Vanderbilt University, Department of Biological Sciences, Nashville, TN 37235, USA.
Dev Biol. 2011 Oct 1;358(1):251-61. doi: 10.1016/j.ydbio.2011.07.038. Epub 2011 Aug 5.
The formation of the embryonic brain requires the production, migration, and differentiation of neurons to be timely and coordinated. Coupling to the photoperiod could synchronize the development of neurons in the embryo. Here, we consider the effect of light and melatonin on the differentiation of embryonic neurons in zebrafish. We examine the formation of neurons in the habenular nuclei, a paired structure found near the dorsal surface of the brain adjacent to the pineal organ. Keeping embryos in constant darkness causes a temporary accumulation of habenular precursor cells, resulting in late differentiation and a long-lasting reduction in neuronal processes (neuropil). Because constant darkness delays the accumulation of the neurendocrine hormone melatonin in embryos, we looked for a link between melatonin signaling and habenular neurogenesis. A pharmacological block of melatonin receptors delays neurogenesis and reduces neuropil similarly to constant darkness, while addition of melatonin to embryos in constant darkness restores timely neurogenesis and neuropil. We conclude that light and melatonin schedule the differentiation of neurons and the formation of neural processes in the habenular nuclei.
胚胎大脑的形成需要神经元的及时产生、迁移和分化。与光周期的耦合可以使胚胎中的神经元发育同步。在这里，我们考虑光和褪黑素对斑马鱼胚胎神经元分化的影响。我们检查了位于靠近大脑背表面的松果体附近的成对结构缰核中神经元的形成。将胚胎保持在持续黑暗中会导致缰核前体细胞的暂时积累，导致神经元分化延迟和神经元突起（神经原纤维）的持久减少。由于持续的黑暗会延迟胚胎中神经内分泌激素褪黑素的积累，因此我们寻找褪黑素信号与缰核神经发生之间的联系。褪黑素受体的药理学阻断同样延迟了神经发生并减少了神经原纤维，而将褪黑素添加到持续黑暗中的胚胎中会恢复及时的神经发生和神经原纤维。我们得出结论，光和褪黑素调节了神经元的分化和缰核中神经突起的形成。
