Danger J M, Leboulenger F, Guy J, Tonon M C, Benyamina M, Martel J C, Saint-Pierre S, Pelletier G, Vaudry H
Life Sci. 1986 Sep 29;39(13):1183-92. doi: 10.1016/0024-3205(86)90350-4.
The presence of neuropeptide tyrosine (NPY) in the intermediate lobe of the frog pituitary was demonstrated using indirect immunofluorescence, the immunogold technique and a specific radioimmunoassay combined with high pressure liquid chromatography (HPLC). A high density of NPY-containing fibers, was found among the parenchymal cells of the intermediate lobe. These fibers originated from the ventral infundibular nucleus, travelled via the median eminence to the pars intermedia. At the electron microscopic level, NPY-like material was found exclusively in nerve fibers where the product of the immunoreaction was associated to dense-core vesicles. High concentrations of NPY-like peptide were found in neurointermediate lobe extracts. After Sephadex G-50 gel filtration the major peak of immunoreactive material appeared to co-elute with synthetic porcine NPY. Conversely, HPLC analysis revealed that the NPY-like peptide of the frog pituitary had a retention time shorter than the porcine NPY. The localization of NPY-like material in the pars intermedia suggested a possible role of NPY in the regulation of melanotropic cell secretion. In fact, graded concentrations of synthetic NPY induced a dose-dependent inhibition of alpha-melanotropin (alpha-MSH) release in vitro. The lack of effect of a dopaminergic antagonist on NPY-induced alpha-MSH release inhibition demonstrated that the local dopaminergic system could not account for the NPY action. These results indicate that NPY located in the hypothalamo-hypophyseal system of the frog may act as a melanotropin-release inhibiting factor.
运用间接免疫荧光法、免疫金技术以及结合高压液相色谱法（HPLC）的特异性放射免疫分析法，证实了蛙脑垂体中间叶中存在神经肽Y（NPY）。在中间叶的实质细胞之间发现了高密度的含NPY纤维。这些纤维起源于腹侧漏斗核，经正中隆起到达中间部。在电子显微镜水平上，仅在神经纤维中发现了NPY样物质，免疫反应产物与致密核心囊泡相关。在神经中间叶提取物中发现了高浓度的NPY样肽。经Sephadex G - 50凝胶过滤后，免疫反应性物质的主要峰似乎与合成猪NPY共洗脱。相反，HPLC分析显示蛙脑垂体的NPY样肽的保留时间比猪NPY短。NPY样物质在中间部的定位表明NPY在促黑素细胞分泌调节中可能发挥作用。事实上，体外合成NPY的分级浓度诱导了α - 促黑素（α - MSH）释放的剂量依赖性抑制。多巴胺能拮抗剂对NPY诱导的α - MSH释放抑制无作用，表明局部多巴胺能系统不能解释NPY的作用。这些结果表明，位于蛙下丘脑 - 垂体系统中的NPY可能作为促黑素释放抑制因子发挥作用。
