维生素D3对溃疡性结肠炎豚鼠结肠组织凋亡作用的研究

INHIBITION OF COLONIC APOPTOSIS BY VITIMIN D3 IN GUINEA PIGS WITH ULCERATIVE COLITIS

目的探究补充VD3是否可以抑制结肠组织的凋亡作用,进而改善豚鼠溃疡性结肠炎。方法将18只雄性豚鼠根据体质量随机分为3组,每组6只:对照组[VD35μg/(kg·d)]、正常剂量VD3组[VD35μg/(kg·d)]和低剂量VD3组[VD30.25μg/(kg·d)]。试验期间用不含VD3配方的饲料喂养,采用改良豚鼠灌胃法给予每组相应剂量的VD3进行干预。干预5w后,正常剂量VD3组和低剂量VD3组豚鼠自由饮用2%的葡聚糖硫酸钠(dextran sulfate sodium,DSS)进行造模,对照组自由饮用蒸馏水。造模期间进行疾病活动指数评分(disease activity index,DAI);4d后处死,进行结肠大体形态学评分;经苏木素-伊红(HE)染色进行组织病理学评分;采用实时定量PCR(RT-PCR)检测结肠组织中细胞凋亡相关分子Caspase-3、Bax、Bcl-2的mRNA表达水平;透射电镜观察结肠上皮细胞结构。结果与对照组相比,正常剂量VD3组和低剂量VD3组DAI、结肠大体形态学以及组织病理学评分均升高(P<0.05),正常剂量VD3组DAI和组织病理学评分均低于低剂量VD3组(P<0.05)。与对照组相比,正常剂量VD3组和低剂量VD3组豚鼠结肠组织Caspase-3的mRNA表达水平[分别为(0.87±0.39、5.58±1.41、4.81±1.33)]明显增加(P<0.05);与低剂量VD3组相比,Bax在正常剂量VD3组转录降低[分别为(7.33±1.89、2.76±1.34,P<0.05)];与对照组相比,Bcl-2在正常剂量VD3组和低剂量VD3组的转录水平均降低[分别为(0.95±0.07、0.43±0.06、0.35±0.20,P<0.05)]。结论补充正常剂量的VD3可以抑制结肠组织的异常凋亡,对肠粘膜有一定的保护作用,缓解了DSS引发的结肠损伤。

Objective To investigate whether supplementation of VD3 can inhibit the apoptosis of colon tissue,thereby improving ulcerative colitis in guinea pigs.Methods Eighteen male guinea pigs were randomly divided into three groups(n=6)according to their body weight:control group(5μg/(kg·d)VD3),normal dose of VD3 group(5μg/(kg·d)VD3),and low dose of VD3 group(0.25μg/(kg·d)VD3).During the test period,the feed containing no VD3 formula was fed,and the corresponding dose of VD3 was administered to each group by modified guinea pig gavage.After 5 weeks of intervention,the control group was free to drink distilled water,and the other two groups were free to drink 2%dextran sulfate sodium(DSS)solution for modeling.Disease activity index(DAI)scores were assessed during modeling.The colonic gross morphology score was evaluated after 4 days.Hematoxylin-Eosin(HE)staining was used for histopathological scoring.Real-time quantitative PCR(RT-PCR)was used to detect the mRNA expression of apoptosis-related Caspase-3,Bax and Bcl-2 in colon tissue.Transmission electron microscope observation of colonic epithelial cell structure was conducted.Results Compared with the control group,the DAI,colon gross morphology and histopathological scores of the normal dose of VD3 group and the low dose of VD3 group were increased(P<0.05),and the DAI and histopathology scores of the normal dose of VD3 group were lower than the low dose of VD3 group(P<0.05).Compared with the control group,the mRNA expression level of Caspase-3 in the colon tissue of two other groups was significantly increased(0.87±0.39,5.58±1.41,4.81±1.33)(P<0.05).Compared with the low dose of VD3 group,Bax transcription was decreased in the normal dose of VD3 group(7.33±1.89,2.76±1.34)(P<0.05).Compared with the control group,the transcription level of Bcl-2 was reduced in the two VD3 groups(0.95±0.07,0.43±0.06,0.35±0.20)(P<0.05).Conclusion Supplementation of normal dose of VD3 can inhibit abnormal apoptosis of colon tissue,and alleviate colonic damage caused by DSS.