In Vivo Complete Neural Isolation of the Rat Jejunoileum: A Simple Model to Study Denervation Sequelae of Intestinal Transplantation

Silencing salusin-β attenuates cardiovascular remodeling and hypertension in spontaneously hypertensive rats

Salusin-β is a bioactive peptide involved in vascular smooth muscle cell proliferation, vascular fibrosis and hypertension. The present study was designed to determine the effects of silencing salusin-β on hypertension and cardiovascular remodeling in spontaneously hypertensive rats (SHR). Thirteen-week-old male SHR and normotensive Wistar-Kyoto rats (WKY) were subjected to intravenous injection of PBS, adenoviral vectors encoding salusin-β shRNA (Ad-Sal-shRNA) or a scramble shRNA. Salusin-β levels in plasma, myocardium and mesenteric artery were increased in SHR. Silencing salusin-β had no significant effect on blood pressure in WKY, but reduced blood pressure in SHR. It reduced the ratio of left ventricle weight to body weight, cross-sectional areas of cardiocytes and perivascular fibrosis, and decreased the media thickness and the media/lumen ratio of arteries in SHR. Silencing salusin-β almost normalized plasma norepinephrine and angiotensin II levels in SHR. It prevented the upregulation of angiotensin II and AT₁ receptors, and reduced the NAD(P)H oxidase activity and superoxide anion levels in myocardium and mesenteric artery of SHR. Knockdown of salusin-β attenuated cell proliferation and fibrosis in vascular smooth muscle cells from SHR. These results indicate that silencing salusin-β attenuates hypertension and cardiovascular remodeling in SHR.

Salusin-β contributes to vascular remodeling associated with hypertension via promoting vascular smooth muscle cell proliferation and vascular fibrosis

Vascular smooth muscle cell (VSMC) proliferation and vascular fibrosis are closely linked with hypertension and atherosclerosis. Salusin-β is a bioactive peptide involved in the pathogenesis of atherosclerosis. However, it is still largely undefined whether salusin-β is a potential candidate in the VSMC proliferation and vascular fibrosis. Experiments were carried out in human vascular smooth muscle cells (VSMCs) and in rats with intravenous injection of lentivirus expressing salusin-β. In vitro, salusin-β promoted VSMCs proliferation, which was attenuated by adenylate cyclase inhibitor SQ22536, PKA inhibitor Rp-cAMP, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478, ERK inhibitor U0126 or cAMP response element binding protein (CREB) inhibitor KG501. It promoted the phosphorylation of ERK1/2, CREB and EGFR, which were abolished by SQ22536 or Rp-cAMP. Furthermore, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478 diminished the salusin-β-evoked ERK1/2 and CREB phosphorylation. On the other hand, salusin-β increased collagen-I, collagen-III, fibronectin and connective tissue growth factor (CTGF) mRNA and phosphorylation of Smad2/3, which were prevented by ALK5 inhibitor A83-01. In vivo, salusin-β overexpression increased the media thickness, media/lumen ratio coupled with ERK1/2, CREB, EGFR and Smad2/3 phosphorylation, as well as the mRNA of collagen-I, collagen-III, fibronectin, transforming growth factor-β1 (TGF-β1) and CTGF in arteries. Moreover, salusin-β overexpression in rats caused severe hypertension. Intravenous injection of salusin-β dose-relatedly increased blood pressure, but excessive salusin-β decreased blood pressure and heart rate. These results indicate that salusin-β promotes VSMC proliferation via cAMP-PKA-EGFR-CREB/ERK pathway and vascular fibrosis via TGF-β1-Smad pathway. Increased salusin-β contributes to vascular remodeling and hypertension.

Premedication with erythromycin improves endoscopic visualization of the gastric mucosa in patients with subtotal gastrectomy: a prospective, randomized, controlled trial

BACKGROUND

Food residue in the remnant stomach after subtotal gastrectomy (STG) interferes with endoscopic observation. We investigated whether intravenous erythromycin improves gastric mucosa visualization in patients with STG.

