Synthesis of seminal ribonuclease in isolated lobules of bull seminal vesicles

A procedure is described for preparing and maintaining in culture isolated lobules of bovine seminal vesicles, consisting of glandular acini, surrounded by little connective tissue and with free access to the external medium, in which secreted material can be collected. After 48 h in culture, the isolated lobules appeared indistinguishable, by morphological and biochemical criteria, from freshly isolated lobules. After much longer culture times about one third of the glandular cells were still capable of effective protein synthesis. Studying the biosynthesis of seminal ribonuclease with preparations of isolated lobules we found that the enzyme was synthesized and secreted; only the fully amidated isoenzyme was synthesized and secreted, indicating that production of the selectively deamidated isoenzymic forms occurred after secretion, newly synthesized protein was rapidly exported, indicating that the high levels of enzyme previously reported for the seminal vesicle tissue were essentially due to its content of stored secretion.     

Expression of opioid genes in bovine seminal vesicles

In seminal vesicles, the organ producing most of seminal plasma in the bovine species, the pro-opiomelanocortin and the proenkephalin genes are transcribed and translated, and their translation products processed into opioid peptides, which are secreted into the seminal plasma. By using a micro-organ preparation of seminal vesicles we found that, after 20 h of incubation with labelled methionine, a multiplicity of opioids was produced. Among these, [Met]enkephalin and beta-endorphin were positively identified, whereas in the newly formed secretion only [Met]enkephalin was detected. This may be correlated to the finding that the concentration of beta-endorphin in an extract of seminal plasma was one order of magnitude lower than that of [Leu]enkephalin and [Met]enkephalin. These findings expand the picture of the presence of opioid peptides in the male reproductive tract, indicating that they should have a role(s) in the physiology of reproduction, not only in the hypothalamus-pituitary-gonadal axis, determining the reproductive potential, but also in the so-termed sex accessory glands, determining the actual events leading to reproduction. To our knowledge this is also the first case studied of opioid peptides produced as exocrine hormones.