
