INTRODUCTION: Visfatin, an adipocytokine involved in the metabolic homeostasis, has been implicated in reproductive regulation; however, its direct effects on hypothalamic gonadotropin-releasing hormone (GnRH) neurons remain unclear.

AIM(S): We hypothesized that visfatin directly modulates GnRH neuronal activity by stimulating GnRH secretion via a protein kinase C (PKC)-dependent signaling pathway. Therefore, the aims of this study were: (i) to confirm the expression of visfatin in mouse hypothalamic GnRH neurons, (ii) to determine whether visfatin directly affects GnRH secretion and expression in GT1-7 cells, and (iii) to elucidate the involvement of PKC-dependent signaling in visfatin-induced modulation of GnRH neuronal activity.

METHOD(S): In vitro experiments were performed using the mouse hypothalamic GnRH neuronal GT1-7 cell line. Firstly, visfatin expression was confirmed at the mRNA level by RT-qPCR and showed co-localization with GnRH by immunocytochemistry. Secondly, cells were treated with visfatin (10 or 100 ng/mL) for 15 or 30 min and then GnRH secretion was quantified by ELISA, protein expression by Western blot, and mRNA levels by RT-qPCR. Finally, the involvement of PKC signaling on the regulation of GnRH level was assessed using the pharmacological inhibitor Bisindolylmaleimide I (2 nM). Statistical analysis employed Student’s t test (n ≥ 4; p < 0.05).

RESULTS: Visfatin significantly stimulated GnRH secretion at both time points, accompanied by increased GnRH protein levels. Pharmacological inhibition of PKC markedly attenuated visfatin-induced GnRH secretion.

CONCLUSIONS: In conclusion, visfatin acts as a direct modulator of GnRH neuronal activity at the secretory level via PKC-dependent signaling. These findings provide new evidence linking adipocytokine signaling with hypothalamic control of reproduction and highlight visfatin as a potential mediator of metabolic–reproductive crosstalk.

FINANCIAL SUPPORT: National Science Centre (project no. 2021/42/E/NZ4/00088)