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EFFECT OF 3 DAY INFUSION OF ACTH OR CRF ON THE PITUITARY‐ADRENAL AXIS
Author(s) -
Silberberg Suzanne,
Funder John W.
Publication year - 1988
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1988.tb01004.x
Subject(s) - medicine , endocrinology , corticosterone , receptor , subcutaneous injection , adrenal gland , adrenocorticotropic hormone , stimulation , chemistry , hormone
SUMMARY 1. The effects of 72 h subcutaneous infusion of graded doses of rat CRF and ACTH(1–24) were studied in rats of initial weight 150–170 g. Rat CRF was infused at 30, 100 or 300 ng/h, and ACTH(1–24) at 125, 250 or 500 ng/h. 2. There was a progressive though modest increase in adrenal weight for all CRF doses, and an associated reduction of thymus weight. Circulating ir‐ACTH, ir‐β‐endorphin and corticosterone levels, and adrenal DN A content, were not increased after 3 days. Adrenal RNA and protein content were increased at the highest CRF dose used. 3. ACTH infusion caused a progressive increase in adrenal weight and thymie involution which was marked at the higher doses; circulating corticosterone levels were not significantly altered by the lowest dose but were significantly raised by the higher doses. As expected, plasma ir‐β‐endorphin was suppressed to low levels with all doses. Adrenal DNA did not alter but there were progressive increases in adrenal protein and RNA. 4. There was a marked difference in gain between the two infusion regimens in terms of all parameters measured, suggesting that potent mechanisms exist to temper the pituitary‐adrenal response to markedly different levels of peripheral CRF input. The damped effect of CRF infusion compared with that of ACTH may represent desensitization of CRF receptors at the pituitary; alternatively, it may reflect binding and substantial inactivation of CRF in peripheral blood.