Departamento de Neurobiología del Desarrollo y Neurofisiología, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, Mexico.
Neuropeptides. 2013 Apr;47(2):117-23. doi: 10.1016/j.npep.2012.09.008. Epub 2012 Oct 24.
Oxytocin (OT) secreted by the hypothalamo-spinal projection exerts antinociceptive effects in the dorsal horn. Electrophysiological evidence indicates that OT could exert these effects by activating OT receptors (OTR) directly on dorsal horn neurons and/or primary nociceptive afferents in the dorsal root ganglia (DRG). However, little is known about the identity of the dorsal horn and DRG neurons that express the OTR. In the dorsal horn, we found that the OTR is expressed principally in neurons cell bodies. However, neither spino-thalamic dorsal horn neurons projecting to the contralateral thalamic ventral posterolateral nucleus (VPL) and posterior nuclear group (Po) nor GABaergic dorsal horn neurons express the OTR. The OTR is not expressed in skin nociceptive terminals or in dorsal horn nociceptive fibers. In the DRG, however, the OTR is expressed predominantly in non-peptidergic C-fiber cell bodies, but not in peptidergic or mechanoreceptor afferents or in skin nociceptive terminals. Our results suggest that the antinociceptive effects of OT are mediated by direct activation of dorsal horn neurons and peripheral actions on nociceptive, non-peptidergic C-afferents in the DRG.
催产素（OT）由下丘脑-脊髓投射分泌，在背角发挥镇痛作用。电生理证据表明，OT 可以通过直接激活背角神经元和/或背根神经节（DRG）中的初级伤害性传入纤维上的 OT 受体（OTR）发挥这些作用。然而，对于表达 OTR 的背角和 DRG 神经元的特性知之甚少。在背角中，我们发现 OTR 主要表达在神经元胞体上。然而，投射到对侧丘脑腹后外侧核（VPL）和后核群（Po）的棘-丘脑背角神经元以及 GABA 能背角神经元均不表达 OTR。OTR 不在皮肤伤害性末梢或背角伤害性纤维中表达。然而，在 DRG 中，OTR 主要表达在非肽能 C 纤维胞体上，但不在肽能或机械感受器传入纤维或皮肤伤害性末梢上表达。我们的结果表明，OT 的镇痛作用是通过直接激活背角神经元和外周作用于 DRG 中的伤害性、非肽能 C-传入纤维来介导的。
