Seminal plasma induces ovulation in llamas in the absence of a copulatory stimulus: Role of nerve growth factor as an ovulation-inducing factor

Marco A. Berland, Cesar Ulloa-Leal, Miguel Barría, Hollis Wright, Gregory Dissen, Mauricio E. Silva, Sergio Ojeda, Marcelo H. Ratto

    Research output: Contribution to journalArticle

    20 Scopus citations

    Abstract

    Llamas are considered to be reflex ovulators. However, semen from these animals is reported to be rich in ovulation-inducing factor(s), one of which has been identified as nerve growth factor (NGF). These findings suggest that ovulation in llamas may be elicited by chemical signals contained in semen instead of being mediated by neural signals. The present study examines this notion. Llamas displaying a preovulatory follicle were assigned to four groups: group 1 received an intrauterine infusion (IUI) of PBS; group 2 received an IUI of seminal plasma; group 3 was mated to a male whose urethra had been surgically diverted (urethrostomized male); and group 4 was mated to an intact male. Ovulation (detected by ultrasonography) occurred only in llamas mated to an intact male or given an IUI of seminal plasma and was preceded by a surge in plasma LH levels initiated within an hour after coitus or IUI. In both ovulatory groups, circulating β-NGF levels increased within 15 minutes after treatment, reaching values that were greater and more sustained in llamas mated with an intact male. These results demonstrate that llamas can be induced to ovulate by seminal plasma in the absence of copulation and that copulation alone cannot elicit ovulation in the absence of seminal plasma. In addition, our results implicate β-NGF as an important mediator of seminal plasma-induced ovulation in llamas because ovulation does not occur if β-NGF levels do not increase in the bloodstream, a change that occurs promptly after copulation with an intact male or IUI of seminal plasma.

    Original languageEnglish (US)
    Pages (from-to)3224-3232
    Number of pages9
    JournalEndocrinology
    Volume157
    Issue number8
    DOIs
    StatePublished - Aug 1 2016

    ASJC Scopus subject areas

    • Medicine(all)
    • Endocrinology

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