Chronic oesophagitis in the cat

Establishment of animal model of gastroesophageal reflux disease by per-oral endoscopic tunneling: a preliminary study

Background

Although a variety of antireflux procedures and medications are used to treat gastroesophageal reflux disease (GERD), reliable large-animal models of GERD that can be used to objectively compare the efficacy of these treatments are lacking. We developed a method to establish large animal models of GERD by endoscopic sphincterotomy to develop an endoscopic treatment for GERD.

Methods

In this study six flesh swine carcasses were used. A full thickness incision was made at the esophageal site 5 cm above the dentate line by per-oral endoscopic tunneling. Esophageal radiography was conducted before and after surgery to observe changes at the site of the lower esophagus 5 cm above the dentate line and in the cardia.

Results

There was no significant change in the diameter of the esophageal site 5 cm above the dentate line before and after surgery, while the cardiac orifice significantly relaxed after surgery and enabled the contrast agent to smoothly travel through. The difference in diameter was statistically significant (P<0.05).

Conclusions

Our experiments showed that it is a minimally invasive and mature technology of establishing GERD animal models by using the per-oral endoscopic tunneling technique, and might be a new method to establishing GERD large animal models.

Gastroesophageal reflux disease in baboons (Papio sp.): a new animal model

BACKGROUND

Gastroesophageal reflux disease (GERD) is increasingly prevalent in the human population. Current animal models require surgical or other manipulation to produce symptoms. An animal model that exhibits spontaneous GERD would provide the opportunity for much-needed research examining the susceptibility, diagnosis, and treatment of GERD.

METHODS

Eight baboons (Papio hamadryas sp.) were diagnosed with GERD histopathologically using biopsies or postmortem tissues.

RESULTS

The disease was characterized by a spectrum of symptoms comparable with that found in the human population. Some subjects had no gross signs of clinical disease, but were diagnosed by histopathological examination. Almost all subjects presented with at least one clinical sign of the disease. Regurgitation was the most common.

CONCLUSIONS

The baboon may be a superior animal model for GERD research because it is a naturally occurring model and is anatomically and physiologically similar to humans.

American and Japanese rats of the same species: are they same?

BACKGROUND

We have previously reported a chronic acid reflux esophagitis model using Japanese Wistar male (JWM) rats. The aim of this study is to discuss unexpected differences encountered within the same species bred in different countries.

MATERIALS AND METHODS

In JWM rats via a midline laparotomy the limiting ridge of the stomach was ligated and the duodenum was covered with a small piece of an 18 Fr. catheter. We subsequently tried to reproduce the same model using American Wistar male (AWM) and subsequently with female (AWF) rats.

RESULTS

The 3-wk survival rate of AWM rats (30%) was significantly lower than for JWM rats (90%) due to differences in growth curve and eating behaviors. On the other hand, the growth curve of AWF rats was similar to JWM rats. Still, the 3-wk survival rate was only 40% mainly due to different eating patterns. Since then we have modified our postoperative care to include restricted access to food and other objects and have achieved a 3-wk survival of 80%, which is the same as JWM rats.

CONCLUSIONS

Growth curve and eating behavior of rats from different countries exhibit significant differences even within the same species. It is important that such differences be taken into account when reproducing animal models created elsewhere.

Different effects of electroacupuncture on esophageal motility and serum hormones in cats with esophagitis

We aim to investigate the effects of different electroacupuncture (EA) frequencies at ST-36 on esophageal motility, and to compare the effect of EA on serum gastrin (GAS), motilin (MTL), and vasoactive intestinal peptide (VIP). Thirty-two cats were divided into four equal groups. All animals underwent a Heller myotomy. After esophagitis developed two frequencies (2/15 Hz or 2/100 Hz) of EA were delivered into ST-36 (LEA group [low EA], HEA group [high EA]). Animals submitted to EA on a non-point region (EANP) were used as controls (LEANP group, HEANP group), respectively. Esophageal motility was continuously monitored. The lower esophageal sphincter pressure (LESP) decreased significantly after myotomy. The LESP decreased in both LEA and LEANP cats, and in LEA cats the pressure decrease was greater. The LESP increased in the HEA group, which was higher than that in the HEANP group (P < 0.05). High-frequency EA significantly increased the peak amplitude in esophageal peristalsis. There was a decrease in serum GAS and MTL in LEA cats compared with LEANP cats (both P < 0.01). GAS and MTL were higher in the HEA group than in the HEANP group (both P < 0.01). Serum VIP decreased in the HEA group (P < 0.05), while it increased in the LEA group (P < 0.05), compared with EANP groups, respectively. EA with a high frequency at ST-36 enhances LESP as well as esophageal motility, while EA with a low frequency decreases LESP. The effect of EA is acupoint-specific, and this effect appears to be mediated through GAS, MTL and VIP.

Hydrogen peroxide reduces lower esophageal sphincter tone in human esophagitis

BACKGROUND & AIMS

We have previously used the normal lower esophageal sphincter (N-LES) of human organ donors to examine the physiologic signal transduction of lower esophageal sphincter (LES) circular muscle. Now, for the first time, we have obtained a human LES specimen with esophagitis (E-LES) and characterized its pathophysiologic mechanical and inflammatory profiles.

METHODS

E-LES was examined histologically, and its in vitro circular muscle contraction and production of inflammatory mediators were compared with those of N-LES.

RESULTS

E-LES exhibited scattered erosions and displayed inflammatory cells in the epithelial layer, basal zone hyperplasia, and elongation of lamina propria papillae, characteristic of chronic reflux esophagitis. E-LES muscle strips developed lower in vitro tone (0.78 g) than N-LES (3.3 +/- 0.2 g). E-LES tone was essentially restored to normal by the H2O2 scavenger catalase, suggesting that H2O2 was responsible for reduction of tone. NOX5 cDNA was higher and H2O2 levels were 4 times higher in E-LES circular muscle (0.85 nmol/mg protein) than in N-LES (0.19 +/- 0.05 nmol/mg protein). When N-LES smooth muscle was incubated in H2O2 (70 micromol/L, 2 hours), platelet activating factor (PAF), prostaglandin E2 (PGE2), and F2-isoprostane increased 2.5, 5.2, and 36 times, respectively. In E-LES, levels of PAF, PGE2, and F2-isoprostane were 4, 6, and 40 times, respectively, higher than in N-LES. PAF, PGE2, and F2 isoprostane produced dose-dependent reductions in tone of N-LES muscle strips.

CONCLUSIONS

We conclude that an excessive production of H2O2 triggers an increased production of PAF, PGE2, and F2-isoprostane, which are responsible for reducing LES tone in human esophagitis.

Estudo manométrico do esôfago distal de gatos anestesiados com tiopental sódico

OBJETIVO: Obter o padrão de normalidade da pressão e comprimento do esfíncter inferior do esôfago (EIE) em gatos anestesiados com tiopental e analisar a viabilidade prática do anestésico para uso neste tipo de investigação sobre atividade motora do esôfago de felinos. MÉTODOS: Em 12 gatos anestesiados com tiopental sódico foram realizados estudos manométricos do EIE, com leitura por perfusão em três canais radiais. Foram avaliadas as pressões e comprimentos do EIE. RESULTADOS: Os valores médios da pressão e comprimento do EIE foram 33,52 ± 12,42 mmHg e 1,6 ± 0,4 cm, respectivamente. CONCLUSÃO: Foi possível estabelecer valor de referência para a pressão e comprimento do EIE de felinos, com uma contenção e retorno confortáveis para o animal, utilizando o tiopental sódico como agente anestésico.