[Study on the development of the radioimmunoassay of the corticotropin releasing factor (CRF)].

Synthetic ovine CRF was conjugated to bovine serum albumin (BSA) with glutaraldehyde and used as an immunogen to generate antibodies in rabbits. One of the antisera revealed 40% binding with 125I-CRF at 1 : 12,000 dilution in RIA. The antiserum did not show any significant crossreaction with other hormones. The Chloramine-T method was used to label CRF with 125I and purified by Sephadex G-50 fine (1 X 103 cm) chromatography with 0.03 M phosphate buffer (pH 7.2) containing 0.1% BSA, 20mM EDTA, 200 KIU/ml Trasyrol was used for the RIA buffer and the separation of free and antibody-bound CRF was performed by the Dextran-Charcoal method. The tentative minimum sensitivity of the assay was 20-100 pg/tube. The dilution curve of 125I-CRF in the hypothalamus of rat was parallel to that of the standard. Immunoreactive CRF content in the hypothalamus of male, female and post ovariectomized rats was measured by RIA. The content in those of male and post ovariectomized rats was significantly higher than in female rats. These data indicate that the pituitary-adrenal axis may have some effects on post-menopausal status.