Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan.
Psychoneuroendocrinology. 2014 Feb;40:37-47. doi: 10.1016/j.psyneuen.2013.10.013. Epub 2013 Nov 1.
Seasonal affective disorder (SAD) is characterized by depression during specific seasons, generally winter. The pathophysiological mechanisms underlying SAD remain elusive due to a limited number of animal models with high availability and validity. Here we show that laboratory C57BL/6J mice display photoperiodic changes in depression-like behavior and brain serotonin content. C57BL/6J mice maintained under short-day conditions, as compared to those under long-day conditions, demonstrated prolonged immobility times in the forced swimming test with lower brain levels of serotonin and its precursor l-tryptophan. Furthermore, photoperiod altered multiple parameters reflective of peripheral metabolism, including the ratio of plasma l-tryptophan to the sum of other large neutral amino acids that compete for transport across the blood-brain barrier, responses of circulating glucose and insulin to glucose load, sucrose intake under restricted feeding condition, and sensitivity of the brain serotonergic system to peripherally administered glucose. These data suggest that the mechanisms underlying SAD involve the brain-peripheral tissue network, and C57BL/6J mice can serve as a powerful tool for investigating the link between seasons and mood.
季节性情感障碍（SAD）的特征是在特定季节（通常是冬季）出现抑郁。由于具有高可用性和有效性的动物模型数量有限，SAD 的病理生理机制仍难以捉摸。在这里，我们展示了实验室 C57BL/6J 小鼠在抑郁样行为和大脑血清素含量方面表现出光周期变化。与长日照条件相比，在短日照条件下饲养的 C57BL/6J 小鼠在强迫游泳试验中表现出更长的不动时间，大脑中的血清素及其前体 l-色氨酸水平较低。此外，光周期改变了反映外周代谢的多个参数，包括血浆 l-色氨酸与竞争穿过血脑屏障运输的其他大中性氨基酸总和的比值、循环葡萄糖和胰岛素对葡萄糖负荷的反应、在限制喂养条件下摄入的蔗糖量以及大脑血清素系统对外周给予葡萄糖的敏感性。这些数据表明，SAD 的机制涉及大脑-外周组织网络，C57BL/6J 小鼠可以作为研究季节和情绪之间联系的有力工具。
