Differential Effects of Glucocorticoids on Corticotrophin-Releasing Factor in the Rat Pituitary Neurointermediate Lobe and Median Eminence

We have investigated the effects of glucocorticoid manipulation on corticotrophin-releasing factor (CRF-41) in the neurointermediate lobe (NIL) and median eminence (ME) of the rat using a radioimmunoassay specific for CRF-41. CRF-41 content in the NIL (88+/-7 fmol, mean +/- SEM) was not significantly altered by administration of dexamethasone in drinking water for 12 days (67+/-9 fmol) or adrenalectomy for 12 days (96+/-17 fmol). The saline-stimulated increase in NIL CRF-41 content (154+/-24 fmol) was not affected by dexamethasone (152+/-24 fmol) or adrenalectomy (179+/-21 fmol). In contrast, the content of CRF-41 in the ME declined following dexamethasone treatment (1247+/-92 fmol to 864+/-26 fmol), or adrenalectomy (854+/-78 fmol). Our results provide further evidence that CRF-41 in the NIL and ME can be differentially regulated.