Benabid N, Mesfioui A, Ouichou A
Unité de Physiologie Nerveuse et Endocrinienne, Laboratoire de Génétique et Physiologie Neuroendocrinienne, Faculté des Sciences, Université Ibn Tofaïl, Kénitra, Maroc.
Brain Res Bull. 2008 Jan 31;75(1):53-9. doi: 10.1016/j.brainresbull.2007.07.016. Epub 2007 Aug 7.
Seasonal changes are often gone with mood and behaviour changes which are probably linked to change in day length or photoperiod. The experiments developed in this work are based on the hypothesis that changes in photoperiod affect emotionality in rats. To check this hypothesis, female rats were exposed to four different photoperiods (LP: 16L/8D; MP: 12L/12D; SP: 8L/16D; SP-F: 8L/16D with a light pulse in midpoint of the dark phase). Eight or 14 weeks later, rats were subjected to two behavioural tests to quantify anxiety level. Independently of duration, rats exposed to SP exhibited higher levels of anxious-like behaviour than rats raised in LP and SP-F, in an open field test (OFT) and in elevated plus maze (EPM). Significant differences in EPM are obtained only after 14 weeks of treatment. Moreover rats treated more long time showed greater suprarenal gland mass. Compared to all other groups, females exposed to SP had greater suprarenal gland. Our results indicate that changes in day length are associated with different levels of anxious-like behaviours consistent with the conjecture that short days may have an anxiogenic effect in female rats.
季节变化常常伴随着情绪和行为的改变，这可能与白昼长度或光周期的变化有关。本研究开展的实验基于这样一个假设：光周期的变化会影响大鼠的情绪。为验证这一假设，将雌性大鼠暴露于四种不同的光周期条件下（长光周期：16小时光照/8小时黑暗；中等光周期：12小时光照/12小时黑暗；短光周期：8小时光照/16小时黑暗；短光周期-闪光组：8小时光照/16小时黑暗，在黑暗期中点给予一个光脉冲）。8周或14周后，对大鼠进行两项行为测试以量化焦虑水平。在旷场试验（OFT）和高架十字迷宫（EPM）中，无论暴露时长如何，暴露于短光周期的大鼠比饲养在长光周期和短光周期-闪光组的大鼠表现出更高水平的焦虑样行为。仅在治疗14周后，高架十字迷宫试验中才出现显著差异。此外，接受更长时间治疗的大鼠肾上腺质量更大。与所有其他组相比，暴露于短光周期的雌性大鼠肾上腺更大。我们的结果表明，白昼长度的变化与不同水平的焦虑样行为相关，这与短日照可能对雌性大鼠产生致焦虑作用的推测一致。
