Marinelli Silvia, Di Marzo Vincenzo, Florenzano Fulvio, Fezza Filomena, Viscomi Maria Teresa, van der Stelt Mario, Bernardi Giorgio, Molinari Marco, Maccarrone Mauro, Mercuri Nicola B
Experimental Neurology, IRCCS Fondazione Santa Lucia, Rome, Italy.
Neuropsychopharmacology. 2007 Feb;32(2):298-308. doi: 10.1038/sj.npp.1301118. Epub 2006 Jun 7.
In the present study, we used electrophysiological, biochemical, and confocal microscopy techniques, to investigate the functional role of transient receptor potential vanilloid type 1 (TRPV1) and cannabinoid type 1 receptors (CB1-R) in the substantia nigra pars compacta (SNpc) and their stimulation by the endocannabinoid N-arachidonoyl-dopamine (NADA). Liquid chromatography-mass spectrometry analyses revealed that a NADA-like compound is produced in substantia nigra slices, in conditions of hyperactivity. Moreover, the functional role of both TRPV1 and CB1-R in modulating synaptic transmission in this area was suggested by confocal microscopy data, showing TRPV1 and CB1-R immunoreactivity in punctate structures, probably representing synaptic contacts on cell bodies of the SNpc. In patch-clamp recordings from dopamine (DA) neurons of the SNpc, we found that NADA increases or reduces glutamatergic transmission onto DA neurons by activating TRPV1 and CB1 receptors, respectively, whereas it decreases GABAergic transmission via CB1 stimulation. Facilitation of glutamate release through TRPV1 was blocked in the presence of a selective blocker of the putative endocannabinoid membrane transporter (EMT), indicating that NADA needs to be taken up by cells to interact with this receptor. In line with these data, biochemical results demonstrated that NADA selectively acted at CB1-R when its re-uptake was blocked. Altogether these data demonstrate a significant role exerted by the endocannabinoid/endovanilloid NADA in the regulation of synaptic transmission to DA neurons of the SNpc. Moreover, they highlight a key function of the EMT transporter in promoting the stimulation of TRPV1 or CB1-R, thus favoring facilitation or inhibition of glutamate synaptic release.
在本研究中，我们使用电生理、生化和共聚焦显微镜技术，来研究瞬时受体电位香草酸亚型1（TRPV1）和大麻素1型受体（CB1-R）在黑质致密部（SNpc）中的功能作用，以及内源性大麻素N-花生四烯酰多巴胺（NADA）对它们的刺激作用。液相色谱-质谱分析显示，在活动亢进的情况下，黑质切片中会产生一种类似NADA的化合物。此外，共聚焦显微镜数据表明TRPV1和CB1-R在调节该区域突触传递中具有功能作用，显示出TRPV1和CB1-R在点状结构中的免疫反应性，这些点状结构可能代表SNpc细胞体上的突触接触。在对SNpc多巴胺（DA）神经元进行的膜片钳记录中，我们发现NADA分别通过激活TRPV1和CB1受体来增加或减少谷氨酸能传递至DA神经元，而它通过刺激CB1来减少GABA能传递。在存在假定的内源性大麻素膜转运体（EMT）的选择性阻断剂时，通过TRPV1促进谷氨酸释放的作用被阻断，这表明NADA需要被细胞摄取才能与该受体相互作用。与这些数据一致，生化结果表明，当NADA的再摄取被阻断时，它选择性地作用于CB1-R。总之，这些数据证明内源性大麻素/内源性香草酸NADA在调节向SNpc的DA神经元的突触传递中发挥着重要作用。此外，它们突出了EMT转运体在促进TRPV1或CB1-R的刺激方面的关键功能，从而有利于促进或抑制谷氨酸突触释放。
