Effect of Maternal High Fat Diet on the Hypothalamus-Pituitary-Adrenal Gland (HPA) Axis of the Offspring in Sheep

Maternal consumption of a high fat diet (HFD) during pregnancy is associated with metabolic dysfunction and altered HPA axis function in the offspring. These effects are well established in species with short gestation length (e.g., rodents), but less established in species with longer gestation periods more comparable with humans. The objective of the study was to determine the effect of maternal HFD on basal and stimulated cortisol secretion in the offspring at 16 weeks of age in sheep. All experiments were approved by the Institutional Animal Care and Use Committee at Cal Poly Pomona. Pregnant ewes were assigned to control (n=3) and HFD (n=3) groups. The control group was fed farmers best complete ewe and ram pellets. The HFD group was fed the same diet with an additional 30% rumen protected fat (Megalac, Volac Wilmar Feed Ingredients Ltd). After birth lambs were weaned at 12 weeks of age and given free access to control pellet diet with grains. To assess adrenal cortisol secretion at 16 weeks, lambs were infused intravenously with adrenocorticotropic hormone (ACTH; 2 ug/kg cortrosyn in 1 mL saline). Blood samples (1 mL) were taken through the jugular catheter at −30, −15, and 0 min (immediately before) and 5, 15, 30, 60, 90, and 120 min after ACTH administration for measurement of plasma cortisol by ELISA. Data were analyzed by two-way repeated measures ANOVA with a Tukey posthoc test. Basal plasma cortisol tended to be higher in HFD (32±8 ng/mL) than control (13±3 ng/mL) lambs, but this did not reach statistical significance. Plasma cortisol was higher than baseline from 15 to 90 minutes after ACTH administration in all lambs (p<0.05). The increment in plasma cortisol was higher in HFD than control lambs from 15-90 minutes (p<0.05). Accordingly, the maximum increase in plasma cortisol at 60 minutes and was higher in HFD (245±8 ng/mL) than control lambs (121±50 ng/mL p<0.05). These preliminary data suggest that maternal consumption of a high fat diet during pregnancy may increase basal and stimulated activity of the HPA axis in sheep. The study was funded by a Strategic Interdisciplinary Research Grant (SIRG) at California State Polytechnic University, Pomona. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.