Department of Obstetrics and Gynecology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
Program in Neuroscience, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA.
Neuroscience. 2019 May 15;406:268-277. doi: 10.1016/j.neuroscience.2019.03.013. Epub 2019 Mar 14.
Photoperiod and diet are factors known to modulate the hypothalamic-pituitary-adrenal (HPA) axis. Specifically, shifts in photoperiod have been previously linked with affective and anxiety disorders. Furthermore, isoflavones have been shown to mediate behavioral outcome in response to the environment of the animal. Here, we investigated the effect of photoperiod alteration on the HPA axis and how the addition of isoflavones might modulate the response to stress. Male C57BL/6J mice were maintained on either a 12:12 or a 16:8 light-dark (LD) cycle for 10 days, and fed a diet of either standard rodent chow or an isoflavone free (IF) chow beginning 3 weeks prior to light alteration. Consistent with previous work, mice in the shorter active period (16:8 LD cycle) showed increased basal corticosterone (CORT) secretion. In the absence of isoflavones, this response was attenuated. Increases in mineralcorticoid (MR) and glucocorticoid (GR) receptor mRNA expression were seen in the pituitary following photoperiod alteration. However, animals fed the standard isoflavone rich chow showed increases in the ratio of MR:GR mRNA in the anterior bed nucleus of the stria terminalis following photoperiod alteration. Decreases in corticotrophin-releasing factor receptor 1 (CRFR1) mRNA expression were seen in animals fed the IF chow in the amygdala, prefrontal cortex and ventral hippocampus. These data suggest that alterations in CORT secretion following photoperiod alteration may be mediated through differences in CRFR1 gene expression or changes in MR:GR mRNA ratios. These findings provide insight into the potential mechanisms by which the HPA axis adapts to photoperiod and diet.
光周期和饮食是已知调节下丘脑-垂体-肾上腺 (HPA) 轴的因素。具体来说，光周期的变化以前与情感和焦虑障碍有关。此外，已经表明异黄酮可以调节动物环境对行为结果的影响。在这里，我们研究了光周期改变对 HPA 轴的影响，以及异黄酮的添加如何调节对压力的反应。雄性 C57BL/6J 小鼠分别维持在 12:12 或 16:8 光照-黑暗 (LD) 周期 10 天，并在光照改变前 3 周开始食用标准啮齿动物饲料或不含异黄酮的 (IF) 饲料。与之前的工作一致，在较短的活动期（16:8 LD 周期）的小鼠中，基础皮质酮 (CORT) 分泌增加。在没有异黄酮的情况下，这种反应减弱了。光照改变后，垂体中矿物质皮质激素 (MR) 和糖皮质激素 (GR) 受体 mRNA 表达增加。然而，在标准富含异黄酮的饲料喂养的动物中，光周期改变后前终纹床核中的 MR:GR mRNA 比值增加。在 IF 饲料喂养的动物的杏仁核、前额皮质和腹侧海马体中，促肾上腺皮质激素释放因子受体 1 (CRFR1) mRNA 表达减少。这些数据表明，光周期改变后 CORT 分泌的变化可能是通过 CRFR1 基因表达的差异或 MR:GR mRNA 比值的变化来介导的。这些发现为了解 HPA 轴如何适应光周期和饮食提供了潜在机制的见解。
