Oka Y, Ichikawa M
Zoological Institute, Faculty of Science, University of Tokyo, Japan.
J Comp Neurol. 1990 Oct 22;300(4):511-22. doi: 10.1002/cne.903000406.
The present paper aims to give a morphological basis for the study of the terminal nerve system and its relation to the whole gonadotropin-releasing hormone (GnRH) immunoreactive (ir) neuronal system. We examined the GnRH-ir neuronal system of a tropical fish, the dwarf gourami, by using a recently developed monoclonal antibody against GnRH (LRH13) which recognizes the amino acid sequence common to all known variants of GnRH (Park and Wakabayashi, Endocrinol. Jpn. 33:257-272, '86). The ganglion cells of the terminal nerve (TN-ggl cells) in the transitional area between the olfactory bulb and the telencephalon reacted strongly with the LRH13. A distinct bundle of axons emanating from the TN-ggl cells ran caudally through the ventral telencephalon and the preoptic area. Some of these axons entered the optic nerve and innervated the retina. The remaining axons continued caudally to enter the hypothalamus and the midbrain. A second group of GnRH-ir cell bodies was found in the preoptic area. A distinct bundle of GnRH-ir fibers originating from these cell bodies innervated the pituitary. This pathway is equivalent to the preoptico-infundibular pathway of other vertebrates, and the GnRH in this pathway is presumed to function as hypophysiotrophic hormone to facilitate the release of gonadotropins from the pituitary. The distribution of GnRH-ir fibers in the brain was extensive. Most fibers apparently originated from the TN-ggl cells and covered various brain regions from the olfactory bulb to the spinal cord. They were especially abundant in the olfactory bulb, ventral telencephalon, preoptic area, optic tectum, and some hypothalamic areas. Thus, GnRH might function as a neuromodulator and/or neurotransmitter in these areas. The abundant GnRH-ir fibers in the ventral telencephalon and the preoptic area might affect some aspects of sexual behavior, since these areas have been suggested to be involved in the control of sexual behavior in teleosts.
本文旨在为终末神经系统的研究及其与整个促性腺激素释放激素（GnRH）免疫反应性（ir）神经元系统的关系提供形态学基础。我们使用最近开发的一种针对GnRH的单克隆抗体（LRH13）来检测一种热带鱼——侏儒斗鱼的GnRH-ir神经元系统，该抗体可识别所有已知GnRH变体共有的氨基酸序列（Park和Wakabayashi，《日本内分泌学杂志》33:257 - 272，'86）。嗅球和端脑之间过渡区域的终末神经节细胞（TN-ggl细胞）与LRH13发生强烈反应。从TN-ggl细胞发出的一束明显的轴突尾向穿过腹侧端脑和视前区。其中一些轴突进入视神经并支配视网膜。其余轴突继续尾向延伸进入下丘脑和中脑。在视前区发现了第二组GnRH-ir细胞体。源自这些细胞体的一束明显的GnRH-ir纤维支配垂体。这条通路等同于其他脊椎动物的视前-漏斗通路，并且这条通路中的GnRH被推测作为促垂体激素发挥作用，以促进垂体释放促性腺激素。GnRH-ir纤维在脑中的分布广泛。大多数纤维显然源自TN-ggl细胞，并覆盖从嗅球到脊髓的各个脑区。它们在嗅球、腹侧端脑、视前区、视顶盖和一些下丘脑区域尤其丰富。因此，GnRH可能在这些区域作为神经调质和/或神经递质发挥作用。腹侧端脑和视前区丰富的GnRH-ir纤维可能影响性行为的某些方面，因为这些区域已被认为参与硬骨鱼性行为的控制。
