Presence and steroidogenetic activity of beta-endorphin in the ovary of the lizard, Podarcis s. sicula raf.
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.
Polzonetti-Magni
A
A
Dipartimento di Biologia Molecolare, Cellulare e Animale, Università di Camerino, Italy.
Facchinetti
F
F
Carnevali
O
O
Mosconi
G
G
Pestarino
M
M
Vallarino
M
M
Ciarcia
G
G
D000107:Acetylation; D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004958:Estradiol / Q000096:biosynthesis; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism; D008116:Lizards / Q000378:metabolism*; D008969:Molecular Sequence Data; D009270:Naloxone / Q000494:pharmacology; D010053:Ovary / Q000187:drug effects / Q000378:metabolism*; D010902:Pituitary Gland / Q000502:physiology; D012621:Seasons; D014020:Tissue Extracts / Q000494:pharmacology; D001615:beta-Endorphin / Q000494:pharmacology / Q000502:physiology*
D014020:Tissue Extracts; D009270:Naloxone; D004958:Estradiol; D001615:beta-Endorphin