Title: The inhibin / activin family and pro-opiomelanocortin-derived peptides as intratesticular regulators of cellular function.

POPLINE Document Number: 075754

Author(s):

Morris PL
Chen CL
Feng ZM
Vaughan J
Vale WW
Bardin CW

Source citation:

In: Growth factors in fertility regulation. Proceedings of the Symposium on Potential of Molecular Biology in Fertility Regulation: Growth Regulatory Factors, jointly sponsored by the World Health Organization and the National Institute of Child Health and Human Development and held at the National Institutes of Health, Bethesda, Maryland, on September 22-24, 1988, edited by Florence P. Haseltine, Jock K. Findlay. Cambridge, England, Cambridge University Press, 1991. :209-28. (Scientific Basis of Fertility Regulation)

Abstract:

Evidence that gene expression and peptide secretion by testicular cells are regulated by the inhibin and activin, and the POMC group of peptides, acting as paracrine and autocrine effectors on Sertoli and Leydig cells is collected in this review. POMC refers to pro-opio-melano-cortin, or beta-endorphin, melanocyte-stimulating hormone, and adrenocorticotropic hormone (ACTH), which are a group of intratesticular messengers secreted in Leydig cells into the testicular interstitial fluid. The evidence that inhibin and activin are produced by the testis includes isolation of inhibin from rete testis fluid, cloning inhibin cDNA from testicular libraries and comparing them to ovary and placenta, localizing inhibin in the tubular epithelium, and studies of the regulation of inhibin gene expression and secretion. Inhibin mRNA for the alpha subunit peaked in rat testis at 20-25 days of age, and is maintained by follicle stimulating hormone (FSH). POMC peptides and mRNA, at levels comparable to those in the hypothalamus, were demonstrated in Leydig cells. Immunologic assays showed beta-endorphin and other POMC peptides at heightened levels in Leydig cells in fetal life and puberty. Studies in vitro suggest that POMC in testis is controlled by the pituitary along with changes in testosterone. ACTH/MSH peptides make Sertoli cells more sensitive to FSH, and act by the cyclic AMP system. In contrast, beta-endorphin inhibits Sertoli cell division, adenylate cyclase activity, and protein secretion. Inhibin and activin have opposing effects on sensitivity of Sertoli cells to LH. Many studies show that ACTH/MSH peptides stimulate Sertoli cell function, and beta-endorphin inhibits Sertoli cells as a paracrine regulator, but stimulates Leydig cells as an autocrine. Thus the POMC peptides and inhibin are components of an intratesticular feedback system that modulates the functions of Sertoli and Leydig cells.

Keywords:

Clinical Research
Physiology
Testis
Adenosine Cyclic Monophosphate
Testosterone
Adrenal Cortex Hormones
Follicle Stimulating Hormone
Luteinizing Hormone
Pituitary Hormones
Hormone Receptors
Proteins
Animals, Laboratory
In Vitro
Models, Experimental
Research Methodology
Biology
Genitalia, Male
Genitalia
Urogenital System
Androgens
Hormones
Endocrine System
Gonadotropins, Pituitary
Gonadotropins
Membrane Proteins