Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01189 (beta-endorphin)
 21,003 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

It is known that the same peptide can be identified in different secretory tissues and in the central nervous system (CNS). We now provide evidence that the same peptides can be found in different organs related to the control of a single function, and speculate on the possibility that this reflects a common neuroendocrine programming. Endogenous opioid peptides (EOP) inhibit the reproductive function acting via the CNS. EOP inhibit gonadotropin secretion in rodents and humans via inhibition of GnRH release and have direct inhibitory actions at the pituitary level via specific binding sites on the gonadotrophs. However, EOP can also be synthesized in the testis and in different compartments of the male genital tract. Several findings indicate that EOP of the reproductive tract have a local, paracrine role. These include: (1) the detection of significant beta-endorphin (beta-EP) production by rat Leydig cells (Lc) in cultures; (2) the hormonal regulation of Lc beta-EP production by positive (gonadotropins) and negative (steroids, glucocorticoids, GnRH) factors; (3) the presence of opioid binding sites (Kd in the nanomolar range) in tubular homogenates and Sertoli cells (Sc) in culture of adult and immature rat testes; (4) the inhibition of basal and FSH-stimulated ABP production by Sc in culture when chronically exposed to beta-EP treatment; (5) the detection of high levels of beta-EP and met-enkephalin in human semen with values 6-12 times higher than in plasma; (6) the evidence for inhibitory functions of seminal opioids on sperm motility, vas deferens muscle contraction and partner immune system. Thus the same peptides, i.e. EOP, may control the reproductive function at multiple sites, operating as a multimessenger system in which the central and peripheral level are unified by the common chemical and inhibitory nature of the message.
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PMID:Neuroendocrine control of male reproductive function. The opioid system as a model of control at multiple sites. 264 37

Spermatogenesis and spermiogenesis are controlled by FSH and testosterone but need also the participation of several paracrine and autocrine mechanisms of regulations. The relationships between peritubular, Sertoli and Leydig cells are currently investigated. High intratesticular testosterone levels are maintained by a binding to a protein called ABP which is synthetized by Sertoli cell and regulated by pituitary FSH. Leydig cell testosterone, peritubular cell P-Mod-S (protein modulating Sertoli function) and Sertoli cell FRP (follicle regulatory protein). Accumulation of testosterone results to aromatase activity modulation. Aromatization is stimulated by FSH, activin, alpha-MSH but is inhibited by aromatase inhibitor, inhibin, FSHBI (FSH binding inhibitor). Other molecules, growing factors, mitogenic factors, energetic substrates are synthetized in the testis under the control of germ cells. Understanding of these mechanisms of intratesticular regulation will permit to discover therapies capable of correcting certain fertility dysfunctions.
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PMID:[Paracrine regulation of testicular function]. 265 82

Using antibodies against peptides derived from different portions of the POMC molecule, immunocytochemical evidence suggests that this precursor and/or the peptides present within it are localized in testicular Leydig cells of at least five species. There is no evidence for the localization of these peptides or their precursor in any other cell type in this organ. Examination of testicular extracts by gel filtration, SDS-PAGE, and RP-HPLC indicate that the testis contains low concentrations of POMC-derived peptides relative to brain. Further analysis indicates that POMC is processed to alpha-MSH and beta-endorphin similar to its processing in intermediate pituitary lobe and brain. The relative mobilities of immunoreactive alpha-MSH and beta-endorphin on RP-HPLC columns indicate that they are in the unacetylated state as in brain and in contrast to the acetylated forms in the intermediate pituitary lobe. The potential for Leydig cells to synthesize POMC and its peptides was suggested by the demonstration of POMC-like mRNA in total testis and Leydig cell cultures. The size of the POMC-like mRNA is approximately 150 base pairs shorter than anterior or intermediate pituitary POMC mRNA. POMC-like mRNA activity has also been localized to Leydig cells in sections of testes using in situ hybridization. Immunostainable beta-endorphin and other POMC-derived peptides are present in testicular Leydig cells during fetal life and following puberty at times when testosterone secretion is maximal. The accumulation of immunostainable POMC-derived peptides in Leydig cells is dramatically increased by LH and hCG. A variety of observations suggests that testicular cells can respond to POMC-derived peptides. ACTH and the MSHs stimulate growth and cAMP accumulation in Sertoli cells. By contrast, studies using antagonists suggested that beta-endorphin and/or another testicular opioid inhibit Sertoli cell proliferation and ABP secretion. These observations are consistent with the postulate that different portions of the POMC molecule may have opposite effects on Sertoli cell function and suggest a mechanism by which Leydig cells could modulate Sertoli cell activity. Intratesticular administration of opiate antagonists inhibits testosterone secretion both in vivo and in vitro. These observations suggest that Leydig cell-derived beta-endorphin may facilitate testosterone secretion either directly or indirectly. The finding of POMC and its derivative peptides in testis, ovary, adrenal, and placenta suggests that all steroid hormone-secreting organs in mammals may utilize this peptidergic system.
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PMID:Identification and possible function of pro-opiomelanocortin-derived peptides in the testis. 610 19