Ovarian contents of immunoreactive beta-endorphin and alpha-N-acetylated opioid peptides in rats.
beta-Endorphin was measured by radioimmunoassay in homogenates of ovaries from immature Sprague-Dawley rats (21-29 days of age) and found to be present at levels of about 0.6-0.7 ng/ovary. After administration of PMSG there was approximately a 4-fold increase (2-3 ng/ovary) in total ovarian immunoreactive (ir) beta-endorphin 48 h after injection. Analysis of follicular fluid from similarly treated rats indicated about the same amount of ovarian ir-beta-endorphin (2-3 ng/ovary) as in ovarian homogenates, suggesting that most of the ir-beta-endorphin is localized in follicular fluid of PMSG-primed immature rats. Immature rats were made pseudopregnant by administration of hCG 48 h after PMSG, and at 24 h after injection of hCG there was a slight, but significant and reproducible, increase in the ovarian content of ir-beta-endorphin. The serum concentration of ir-beta-endorphin was in the range of 1-3 ng/ml and was unaffected by PMSG and PMSG/hCG; likewise, the pituitary content of ir-beta-endorphin did not change following administration of gonadotrophins to immature rats. In mature cyclic animals, levels of 2-4 ng ir-beta-endorphin/ovary were found, comparable to those in the ovaries of PMSG-primed immature rats, and there were only small changes during the oestrous cycle. In addition to ir-beta-endorphin, we also obtained evidence for the presence of alpha-N-acetylated opioid peptides (endorphins or enkephalins) in the ovaries of PMSG-primed immature and mature rats. The physiological role of the opioid peptides in reproductive tissue is unknown, but they are presumably acting in an autocrine or paracrine fashion.
Lovegren
E S
ES
Reproductive Sciences, Laboratories, University of Miami School of Medicine, Florida 33101.
Zimniski
S J
SJ
Puett
D
D
D000107:Acetylation; D000818:Animals; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004723:Endorphins / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism; D006064:Gonadotropins, Equine / Q000494:pharmacology; D010053:Ovary / Q000187:drug effects / Q000378:metabolism*; D011555:Pseudopregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation / Q000502:physiology; D001615:beta-Endorphin / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D004723:Endorphins; D004745:Enkephalins; D006064:Gonadotropins, Equine; D001615:beta-Endorphin