Polzonetti-Magni A, Facchinetti F, Carnevali O, Mosconi G, Pestarino M, Vallarino M, Ciarcia G
Dipartimento di Biologia Molecolare, Cellulare e Animale, Università di Camerino, Italy.
Biol Reprod. 1994 May;50(5):1059-65. doi: 10.1095/biolreprod50.5.1059.
In mammals, proopiomelanocortin (POMC)-related peptides are involved in reproductive processes at both the hypothalamopituitary and ovarian levels. Through immunocytochemical and physiological in vitro studies, evidence for a diffuse POMC-related opioid system in the lizard Podarcis s. sicula is provided. In the lizard ovary, beta-endorphin (beta-EP)-like immunoreactive cells were observed within the granulosa layer; the immunoresponse showed seasonal variation, being most pronounced in the winter ovary. HPLC followed by immunoassay showed that acetyl beta-EP is the main form of POMC-related peptide in both pituitary and ovary. In vitro studies showed that picomolar amounts of beta-EP stimulate follicular estrogen production during both the reproductive and winter phases; induction was found to be higher in the reproductive phase. The data reported here provide evidence for the physiological role played by beta-EP in the reproductive function of Podarcis s. sicula via induction of ovarian production of estradiol-17 beta, which is the main factor responsible for the vitellogenic process.
