Melanocyte-stimulating hormone activity of synthetic MSH and ACTH peptides, in vivo and in vitro.

Abstract

SIMULTANEOUSLY performed in vivo and in vitro determinations of the melanocyte-stimulating hormone (MSH) activity of a large number of synthetic MSH and ACTH peptides have not been reported previously. The work recorded here compares by both methods the MSH activity of 10 stereoisomeric pentapeptide fragments of MSH and 8 synthetic peptides related to ACTH. The MSH activity of most of the stereoisomers appeared greater in vivo than in vitro. When, these compounds were assayed at various time intervals, some of the pentapeptides revealed differences which may help partially to explain this discrepancy in activity between the two methods. These differences may also help in understanding the alterations of α-MSH induced by sodium hydroxide1,2. In addition, preliminary studies were performed on the inhibitory properties of the stereoisomers.