Characterization of Immunoreactive Proopiomelanocortin-Related Peptides in Rat Testes

Abstract

alpha-Endorphin, beta-endorphin, gamma-endorphin, and N-terminal ACTH immunoreactivity were detectable in acid extracts of rat testes with concentrations of 0.07 +/- 0.01, 0.18 +/- 0.03, 0.06 +/- 0.01, and 0.33 +/- 0.08 (+/- SD) pmol/g wet wt, respectively. The forms of these immunoreactive peptides were characterized by reverse phase high performance liquid chromatography. Immunoreactive beta-endorphin was also analyzed by gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results indicated that the major form of immunoreactive beta-endorphin present appears to be beta-endorphin-(1-31). No alpha-N-acetylated forms of beta-endorphin or beta-lipotropin-sized material were detected. Immunoreactive alpha- and gamma-endorphin appear to be present as alpha-endorphin and des-Tyr1-gamma-endorphin, respectively. Immunoreactive alpha MSH was present as its desacetylated form. No immunoreactive ACTH fractionating with ACTH-(1-39) or its glycosylated forms was detected. This peptide profile is most similar to that seen for proopiomelanocortin-derived peptides in the brain. The low concentrations of these peptides in rat testes suggest a paracrine function.

N-acetyl endorphin in rat spermatogonia and primary spermatocytes.

“…3). The minor peaks on each side of N-Ac- This is consistent with a recent report (9) (17) to be temporally important. Similarly, in the retina, a complementary role for cholinesterase has been proposed in the processing and activation of pro-enkephalin (18).…”

“…In both intracranial and other tissues, the extent of proteolytic cleavage and posttranslational processing (glycosylation, amidation, and acetylation) varies widely. Although a-N-acetylated EPs have been demonstrated primarily in the neurointermediate lobe of the pituitary (8), a recent report noted that acetylated EPs were present as a minor component in the testis (9). In the present study we have used specific antisera to demonstrate that N-acetyl (Ac) EPs are a major immunoreactive form of the peptide in the testis, and that, in contrast with f3-EP which appears confined to interstitial cells, N-Ac-EPs are found in spermatogonia and primary spermatocytes.…”

Intratesticular distribution of testosterone in rats and the relationship to the concentrations of a peptide that stimulates testosterone secretion

“…changes in the turnover of interstitial fluid as the cause or it may indicate the involvement of some other secretory product of the Leydig cells such as ß-endorphin (Margioris, Liotta, Vaudry, Bardin & Krieger, 1983; Bardin et ai, 1984), and experiments to test this possibility are in progress.…”

Action of proteolytic enzymes on lipotropins and endorphins: Biosynthesis, biotransformation and fate

“…Subsequently, several reports have indicated indirectly the presence of ~t-and 7-endorphins in pituitary tissue by detecting peptides with opiate-like properties of the size of these/~-endorphin fragments (Giagnoni et al, 1977;Sabol, 1978;Lissitsky et al, 1978). Peptides related to ct-and 7-endorphin have been immunologically and/or chromatographically characterized in extracts of rat anterior and intermediate pituitary (Jegou et al, 1978(Jegou et al, , 1979Fukata et al, 1979;Verhoef et al, 1980aVerhoef et al, ,b, 1982Dorsa et al, 1982;Wiegant et al, 1983a,b), in rat brain (Verhoef et al, 1980(Verhoef et al, , 1982aDorsa et al, 1981;Wiegant et al, 1983a,b), in human pituitary and brain (Burbach and Wiegant, 1983; unpublished observations), in guinea pig myenteric plexus (Opmeer et al, 1980), and in rat testicular tissue (Tsong et al, 1982;Shu-Dong et al, 1982;Margioris et al, 1983). Immunohistochemical localization studies have shown the storage of ct-endorphin and 7-endorphins in pituitary and rat brain (B6geot et al, 1978;Vaudry et al, 1980).…”