Extrahypothalamic Corticotropin and <i>α</i>-Melanotropin in Human Brain

Abstract

The distribution of corticotropin (ACTH) and α-melanotropin (α-MSH) in human brain was investigated by radioimmunoassay using an antiserum which recognized h-ACTH_1-39 and α-MSH to an equal degree on a molar basis. Significant amounts of material, which migrated on calibrated Sephadex G-50 columns as synthetic h-ACTH_1-39 and synthetic α-MSH, were detected in distinct brain areas. The highest concentrations of ACTH and α-MSH were found in the diencephalon (hypothalamus 4.2 and 12.5 pmol/g wet weight, respectively) and in midbrain (periaqueductal gray 0.5 and 1.7 pmol/g, respectively) and smaller quantities in the rhombencephalon and telencephalon. The ACTH concentration in human pituitary (adenohypophysis) was 10⁴-fold greater than that in the hypothalamus. α-MSH was confined to the midpart and/or stalk region of the pituitary.

Characterization of α-MSH-like immunoreactivity in human plasma

“…Due to the rather large variation in sensitivity of the assays employed, most of these reports have been rather contradictory about the actual presence of this peptide in the human circulation (Clark et al 1978;Nieuwenhuijzen Kruseman et al 1985;Ratter et al 1981). Nevertheless, it has been well established that the hu¬ man foetal pituitary contains a substantial number of a-MSH producing cells located in a distinct pars intermedia (Visser & Swaab 1979) and that a-MSH from these cells might, among others be functional in stimulating foetal adrenal growth and development (Silman et al 1976(Silman et al , 1981 (Kleber et al 1980;Visser & Swaab 1979). At this time the matured adrenals seem no longer dependent on a-MSH for their function¬ ing, and ACTH has become predominant adrenal corticotropic hormone (Silman et al 1976(Silman et al , 1981.…”