Abstract
Summary Plasma corticosterone concentrations and adrenal corticoid production in vitro are determined in rats which have been subjected to stress at different time intervals after subcutaneous injection of a high dose of corticosterone. The inhibiting effect of this injection on the pituitary-adrenal response to stress in these rats appears not to run parallel with the induced elevation in plasma corticosterone levels. It is concluded that pituitary impairment by corticoid administration is not correlated with the existing blood level of corticoids.