Motilin receptor neuropharmacology: revised understanding

Erythromycin prior to endoscopy for acute upper gastrointestinal haemorrhage

BACKGROUND

Upper endoscopy is the definitive treatment for upper gastrointestinal haemorrhage (UGIH). However, up to 13% of people who undergo upper endoscopy will have incomplete visualisation of the gastric mucosa at presentation. Erythromycin acts as a motilin receptor agonist in the upper gastrointestinal (GI) tract and increases gastric emptying, which may lead to better quality of visualisation and improved treatment effectiveness. However, there is uncertainty about the benefits and harms of erythromycin in UGIH.

OBJECTIVES

To evaluate the benefits and harms of erythromycin before endoscopy in adults with acute upper gastrointestinal haemorrhage, compared with any other treatment or no treatment/placebo.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 15 October 2021.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that investigated erythromycin before endoscopy compared to any other treatment or no treatment/placebo before endoscopy in adults with acute UGIH.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. UGIH-related mortality and 2. serious adverse events. Our secondary outcomes were 1. all-cause mortality, 2. visualisation of gastric mucosa, 3. non-serious adverse events, 4. rebleeding, 5. blood transfusion, and 5. rescue invasive intervention. We used GRADE criteria to assess the certainty of the evidence for each outcome.  MAIN RESULTS: We included 11 RCTs with 878 participants. The mean age ranged from 53.13 years to 64.5 years, and most participants were men (72.3%). One RCT included only non-variceal haemorrhage, one included only variceal haemorrhage, and eight included both aetiologies. We defined short-term outcomes as those occurring within one week of initial endoscopy. Erythromycin versus placebo Three RCTs (255 participants) compared erythromycin with placebo. There were no UGIH-related deaths. The evidence is very uncertain about the short-term effects of erythromycin compared with placebo on serious adverse events (risk difference (RD) -0.01, 95% confidence interval (CI) -0.04 to 0.02; 3 studies, 255 participants; very low certainty), all-cause mortality (RD 0.00, 95% CI -0.03 to 0.03; 3 studies, 255 participants; very low certainty), non-serious adverse events (RD 0.01, 95% CI -0.03 to 0.05; 3 studies, 255 participants; very low certainty), and rebleeding (risk ratio (RR) 0.63, 95% CI 0.13 to 2.90; 2 studies, 195 participants; very low certainty). Erythromycin may improve gastric mucosa visualisation (mean difference (MD) 3.63 points on 16-point ordinal scale, 95% CI 2.20 to 5.05; higher MD means better visualisation; 2 studies, 195 participants; low certainty). Erythromycin may also result in a slight reduction in blood transfusion (MD -0.44 standard units of blood, 95% CI -0.86 to -0.01; 3 studies, 255 participants; low certainty). Erythromycin plus nasogastric tube lavage versus no intervention/placebo plus nasogastric tube lavage Six RCTs (408 participants) compared erythromycin plus nasogastric tube lavage with no intervention/placebo plus nasogastric tube lavage. There were no UGIH-related deaths and no serious adverse events. The evidence is very uncertain about the short-term effects of erythromycin plus nasogastric tube lavage compared with no intervention/placebo plus nasogastric tube lavage on all-cause mortality (RD -0.02, 95% CI -0.08 to 0.03; 3 studies, 238 participants; very low certainty), visualisation of the gastric mucosa (standardised mean difference (SMD) 0.48 points on 10-point ordinal scale, 95% CI 0.10 to 0.85; higher SMD means better visualisation; 3 studies, 170 participants; very low certainty), non-serious adverse events (RD 0.00, 95% CI -0.05 to 0.05; 6 studies, 408 participants; very low certainty), rebleeding (RR 1.13, 95% CI 0.63 to 2.02; 1 study, 169 participants; very low certainty), and blood transfusion (MD -1.85 standard units of blood, 95% CI -4.34 to 0.64; 3 studies, 180 participants; very low certainty). Erythromycin versus nasogastric tube lavage Four RCTs (287 participants) compared erythromycin with nasogastric tube lavage. There were no UGIH-related deaths and no serious adverse events. The evidence is very uncertain about the short-term effects of erythromycin compared with nasogastric tube lavage on all-cause mortality (RD 0.02, 95% CI -0.05 to 0.08; 3 studies, 213 participants; very low certainty), visualisation of the gastric mucosa (RR 1.19, 95% CI 0.79 to 1.79; 2 studies, 198 participants; very low certainty), non-serious adverse events (RD -0.10, 95% CI -0.34 to 0.13; 3 studies, 213 participants; very low certainty), rebleeding (RR 0.77, 95% CI 0.40 to 1.49; 1 study, 169 participants; very low certainty), and blood transfusion (median 2 standard units of blood, interquartile range 0 to 4 in both groups; 1 study, 169 participants; very low certainty). Erythromycin plus nasogastric tube lavage versus metoclopramide plus nasogastric tube lavage One RCT (30 participants) compared erythromycin plus nasogastric tube lavage with metoclopramide plus nasogastric tube lavage. The evidence is very uncertain about the effects of erythromycin plus nasogastric tube lavage on all the reported outcomes (serious adverse events, visualisation of gastric mucosa, non-serious adverse events, and blood transfusion).

