内脏脂肪素在大鼠结肠平滑肌收缩障碍中的作用及其机制研究

Role and Mechanism of Visfatin in Dysfunction of Colonic Smooth Muscle Contraction in Rats

背景:肥胖与多种功能性胃肠病相关,肥胖者常存在胃肠动力障碍,且血清脂肪细胞因子内脏脂肪素(VF)水平明显升高。既往研究显示VF可抑制子宫、血管平滑肌收缩。目的:探讨VF对大鼠结肠平滑肌收缩的影响及其可能机制。方法:取正常Sprague-Dawley(SD)大鼠远端结肠制备成0.3cm×0.8cm的肌条,使用生物信号分析系统记录VF对肌条收缩活动的影响。体外培养SD乳大鼠结肠平滑肌细胞,予VF干预,以蛋白质印迹法检测肌球蛋白轻链(MLC)磷酸化水平和钙通道Cav1.2(α1亚基)表达;以激光共聚焦显微镜观察细胞外有或无Ca^2+的情况下乙酰胆碱刺激引起的细胞内Ca^2+浓度变化。结果:在肌条收缩实验中,VF(200ng/mL)可显著减弱正常大鼠结肠平滑肌肌条的收缩张力(P<0.05)。在结肠平滑肌细胞实验中,VF(200ng/mL)可下调Cav1.2通道表达,降低细胞内Ca^2+浓度和MLC磷酸化水平(P<0.05)。结论:VF可能通过下调结肠平滑肌细胞膜Cav1.2通道表达降低细胞内Ca^2+浓度,引起结肠平滑肌收缩障碍,从而参与结肠动力障碍的发生。

Background:Obesity is associated with many functional gastrointestinal disorders,such as gastrointestinal motility disorder.Previous studies showed that adipose tissue-derived adipokine visfatin(VF),which increased in obesity,might impair myometrial contractility and cause vascular smooth muscle relaxation.Aims:To investigate the effect of VF on contractility of colonic smooth muscle in rats and its underlying mechanism.Methods:Segments of distal colon from normal Sprague-Dawley(SD)rats were dissected into strips(0.3 cm×0.8 cm),and the effect of VF on contractility of muscle strips was measured by biological signal collection system.In in vitro study,colonic smooth muscle cells(SMCs)from neonatal SD rats were cultured and treated with VF;phosphorylation of myoglobulin light chain(MLC)and expression of calcium channel protein Cav1.2(α1 subunit)were assessed by Western blotting.Cultured in buffer solution with or without calcium,the acetylcholine-stimulated intracellular Ca^2+level in SMCs was detected by confocal laser scanning microscopy.Results:In muscle strip contractility assay,VF(200 ng/mL)significantly inhibited the contractility of colonic smooth muscle strip from normal adult rats(P<0.05).In cultured colonic SMCs,VF(200 ng/mL)downregulated the calcium channel protein Cav1.2 expression and reduced the intracellular Ca^2+level and MLC phosphorylation(P<0.05).Conclusions:VF may down-regulate the expression of calcium channel protein Cav1.2 on the membrane of colonic SMCs and cause colonic dysmotility by interfering with Ca^2+signaling and smooth muscle contractility.