Utilizza questo identificativo per citare o creare un link a questo documento:
|Titolo:||Ovarian opioids and the reproductive cycle of the frog Rana esculenta|
|Autori interni:||CARNEVALI, Oliana|
POLZONETTI, Alberta Maria
|Data di pubblicazione:||1992|
|Abstract:||In mammals, proopiomelanocortin-related peptides are involved in reproductive processes both at the hypothalamo-pituitary and ovarian levels. Using immunocytochemical, biochemical and physiological 'in vitro' studies, we provide here evidence for a diffuse POMC-related opioid system in the frog Rana esculenta. Ovarian β-endorphin (β-EP) is expressed in thecal cells and changes during the reproductive cycle in an inverse relationship with follicular development. Seasonal changes in the ovary are different to those in the brain or in the pituitary. The ratio of acetylated vs native β-EP in the ovary also changes over the reproductive period, affecting the biological activity of the peptide. During both the reproductive spring period and the summer post-reproductive phase pMol amounts of β-EP stimulate follicular androgen secretion in vitro, in a naloxone-reversible way. In either period, an inhibition of estradiol, possibly mediated via other factors, is the result of opioid action. In conclusion, these data demonstrate for the first time the widespread presence of β-EP-related peptides in the frog Rana esculenta. Both immunocytochemical and biochemical evidence, as well as in vitro responses, support a physiological role for β-EP in ovarian seasonality during the reproductive cycle of this amphibian.|
|Appare nelle tipologie:||Articolo|
File in questo prodotto:
Non ci sono file associati a questo prodotto.
- PubMed Central loading...
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.