Neuromedin B Regulates Cell Proliferation, Apoptosis and Steroidogenesis of Porcine Ovarian Granulosa Cells via NMBR

Granulosa cells (GCs) critically govern follicular development through the coordinated regulation of proliferation, apoptosis, and steroidogenesis. Neuromedin B (NMB), a local regulatory peptide, has been implicated in female reproductive processes. However, its precise effects on porcine GCs remain to be elucidated. In this study, we characterized the ovarian distribution of NMBR, investigated the effects of NMB on GC function, and further explored the involvement of NMBR in these effects using the NMBR antagonist PD168368. The results showed that higher NMBR expression was observed in follicles of larger diameter. NMB treatment differentially regulated the functional activities of porcine ovarian GCs. Specifically, certain concentrations of NMB significantly increased cell viability and altered the expression levels of the proliferation-related markers Cyclin B1 and PCNA; reduced the cell apoptosis rate and modulated the expression levels of apoptosis-related genes and proteins (Bax, Bcl-2, and Caspase-3); and affected steroidogenic responses, including increased E2 concentrations at selected concentrations while altering expression of STAR, CYP11A1, HSD3B1, and CYP19A1. Importantly, several of these effects were attenuated by PD168368 treatment. Collectively, these findings suggest that NMB may regulate multiple functions of porcine with the involvement of NMBR. These findings provide a theoretical basis for elucidating the neuroendocrine mechanisms underlying porcine follicular development and for further investigating the potential role of NMB/NMBR signaling in porcine follicular physiology.