Expression and regulation of the proenkephalin gene in rat Sertoli cells

Previous studies have shown that multiple forms of proenkephalin RNA are present in the rat and mouse testis that are cell type specific: a 1700-nucleotide transcript, unique to the testis, found in spermatogenic cells, and a 1450-nucleotide form of somatic cell origin. In the present studies, rat Sertoli cells are shown to contain the 1450-nucleotide form of proenkephalin RNA. The concentration of this transcript is quite low immediately after Sertoli cell isolation, but increases after 1 day in culture to a constant level. Proenkephalin RNA levels are stimulated severalfold by FSH and cAMP, but are not significantly affected by LH or testosterone. These studies demonstrate that Sertoli cells are at least one source of the somatic, 1450-nucleotide form of proenkephalin RNA in the rat testis. The expression of opioid peptide genes by Sertoli cells as well as by germ and Leydig cells is further evidence for the postulated autocrine or paracrine functions of these peptides in the testis.