5-羟色胺对肠炎小鼠结肠组织中GRP78表达的影响*
Effects of 5-hydroxytryptamine on expression of GRP78 in colon tissue of mice with colitis

目的:观察5-羟色胺(5-HT)对肠炎小鼠结肠组织葡萄糖调节蛋白78(GRP78)表达的影响。方法:将7～8周龄的C57BL/6小鼠随机分为6组(n=8):正常对照组,低、高剂量5-HT组(分别给予1.0、2.0 mg/kg的5-HT灌肠,每3 d 1次),低、高剂量DSS组(分别饮用10或25 g/L DSS溶液),DSS+5-HT组(给予10 g/L DSS+1.0 mg/kg 5-HT),于第6天结束时处死小鼠。通过疾病活动指数评分、结肠长度测定和HE染色等方法评估肠道炎症程度,采用实时定量PCR技术检测小鼠结肠组织中IL-6、TNF-α和 GRP78 mRNA的表达水平,采用免疫组化法检测小鼠结肠组织中GRP78蛋白的表达。结果:正常对照组,低、高剂量5-HT组小鼠无肠炎,低剂量DSS组有轻微肠炎,高剂量DSS组和DSS+5-HT组有严重肠炎。IL-6和TNF-α mRNA的表达水平随炎症程度而增加。GRP78 mRNA和蛋白在正常对照组、低剂量5-HT组和低剂量DSS组中的表达水平差异无统计学意义(P>0.05),在高剂量5-HT组、DSS+5-HT组和高剂量DSS组,尤其是高剂量DSS组表达增高(P<0.05)。结论:5-HT可能通过上调GRP78蛋白的表达激活内质网应激反应,参与肠道炎症反应。
Aim: To investigate the impact of 5-hydroxytryptamine(5-HT)on the expression of endoplasmic reticulum stress chaperone glucose regulated protein 78(GRP78)in mouse inflammatory colon induced by dextran sulfate sodium(DSS).Methods: Seven to eight-week-old C57BL/6 mice were randomly allocated into 6 groups(n=8). Mice in normal control group drank water freely. Mice in low-dose 5-HT and high-dose 5-HT groups received 1.0 mg/kg and 2.0 mg/kg of 5-HT by enema respectively. Mice in low-dose DSS and high-dose DSS groups received 10 and 25 g/L DSS solution, respectively. Mice in DSS+5-HT group were concurrently treated with 10 g/L DSS solution and 1.0 mg/kg of 5-HT. At the end of the 6th day, they were scarified to gather specimens. The severity of colitis was evaluated by disease activity index(DAI), colon length and pathological inflammatory scores of colon. Inflammatory cytokines such as IL-6 and TNF-α mRNA expressions in colon tissue were measured by quantitative real-time PCR. The protein and mRNA expressions of GRP78 in colon tissue of mice were evaluated by immunohistochemistry and RT-PCR,respectively.Results: There was no colitis in mice of normal control, low-dose 5-HT and high-dose 5-HT groups, while mild colitis was found in mice of low-dose DSS group. However, mice co-treated with DSS and 5-HT had severe colitis, which was comparable to mice treated with high-dose DSS. In addition, the expressions of IL-6 and TNF-α mRNA increased with the deterioration of inflammatory degree. The mRNA and protein expressions of GRP78 in normal control, low-dose 5-HT and low-dose DSS groups was similar, while in high-dose 5-HT,DSS+5-HT and high-dose DSS groups, especially the high-dose DSS group were upregulated(P<0.05).Conclusion: 5-HT may activate endoplasmic reticulum stress response by increasing the expression of GRP78 protein, and participate in intestinal inflammation