Hypothalamo-pituitary adrenocortical function in the rat after treatment with betamethasone

1 Hypothalamo-pituitary-adrenocortical (HPA) activity was suppressed in rats treated with betamethasone. 2 Recovery of normal HPA function occurred after corticosteroid withdrawl. 3 Although corticotrophin release was rapidly restored to its basal rate there was a delay in the return of the normal adrenocorticotrophic response to stress and normal adrenocortical function was evident only after the plasma adrenocorticotrophic hormone had reached 'supra-normal' levels. 4 The physiological significance and possible clinical relevance of the results are discussed.