Presence of immunoreactive beta-endorphin in normal human plasma: a concomitant release of beta-endorphin with adrenocorticotropin after metyrapone administration.
To elucidate whether or not beta-endorphin exists in plasma of normal subjects, plasma extracts obtained before and after metyrapone administration were subjected to gel exclusion chromatography, and fractions obtained were assayed by a sensitive radioimmunoassay for beta-endorphin. The basal plasma level of beta-endorphin was 5.8 +/- 1.1 pg/ml (mean +/- SE, n = 5), which rose significantly to the level of 48.9 +/- 3.8 pg/ml after a single oral dose (30 mg/kg of body wt) of metyrapone administration (P less than 0.001). Plasma ACTH levels also increased from the mean basal level of 73 +/- 4 pg/ml to 269 +/- 41 pg/ml after metyrapone administration. These results indicate that beta-endorphin, distinct from beta-lipotropin, exists in normal human plasma and that it is released from the pituitary concomitantly with ACTH.
D000324:Adrenocorticotropic Hormone / Q000097:blood / Q000378:metabolism; D000328:Adult; D004723:Endorphins / Q000097:blood* / Q000378:metabolism; D006801:Humans; D008297:Male; D008797:Metyrapone / Q000494:pharmacology*; D010902:Pituitary Gland / Q000187:drug effects / Q000378:metabolism; D011863:Radioimmunoassay; D013997:Time Factors; D008083:beta-Lipotropin / Q000097:blood
D004723:Endorphins; D000324:Adrenocorticotropic Hormone; D008083:beta-Lipotropin; D008797:Metyrapone