β-Nerve growth factor is a major component of alpaca seminal plasma and induces ovulation in female alpacas

Abstract

Ovulation in camelids is induced by an unidentified protein in the seminal plasma of the male termed 'ovulation-inducing factor'. This protein has been reported to be a 14-kDa protein under reducing conditions, which, when purified from seminal plasma, induces ovulation in llamas. The identification of this protein and investigation of its potential to induce ovulation in camelids may aid the development of protocols for the induction of ovulation. In the present study, alpaca seminal plasma proteins were separated using one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the most abundant protein of 14 kDa was identified as β-nerve growth factor (β-NGF) by liquid chromatography mass spectrometry. Female alpacas (n = 5 per group) were given intramuscular injections of: (1) 1 mL of 0.9% saline; (2) 4 µg buserelin, a gonadotrophin-releasing hormone agonist; (3) 2 mL alpaca seminal plasma; or (4) 1mg human β-NGF. Ovulation was detected by transrectal ultrasonography 8 days after treatment and confirmed by plasma progesterone concentrations. Ovulation occurred in 0%, 80%, 80% and 80% of animals treated with saline, buserelin, seminal plasma and β-NGF, respectively. Treatment type did not affect the diameter of the corpus luteum, but plasma progesterone concentrations were lower in saline-treated animals than in the other treatment groups owing to the lack of a corpus luteum. The present study is the first to identify the ovulation-inducing factor protein in alpacas. β-NGF successfully induces ovulation in alpacas and this finding may lead to new methods for the induction of ovulation in camelids.

Mapping of tyrosine hydroxylase in the diencephalon of alpaca (Lama pacos) and co-distribution with somatostatin-28 (1-12)

“…However, an induced ovulation mechanism has been demonstrated in alpacas and other camelids (see Adams et al, 2005), and the presence of a potent ovulation-induced factor has been described in the seminal plasma of alpacas and llamas that elicited a surge in the circulating concentrations of LH and induced a luteotropic response (Kersahw-Young et al, 2012). The existence of this factor may be a specific evolutionary mechanism, and it is possible that the hypothalamic regulation of reproduction in alpacas could be different from that of other mammalian species.…”

LH release and ovulatory response after intramuscular, intravenous, and intrauterine administration of β-nerve growth factor of seminal plasma origin in female llamas

“…The ovulation-inducing factor (OIF) present in the seminal plasma recently found to be identical to b-nerve growth factor (b-NGF) [5,6], consistently induced ovulation in camelid species when administered intramuscularly (reviewed in [8]). Ovulation induced by OIF (NGF) was preceded by a rapid increase in plasma LH concentration similar to that observed after copulation [9][10][11].…”

“…In the latter (e.g., rabbits, cats, koalas, and camelids), ovulation is triggered in response to mechanical stimulation of the female genital tract during copulation. However, results of several llama and alpaca studies have clearly showed that ovulation is induced by a protein factor present in seminal plasma; i.e., induction of ovulation is related to the effects of a chemical constituent of seminal plasma, not the physical or mechanical stimulation of copulation [1][2][3][4][5][6]. The results of a recent study supported this concept; female llamas mated with a urethrostomized male ovulated at a significantly lower rate (16%) than those mated with an intact male [7].…”

Double ovulation and occurrence of twinning in alpacas ( Vicugna pacos )

“…It is well established that all camelids are induced ovulators [1]. Ovulation is induced by the combined inflammatory response to mating and the intrauterine deposition of ß-nerve growth factor present in seminal plasma [2,3]. Follicular dynamics are therefore variable depending on whether the female has been induced to ovulate or not.…”