Ossenkopp Klaus-Peter, van Anders Sari M, Engeland Christopher G, Kavaliers Martin
Neuroscience Graduate Program, University of Western Ontario, London, Canada.
Psychoneuroendocrinology. 2005 Oct;30(9):869-79. doi: 10.1016/j.psyneuen.2005.05.001.
This study examined the influence of photoperiod on affective behavior (anxiety) of adult male and female meadow voles (Microtus pennsylvanicus), maintained in either a long or short day photoperiod, when tested in an automated (VersaMax) light-dark test. The light-dark test is based on an innate aversion of rodents to novel, brightly illuminated spaces and has been used with laboratory raised species, such as mice, to assess anxiety and/or fear related behaviors. Male and female meadow voles, housed either in a long day (LD: 16 h light) or short day (SD: 8 h light) photoperiod, were tested in the light-dark apparatus for 30 min on 3 consecutive days. All animals spent significantly (p < 0.001) less time in the brightly lit chamber (900 lux) than in the dark chamber. LD voles, especially females, spent significantly less time in the brightly lit area than did SD voles. Both horizontal and vertical movements occurred less frequently per unit time in the dark area relative to the light, but only in the LD voles. LD female voles were the least active group in the dark area on the first test day but the most active group in the light area, despite spending the least amount of time in this area on the second and third test days. The present results show that LD voles exhibit more anxiety related behaviors in this test situation than do SD voles. LD females avoided the brightly lit area the most, particularly when the apparatus was novel. Thus, both photoperiod and sex influence situation-based anxiety in this species. These findings suggest that meadow voles are an excellent animal model in which to examine the role of gonadal hormones, and their modulation of defence related neural systems, in the induction of anxiety.
本研究探讨了光周期对成年雄性和雌性草甸田鼠（Microtus pennsylvanicus）情感行为（焦虑）的影响。这些草甸田鼠饲养在长日照或短日照光周期条件下，并在自动（VersaMax）明暗箱试验中接受测试。明暗箱试验基于啮齿动物对新颖、明亮照明空间的先天厌恶，已用于评估实验室饲养物种（如小鼠）的焦虑和/或恐惧相关行为。将雄性和雌性草甸田鼠分别饲养在长日照（LD：16小时光照）或短日照（SD：8小时光照）光周期条件下，连续3天在明暗箱装置中测试30分钟。所有动物在明亮照明室（900勒克斯）中停留的时间显著少于黑暗室（p < 0.001）。长日照田鼠，尤其是雌性，在明亮照明区域停留的时间显著少于短日照田鼠。相对于明亮区域，黑暗区域单位时间内的水平和垂直移动频率均较低，但仅在长日照田鼠中如此。长日照雌性田鼠在第一次测试日是黑暗区域中最不活跃的组，但在明亮区域中是最活跃的组，尽管在第二和第三次测试日在该区域停留的时间最少。目前的结果表明，在这种测试情况下，长日照田鼠比短日照田鼠表现出更多与焦虑相关的行为。长日照雌性田鼠最回避明亮照明区域，尤其是当装置新颖时。因此，光周期和性别都会影响该物种基于情境的焦虑。这些发现表明，草甸田鼠是研究性腺激素及其对防御相关神经系统的调节在焦虑诱导中的作用的优秀动物模型。
