Demonstration that corticotropin-releasing factor binding to rat peripheral tissues is modulated by glucocorticoid treatment in vivo and in vitro.
In a recent study we reported the presence of specific binding sites for corticotropin-releasing factor (CRF) in peripheral tissues of the rat (Endocrinology, 116, 2151, 1985). The objective of this study was to determine if CRF binding to peripheral tissues was modified following adrenalectomy and glucocorticoid replacement therapy. Adult male rats were adrenalectomized and CRF binding to liver, spleen and testicular membranes was determined at 5, 7 or 14 days following adrenalectomy. An additional group of adrenalectomized rats received subcutaneous injections of dexamethasone (75 micrograms/day) for 14 days. Adrenalectomy of rats for 14 days increased CRF binding to liver, kidney, testis, spleen and ventral prostate by approximately 65%-125% above sham-control values. CRF binding to membrane preparations obtained from the pancreas of sham-operated rats was undetectable; however, adrenalectomy produced detectable CRF binding in this tissue. Adrenalectomy produced a time-related increase in CRF binding to ventral prostate, spleen and liver tissue. Administration of dexamethasone to adrenalectomized animals prevented increased CRF binding to peripheral tissues observed following adrenalectomy alone. In vitro dexamethasone treatment of prostatic or hepatic homogenates from adrenalectomized rats resulted in a dose-related decrease in CRF binding activity. However, similar in vitro treatment of prostatic or hepatic homogenate with progesterone exhibited no significant effects on CRF binding. Our results suggest that glucocorticoids may be a regulator of peripheral CRF receptors.
D000315:Adrenalectomy; D000818:Animals; D001665:Binding Sites; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005938:Glucocorticoids / Q000494:pharmacology*; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008297:Male; D011374:Progesterone / Q000494:pharmacology; D011467:Prostate / Q000378:metabolism; D051381:Rats; D013154:Spleen / Q000378:metabolism; D013737:Testis / Q000378:metabolism; D013997:Time Factors
D005938:Glucocorticoids; D011374:Progesterone; D003907:Dexamethasone; D003346:Corticotropin-Releasing Hormone