Stimulation of Adenosine 3′,5′-Monophosphate Production in Rat Sertoli Cells byα-Melanotropin- Stimulating Hormone (αMSH) and Des-AcetylαMSH*

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Abstract
Proopiomelanocortin and its derivative peptides .alpha.MSH and .beta.-endorphin are produced by Leydig cells. .beta.-Endorphin or another testicular opiate is believed to suppress Sertoli cell hypertrophy. The goal of this study was to determine the effects of another proopiomelanocortin-derived peptide on Sertoli cells. The activities of both .alpha.MSH and des-acetyl .alpha.MSH have been compared, since this latter peptide has been identified in testicular extracts. Both .alpha.MSH and des-acetyl .alpha.MSH stimulated cAMP accumulation in the media of primary Sertoli cell cultures when incubated in the presence of a phosphodiesterase inhibitor, FSH or forskolin. Both peptides shifted the FSH dose-response curve to the left, making the cells more sensitive to this gonadotropin. The apparent potencies of .alpha.MSH and its des-acetyl derivative, as measured in Sertoli cells, were similar. We conclude that the MSHs are one of a group of modulators regulating Sertoli cells via the cAMP system, and Sertoli cells are equally responsive to .alpha.MSH and des-acetyl .alpha.MSH, unlike central nervous system and melanocytes which show differential responses to these peptides.