抄録
1. Glucocorticoids, cortisol and prednisolone, inhibited the ACTH effect in vitro. At the concentration of about 10-5M of glucocorticoid, the ACTH effect was almost completely inhibited, but this inhibitory action was not observed below the concentration of 10-6M. The inhibitory action on the ACTH effect of glucocorticoid could be removed by a previous addition of ACTH.
2. Tetrahydrocortisol, methyltestosterone and estradiol-17β did not inhibit the ACTH effect. Estradiol-17β increased the production of corticosterone in an ACTH-free medium.
3. It was suggested that the inhibitory action of glucocorticoid might be based on the result of inhibited metabolism of phosphorous in the adrenal cortex.
4. The data obtained indicate a possibility that the inhibition of the pituitary adrenal system following the administration of corticoids occurs not only at the level of the pituitary but also at the level of the adrenal cortex.
