PSII-37 - Program Chair Poster Pick: The effect of glucocorticoids on circulating plasma concentrations of ghrelin in sheep
Monday, July 20, 2020
7:00 AM – 5:00 PM
Location: Poster Sessions
Activation of the hypothalamic-pituitary-adrenal (HPA) axis to release adrenocorticotropic hormone (ACTH) culminates in glucocorticoid production in sheep. Glucocorticoids alter metabolic function, which suggests concentrations of metabolically important hormones, ghrelin and growth hormone (GH), might be affected by components of the HPA axis. To clarify the relationship between the HPA axis and these hormones in ruminants, 10 Katahdin ewe lambs (1 year old; 43.3 +/- 1.3 kg) received an intravenous injection of ACTH (0.2 µg/kg BW) or saline. In a second experiment, the same lambs received an intravenous injection of the synthetic glucocorticoid, dexamethasone (DEX; 2 mg/kg BW) or saline. Blood samples were collected in 15 min intervals from 1 h before injection to 2 h after. Plasma concentrations of cortisol, ghrelin, and GH were analyzed by radioimmunoassay analysis. Data were tested for effect of treatment (saline or ACTH and saline or DEX), time, and treatment by time interaction using procedures for repeated measures with JMP software (version 10; SAS Inst. Inc.). Cortisol concentrations increased in response to both ACTH and dexamethasone administration (P < 0.0001). Neither ghrelin nor GH concentrations were affected by ACTH or DEX administration (P ≥ 0.4372). These data confirm ACTH influences cortisol secretion but suggest neither ACTH nor glucocorticoids impact plasma concentrations of ghrelin and GH in sheep.