Liposits Z, Merchenthaler I, Reid J J, Negro-Vilar A
Department of Anatomy, University Medical School, Pécs, Hungary.
Endocrinology. 1993 Feb;132(2):917-23. doi: 10.1210/endo.132.2.7678803.
The anterior periventricular nucleus (PeN) regulates GH secretion by synthesizing and releasing somatotropin release-inhibiting factor (SRIF) into the portal circulation. This territory of the diencephalon is heavily innervated by axons of galanin (GAL)-immunoreactive (IR) neurons. The connections between GAL-IR fibers and hypophysiotropic SRIF neurons were studied by means of immunocytochemical double labeling at the light and electron microscopic levels. Retrograde axonal labeling with Fluoro-Gold revealed the anterior PeN as the main site of hypophysiotropic SRIF-synthesizing neurons. These cells were densely surrounded by GALergic axons that made contacts with their cell bodies and dendrites. At the ultrastructural level, diaminobenzidine-labeled SRIF neurons received synapsing GAL-IR axons marked with silver-gold particles. Both axo-somatic and axo-dendritic forms of connections were observed. These morphochemical data revealed an interaction between GAL- and SRIF-synthesizing neurons in the anterior PeN. Furthermore, the presence of synaptic connections between these neuronal systems suggests a role for GAL in the control of SRIF secretion and, in turn, in the regulation of GH release.
室周前核（PeN）通过合成生长抑素释放抑制因子（SRIF）并将其释放到门脉循环中来调节生长激素（GH）的分泌。间脑的这一区域受到甘丙肽（GAL）免疫反应性（IR）神经元轴突的大量支配。通过光镜和电镜水平的免疫细胞化学双重标记研究了GAL-IR纤维与促垂体SRIF神经元之间的联系。用荧光金逆行轴突标记显示室周前核是促垂体SRIF合成神经元的主要部位。这些细胞被GAL能轴突紧密包围，这些轴突与其细胞体和树突形成接触。在超微结构水平上，二氨基联苯胺标记的SRIF神经元接受了用银金颗粒标记的突触GAL-IR轴突。观察到了轴-体和轴-树突两种连接形式。这些形态化学数据揭示了室周前核中GAL合成神经元与SRIF合成神经元之间的相互作用。此外，这些神经元系统之间突触连接的存在表明GAL在控制SRIF分泌进而调节GH释放中起作用。
