Effects of Single-Dose Prucalopride on Intestinal Hypomotility in Horses: Preliminary Observations

The effects of bit chewing on borborygmi, duodenal motility, and gastrointestinal transit time in clinically normal horses

OBJECTIVE

To determine the influence of bit chewing on gastrointestinal transit in clinically normal horses.

STUDY DESIGN

Prospective crossover designed study.

ANIMALS

Six healthy adult horses.

METHODS

Horses were assigned randomly to treatment (apple flavored bit) and control (no-bit) groups and studied for 2 × 1-week trial periods with a 2-week washout period between trials. Horses were fasted for 24 h and slowly refed over 3 days. The bit was placed for 20 min every 6 h. Duodenal contractions and borborygmi auscultations were evaluated every 12 h, approximately 5 min following bit placement. Gastrointestinal total transit time (GI TTT) was measured by administering 200 colored beads via stomach tube and then collected in the manure until 50% and 80% were recovered. Measured variables were compared using an ANOVA or Wilcoxon signed-rank test and the P value was noted.

RESULTS

The GI TTT was shortened in the bit chewing group (median: 106.37 h, range: 70-171 h) compared to the no-bit group (median: 170.1 h, range: 149-186 h) (P = .0156) at 80% bead passage (only 4/6 horses passed 80%). Borborygmi (P = .8193), duodenal contractions (P = .2605), and 50% bead passage (P = .0781) showed no differences.

CONCLUSION

Bit chewing was safe, inexpensive, and well tolerated. Bit chewing shortened GI TTT and might be an adjunct therapy to augment GI TTT. Further clinical studies are warranted.

CLINICAL SIGNIFICANCE

Ileus is a common complication following equine abdominal surgery with no current consistently successful treatment. Bit chewing may be a simple and inexpensive way to augment progressive GI motility.

Ultrasonographic evaluation of the effects of the administration of neostigmine and metoclopramide on duodenal, cecal, and colonic contractility in Arabian horses: A comparative study

Background and Aim

As means for enhancing gastrointestinal (GI) motility, prokinetics have previously been evaluated in different breeds of horses with varying success. No previous studies were conducted to evaluate the effect of prokinetics on the intestinal tract of Arabian horses breed. Using B-mode ultrasound in the quantification of intestinal contractility, this study aimed to compare the impact of neostigmine and metoclopramide on the intestinal motility of healthy Arabian horses.

Materials and Methods

Twenty-one clinically healthy Arabian horses were equally distributed into three groups. The control group was administered with 5 mL normal saline intramuscularly (IM). The second group was administered with neostigmine (0.044 mg/kg body weight [BW], IM), and the third group was administered with metoclopramide (0.25 mg/kg BW, IM). Duodenal, cecal, and colonic contractions were counted through ultrasonography for 3 min (pre-administration and 15, 30, 60, 120, and 180 min post-administration).

Results

In the neostigmine group, a significant (p<0.05) increase in duodenal, cecal, and colonic contractions was observed 15 min post-administration compared with that in the control group (15±1.0, 11.33±1.53, and 12.33±2.31 vs. 11.0±2.0, 6.33±0.58, and 5.33±0.58 contractions per 3 min, respectively), continuing to 60 min post-administration for the duodenum and cecum and 120 min for colon and then returning to the normal; however, the metoclopramide group showed a significant (p<0.05) increase only in cecal and colonic contractions 60 min post-administration compared with the control group (11.0±1.0 and 12.33±0.58 vs. 6±1.0 and 5.67±0.58 contractions per 3 min, respectively), continuing until the end of the experiment. Excessive sweating, excitation, and straining were recorded following the administration of neostigmine, whereas no side effects were observed in the metoclopramide group.

Conclusion

Neostigmine improves duodenal, cecal, and colonic contractions in healthy adult Arabian horses, whereas metoclopramide only improves cecal and colonic contractions. Metoclopramide appears to be safer and longer acting than neostigmine in the Arabian horse breed. Ultrasonography is a valuable noninvasive tool for the quantification of intestinal contractility. Future studies should consider the use of various dosages of metoclopramide and administration routes and investigate its impact on horses with GI transit disorders and inclusion in colic post-operative care.

Abnormal gut motility in inflammatory bowel disease: an update

BACKGROUND

There is substantial evidence linking disturbed gastrointestinal motility to inflammation. Thus, it is not surprising that abnormalities of gastrointestinal motility play a role in inflammatory bowel disease (IBD), affecting patient outcomes. We performed a review of the literature to investigate the relationship between abnormal gut motility and IBD.

METHODS

With an extensive literature search, we retrieved the pertinent articles linking disturbed gut motility to IBD in various anatomical districts.

