Baker B, Levy A, Hall L, Lightman S
School of Biology and Biochemistry, Bath University, UK.
Neuroendocrinology. 1995 Jan;61(1):67-76. doi: 10.1159/000126814.
Salmonids, a group of tetraploid fish including salmon and trout, produce the vertebrate neuropeptide melanin-concentrating hormone (MCH) in a group of hypothalamic magnocellular neurons in the nucleus lateralis tuberis (NLT). NLT neurons project both to the brain and to the neural lobe of the pituitary gland from where MCH is released into the circulation to play a central role in camouflage (+/- stress). We have cloned and sequenced the MCH1 and MCH2 genes from the rainbow trout, Oncorhynchus mykiss, and used the data firstly to examine the position of O. mykiss in salmonid phylogeny, and secondly to enable central nervous system MCH1 and MCH2 gene expression to be mapped. In the immature adult female trout brain, only MCH2 was detectable at the hybridization stringency used. In addition to the known location of MCH-positive neurons, immunocytochemistry and in situ hybridization histochemistry revealed a previously undescribed nucleus of MCH-positive neurons located more dorsal and posterior to those of the NLT, over the paraventricular organ of the lateral ventricular recess. Axons from this second group of MCH neurons project dorsally into the brain, while a few extend down toward the lateral ventricle near the paraventricular organ. They make little, if any, direct contact with the neurohypophysis, and thus may subserve a central function, unrelated to hormonal colour regulation.
鲑科鱼类是一类包括鲑鱼和鳟鱼在内的四倍体鱼类，它们在侧结节核（NLT）的一组下丘脑大细胞神经元中产生脊椎动物神经肽黑色素浓缩激素（MCH）。NLT神经元既投射到大脑，也投射到垂体神经叶，MCH从垂体神经叶释放到循环系统中，在伪装（±应激）中发挥核心作用。我们已经从虹鳟（Oncorhynchus mykiss）中克隆并测序了MCH1和MCH2基因，并首先利用这些数据来研究虹鳟在鲑科系统发育中的位置，其次用于绘制中枢神经系统中MCH1和MCH2基因的表达图谱。在未成熟成年雌性虹鳟的大脑中，在所使用的杂交严谨度下，只能检测到MCH2。除了已知的MCH阳性神经元的位置外，免疫细胞化学和原位杂交组织化学还揭示了一个以前未描述的MCH阳性神经元核，它位于NLT的背侧和后侧，在侧脑室隐窝的室旁器官上方。第二组MCH神经元的轴突向背侧投射到大脑中，而少数轴突向下延伸到室旁器官附近的侧脑室。它们与神经垂体几乎没有直接接触，因此可能具有与激素颜色调节无关的中枢功能。
