Effects of the adrenal steroidogenesis inhibitor trilostane on serum cortisol concentrations and growth in pigs

There is evidence that the growth of female rats and sheep may be constrained by physiological concentrations of glucocorticoid hormones. This study was designed to examine the effects of trilostane, an inhibitor of adrenal steroidogenesis, on serum cortisol concentrations and growth in pigs. First, trilostane was tested at three doses (250 mg, 500 mg and 1000 mg per pig) to examine its effect on serum cortisol concentrations. A reduction in serum cortisol concentration was observed 2 to 4 h after oral administration of trilostane (P < 0·05) and the adrenal response to a challenge dose of ACTH was reduced 4 to 6 h after administration (P < 0·05), at all doses tested. In a second experiment, trilostane (9·24 mg/kg body weight) was administered orally to 10 pigs twice daily for 35 days to examine its effects on growth rate. A further 10 pigs received a placebo. Trilostane did not affect weight gain or carcass composition, but caused a reduction in food intake (P < 0·05). Adrenal weight was increased by trilostane treatment and liver weight was reduced. These results show that trilostane is effective at lowering serum cortisol concentrations acutely, but suggest that physiological concentrations of glucocorticoid hormones may not retard growth rate in barrows.