RESUMEN
<p><b>OBJECTIVE</b>To explore the mechanism of serotonin-promoted osteoblast differentiation.</p><p><b>METHODS</b>Expression levels of collagen I and lysyl oxidase (LOX) in osteoblast were measured by RT-PCR after treated by (50, 100, 200 and 400 ng/L) serotonin. LOX siRNA effect was measured by Western blot, and protein levels of collagen I were determined by ELISA after treated by serotonin. Expression levels of Smad2 and Smad3 in osteoblasts were also measured by RT-PCR after treated by serotonin.Moreover, expression levels of LOX were measured by RT-PCR after Smad3 was knockout.</p><p><b>RESULTS</b>Serotonin promoted collagen I and LOX expression. The expression level of collagen I was significantly decreased by LOX siRNA. Furthermore, serotonin up-regulated the expression of Smad2 and Smad3 in osteoblasts, and the expression level of LOX was inhibited by Smad3 siRNA.</p><p><b>CONCLUSION</b>Serotonin promoted collagen I expression by activating Smads signaling pathway and up-regulating the LOX expression.</p>