S100 calcium-binding protein B ameliorates premature ejaculation in rats via regulation of the BDNF/5-HT pathway

BACKGROUND: Premature ejaculation (PE) is one of the most common forms of male sexual dysfunction, yet its underlying neurobiological mechanisms remain unclear. AIM: This study aims to explore the role of S100 calcium-binding protein B (S100B) in PE and its regulatory relationship with brain-derived neurotrophic factor (BDNF) and serotonin (5-HT) signaling. METHODS: A rat model of PE was established using behavioral screening criteria. Sexual behavior parameters were recorded, and the expression levels of S100B, BDNF, and 5-HT in brain tissues were measured using enzyme-linked immunosorbent assay, quantitative real-time PCR, Western blotting, immunohistochemistry, and immunofluorescence. The impact of S100B knockdown on PE-related behaviors and molecular expression was evaluated. OUTCOMES: The primary outcome was the effect of S100B regulation on PE-related behaviors and its interaction with the BDNF/5-HT signaling pathway. RESULTS: PE rats exhibited classical behavioral features, including shortened ejaculation latency and increased ejaculation frequency. Transcriptomic and protein analyses showed that S100B expression was significantly upregulated, while BDNF and 5-HT levels were markedly reduced in PE rats. S100B expression increased across several brain regions. Knockdown of S100B restored 5-HT and BDNF levels, prolonged ejaculation latency, and alleviated PE behaviors. BDNF overexpression elevated 5-HT levels and improved sexual behavior. Importantly, BDNF silencing reversed the beneficial effects of S100B knockdown, suggesting that S100B regulates ejaculation via the BDNF/5-HT pathway. CLINICAL IMPLICATIONS: Targeting S100B and its regulation of the BDNF/5-HT pathway may provide potential therapeutic strategies for managing premature ejaculation. STRENGTHS & LIMITATIONS: Strengths include comprehensive molecular and behavioral analyses in a rat model provide insights into PE pathophysiology. Although this effect has been demonstrated in animal models, these models may not fully recapitulate the pathophysiological processes of human PE, and further clinical validation is required. CONCLUSION: Our findings indicate that S100B is upregulated in PE and may contribute to the pathophysiology of PE by modulating the BDNF/5-HT signaling pathway. This study provides a molecular basis for the development of therapeutic strategies targeting PE.