Nishiwaki-Ohkawa Taeko, Yoshimura Takashi
Laboratory of Animal PhysiologyGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan Institute of Transformative Bio-Molecules (WPI-ITbM)Nagoya University, Nagoya, Japan.
Laboratory of Animal PhysiologyGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan Institute of Transformative Bio-Molecules (WPI-ITbM)Nagoya University, Nagoya, Japan Division of Seasonal BiologyNational Institute for Basic Biology, Okazaki, Japan Avian Bioscience Research CenterGraduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan
J Endocrinol. 2016 Jun;229(3):R117-27. doi: 10.1530/JOE-16-0066. Epub 2016 Apr 11.
Animals that inhabit mid- to high-latitude regions exhibit various adaptive behaviors, such as migration, reproduction, molting and hibernation in response to seasonal cues. These adaptive behaviors are tightly regulated by seasonal changes in photoperiod, the relative day length vs night length. Recently, the regulatory pathway of seasonal reproduction has been elucidated using quail. In birds, deep brain photoreceptors receive and transmit light information to the pars tuberalis in the pituitary gland, which induces the secretion of thyroid-stimulating hormone. Thyroid-stimulating hormone locally activates thyroid hormone via induction of type 2 deiodinase in the mediobasal hypothalamus. Thyroid hormone then induces morphological changes in the terminals of neurons that express gonadotropin-releasing hormone and facilitates gonadotropin secretion from the pituitary gland. In mammals, light information is received by photoreceptors in the retina and neurally transmitted to the pineal gland, where it inhibits the synthesis and secretion of melatonin, which is crucial for seasonal reproduction. Importantly, the signaling pathway downstream of light detection and signaling is fully conserved between mammals and birds. In fish, the regulatory components of seasonal reproduction are integrated, from light detection to neuroendocrine output, in a fish-specific organ called the saccus vasculosus. Various physiological processes in humans are also influenced by seasonal environmental changes. The findings discussed herein may provide clues to addressing human diseases, such as seasonal affective disorder.
栖息在中高纬度地区的动物会表现出各种适应性行为，比如迁徙、繁殖、换羽和冬眠，以应对季节性线索。这些适应性行为受到光周期（相对白昼时长与黑夜时长）季节性变化的严格调控。最近，利用鹌鹑已阐明了季节性繁殖的调控途径。在鸟类中，深部脑光感受器接收光信息并将其传递至垂体的结节部，后者诱导促甲状腺激素的分泌。促甲状腺激素通过在中基底下丘脑诱导2型脱碘酶的表达来局部激活甲状腺激素。然后，甲状腺激素诱导表达促性腺激素释放激素的神经元终末发生形态变化，并促进垂体分泌促性腺激素。在哺乳动物中，光信息由视网膜中的光感受器接收，并通过神经传导至松果体，在那里它抑制褪黑素的合成与分泌，而褪黑素对季节性繁殖至关重要。重要的是，光检测和信号传导下游的信号通路在哺乳动物和鸟类之间是完全保守的。在鱼类中，季节性繁殖的调控成分，从光检测到神经内分泌输出，都整合在一个名为血管囊的鱼类特有的器官中。人类的各种生理过程也受到季节性环境变化的影响。本文讨论的这些发现可能为解决诸如季节性情感障碍等人类疾病提供线索。
