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Dietary Manipulations That Induce Ketosis Activate the HPA Axis in Male Rats and Mice: A Potential Role for Fibroblast Growth Factor-21.

Citation
Ryan, K. K., et al. “Dietary Manipulations That Induce Ketosis Activate The Hpa Axis In Male Rats And Mice: A Potential Role For Fibroblast Growth Factor-21.”. Endocrinology, pp. 400-413.
Center University of Michigan
Author Karen K Ryan, Amy E B Packard, Karlton R Larson, Jayna Stout, Sarah M Fourman, Abigail M K Thompson, Kristen Ludwick, Kirk M Habegger, Kerstin Stemmer, Nobuyuki Itoh, Diego Perez-Tilve, Matthias H Tschöp, Randy J Seeley, Yvonne M Ulrich-Lai
Abstract

In response to an acute threat to homeostasis or well-being, the hypothalamic-pituitary-adrenocortical (HPA) axis is engaged. A major outcome of this HPA axis activation is the mobilization of stored energy, to fuel an appropriate behavioral and/or physiological response to the perceived threat. Importantly, the extent of HPA axis activity is thought to be modulated by an individual's nutritional environment. In this study, we report that nutritional manipulations signaling a relative depletion of dietary carbohydrates, thereby inducing nutritional ketosis, acutely and chronically activate the HPA axis. Male rats and mice maintained on a low-carbohydrate high-fat ketogenic diet (KD) exhibited canonical markers of chronic stress, including increased basal and stress-evoked plasma corticosterone, increased adrenal sensitivity to adrenocorticotropin hormone, increased stress-evoked c-Fos immunolabeling in the paraventricular nucleus of the hypothalamus, and thymic atrophy, an indicator of chronic glucocorticoid exposure. Moreover, acutely feeding medium-chain triglycerides (MCTs) to rapidly induce ketosis among chow-fed male rats and mice also acutely increased HPA axis activity. Lastly, and consistent with a growing literature that characterizes the hepatokine fibroblast growth factor-21 (FGF21) as both a marker of the ketotic state and as a key metabolic stress hormone, the HPA response to both KD and MCTs was significantly blunted among mice lacking FGF21. We conclude that dietary manipulations that induce ketosis lead to increased HPA axis tone, and that the hepatokine FGF21 may play an important role to facilitate this effect.

Year of Publication
2018
Journal
Endocrinology
Volume
159
Issue
1
Number of Pages
400-413
Date Published
12/2018
ISSN Number
1945-7170
DOI
10.1210/en.2017-00486
Alternate Journal
Endocrinology
PMID
29077838
PMCID
PMC5761593
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