Impact of genotype and fetal and pre-weaning growth on steroidogenic capacity of the adult bovine adrenal

Background: Recent studies have suggested a role of the hypothalamic-pituitary-adrenal axis in the epidemiological association between birth weight and cardiovascular disease. Aims and Study design: The aims of this study were to determine if the steroidogenic capacity of the adult adrenal gland is permanently programmed by exposure to either high or low nutrition and growth before birth followed by either high or low nutrition and growth from birth to weaning at 7mo offspring from lean (Piedmontese; mutation in myostatin gene; PxH) and higher fat 'bovine' sire-breeds (Wagyu; WxH). Outcome Measures: Adrenal glands (n = 66) were collected from steers at 2.5yrs age, and adrenal RNA extracted for determination of steroidogenic enzyme gene [cytochrome P450 cholesterol side-chain cleavage (CYP11A1), cytochrome P450 17ahydroxylase (CYP17) and 3b hydrosteroid dehydrogenase (3BHSD)] and adrenocorticoptropin-receptor (MC2R) expression by Real-Time PCR. Results: The higher-fat bovine-sired (WxH) steers had increased expression of MC2R, CYP11A1, CYP17, and 3BSHD mRNA compared with the lean (PxH) steers. Nutrition resulting in low growth rate during the pre-weaning period was associated with reduced MC2R, CYP11A1 and CYP17 mRNA expression in the PxH steers. Conclusions: These findings suggest that growth early in life and genetic predisposition to either high or low body-fat alter the steroidogenic capacity of the adult adrenal gland through a mechanism that may involve regulation by the ACTH receptor.