Kapoor J R, Sladek C D
Department of Physiology and Biophysics, Finch University of Health Sciences/ The Chicago Medical School, North Chicago, Illinois 60064, USA.
Am J Physiol Regul Integr Comp Physiol. 2001 Jan;280(1):R69-78. doi: 10.1152/ajpregu.2001.280.1.R69.
The supraoptic nuclei are innervated by the A1 neurons of the caudal ventrolateral medulla. Substances colocalized in the A1 terminals include norepinephrine (NE), substance P (SP), ATP, and neuropeptide Y (NPY). ATP, acting at P(2x) receptors, caused rapid and unsustained stimulation of vasopressin (VP) and oxytocin (OT) release from perifused explants of the hypothalamo-neurohypophysial system. SP elicited a concentration-dependent stimulation of VP and OT release that was large and sustained compared with other stimuli. ATP, but not phenylephrine (PE, alpha(1)-adrenergic agonist), augmented the response to SP (1 microM). In contrast, NPY did not alter basal nor ATP-induced VP or OT release, but it did cause sustained potentiation of PE-induced VP and OT release. The Y(1)-agonist, [Leu(31),Pro(34)]-NPY, increased VP and OT release, suggesting that the ineffectiveness of NPY reflects opposing actions at pre- and postsynaptic receptors. However, [Leu(31),Pro(34)]-NPY did not potentiate hormone responses to ATP or PE. The differential responses to these colocalized neurotransmitters and neuropeptides illustrate the range of potential responses that stimulation of this pathway might elicit from supraoptic neurons.
视上核由延髓尾端腹外侧的A1神经元支配。A1终末中共定位的物质包括去甲肾上腺素（NE）、P物质（SP）、ATP和神经肽Y（NPY）。ATP作用于P(2x)受体，可快速且短暂地刺激下丘脑 - 神经垂体系统灌流外植体释放血管加压素（VP）和催产素（OT）。与其他刺激相比，SP可引起浓度依赖性的VP和OT释放刺激，且这种刺激量大且持续。ATP而非去氧肾上腺素（PE，α(1) - 肾上腺素能激动剂）增强了对SP（1微摩尔）的反应。相反，NPY既不改变基础状态下的VP或OT释放，也不改变ATP诱导的释放，但它确实能使PE诱导的VP和OT释放持续增强。Y(1) - 激动剂[Leu(31),Pro(34)] - NPY可增加VP和OT释放，这表明NPY无效反映了其在突触前和突触后受体上的相反作用。然而，[Leu(31),Pro(34)] - NPY并未增强激素对ATP或PE的反应。对这些共定位的神经递质和神经肽的不同反应说明了刺激该通路可能从视上核神经元引发的潜在反应范围。
