Departamento de Neurobiología del Desarrollo y Neurofisiología y.
Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Campus UNAM-Juriquilla, Querétaro, México.
Pain. 2017 Nov;158(11):2117-2128. doi: 10.1097/j.pain.0000000000001024.
Oxytocin (OT) has emerged as a mediator of endogenous analgesia in behavioral and electrophysiological experiments. In fact, OT receptors (OTRs) in the spinal dorsal horn participate in a selective inhibition of the neuronal activity mediated by Aδ and C fibers but not Aβ fibers. This study shows that OTRs are expressed in the terminal nerve endings and are able to inhibit nociceptive neuronal firing. Indeed, local peripheral OT blocked the first sensorial activity of Aδ and C fibers recorded in the spinal cord neurons. Furthermore, using the formalin behavioral nociceptive test, we demonstrated that only ipsilateral OTR activation inhibits pain behavior. Our data are reinforced by the fact that the OTR protein is expressed in the sciatic nerve. Consistent with this, immunofluorescence of primary afferent fibers suggest that OTRs could be located in nociceptive-specific terminals of the skin. Taken together, our results suggest that OTRs could be found in nociceptive terminals and that on activation they are able to inhibit nociceptive input.
缩宫素（OT）已成为行为和电生理实验中内源性镇痛的介质。事实上，脊髓背角中的 OT 受体（OTRs）参与了对 Aδ 和 C 纤维介导的神经元活动的选择性抑制，但不参与 Aβ 纤维介导的抑制。本研究表明，OTRs 表达在末梢神经末端，能够抑制伤害性神经元的放电。实际上，局部外周 OT 阻断了在脊髓神经元中记录到的 Aδ 和 C 纤维的第一感觉活动。此外，使用福马林行为性疼痛测试，我们证明只有同侧 OTR 激活可以抑制疼痛行为。我们的数据得到了以下事实的支持：OTR 蛋白在坐骨神经中表达。与之一致的是，初级传入纤维的免疫荧光表明，OTRs 可能位于皮肤的伤害性特异性末端。总之，我们的结果表明，OTRs 可能存在于伤害性末端，并且在激活时能够抑制伤害性传入。
