Excitatory and inhibitory enteric innervation of horse lower esophageal sphincter

Nebulization of 2% lidocaine has no detectable impact on the healthy equine respiratory microbiota

Glucocorticosteroids remain the most common pharmaceutical approach for the treatment of equine asthma but can be associated with significant side effects, including respiratory microbiome alterations. The goal of the study was to assess the impact of 2% lidocaine nebulization, a projected alternative treatment of equine asthma, on the healthy equine respiratory microbiota. A prospective, randomized, controlled, blinded, 2-way crossover study was performed, to assess the effect of 1 mg/kg 2% lidocaine (7 treatments over 4 days) on the equine respiratory microbiota compared to control horses (saline and no treatment). Clinical assessments and respiratory samples, including nasal wash, endoscopic tracheal aspirate and bronchoalveolar lavage fluid, were obtained at each sample collection timepoint. The profile of the respiratory bacterial microbiota was evaluated using 16S amplicon sequencing, and clinical data compared using related samples analyses, based on data normality. The treatment did not affect the clinical data or alter the tracheal and nasal microbiota in healthy horses. However, time explained 12.6% of microbiota variation among samples. A significant difference in bacterial composition was observed between nasal and tracheal samples, showing the greatest relative abundance of Actinobacteria and Firmicutes, respectively. Bacterial DNA from bronchoalveolar lavage fluid did not amplify with generic primers targeting the V4 variable region of the prokaryotic small subunit ribosomal RNA gene, despite attempting multiple DNA extraction methods and PCR protocols, and after excluding PCR inhibition. This observation indicates that bronchoalveolar lavage fluid of healthy horses has a low bacterial load.

The treatment effects of acotiamide in esophagogastric outflow obstruction: a prospective longitudinal observational study

OBJECTIVES

We have found that an altered lower esophageal sphincter (LES) accommodation response is an underlying cause of esophagogastric junction outflow obstruction (EGJOO). The objective of this study was to examine the treatment effect of acotiamide, a prokinetic agent which improves impaired gastric accommodation in functional dyspepsia, in patients with EGJOO.

METHODS

A prospective observational longitudinal study was conducted between October 2014 and March 2020. Acotiamide (100 mg, 3 times a day) was administered to 25 patients with EGJOO for 4 weeks. High-resolution manometry (HRM) was performed just before and after 4 weeks of treatment.

RESULTS

As the primary outcome, the extent of integrated relaxation pressure (IRP) after treatment (14.6, 12.1-22.0 mmHg) was significantly lower than that before treatment (19.4, 17.1-27.4 mmHg). The extent of LES accommodation index after treatment (32.7, 21.0-40.0 mmHg) was also significantly lower than that before treatment (39.3, 31.2-50.2 mmHg). Acotiamide normalized the IRP (< 15 mmHg) in 13 of 25 patients with EGJOO (52%), and the IRP was decreased in 20 of 25 patients with EGJOO (80%). As the secondary outcome, the total FSSG score in 25 patients with EGJOO before and after acotiamide treatment showed no significant difference. In a sub-analysis of 13 patients in whom EGJOO was normalized by acotiamide, however, dysphagia was reported to be significantly improved by acotiamide.

CONCLUSIONS

Acotiamide has a treatment effect on patients with EGJOO via a reduction in the IRP level through the lowering of both the basal LES pressure and LES accommodation response. Dysphagia is a key symptom to be evaluated and treated in patients with EGJOO.

Ex vivo ultrasonographic and histological morphometry of small intestinal wall layers in horses

Ultrasonographic morphometry of wall layers is commonly used in veterinary patients with suspected small intestinal disease, however published studies comparing this method with histopathology in horses are limited. This prospective, methods comparison study compared the qualitative and quantitative characteristics of small intestinal wall layers using ex vivo high‐frequency ultrasound versus histopathology in a sample of 16 horses. Transverse section images of duodenum, distal jejunum, and ileum were acquired with a high‐frequency linear transducer (7–15 MHz). Transverse histological cryosections were obtained at the same level. Appearance and measurements of the intestinal wall layers were assessed on the ultrasonographic and histological images. High‐frequency scanning with the probe in close contact with the serosal surface of the equine intestinal wall allowed a clear and detailed definition of wall layers. A hyperechoic line was consistently detected within the tunica muscularis in all the intestinal tracts, corresponding histologically to the interface between its longitudinal and circular muscle layers. The overall trend of the values for wall layers thickness was comparable between ex vivo ultrasonography and histology. However, a poor agreement was found between the two methods for all layers. The ultrasonographic measurements were thicker compared to histological measurements, with the exception of the total wall and the muscular layer thicknesses. These layers were thinner on ultrasonography in the duodenum and in all the intestinal segments, respectively. Findings from the current study can be used as background for future ultrasonographic investigations of small intestinal diseases in horses.

