Glucocorticoid Induced Stress Susceptibility in Swine: Adrenocortical Pathology

Abstract The studies reported here were undertaken to better characterize the role of the adrenal cortex in the increased susceptibility to stress observed in porcine stress syndrome. Since adrenal hypofunction was suggested during early studies as a factor in events leading to porcine stress syndrome it was decided to produce such a state by the exogenous administration of the glucocorticoids prednisolone and fluoroprednisolone. A total of 34 pigs (weighing 90 to 100 kg) received a series of graded doses (given intramuscularly) of one or the other of the foregoing compounds and were necropsied 48, 72, and 120 hours after the last treatment. The major adrenocortical changes produced by these treatments were atrophy, an accentuation of degenerative changes which could be observed in milder form in many of the 30 control pigs examined, a marked increase in stainable lipid 120 hours after the last fluoroprednisolone treatment and, ultrastructurally, an increase in lysosome-like bodies and cellular debris (“myelin bodies”). Adrenocortical atrophy is not a feature of porcine stress syndrome nor were the localized depositions of stainable lipid within the zona reticularis, described in porcine stress syndrome, found in the glucocorticoid treated pigs. Consequently, the findings reported here bear a somewhat limited resemblance to those observed in pigs affected by porcine stress syndrome and cast some doubt on whether adrenal hypofunction plays a role in the pathogenesis of the latter condition.