Ketogenic Diet Partially Attenuates Deleterious Effects of Chronic Stress

Abstract

Ketogenic diets (KDs) are high-fat low-carbohydrate diets that can exert positive effects on physical and neurological health. The more established therapeutic effects of KD are for treating epilepsy and diabetes. However, KD protective effects may apply to other inflammation related disorders associated with Hypothalamic-Pituitary-Adrenal (HPA) axis dysregulation, such as mood disorders. Chronic stress has been shown to elevate cytokine levels, disrupt neuroendocrine homeostasis, and cause anxiety and depressive-like behavior in animal models. In vitro experiments have shown that ketone bodies, a metabolite produced while on KD, can prevent the production of cytokines elevated in response to chronic stress and other pre-clinical experiments have suggested that ketone bodies can prevent anxiety-like behavior. Although this suggests that KDs have anti-inflammatory and mood stabilizing potential, these effects have yet to be explored. In this experiment, we assessed the behavioral and neuroendocrine effects of KD using male and female Long-Evans rats. Animals underwent three weeks of Chronic Mild Stress (CMS) while on KD or control Chow (CH). Body weight and food intake data were recorded daily, and depressive-like behaviors were assayed after the three weeks. Plasma Beta-Hydroxybutyrate (HB), Corticosterone (CORT) and Interleukin-1 beta (IL-1) were measured after behavior testing, along with hypothalamic Corticotropin-Releasing Hormone (CRH) and Neuropeptide Y (NPY) mRNA expression. CMS induced weight loss and reduced food intake in the control-diet groups, however the KD-fed male and female rats were resistant to CMS-induced weight loss and reduced food take. Female rats fed KD were protected from CMS-induced reductions in plasma CORT and hypothalamic NPY expression. Collectively, these data suggest anti-depressant potential of KDs against chronic stress, particularly in females.