Dulcis Davide, Spitzer Nicholas C
Neurobiology Section, Division of Biological Sciences and Center for Molecular Genetics, Kavli Institute for Brain and Mind, UCSD La Jolla, California 92093-0357, USA.
Nature. 2008 Nov 13;456(7219):195-201. doi: 10.1038/nature07569.
Specification of the appropriate neurotransmitter is a crucial step in neuronal differentiation because it enables signalling among populations of neurons. Experimental manipulations demonstrate that both autonomous and activity-dependent genetic programs contribute to this process during development, but whether natural environmental stimuli specify transmitter expression in a neuronal population is unknown. We investigated neurons of the ventral suprachiasmatic nucleus that regulate neuroendocrine pituitary function in response to light in teleosts, amphibia and primates. Here we show that altering light exposure, which changes the sensory input to the circuit controlling adaptation of skin pigmentation to background, changes the number of neurons expressing dopamine in larvae of the amphibian Xenopus laevis in a circuit-specific and activity-dependent manner. Neurons newly expressing dopamine then regulate changes in camouflage colouration in response to illumination. Thus, physiological activity alters the numbers of behaviourally relevant amine-transmitter-expressing neurons in the brain at postembryonic stages of development. The results may be pertinent to changes in cognitive states that are regulated by biogenic amines.
确定合适的神经递质是神经元分化过程中的关键步骤，因为它能使神经元群体之间进行信号传递。实验操作表明，自主和活动依赖的基因程序在发育过程中都对这一过程有贡献，但自然环境刺激是否能在神经元群体中指定递质表达尚不清楚。我们研究了硬骨鱼、两栖动物和灵长类动物中腹侧视交叉上核的神经元，它们响应光线调节神经内分泌垂体功能。在这里我们表明，改变光照暴露会改变对控制皮肤色素沉着适应背景的回路的感觉输入，以一种特定于回路且依赖活动的方式改变两栖动物非洲爪蟾幼体中表达多巴胺的神经元数量。新表达多巴胺的神经元随后会根据光照调节伪装颜色的变化。因此，生理活动在发育的胚胎后期改变了大脑中表达行为相关胺类递质的神经元数量。这些结果可能与受生物胺调节的认知状态变化有关。
