Objective      To investigate the role of Rho kinase (Rock) signaling pathway in the proliferation of rabbit basilar artery vascular smooth muscle cells (VSMCs) stimulated by tumor necrosis factor-α (TNF-α).       Methods      VSMCs were isolated and primarily cultured from rabbit basilar artery. After Y-27632

Rock inhibitor at different concentrations was added into the culture

medium

followed by the stimulation of TNF-α. Cell viability was determined with CCK-8 assay. Cell cycle of VSMCs was determined by flow cytometry. The expression of proliferating cell nuclear antigen (PCNA) in the VSMCs was measured with immunocytochemical staining and Western blot analysis.       Results      Compared with normal control cells

TNF-α treatment at 20 ng/mL for 24 h markedly induced VSMCs proliferation (

P

0.01)

increased the percentage of cells in S and G

2

/M phase (

P

0.05)

and enhanced PCNA expression (

P

0.01). Pretreatment with Y-27632

however

significantly reversed the above effects induced by 20 ng/mL TNF-α

that is

significantly inhibited cell proliferation (

P

0.01)

decreased expression of PCNA protein (

P

0.05) and the amounts of cells at S and G

2

/M phase (

P

0.05).       Conclusion      TNF-α promotes the proliferation of VSMCs and cell cycle

but Rock inhibitor

Y-27632

effectively reverses the above effects induced by TNF-α. Rock signaling pathway mediates TNF-α-induced acceleration of VSMCs proliferation and cell cycle progression.