Inducible nitric oxide synthase promotes differentiation of satellite cells and prevents stress urinary incontinence via HGF-mediated p38/MAPK signaling.

PURPOSE Satellite cells (SCs) are multipotent skeletal muscle precursor cells, which can lead to muscle regeneration, a crucial process for the treatment of stress urinary incontinence (SUI). The activation of SCs is likely to be caused by inducible nitric oxide synthase (iNOS). This study examines the underlying mechanism of iNOS in SC activation, and the implications of a potential treatment of SUI. METHODS SCs were isolated from the levator ani muscles of rats, followed by measurement of iNOS, paired box gene 7 (Pax7) and myosin D (MyoD) protein expression. Flow cytometric and cell counting kit-8 assays were conducted to assess SC proliferation, apoptosis, cell cycle distribution. SC myotube formation was observed under a light microscope. A rat model of SUI was established using vaginal dilation and bilateral ovarian castration, followed by assessment of leaking point pressure (LPP) and a sneezing test. The levels of MyoD, Pax7, hepatocyte growth factor (HGF) and p-38 in the levator ani muscles were detected by immunohistochemical and western blot analyses. RESULTS SCs successfully isolated from rat levator ani muscles showed increased MyoD and reduced Pax7 expression. Upregulation of iNOS promoted differentiation and myotube formation of SCs. iNOS elevated the expression of HGF, which in turn activated the p38/MAPK signaling pathway, promoting the differentiation of SCs. SCs overexpressing iNOS increased LPP, thus preventing SUI in an in vivo rat model. CONCLUSION Our results show that iNOS could activate the HGF-dependent p38/MAPK signaling pathway to alleviate SUI, potentially providing a novel therapeutic strategy for SUI.