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The actions of ethinyloestradiol on the pituitary‐adrenal system of the rat
Author(s) -
FLACK J. D.
Publication year - 1970
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1970.tb08520.x
Subject(s) - medicine , endocrinology , corticosterone , adrenal gland , adrenocorticotropic hormone , pituitary gland , corticosteroid , hormone , biology
Summary1 . Single doses of ethinyloestradiol stimulate the pituitary adrenal axis of the female rat during quiescent conditions. 2 . After a stimulus which releases endogenous ACTH, there is an inhibition of the release of corticosterone from the adrenal gland, but an increase in the corticosterone stored in the gland. 3 . Ethinyloestradiol (1·0 mg/kg) injected acutely or daily for 7 days does not affect the corticosterone binding capacity of plasma in female rats, or the clearance rate of an injection of corticosterone. 4 . Prolonged treatment with ethinyloestradiol and ACTH inhibits the pituitary‐adrenal response to a stress and to an ACTH injection, indicating a block at the adrenal and pituitary level. 5 . The adrenal gland recovers more rapidly than the pituitary after cessation of the oestrogen treatment. 6 . The inhibition of the pituitary‐adrenal response to stress after oestrogen is probably caused by inhibition of cholesterol synthesis as suggested by others. Oestrogens can increase corticoid secretion during non‐stress conditions, however, so precursor lack through exhaustion cannot be excluded. 7 . It is suggested that the inhibition of the stress response after prolonged ACTH treatment is due to a decrease in sensitivity of the adrenal cortex after frequent ACTH stimulation, but the possibility that it is due to a reduction in circulating cholesterol cannot be ruled out.