METHODS

This study was conducted from April 2012 to October 2012 as a double-blinded, placebo-controlled, randomized trial. Patients who received STG with complete resection (stage T1-2N0M0) were included. Exclusion criteria were diabetes mellitus, neurologic disease, myopathy, recent viral enteritis history, concomitant therapy influencing gastrointestinal motility and severe comorbidity. Patients were instructed to consume a soft diet for dinner between 1800 and 2000 h, and endoscopies were performed between 0900 and 1200 h. Patients were assigned randomly to receive either erythromycin (125 mg in normal saline 50 cc) or placebo saline. The endoscopy was performed 15 min after infusion. Grade of residual food was rated as follows: G0, no residual food; G1, a small amount of residual food; G2, a moderate amount of residual food; G3, a moderate amount of residual food that hinders observation of the entire surface, even with body rolling; G4, a great amount of residual food such that endoscopic observation is impossible.

RESULTS

When good visibility was defined as G0+G1, visibility was significantly better in the erythromycin group (61 + 19 %) than in the placebo group (38 + 12 %, p < 0.001). However, this effect was not seen in patients within 6 months after gastrectomy. The risk factor for food stasis in the placebo group (n = 58) was food stasis at last endoscopy. The only factor predicting erythromycin response in the erythromycin group (n = 56) was elapsed time since surgery. Adverse effects included nausea [11 (19.7 %)] and vomiting [1 (1.8 %)] in the erythromycin group and vomiting [3 (5.2 %)] in the placebo group. However, they were transient and tolerable.

CONCLUSIONS

Premedication with erythromycin improves mucosal visualization during endoscopy in patients with STG. (

CLINICAL TRIALS REGISTRATION NUMBER

NCT01659619).

Intestinal epithelial stem/progenitor cells are controlled by mucosal afferent nerves

Background

The maintenance of the intestinal epithelium is of great importance for the survival of the organism. A possible nervous control of epithelial cell renewal was studied in rats and mice.

Methods

Mucosal afferent nerves were stimulated by exposing the intestinal mucosa to capsaicin (1.6 mM), which stimulates intestinal external axons. Epithelial cell renewal was investigated in the jejunum by measuring intestinal thymidine kinase (TK) activity, intestinal ³H-thymidine incorporation into DNA, and the number of crypt cells labeled with BrdU. The influence of the external gut innervation was minimized by severing the periarterial nerves.

Principal Findings

Luminal capsaicin increased all the studied variables, an effect nervously mediated to judge from inhibitory effects on TK activity or ³H-thymidine incorporation into DNA by exposing the mucosa to lidocaine (a local anesthetic) or by giving four different neurotransmitter receptor antagonists i.v. (muscarinic, nicotinic, neurokinin1 (NK1) or calcitonin gene related peptide (CGRP) receptors). After degeneration of the intestinal external nerves capsaicin did not increase TK activity, suggesting the involvement of an axon reflex. Intra-arterial infusion of Substance P (SP) or CGRP increased intestinal TK activity, a response abolished by muscarinic receptor blockade. Immunohistochemistry suggested presence of M3 and M5 muscarinic receptors on the intestinal stem/progenitor cells. We propose that the stem/progenitor cells are controlled by cholinergic nerves, which, in turn, are influenced by mucosal afferent neuron(s) releasing acetylcholine and/or SP and/or CGRP. In mice lacking the capsaicin receptor, thymidine incorporation into DNA and number of crypt cells labeled with BrdU was lower than in wild type animals suggesting that nerves are important also in the absence of luminal capsaicin, a conclusion also supported by the observation that atropine lowered thymidine incorporation into DNA by 60% in control rat segments.

Conclusion

Enteric nerves are of importance in maintaining the intestinal epithelial barrier.

Description of a new model of intestinal denervation and in situ ischemia-reperfusion injury using the cecal artery for perfusion

BACKGROUND

The main purpose of the present investigation was to describe a model of intestinal denervation and in situ intestinal ischemia-reperfusion injury in adult rats, with utilization of the distal branch of the superior mesenteric artery close to the cecum for perfusion.