AUTHORS' CONCLUSIONS

We are unsure if erythromycin before endoscopy in people with UGIH has any clinical benefits or harms. However, erythromycin compared with placebo may improve gastric mucosa visualisation and result in a slight reduction in blood transfusion.

Gut Hormones as Potential Therapeutic Targets or Biomarkers of Response in Depression: The Case of Motilin

Recent research has identified the gut–brain axis as a key mechanistic pathway and potential therapeutic target in depression. In this paper, the potential role of gut hormones as potential treatments or predictors of response in depression is examined, with specific reference to the peptide hormone motilin. This possibility is explored through two methods: (1) a conceptual review of the possible links between motilin and depression, including evidence from animal and human research as well as clinical trials, based on a literature search of three scientific databases, and (2) an analysis of the relationship between a functional polymorphism (rs2281820) of the motilin (MLN) gene and cross-national variations in the prevalence of depression based on allele frequency data after correction for potential confounders. It was observed that (1) there are several plausible mechanisms, including interactions with diet, monoamine, and neuroendocrine pathways, to suggest that motilin may be relevant to the pathophysiology and treatment of depression, and (2) there was a significant correlation between rs2281820 allele frequencies and the prevalence of depression after correcting for multiple confounding factors. These results suggest that further evaluation of the utility of motilin and related gut peptides as markers of antidepressant response is required and that these molecular pathways represent potential future mechanisms for antidepressant drug development.

The repertoire of family A-peptide GPCRs in archaic hominins

Given the importance of G-protein coupled receptors in the regulation of many physiological functions, deciphering the relationships between genotype and phenotype in past and present hominin GPCRs is of main interest to understand the evolutionary process that contributed to the present-day variability in human traits and health. Here, we carefully examined the publicly available genomic and protein sequence databases of the archaic hominins (Neanderthal and Denisova) to draw up the catalog of coding variations in GPCRs for peptide ligands, in comparison with living humans. We then searched in the literature the functional changes, phenotypes and risk of disease possibly associated with the detected variants. Our survey suggests that Neanderthal and Denisovan hominins were likely prone to lower risk of obesity, to enhanced platelet aggregation in response to thrombin, to better response to infection, to less anxiety and aggressiveness and to favorable sociability. While some archaic variants were likely advantageous in the past, they might be responsible for maladaptive disorders today in the context of modern life and/or specific regional distribution. For example, an archaic haplotype in the neuromedin receptor 2 is susceptible to confer risk of diabetic nephropathy in type 1 diabetes in present-day Europeans. Paying attention to the pharmacological properties of some of the archaic variants described in this study may be helpful to understand the variability of therapeutic efficacy between individuals or ethnic groups.

Structure and Function of Peptide-Binding G Protein-Coupled Receptors

G protein-coupled receptors (GPCRs) are the largest family of cell surface receptors and are important human drug targets. Of the 826 human GPCRs, 118 of them recognize endogenous peptide or protein ligands, and 30 of the 118 are targeted by approved drug molecules, including the very high-profile class B glucagon-like peptide 1 receptor. In this review, we analyze the 21 experimentally determined three-dimensional structures of the known peptide-binding GPCRs in relation to the endogenous peptides and drug molecules that modulate their cell signaling processes. Our integrated analyses reveal that half of the marketed drugs and most of the drugs in clinical trials that interact with peptide GPCRs are small molecules with a wide range of binding modes distinct from those of large peptide ligands. As we continue to collect additional data on these receptors from orthogonal approaches, including nuclear magnetic resonance and electron microscopy, we are beginning to understand how these receptors interact with their ligands at the molecular level and how improving the pharmacology of GPCR signal transduction requires us to study these receptors using multiple biophysical techniques.

Effects of Chinese herbal medicine Xiangbin prescription on gastrointestinal motility

AIM

To investigate the effects of Xiangbin prescription (XBP), a Chinese herbal concoction, on gastrointestinal motility.

METHODS

Forty healthy volunteers were recruited for this randomized controlled trial of XBP. Antroduodenojejunal manometry was used to monitor gastrointestinal motility in these subjects. After the subjects had fasted for at least 12 h, XBP (n = 30) or placebo (n = 10) was orally administrated and gastrointestinal motility was recorded for 4 h. Plasma motilin and ghrelin were measured by enzyme-linked immunosorbent assay.

