Involvement of intestinal hypoperfusion related with Indoleamine 2,3-peroxidase activation and 5-HT metabolism abnormality in intestinal dysfunction after acute myocardial infarction

Abstract

Background To investigate the intestinal dysfunction after acute myocardial infarction (AMI) and discuss the underlying mechanism. Methods Rats were divided into three groups randomly, including AMI group, Sham group and Normal (N) group. An AMI model was established with ligating the left anterior descending artery (LAD) without ventilator assisted. The body surface electrocardiogram (ECG), HE staining of myocardial tissues and echocardiogram were used to evaluate whether the model was established successfully. The HE staining for ileum tissue was applied to evaluate the structure of the ileum, the intestinal propulsive rate were conducted to investigate the intestinal dysfunction, and laser speckle technique was developed in order to measure the mesenteric blood flow. immunohistochemical method was used to determined the expression of Indoleamine 2, 3-dioxygenase (IDO) in ileum, high-performance liquid chromatography was used to detected 5-hydroxytryptamine(5-HT) metabolism in rats plasma and ileum. Results After AMI in rats, the ECG shows ST segment elevation in lead Ⅱ for more than 30 minutes and pathological Q wave appeared at 4 weeks after surgery. HE staining showed at 4 weeks after AMI, the ventricular wall of the infarcted area of the rats became thin and white. Echocardiogram showed Left ventricular internal diameters of systole(LVIDs) and Left ventricular internal diameters of diastole(LVIDd) in the AMI group increased significantly, and Interventricular septal thickness at end diastole(IVSd) decreased significantly. Left ventricular ejection fraction(LVEF) and Fractional shortening(FS) values in the AMI group were significantly decreased. HE staining showed intestinal mucosa was hyperemia, edema, and it was infiltrated by a large number of neutrophils. The intestinal propulsive rate was increased in AMI group. Laser speckle technique shows the mesenteric blood flow was decreased in AMI group. Immunohistochemistry showed the expression of IDO was increased in AMI group. High-performance liquid chromatography showed the 5-HT content in the plasma was increased, and the content of 5-HT and 5-hydroxy indole acetic acid (5-HIAA) in the ileum was increased in AMI group. Conclusion Intestinal dysfunction after AMI may be achieved by decreased intestinal blood perfusion, IDO-related inflammation and the dysfunction of 5-HT metabolic pathway.