Localisation of Cannabinoid and Cannabinoid-Related Receptors in the Horse Ileum

Colic is a common digestive disorder in horses and one of the most urgent problems in equine medicine. A growing body of literature has indicated that the activation of cannabinoid receptors could exert beneficial effects on gastrointestinal inflammation and visceral hypersensitivity. The localisation of cannabinoid and cannabinoid-related receptors in the intestine of the horse has not yet been investigated. The purpose of this study was to immunohistochemically localise the cellular distribution of canonical and putative cannabinoid receptors in the ileum of healthy horses. Distal ileum specimens were collected from six horses at the slaughterhouse. The tissues were fixed and processed to obtain cryosections which were used to investigate the immunoreactivity of canonical cannabinoid receptors 1 (CB1R) and 2 (CB2R), and three putative cannabinoid-related receptors: nuclear peroxisome proliferator-activated receptor-alpha (PPARα), transient receptor potential ankyrin 1 and serotonin 5-HT1a receptor (5-HT1aR). Cannabinoid and cannabinoid-related receptors showed a wide distribution in the ileum of the horse. The epithelial cells showed immunoreactivity for CB1R, CB2R and 5-HT1aR. Lamina propria inflammatory cells showed immunoreactivity for CB2R and 5-HT1aR. The enteric neurons showed immunoreactivity for CB1R, transient receptor potential ankyrin 1 and PPARα. The enteric glial cells showed immunoreactivity for CB1R and PPARα. The smooth muscle cells of the tunica muscularis and the blood vessels showed immunoreactivity for PPARα. The present study represents a histological basis which could support additional studies regarding the distribution of cannabinoid receptors during gastrointestinal inflammatory diseases as well as studies assessing the effects of non-psychotic cannabis-derived molecules in horses for the management of intestinal diseases.

Cannabinoid and Cannabinoid-Related Receptors in the Myenteric Plexus of the Porcine Ileum

An important piece of evidence has shown that molecules acting on cannabinoid receptors influence gastrointestinal motility and induce beneficial effects on gastrointestinal inflammation and visceral pain. The aim of this investigation was to immunohistochemically localize the distribution of canonical cannabinoid receptor type 1 (CB1R) and type 2 (CB2R) and the cannabinoid-related receptors transient potential vanilloid receptor 1 (TRPV1), transient potential ankyrin receptor 1 (TRPA1), and serotonin receptor 5-HT1a (5-HT1aR) in the myenteric plexus (MP) of pig ileum. CB1R, TRPV1, TRPA1, and 5-HT1aR were expressed, with different intensities in the cytoplasm of MP neurons. For each receptor, the proportions of the immunoreactive neurons were evaluated using the anti-HuC/HuD antibody. These receptors were also localized on nerve fibers (CB1R, TRPA1), smooth muscle cells of tunica muscularis (CB1R, 5-HT1aR), and endothelial cells of blood vessels (TRPV1, TRPA1, 5-HT1aR). The nerve varicosities were also found to be immunoreactive for both TRPV1 and 5-HT1aR. No immunoreactivity was documented for CB2R. Cannabinoid and cannabinoid-related receptors herein investigated showed a wide distribution in the enteric neurons and nerve fibers of the pig MP. These results could provide an anatomical basis for additional research, supporting the therapeutic use of cannabinoid receptor agonists in relieving motility disorders in porcine enteropathies.

Localization of cannabinoid and cannabinoid related receptors in the cat gastrointestinal tract

A growing body of literature indicates that activation of cannabinoid receptors may exert beneficial effects on gastrointestinal inflammation and visceral hypersensitivity. The present study aimed to immunohistochemically investigate the distribution of the canonical cannabinoid receptors CB₁ (CB1R) and CB₂ (CB2R) and the putative cannabinoid receptors G protein-coupled receptor 55 (GPR55), nuclear peroxisome proliferator-activated receptor alpha (PPARα), transient receptor potential ankyrin 1 (TRPA1), and serotonin receptor 5-HT1a 5-HT1aR) in tissue samples of the gastrointestinal tract of the cat. CB1R-immunoreactivity (CB1R-IR) was observed in gastric epithelial cells, intestinal enteroendocrine cells (EECs) and goblet cells, lamina propria mast cells (MCs), and enteric neurons. CB2R-IR was expressed by EECs, enterocytes, and macrophages. GPR55-IR was expressed by EECs, macrophages, immunocytes, and MP neurons. PPARα-IR was expressed by immunocytes, smooth muscle cells, and enteroglial cells. TRPA1-IR was expressed by enteric neurons and intestinal goblet cells. 5-HT1a receptor-IR was expressed by gastrointestinal epithelial cells and gastric smooth muscle cells. Cannabinoid receptors showed a wide distribution in the feline gastrointestinal tract layers. Although not yet confirmed/supported by functional evidences, the present research might represent an anatomical substrate potentially useful to support, in feline species, the therapeutic use of cannabinoids during gastrointestinal inflammatory diseases.

Zinc Transporter 3 (Znt3) as an Active Substance in the Enteric Nervous System of the Porcine Esophagus

Zinc transporter 3 (ZnT3), a member of the SLC 30 zinc transporter family, is involved in the transport of zinc ions from the cytoplasm into synaptic vesicles or intracellular organelles. The aim of the present study was to investigate for the first time the percentage of ZnT3-like immunoreactive (ZnT3-LI) neurons in the enteric nervous system (ENS) of the porcine esophagus and denotation of their neurochemical coding. Routine double- and triple-immunofluorescence labeling of cervical, thoracic, and abdominal fragments of esophagus for ZnT3 with protein gene product (PGP 9.5; used as pan-neuronal marker), nitric oxide synthase (NOS), somatostatin, vasoactive intestinal peptide (VIP), vesicular acetylcholine transporter (VAChT), neuropeptide Y (NPY), and galanin (GAL) was performed. The percentage of ZnT3-LI neurons in myenteric ganglia amounted to 50.2 ± 4.7, 63.4 ± 8.3, and 77.1 ± 1.1 % of all PGP 9.5-like immunoreactive neuronal cells in cervical, thoracic, and abdominal esophagus, respectively. In submucous ganglia, these values in particular parts of esophagus amounted to 46.3 ± 6.3, 81.0 ± 8.1, and 74.4 ± 4.4 %. Znt3 co-localized mainly with VAChT, NPY, GAL, NOS, and VIP, but the degree of co-localization depended on the “kind” of enteric ganglia and part of esophagus studied. The obtained results suggest that both ZnT3 and zinc ions may play important and various roles in the neuronal regulation of esophageal functions.