The Major Immunoreactive α-Melanocyte-Stimulating Hormone (αMSH)-Like Substance Found in Human Fetal Pituitary Tissue Is Not αMSH but May Be Desacetyl αMSH (Adrenocorticotropin1–13NH2)*

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Abstract
Pituitary glands were obtained from human abor-tuses during the second half of gestation. Acid extracts were made from the anterior and neurointermediate lobes, and aMSH immunonoreactivity (αMSHi) was quantified by RIA. αMSH; wasfound in both lobes of the pituitary gland, with 20–80% of the total pituitary αMSHi being present in extracts of the anterior lobe. Anterior and neurointermediate lobe extracts subjected t o gel filtration on Sephadex G-50 revealed one peak of αMSHi having an elution profile identical to those of αMSH and desacetyl αMSH (ACTH1−13NH2). To characterize further)the αMSHi, extracts were subjected to high pressure liquid chromatography. No αMSH could be identified in extracts of the anterior lobe, and most of the αMSHi had an elution profile identical to that of desacetyl αMSH. Although small amounts of αMSH might be present in the neurointermediate lobe, most of the αMSHi in this lobe coeluted with desacetyl αMSH. Since αMSH was not converted to desacetyl αMSH during the extraction and chromatographic procedures, we hypothesize that the predominant form of αMSH-like material in the human fetal pituitary gland may be desacetyl αMSH.