Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
Physiol Behav. 2010 Mar 3;99(3):276-85. doi: 10.1016/j.physbeh.2009.11.002. Epub 2009 Nov 27.
Circadian dysregulation in sleep pattern, mood, and hypothalamic-pituitary-adrenal (HPA) axis activity, often occurring in a sexually dimorphic manner, are characteristics of depression. However, the inter-relationships among circadian phase, HPA function, and depressive-like behaviors are not well understood. We investigated behavioral and neuroendocrine correlates of depressive/anxiety-like responses during diurnal ('light') and nocturnal ('dark') phases of the circadian rhythm in the open field (OF), elevated plus maze (EPM), forced swim (FST), and sucrose contrast (SC) tests. Plasma corticosterone (CORT) was measured after a) acute restraint and OF testing and b) FST. Both phase and sex significantly influenced behavioral responses to stress. Males were more anxious than females on the EPM in the light but not the dark phase. Further, the open:closed arm ratio was lower in the dark for females, but not males. By contrast, in the FST, females showed more "despair" (immobility) when tested in the dark, while phase did not affect males. Acute restraint stress increased OF activity in the light, but not the dark, phase. CORT levels were increased in both sexes following the FST, and in males and light phase females post-OF. As expected, females had higher CORT levels than males, even at rest, and this effect was more pronounced in the dark phase. Together, our data highlight the sexually dimorphic influences of circadian phase and stress on behavioral and hormonal responsiveness.
睡眠模式、情绪和下丘脑-垂体-肾上腺 (HPA) 轴活动的昼夜节律失调，通常以性二态的方式发生，是抑郁症的特征。然而，昼夜节律的相位、HPA 功能和抑郁样行为之间的相互关系尚不清楚。我们研究了在开野 (OF)、高架十字迷宫 (EPM)、强迫游泳 (FST) 和蔗糖对比 (SC) 测试的昼夜（“光”）和夜间（“暗”）节律中，抑郁/焦虑样反应的行为和神经内分泌相关性。在急性束缚和 OF 测试后以及在 FST 后测量了血浆皮质酮 (CORT)。相位和性别都显著影响对压力的行为反应。在光相下，雄性比雌性更焦虑，但在暗相下则不然。此外，在暗相下，雌性的开臂：闭臂比值较低，但雄性则不然。相比之下，在 FST 中，雌性在暗相下测试时表现出更多的“绝望”（不动），而相位则没有影响雄性。急性束缚应激增加了光相下的 OF 活动，但不增加暗相下的活动。FST 后，两性的 CORT 水平均升高，OF 后雄性和光相雌性的 CORT 水平也升高。正如预期的那样，即使在休息时，女性的 CORT 水平也高于男性，而且这种影响在暗相下更为明显。总之，我们的数据强调了昼夜节律相位和应激对行为和激素反应的性别二态影响。
