Isoflavones Alter Hypothalamic–Pituitary–Adrenal Axis Response Following Photoperiod Alteration

Abstract

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 ☆ Disclosure. The opinions or assertions contained herein are the private ones of the authors and are not to be construed as official or reflecting the views of the Department of Defense or the Uniformed Services University of the Health Sciences. The authors report no conflicts of interest in this work.

Knockout of the circadian gene, Per2, disrupts corticosterone secretion and results in depressive‐like behaviors and deficits in startle responses

“…Following previously established protocols, expression of mRNAs was measured using qPCR [ 13 , 15 ], Primer sequences for measured genes are listed in Table 1 . Two ng of cDNA template was amplified using iQ SYBR Green Supermix (BioRad Laboratories, Hercules, CA).…”

Gut microbiota and metabolic marker alteration following dietary isoflavone‐photoperiod interaction

“…The AIN‐93 diet did not differ in macronutrient, mineral and vitamin composition from the Teklad Global 18% Protein Rodent Diet 17 . Both diets were previously characterized by our laboratory for isoflavone content using high performance liquid chromatography based analysis according 16,18,19 . The standard chow contains a total of 199.4 μg/g of isoflavone equivalents, whereas the NIF diet contains 0 μg/g of isoflavone equivalents 18 .…”

“…17 Both diets were previously characterized by our laboratory for isoflavone content using high performance liquid chromatography based analysis according. 16,18,19 The standard chow contains a total of 199.4 μg/g of isoflavone equivalents, whereas the NIF diet contains 0 μg/g of isoflavone equivalents. 18 All experimental groups were acclimated to these diets for 3 weeks prior to photoperiod modification.…”

“…Photoperiod interaction with dietary isoflavones may play a critical role in regulating most physiological functions by closely influencing the gut microbiota 16 . While several studies have established the respective effects of diet and photoperiod on the gut microbiome, a gap in knowledge remains as to how these two environmental cues may ultimately interact to affect the gut microbiome.…”

“…Photoperiod interaction with dietary isoflavones may play a critical role in regulating most physiological functions by closely influencing the gut microbiota. 16 While several studies have established the respective effects of diet and photoperiod on the gut microbiome, a gap in knowledge remains as to how these two environmental cues may ultimately interact to affect the gut microbiome. In this study, we manipulated isoflavone consumption and photoperiod duration to examine how these external cues interact to dictate the temporal stability of the gut microbiome and its relationship with obesity and metabolism.…”