表皮生长因子在醋酸诱导的结肠高敏感模型大鼠中的表达及其作用
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江苏省兴卫工程重点人才项目(RC201163)


The expression of epidermal growth factor and it’s effect on colonic-sensitized rats induced by acetic acid
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    目的:初步探讨表皮生长因子(EGF)在醋酸诱导的结肠高敏感模型大鼠中的表达及其作用-方法:新生雄性乳大鼠20只,于出生第10~21天,模型组(n = 10)给予0.5%醋酸灌肠,建立慢性结肠高敏感模型,对照组(n = 10)给予相同体积生理盐水-通过结直肠扩张(CRD)刺激,记录腹壁撤退反射(AWR) 评分和腹外斜肌肌电活动(EMG),评估内脏敏感性-ELISA法检测两组大鼠血清及结肠组织中EGF和5-羟色胺(5-HT)水平,采用Western blot方法检测模型组与对照组结肠组织中5-HT转运体(SERT)表达,并分析两组大鼠结肠组织EGF水平与SERT蛋白表达间关系-体外细胞实验进一步探讨EGF对SERT表达的影响,大鼠肠上皮细胞(IEC-6细胞)给予不同浓度EGF(0-20-40-80 ng/ml)刺激24 h,检测SERT蛋白表达-结果:结肠高敏感组大鼠AWR评分及EMG幅值较对照组显著增高(P < 0.05),HE染色及髓过氧化物酶(MPO)水平检测显示两组大鼠结肠组织均无明显炎症表现,提示持续内脏高敏感形成-模型组大鼠与对照组相比,血清EGF水平明显降低[(2.639 ± 0.107)ng/ml vs(4.066 + 0.573)ng/ml,P < 0.05],且结肠中EGF表达也明显减低[(3.244 ± 0.135)ng/100 mg vs(3.582 + 0.197)ng/100 mg,P < 0.05]-结肠组织中SERT蛋白表达量,模型组大鼠与对照组相比显著下降[(0.711 ± 0.219)vs(0.980 ± 0.239),P < 0.01]-模型组大鼠血清及结肠组织中5-HT水平显著高于对照组[(6.125 ± 0.534)ng/ml vs(3.540 ± 0.442)ng/ml,(5.527 ± 0.514)ng/100 mg vs(2.650 ± 0.495)ng/100 mg,P < 0.05]-结肠组织中EGF水平与SERT蛋白表达存在显著正相关(r = 0.820,P < 0.001)-体外细胞实验结果显示,予不同浓度EGF(20-40-80 ng/ml)刺激细胞,SERT相对表达量(分别为1.398 ± 0.091-1.725 ± 0.124-1.571 ± 0.088),与0 ng/ml(1.011 ± 0.012)比较,P < 0.05-结论:醋酸诱导结肠高敏感大鼠结肠组织中5-HT水平增高,结肠组织SERT蛋白表达下降,同时其血清及结肠组织中EGF水平下降,且结肠组织中SERT表达与EGF水平呈正相关-体外细胞实验EGF可呈浓度依赖上调IEC-6细胞SERT蛋白表达,提示EGF可能通过影响SERT的表达参与内脏高敏感性形成-

    Abstract:

    Objective:To investigate the expression and effect of epidermal growth factor(EGF) on a rat model with colonic hypersensitivity induced by acetic acid. Methods:A total of 20 neonatal male rats were included in this study. Rat models with colonic hypersensitivity(n = 10) were established by intra-colonic infusion of 0.5% acetic acid(AA) at the age of 10~21 days,the controls(n = 10) received the same volume saline. Abdominal withdrawal reflex(AWR) score and external oblique muscle electromyography(EMG) activities were detected after colorectal expansion(CRD) stimulation to evaluate visceral sensitivity. The levels of EGF and 5-HT in plasma and intestinal tissues were measured by enzyme-linked immunosorbent assay(ELISA). The expression of serotonin transporter (SERT) was determined by Western blot to analyze the relationship between EGF levels and SERT expression in colon tissues. To further confirm the influence of EGF on SERT,rat intestinal epithelial cells (IEC-6) were stimulated at various concentrations of EGF (0,20,40 and 80 ng/ml) for 24 h to examine SERT protein expression. Results:Compared with the control rats,the AWR scores and EMG curve area during CRD in the rats with high colonic hypersensitivity were significantly increased (P < 0.05). HE staining and MPO level detection showed that no inflammation was found in both groups,which indicated that visceral hypersensitivity was successfully established. For visceral sensitized rats,the expression of SERT protein in colon were lower than that in the control group (0.711 ± 0.219 vs 0.980 ± 0.239,P < 0.01),and the levels of EGF in plasma[(2.639 ± 0.107)ng/ml vs(4.066 + 0.573)ng/ml,P < 0.05] and colonic tissues [(3.244 ± 0.135)ng/100 mg vs(3.582 + 0.197)ng/100 mg,P < 0.05] were also decreased compared with the controls. The concentrations of 5-HT in plasma and colonic tissues of model rats were significantly increased compared with those of the controls [(6.125 ± 0.534)ng/ml vs(3.540 ± 0.442)ng/ml,(5.527 ± 0.514)ng/100 mg vs(2.650 ± 0.495)ng/100 mg,respectively in plasma and colon,P < 0.05]. Furthermore,we analyzed the relationship between EGF and SERT level in colon tissues,and found that they were positively correlated (r = 0.820,P < 0.001). In vitro,IEC-6 cells were treated with EGF at different concentration (0,20,40 and 80 ng/ml) for 24 h. Compared with the concentration of 0 ng/ml,the relative expression of SERT was significantly increased (1.398 ± 0.091,1.725 ± 0.124 and 1.571 ± 0.088 at 20,40 and 80 ng/ml,respectively,P < 0.05). Conclusion:In visceral hypersensitivity rats,the EGF levels both in plasma and colonic tissue were decreased,but the 5-HT concentrations were increased. Moreover,the expression of SERT protein was positively correlated with EGF levels in colonic tissue. EGF can up-regulate the expression of SERT protein in IEC-6 cells in dose-dependent manner. These suggest that EGF may be involved in the formation of visceral hypersensitivity by affecting SERT expression.

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崔秀芳,周尾梅,程秀琴,王颖,林琳,张红杰.表皮生长因子在醋酸诱导的结肠高敏感模型大鼠中的表达及其作用[J].南京医科大学学报(自然科学版),2014,(4):427-432

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  • 收稿日期:2013-12-15
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  • 在线发布日期: 2014-04-18
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