RESULTS

The evidence in the literature suggests that abnormal gastrointestinal motility plays a role in the clinical setting of IBD and may confuse the clinical picture.

CONCLUSIONS

Abnormal gut motility may be important in the clinical setting of IBD. However, additional data obtained with modern techniques (e.g., magnetic resonance imaging) are needed to individuate in a more precise manner gastrointestinal motor dysfunctions, to understand the nature of clinical manifestations and properly tailor the treatment of patients.

Guanylin, Uroguanylin and Guanylate Cyclase-C Are Expressed in the Gastrointestinal Tract of Horses

Guanylate cyclase-C (GC-C) is a multifunctional receptor encoded by the GUCY2C gene, representing an attractive target for therapy in several gastrointestinal diseases in humans. Little is known about this system in horses. We investigated for the first time the gene expression of guanylin, uroguanylin and GC-C receptors in different horse’s gastrointestinal tracts. Tissue samples from stomach, duodenum, jejunum, ileum, head and body of cecum, left and right dorsal colon, left and right ventral colon, pelvic flexure, transverse colon, descending colon and rectum were collected from adult horses within 1 h post mortem. For each sample, total RNA was extracted from 100 mg of ground tissue, and qRT-PCR performed on GUCA2a, GUCA2b and GUCY2 transcripts on a CFX96 Touch instrument. Data analysis was carried out with Bio-Rad CFX Manager software, and genes of interest normalized relative to the abundance of the two reference genes (SDHA, HPRT). Additionally, the protein expression levels of GC-C receptor were analyzed through western blotting. A common pattern of expression throughout the gastrointestinal lumen for all three investigated transcripts was found. The expression of GUCA2a, GUCA2b and GUCY2 genes was higher in jejunum, ileum, descending colon and rectum. The levels of expression of GC-C protein confirmed these data. The findings of this study might open new scenarios for the therapeutic approach to enteric diseases of horse using selective agonists of GC-C.

Prucalopride for the treatment of constipation: a view from 2015 and beyond

Prucalopride is a prokinetic drug, that has been commercially available in recent years for the treatment of chronically constipated patients. In this update of a previous 2016 article, we reviewed the more recent data supporting its role in the treatment of constipation and constipation-associated conditions. Areas covered: We carried out an extensive literature review on the effects of prucalopride for the years 2012-2018 by means of scientific databases and manual research. More evidence was found on its possible therapeutic role in conditions in which constipation plays a role as an associated symptom, such as opioid-induced constipation, constipation-predominant irritable bowel syndrome, post-operative ileus, colonic diverticular disease, drug-related constipation, and chronic intestinal pseudo-obstruction. Expert opinion: Based on the added literature evidence, we feel that prucalopride is an effective, although expensive, drug for the treatment of primary and secondary forms of constipation, and of other clinical conditions associated with constipation.

The 5-HT4 receptor agonist prucalopride does not facilitate cholinergic neurotransmission in circular and longitudinal smooth muscle preparations of equine mid-jejunum

BACKGROUND

Postoperative ileus (POI) remains an important cause of death in horses. The recently developed selective 5-HT₄ receptor agonists such as prucalopride target 5-HT₄ receptors on myenteric cholinergic neurons to enhance acetylcholine release and GI motility. No clearcut in vitro evaluation whether highly selective 5-HT₄ receptor agonists enhance submaximal cholinergic neurotransmission towards the muscle layer has been performed in horses.

OBJECTIVES

To identify functional 5-HT₄ receptors in equine jejunum.

STUDY DESIGN

In vitro experimental study.

METHODS

Circular and longitudinal smooth muscle strips (mid-jejunum) were mounted in organ baths between 2 platinum electrodes allowing electrical field stimulation (EFS). To delineate the conditions to obtain purely cholinergic responses, voltage-response curves were studied. To investigate the influence of prucalopride and 5-HT, submaximal cholinergic contractions at a single voltage were induced.

RESULTS

In circular and longitudinal strips, EFS induced voltage-dependent neurogenic on-contractions when the bathing medium contained a NO-synthesis inhibitor and apamin to prevent inhibitory responses to NO and ATP. Contractions at a voltage inducing 50% of maximal amplitude were cholinergic, as they were blocked by atropine. These contractions were not influenced by prucalopride (up to 3μM), even in the presence of the phosphodiesterase inhibitor isobutyl-methyl-xanthine to inhibit breakdown of the second messenger of 5-HT₄ receptors, cAMP. Also the full 5-HT₄ receptor agonist 5-HT did not influence the EFS-induced submaximal cholinergic contractions. Moreover, prucalopride did not influence muscle tone continuously enhanced with KCl.

CONCLUSIONS

There are no functional 5-HT₄ receptors on myenteric cholinergic neurons nor muscular 5-HT₄ receptors in equine jejunum.