Objective    To investigate the effects of norepinephrine on the proliferation of bone marrow mesenchymal stem cells (BMSCs) and the related signaling molecules involved in BMSCs.     Methods   

3

H-thymidine incorporation assay was performed to investigate the effect of norepinephrine on BMSCs proliferation

in the presence of various concentrations (10

-6

to 10

-4

mol/L) for 8 h or with phentolamine (10

-6

mol/L) for 30 min. Effect of norepinephrine on PKC activation was detected by immunofluorescent stai

ning and Western blot analysis.     Results    Norepinephrine treatment (10

-6

  to10

-4

mol/L) for 8 h increased the

3

H-thymidine incorporation in a dose-dependent manner. The maximal stimulatory effect was observed at 10

-5

mol/L of norepinephrine. The stimulatory effect of norepinephrine on cell proliferation was blocked by co-incubation with phentolamine. Norepinephrine induced PKC translocation to the cell membrane

which was blocked by pretreatment with phentolamine for 30 min.     Conclusion    This stimulatory effect of norepinephrine on cell proliferation is mediated through AR/PKC-dependent signaling.