Beta-Nerve Growth Factor acts upstream of GnRH neurons to trigger ovulation in mice - Archive ouverte HAL Accéder directement au contenu
Communication Dans Un Congrès Année : 2022

Beta-Nerve Growth Factor acts upstream of GnRH neurons to trigger ovulation in mice

Résumé

Timed induction of ovulation requires a cascade of events in which GnRH and Kisspeptin (Kp) neurons play a key role. In mammals, ovulation is either spontaneous or induced by mating. In species with induced ovulations, β-Nerve Growth Factor (βNGF) is acknowledged as an important stimulatory factor whereas this role is attributed to Kp in species with spontaneous ovulations. However, recent studies suggested that the βNGF could also contribute in spontaneous ovulatory species. We tested whether βNGF induced ovulation in mice, a spontaneous ovulatory species, and investigated if GnRH and Kp systems are involved in its effect. Fifty mice (21 days) received 5IU of PMSG and, 48 hours later, one of the following treatments: 0.9% NaCl, 5 IU of hCG, or βNGF (0.1µg, 1 µg, or 10 µg/mouse). All three βNGF doses induced ovulation (p <0.001) with an efficacy similar to that of hCG. Ovulation rates were 80% for hCG or βNGF (0.1 µg and 1µg), 100% for βNGF (10 µg), and 10% for NaCl. To determine if βNGF action on ovulation required GnRH receptor activation, we tested responses in mice pre-treated with Cetrorelix, a GnRH receptor antagonist. Prepubertal mice (128) were allocated to five treatment groups: βNGF (1 µg), Cetrorelix (50 ng) + βNGF (1 µg), GnRH (50 ng), Cetrorelix (50 ng) + GnRH (50 ng), or 0.9% NaCl. Both βNGF and GnRH triggered ovulations and this effect was blocked by Cetrorelix (ovulation rate: Cetrorelix + βNGF vs βNGF, p<0.05). These results suggest that the GnRH is implicated in the βNGF-induced ovulation pass through. We then tested responses in Kiss1 and Kiss1r null mice at two ages: adult (KO Kiss1: 23; KO Kiss1r: 16) and prepubertal (KO Kiss:5 ; KO Kiss1r: 9) mice. Each type of mice was allocated into two groups of treatment: βNGF (0.2 µg) or hCG (5UI). In all groups treated with βNGF, the rate of ovulation and the number of corpora lutea per ovary was significantly? lower than in groups treated with hCG. These results suggest that βNGF requires the action of Kp to trigger ovulation. Using double immunohistochemical procedures on adult OVX+E2 female mice, we found both βNGF receptors, p75 NTR and TrkA, localized in the organum vasculosum of the lamina terminalis (OVLT). p75 NTR was also expressed in the arcuate nucleus (ARC) and Median Eminence (ME ). p75 NTR was found in neurons and tanycytes, but was not expressed by GnRH or Kp immunoreactive neurons suggesting the involvement of interneurons. In conclusion, βNGF induces ovulation in the mouse and this probably involves the release of GnRH and Kp. However, because none of these neurons expresses p75 NTR, the transduction of βNGF information is relayed either by interneurons or by glial cells. Among them, tanycytes appear as interesting candidates.

Domaines

Neurobiologie
Fichier non déposé

Dates et versions

hal-03754010 , version 1 (22-08-2022)

Identifiants

  • HAL Id : hal-03754010 , version 1

Citer

Flavie Derouin Tochon, Renaud Fleurot, Laurence Dufourny, Ya-Lin Huang, Didier Lomet, et al.. Beta-Nerve Growth Factor acts upstream of GnRH neurons to trigger ovulation in mice. 10. International Congress of Neuroendocrinology (ICN), Aug 2022, Glasgow, United Kingdom. ⟨hal-03754010⟩
58 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More