Interaction among beta-endorphin, nitric oxide and prostaglandins during ovulation in rats

Alicia G. Faletti, C. Mohn, M. Farina, A. Lomniczi, V. Rettori

Research output: Contribution to journalReview articlepeer-review

18 Scopus citations


The aim of this study was to investigate the relationship between β-endorphin and nitric oxide (NO) during the ovulatory process in rats. Immature rats were treated with equine chorionic gonadotrophin-hCG to induce ovulation. An intrabursal injection of β-endorphin stimulated nitric oxide synthase (NOS) activity. This effect was completely reversed when naltrexone was co-injected with β-endorphin. The stimulatory action of β-endorphin on NOS activity was studied to determine whether it was exerted via prostaglandins. Treatment with prostaglandin E2 (PGE2) completely reversed the β-endorphin-induced stimulation of NOS activity. Moreover, intrabursal injection of meloxicam, an inhibitor of cyclooxygenase 2, increased NOS activity, but this effect was not altered by co-injection with β-endorphin. The presence of both endothelial NOS (eNOS) and inducible NOS (iNOS) in the ovary at 10 h after hCG treatment was studied by western blot analysis. Local administration of β-endorphin inhibited the expression of eNOS protein, whereas expression of iNOS protein was not detectable. Ovarian β-endorphin content was diminished at 10 h after hCG injection. Treatment with prostaglandin synthesis inhibitors in vivo augmented the ovarian β-endorphin content. In conclusion, these results indicate that β-endorphin stimulates the activity of ovarian NOS indirectly by inhibiting prostaglandin production.

Original languageEnglish (US)
Pages (from-to)469-477
Number of pages9
Issue number4
StatePublished - Apr 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Reproductive Medicine
  • Embryology
  • Endocrinology
  • Obstetrics and Gynecology
  • Cell Biology


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