Nozaki M, Ominato K, Gorbman A, Sower S A
Sado Marine Biological Station, Niigata University, Tassha, Aikawa, Sado Niigata, 952-2135, Japan.
Gen Comp Endocrinol. 2000 Apr;118(1):57-67. doi: 10.1006/gcen.1999.7451.
In the sea lamprey, Petromyzon marinus, two forms of GnRH, lamprey GnRH-I and -III, have been demonstrated to be neurohormones regulating the pituitary-gonadal axis. The objective of the present study was to determine the distribution of lamprey GnRH-III in the brains of adult sea lampreys and to compare it to the distribution of lamprey GnRH-I. For this purpose, two kinds of immunostaining were employed: one was a single immunostaining by one of two GnRH antibodies using two successive sections; the other was double immunostaining of a single section. A dense accumulation of neuronal cells immunoreactive (ir) to antisera against either lamprey GnRH-I or -III was found in the arc-shaped preoptico-anterior hypothalamic area. Additional smaller numbers of irGnRH cells were found in the periventricular zone of the posterior hypothalamus. In the above-mentioned locations, the distribution of both irGnRH-I and -III cells was intermixed and very similar, but the cells exhibiting GnRH-III immunoreactivity were distinctly different from those exhibiting GnRH-I immunoreactivity. The relative numbers of irGnRH-III cells were larger than those of irGnRH-I cells in the preoptico-anterior hypothalamic area, and more than 90% of GnRH cells in the posterior hypothalamus were irGnRH-III cells. Both irGnRH-I and -III cells projected their fibers primarily into the neurohypophysis. The relative densities of the accumulated irGnRH-III fibers were similar to those of irGnRH-I fibers in the anterior neurohypophysis but higher than those of irGnRH-I fibers in the posterior neurohypophysis. The present study provides further immunocytochemical data to the already compelling physiological evidence that indicates that both lamprey GnRH-I and -III act through the hypothalamic-pituitary-gonadal axis to modulate reproductive processes in the sea lamprey.
在海七鳃鳗（Petromyzon marinus）中，已证实两种形式的促性腺激素释放激素（GnRH），即七鳃鳗GnRH-I和 -III，是调节垂体-性腺轴的神经激素。本研究的目的是确定成年海七鳃鳗脑中七鳃鳗GnRH-III的分布，并将其与七鳃鳗GnRH-I的分布进行比较。为此，采用了两种免疫染色方法：一种是使用两种GnRH抗体之一对连续的两个切片进行单免疫染色；另一种是对单个切片进行双重免疫染色。在弧形的视前-下丘脑前部区域发现了大量对七鳃鳗GnRH-I或 -III抗血清呈免疫反应（ir）的神经元细胞。在下丘脑后部的室周区域还发现了少量额外的irGnRH细胞。在上述位置，irGnRH-I和 -III细胞的分布相互混合且非常相似，但表现出GnRH-III免疫反应性的细胞与表现出GnRH-I免疫反应性的细胞明显不同。视前-下丘脑前部区域中irGnRH-III细胞的相对数量多于irGnRH-I细胞，并且下丘脑后部超过90%的GnRH细胞是irGnRH-III细胞。irGnRH-I和 -III细胞都主要将其纤维投射到神经垂体。在前部神经垂体中，积累的irGnRH-III纤维的相对密度与irGnRH-I纤维相似，但在后部神经垂体中高于irGnRH-I纤维。本研究为已有确凿生理证据的进一步免疫细胞化学数据提供了支持，该证据表明七鳃鳗GnRH-I和 -III都通过下丘脑-垂体-性腺轴发挥作用，以调节海七鳃鳗的生殖过程。
