Objective      To investigate the effect of cal

citonin gene-related peptide (CGRP) on myocardin expression and inflammatory activation in vascular smooth muscle cells (VSMCs) in vitro.       Methods      VSMCs were obtained by aortic tissue adherent culture and treated with interleukin-1β (IL-1β group)

IL-1β+CGRP (CGRP group)

and IL-1β+CGRP+CGRP 8-37 (CGRP receptor antagonist

CGRP

8-37

group) or transfected with recombinant adenovirus vector over-expressing myocardin (myocardin group) or siRNA-myocardin (siRNA-myocardin group). The expression of myocardin protein and interleukin-6 (IL-6) protein at different time points in the VSMCs were detected by Western blotting.       Results      In the in vitro cultured VSMCs of the IL-1β group

the expression of IL-6 at 24

48 and 72 h were significantly higher than the baseline (P0.05)

and the expression of myocardin was similar. In the myocardin group

the level of IL-6 at any time point was obviously lower than that in the IL-1β group (P0.05). The CGRP group showed higher myocardin expression and lower IL-6 level at any time point than the IL-1β group (myocardin: 1.17±0.03 vs 0.25±0.03 at 24 h; 2.04±0.05 vs 0.19±0.01 at 48 h; 0.96±0.02 vs 0.28±0.02 at 72 h; P0.05; IL-6: 0.23±0.01 vs 0.77±0.03 at 24 h; 0.28±0.02 vs 1.35±0.04 at 48 h; 0.20±0.02 vs 1.04±0.04 at 72 h; P0.05). The level of IL-6 in the siRNA-myocardin group was higher than that in the IL-1β group at any time point (1.74±0.04 vs 0.51±0.01 at 24 h; 1.68±0.03 vs 0.29±0.01 at 48 h; 0.98±0.02 vs 0.31±0.01 at 72 h; P0.05). The comparison had similar results between the CGRP

8-37

group and the CGRP group. Also

there was no difference in the IL-6 level at the same time point between the siRNA-myocardin group and the CGRP

8-37

group.       Conclusion      CGRP may inhibit IL-1β-induced IL-6 protein expression through up-regulating the expression of myocardin protein in the VSMCs

which may be accomplished by binding CGRP and its receptor.