Abstract: Abstract Objective: To explore the alteration of apoptosis of proximal colon smooth muscle cell in diabetic colon dysmotility. Methods: Thirty-six male SD rats were randomly divided into 4 groups which included normal control 6w group、normal control 10w group、DM 6w group and DM 10w group (n=9). Fasting blood glucose(FBG)、gastrointestinal transit rate and the serum level of fasting insulin(FINS) were detected, and the changes in the smooth muscle of proximal colon were examined by HE staining. The mRNA expression levels of bax 、bcl-2 and caspase-3 in the proximal colon smooth muscle cells were determined by real-time quantitative PCR(RT-qPCR).Results: ⑴ FBG of DM group was significantly higher than that of the normal control group. Gastrointestinal transit rate and FINS of DM group were significantly lower than those of the normal control group. The smooth muscle of proximal colon in DM group became thinner than that in the normal control group. The mRNA expression levels of bax and caspase-3 in DM group were higher than those in the normal control group and the mRNA expression level of bcl-2 in DM group was lower than that in the normal control group（P＜0.01）.⑵ FBG of DM 10w group was higher than that of DM 6w group. Gastrointestinal transit rate and FINS in DM 10w group were lower than those in DM 6w group. The smooth muscle of proximal colon in DM 10w group became thinner than that in DM 6w group. The mRNA expression levels of bax and caspase-3 in DM 10w group were higher than those in DM 6w group and the mRNA expression level of bcl-2 in DM 10w group was lower than that in DM 6w group（P＜0.05）.Conclusion: Diabetic colon dysmotility is closely associated with apoptosis of proximal colon smooth muscle cell, and the apoptosis becomes more significant with disease developing.

Key words: diabetes mellitus, colon dysmotility , smooth muscle cell, apoptosis