Beta-endorphin inhibits prostaglandin synthesis in rat ovaries and blocks induced ovulation

Faletti, A.; Viggiano, J.M.; Gimeno, M.F.

doi:10.1016/0090-6980(94)00006-i

Cited by 26 publications

(14 citation statements)

References 24 publications

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“…Prostaglandins and nitric oxide are of particular interest, as they have been shown to play a role in follicle rupture (Brännströ m & Janson 1991, Ellman et al 1993, Shukovski & Tsafriri 1994, Faletti et al 1999. The ovarian concentration of PGs increases after LH surge and gonadotrophin stimulation (Brown & Poyser 1984, Faletti et al 1995. The present study investigated the effect of high levels of leptin on ovarian PGE production by performing in vivo and in vitro assays.…”

Section: Ob-r β-Actinmentioning

confidence: 99%

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Inhibitory effect of leptin on the rat ovary during the ovulatory process

Ricci¹,

Yorio²,

Faletti³

2006

Reproduction

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The aims of this study were to investigate the negative action of leptin on some intraovarian ovulatory mediators during the ovulatory process and to assess whether leptin is able to alter the expression of its ovarian receptors. Immature rats primed with gonadotrophins were used to induce ovulation. Serum leptin concentration was diminished 4 h after human chorionic gonadotrophin (hCG) administration, whereas the ovarian expression of leptin receptors, measured by western blot, was increased by the gonadotrophin treatment. Serum progesterone level, ovulation rate and ovarian prostaglandin E (PGE) content were reduced in rats primed with equine chorionic gonadotrophin (eCG)/hCG and treated with acute doses of leptin (five doses of 5 mg each). These inhibitory effects were confirmed by in vitro studies, where the presence of leptin reduced the concentrations of progesterone, PGE and nitrites in the media of both ovarian explants and preovulatory follicle cultures. We also investigated whether these negative effects were mediated by changes in the expression of the ovarian leptin receptors. Since leptin treatment did not alter the expression of ovarian leptin receptor, the inhibitory effect of leptin on the ovulatory process may not be mediated by changes in the expression of its receptors at ovarian level, at least at the concentrations assayed. In summary, the ovulatory process was significantly inhibited in response to an acute treatment with leptin, and this effect may be due, at least in part, to the direct or indirect impairment of some ovarian factors, such as prostaglandins and nitric oxide.

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Section: Ob-r β-Actinmentioning

confidence: 99%

“…Twenty hours after hCG injection, the rats were killed by cervical dislocation, ovaries were immediately removed and oviducts were dissected and examined by means of a stereoscopic microscope to assess the number of oocytes present within, as described previously (Faletti et al 1995).…”

Section: Ovulation Ratementioning

confidence: 99%

Inhibitory effect of leptin on the rat ovary during the ovulatory process

Ricci¹,

Yorio²,

Faletti³

2006

Reproduction

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“…Although POMC-mRNA is present in the ovaries, and functional roles of POMC-derived peptides have been described [5,8,12,19,21], the relatively low concentration of opioid peptides in reproductive tissue suggests a predominant paracrine or autocrine role within the ovary [11,13,14]. Hamada et al [11] demonstrated that the number of ( 3 …”

mentioning

confidence: 99%

β-endorphin inhibition of progesterone secretion by porcine granulosa cells during follicle development

Gregoraszczuk¹,

Słomczyńska²

1998

Reprod. Nutr. Dev.

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-Exogenous ¡3-endorphin or the opioid antagonist, naloxone, was added to the culture medium of control or LH-treated granulosa cells to elucidate the role of (3-endorphin in follicular steroidogenesis. ¡3-endorphin decreased basal progesterone (P 4 ) production by Gc isolated from small and medium follicles and had no effect on P 4 production by cells from large follicles. (3-endorphin decreased P 4 production by LH-treated Gc isolated from small, medium and large follicles. Naloxone increased basal P 4 production by cells from small and medium follicles and had no effect on P 4 production by Gc from large follicles. Neither agent had any effect on basal oestradiol (E 2 ) secretion by Gc from any of the follicles. However, E 2 secretion by LHtreated Gc from all sizes of follicles was inhibited by (3-endorphin, with the greatest effect on cells from small follicles. We conclude that opioid peptides act in the follicle in a paracrine manner to prevent excessive basal progesterone secretion by Gc and may also be involved in

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“…If such mechanism is present also in the theca cells, thus beta-endorphin could be a natural protector against excess ovulation rates. Supporting this hypothesis, the ovarian betaendorphin concentrations increase during the midcycle LH surge (Petraglia et al 1987), the peptide is mostly concentrated in LH-sensitive ovarian compartments such as theca, corpus luteum and stroma (present study), and is able to counteract the effects of superovulation drugs (Faletti et al 1995).…”

Section: Discussionmentioning

confidence: 61%

“…The maximal intra-ovarian betaendorphin concentration has been found at proestrus, when ovulation occurs (Lolait et al 1985). However, the microinjection of beta-endorphin into the ovarian capsule is able to inhibit pharmacologically induced ovulation in immature rats (Faletti et al 1995), suggesting that the periovulatory increase of ovarian betaendorphin concentration favors an inhibitory rather than stimulatory effect of the peptide on the ovulation process. Indeed, beta-endorphin inhibits intra-ovarian molecular pathways involved in the triggering of ovulation (Faletti et al 2003).…”

Section: Introductionmentioning

confidence: 96%

Effect of the pretreatment with prolactin on the distribution of immunoreactive beta-endorphin through different ovarian compartments in immature, superovulated rats

Reis¹,

Polisseni²,

Pereira³

et al. 2004

J Mol Hist

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Beta-endorphin and prolactin (PRL) are natural inhibitors of ovulation via central and peripheral mechanisms, but their possible interactions within the ovary are still unknown. The aims of the present study were to determine the gene expression and the topographic distribution of beta-endorphin, and the possible changes evoked by the pretreatment with PRL on the ovarian beta-endorphin localization in immature, superovulated rats. Prepuberal female Wistar rats weighing 60-70 g were superovulated with 20 IU equine gonadotrophins and, 48 h later, 20 IU human chorionic gonalotropin (hCG). Four hours after the hCG injection, the rats received either 200 microg rat PRL .i.p. (n = 12) or saline vehicle (n = 10). In the following morning the rats were killed and their ovaries were quickly removed. Beta-endorphin localization was assessed by immunohistochemistry and proopiomelanocortin (POMC) mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR). Beta-endorphin was expressed mostly in the corpora lutea and perivascular stroma, but a weak to moderate immunostaining was also present in the theca cells and some granulosa cells of tertiary/antral and preovulatory follicles. The main differences observed in the distribution of ovarian beta-endorphin between the two groups were a more intense immunostaining in the granulosa cells of antral follicles, corpus luteum and stroma of PRL-treated rats. POMC gene transcripts were detected in 2/5 samples from the control group and in 3/7 samples from the PRL-treated group. Thus, the expression of beta-endorphin in tertiary/antral follicles is enhanced by PRL treatment in immature, superovulated rats, providing a putative mechanism by which PRL could inhibit the ovarian response to induced ovulation.

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Beta-endorphin inhibits prostaglandin synthesis in rat ovaries and blocks induced ovulation

Cited by 26 publications

References 24 publications

Inhibitory effect of leptin on the rat ovary during the ovulatory process

Inhibitory effect of leptin on the rat ovary during the ovulatory process

β-endorphin inhibition of progesterone secretion by porcine granulosa cells during follicle development

Effect of the pretreatment with prolactin on the distribution of immunoreactive beta-endorphin through different ovarian compartments in immature, superovulated rats

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