Objective To investigate the role of Smad signaling pathway in rat model of cerebral in-farction and explore the expression of insulin-like growth factor binding protein 3(IGFBP-3)in brain tissue and its relationship with neural function.Methods Sixty healthy adult male SD rats were randomly and equally divided into model group,sham-operation group,and normal control group.The model of cerebral infarction was established by using intraluminal thread occlusion,and the rats of the sham-operation group were only given exposure of the internal carotid artery and direct suture of the incision.In 1 week after successful modeling,Modified Neurological Seve-rity Score(mNSS)was used to evaluate the neurological function.HE staining was employed to observe the histopathological changes in the brain tissues.Western blotting and RT-PCR were adopted to detect the brain expression of IGFBP-3,Smad2 and Smad4 at protein and mRNA le-vels.Spearman correlation analysis was conducted to analyze the correlation among the expression levels of IGFBP-3,Smad2,Smad4 and P21.Results HE staining displayed that obvious brain ede-ma,characterized by disordered arrangement of brain cells,increased microglia,and blurred nucleo-lus of brain cells were observed in the rats of the model group,with the area of cerebral infarct of 20.55％.The mNSS score and the protein and mRNA levels of IGFBP-3,Smad2 and Smad4 were significantly higher,but the P21 protein and mRNA levels were obviously reduced in the model group than the sham-operation group and normal control group(P＜0.05,P＜0.01).Spearman correlation analysis showed that the mRNA level of IGFBP-3 in cerebral infarction rats was posi-tively correlated with the mNSS score and mRNA expression levels of Smad2 and Smad4(r=0.568,r=0.623,r=0.597;P＜0.01),and negatively with P21 mRNA level in the brain tissue(r=-0.573;P＜0.01).Conclusion The level of IGFBP-3 is significantly increased in brain tissue of rats with cerebral infarction,and it is closely associated with neural function of these rats,which may be related to Smad signaling pathway.