The population of GnRH-containing neurons showing socially mediated size changes project to the pituitary in a teleost, Haplochromis burtoni
The population of GnRH-containing neurons showing socially mediated size changes project to the pituitary in a teleost, Haplochromis burtoni
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DOI：
10.1159/000113287
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发表时间：
1995-12-01
影响因子：
1.7
通讯作者：
Fernald, RD
中科院分区：
文献类型：
--
作者：
Bushnik, TL;Fernald, RD
所有脊椎动物的生殖功能都是由脑垂体性腺轴控制的。在硬骨鱼中，腺垂体内的内分泌细胞聚集在一起，并且每个细胞集合由特定的神经肽纤维支配。生殖控制中的一个重要调节步骤是促性腺激素释放激素（GnRH），其递送到垂体负责其促性腺激素的释放。激素GnRH已被证明在硬骨鱼Haplochromis burtoni的繁殖社会控制中发挥关键作用。然而，没有直接证据表明视前区GnRH神经元投射到垂体。在这项研究中，我们使用了逆行示踪和免疫组织化学，以确定那些含有GnRH的神经元，项目的腺垂体。我们比较了生殖活跃的领土男性与静止的非领土男性，以发现视前区GnRH神经元的连接是否取决于男性的生殖状态。我们发现，无论生殖状态，大多数GnRH神经元在视前区项目的垂体和所有这些GnRH神经元显示索马大小的变化，已与生殖状态在Haplochromis burtoni。基于这些数据，我们提出，有一个单一的人口的GnRH含有细胞在视前区，改变大小作为一个功能的生殖状态，这整个人口项目的垂体。这是第一次直接证明存在这种连接视前区GnRH神经元和垂体的基本回路。
Reproductive function in all vertebrates is controlled by the brain-pituitary-gonadal axis. In teleost fish, endocrine cells within the adenohypophysis are grouped together and each collection of cells is innervated by specific neuropeptide fibers. An important regulatory step in reproductive control is gonadotropin-releasing hormone (GnRH), whose delivery to the pituitary is responsible for its release of gonadotropins. The hormone GnRH has been shown to play a critical role in the social control of reproduction in a teleost fish, Haplochromis burtoni. However, there has been no direct evidence that the preoptic area GnRH neurons project to the pituitary. In this study, we used a retrograde tracer and immunohistochemistry to identify those GnRH containing neurons that project to the adenohypophysis. We compared reproductively active territorial males with quiescent non-territorial males to discover whether the connectivity of the preoptic area GnRH neurons depends on the reproductive status of the male. We found that, irrespective of reproductive status, most GnRH neurons in the preoptic area project to the pituitary and that all of these GnRH neurons show the soma size change that has been associated with reproductive status in Haplochromis burtoni. Based on these data, we propose that there is a single population of GnRH containing cells in the preoptic area that change size as a function of reproductive state and that this entire population projects to the pituitary. This is the first direct demonstration that this essential circuit, linking GnRH neurons in the preoptic area to the pituitary, exists.