METHODS

In the root of the mesentery, the mesenteric artery and vein were completely isolated. Close to the cecal valve, a lymphatic node served as the reference point for the localization of the cecal artery, which was cannulated for perfusion with cold lactated Ringer's solution. One hundred adult male rats were utilized in the study.

RESULTS

In a pilot study, we demonstrated that the cold ischemia time was sufficient to promote histopathologic intestinal changes characteristic of ischemia-reperfusion injury. Among 88 operated animals, 62 (70.5%) survived the procedure.

CONCLUSION

The experimental model described herein has the advantage of preserving the entire intestine, which makes it more suitable for studies of physiological and morphological alterations after intestinal transplantation.

Development of a simple model of extrinsic denervation of the small bowel in mouse

Small bowel transplantation (SBT) is associated with poorly understood enteric dysfunction. The study of SBT in mice is hindered by the technical difficulty of orthotopic SBT in the mouse. Our aim was to develop an easy preparation of extrinsic denervation of the entire jejunoileum in mice as a model of orthotopic SBT. All neurolymphatic tissues accompanying the superior mesenteric artery (SMA) and vein (SMV) were ligated just distal to the middle colic vessels. The SMA and SMV were then stripped of investing adventitia, and the mesentery to jejunum and colon were transected radially. Jejunum and colon were not transected and reanastomosed. To confirm extrinsic denervation 1, 3, and 6 months later, segments of small bowel were stained for protein gene product 9.5 (PGP9.5) and tyrosine hydroxylase (TH). Tyrosine hydroxylase immunoreactive intensity was then quantified using a semiquantitative analysis. Immunohistochemical fluorescence showed persistence of PGP9.5 immunoreactivity confirming enteric nerves in jejunoileum; however, there was no TH immunoreactivity in jejunoileum in denervated mice despite the expected preservation of TH immunoreactivity in the still-innervated duodenum at 1 month. At 3 months, sparse immunoreactivity for TH was present, and by 6 months, reinnervation of TH-containing nerves appeared similar to controls. Quantification of intensity at each time-point further confirmed this trend. This technique in the mouse accomplishes a complete extrinsic denervation of jejunoileum early postoperatively (1 and 3 months); reinnervation occurs by 6 months. This is an easily learned murine model of orthotopic SBT.

Developmental changes of the adrenergic network in the myenteric plexus of the porcine small bowel

Knowledge about the foetal development of the normal enteric nervous system (ENS) is crucial for the understanding of congenital and acquired functional abnormalities of the gut. The ENS is the largest and most complex division of the peripheral nervous system and consists of intrinsic and extrinsic components. Although previous studies have described sympathetic innervation of the myenteric plexus, little is known regarding its age-related changes. The aim of this study was to investigate the age-related changes in the sympathetic innervation of the myenteric plexus. Whole mount and paraffin sections of the small bowel specimens from six different age groups (60 and 90 days gestation; newborn; 4 and 12 weeks old; and adult) were stained using tyrosine hydroxylase immunohistochemistry. Specimens were then analysed using fluorescence and laser scanning microscopy in detail. The tyrosine hydroxylase positive nerve fibres were first seen within the myenteric plexus at 90 days of gestation (E90). There was a significant increase in nerve fibres and varicosities observed from E90 to 12 weeks of age and stabilisation thereafter. The degree of varicosities around the ganglia, clearly seen on the whole-mount preparations, was also noted to increase up to 12 weeks of age, after which time there was no general variation noted into adulthood. Our findings show, for the first time, that sympathetic innervation of the myenteric plexus starts in the last quarter of gestation and continues till 12 weeks of age. Segmental sympathetic denervation, following bowel resection and anastomosis, during this developmental period may explain the motility dysfunction seen in newborn infants operated for necrotising enterocolitis, bowel atresia and Hirschsprung's disease.