[Substance P regulates function of osteoclasts via neurokinin-1 receptor].

OBJECTIVE:To investigate the effects of substance P on cultured rat osteoclasts. METHODS:Neurokinin-1 (NK1) receptor expression in osteoclasts was examined by immunohitochemical method, and changes of bone resorption activity caused by substance P and NK1 receptor antagonists were detected by pit formation assay. RESULTS:Immunoreactivity for NK1 receptor was distributed in the cytoplasm of osteoclasts. The average of pit formation areas significantly increased with addition of substance P (10(-7)-10(-4) mol/L) (P < 0.05), but the number of pitformations did not change (P > 0.05). NK1 receptor antagonists inhibited the enhancement of the bone resorption by substance P addition. CONCLUSION:The findings suggested that substance P may stimulate osteoclasts and result in bone resorption by the mediation of NK1 receptor.