RESULTS

Oral administration of XBP significantly increased the amplitude of duodenal contractions [19.5 (13.0-26.7) vs 16.9 (12.3-23.9), P < 0.05], jejunal contractions [18.3 (15.3-25.0) vs 15.4 (11.7-23.9), P < 0.01], and the motility index of duodenal contractions [522.0 (146.0-139.0) vs 281.0 (76.5-1006.0), P < 0.01] in phase II of the migratory motor complex (MMC), which subsequently initiated the MMC cycle [74.0 (30.0-118.0) vs 116.5 (24.0-219.0), P < 0.05], shortened the duration of phase I of the MMC [42.0 (0.0-90.0) vs 111.5 (42.0-171.0), P < 0.01], and lengthened the duration of phase II of the MMC [120 (21-240) vs 58 (16-170), P < 0.01] compared to the duration before XBP administration. There were significant differences in the amplitude of jejunal contractions [19.8 (14.0-30.0) vs 18.0 (13.0-28.5), P < 0.05], the motility index of duodenal contractions [236.0 (115.0-306.0) vs 195.0 (109.0-310.0), P < 0.05)], and jejunal contractions [214.0 (95.0-403.0) vs 178.0 (55.0-304.0), P < 0.01] in phase III of the MMC. Oral administration of XBP greatly increased plasma motilin (57.69 ± 9.03 vs 49.38 ± 8.63, P < 0.01) and ghrelin (279.20 ± 104.31 vs 238.73 ± 115.59, P < 0.01) concentrations compared to concentrations after oral administration of the placebo.

CONCLUSION

XBP can stimulate duodenal and jejunal motility and increase the concentrations of plasma motilin and ghrelin. The clinical applicability of XBP in treating GDIM deserves investigation.

Early traditional Chinese medicine bundle therapy for the prevention of sepsis acute gastrointestinal injury in elderly patients with severe sepsis

This study aimed to study the effect of early traditional Chinese medicine bundle therapy on the prevention of sepsis-associated acute gastrointestinal injury (AGI). This was a multicenter, prospective, observational, non-randomized cohort study of 296 consecutive patients with severe sepsis during 2013/3 and 2014/11; 150 patients received standard treatments (controls) and 146 received traditional Chinese medicine bundle therapy (intervention group) (herbal decoction gavage based on syndrome differentiation, Chinese acupuncture, application of mirabilite, and defecation mixture). D-lactic acid, diamine oxidase, endotoxin, gastrin, motilin, and intra-abdominal pressure were measured. AGI was categorized into four levels. Compared with controls, D-lactic acid, diamine oxidase, endotoxin, gastrin, and intra-abdominal pressure in the intervention group were decreased, and motilin was increased on day 7. AGI incidence in the intervention group was lower than in controls. GIF scores of the intervention AGI II and III groups were lower than in controls. The APACHE II scores of the intervention AGI II, III, and IV groups were lower than in controls. Compared with controls, mechanical ventilation time and ICU stay in the intervention group were shorter, and 28-day overall and AGI-attributed mortality were lower. For elderly patients with severe sepsis, early traditional Chinese medicine bundle therapy could decrease AGI incidence and improve prognosis.

Serum motilin levels and motilin gene polymorphisms in children with functional constipation

BACKGROUND

Functional constipation is an important clinical problem among chidren all over the world. Its main cause is not completely understood. Motilin is a gastrointestinal hormone that increases intestinal motility. In this study, we aimed to investigate the serum motilin levels and its relationship with stool consistency and motilin gene polymorphisms in constipated children.

METHODS

In this study we investigated 91 constipated patients (mean age 6.84±3.55 years) and 100 healthy controls (mean age 7.78±4.25 years). Serum motilin levels were assessed by sandwich enzyme-linked immunosorbent assay. rs2281820 (c.44 C>T) and rs2281818 (c.66 C>T) mutations were evaluated for motilin gene polymorphisms.

RESULTS

Serum motilin levels were significantly lower in constipated children than healthy controls (6.20±7.86 vs. 11.54±17.89 pg/mL, respectively, P=0.008). Serum motilin levels were significantly correlated with Bristol stool scale rate (r=0.193, P=0.011) in whole study group, but in the constipation group there was no significant correlation (r=-0.072, P=0.528). There were no differences in terms of presence or distribution of the polymorphisms of rs2281820 (c.44 C>T) and rs2281818 (c.66 C>T) in both groups. There was not a significant difference between different polymorphism groups regarding serum motilin concentrations in whole study group and also in both of the study groups.

CONCLUSIONS

This study indicated for the first time that serum motilin levels decreased in constipated children. Further studies are needed to clarify whether motilin or motilin gene polymorphisms has a role in pathogenesis of functional constipation.

Molecular cloning of motilin and mechanism of motilin-induced gastrointestinal motility in Japanese quail

Motilin, a peptide hormone produced in the upper intestinal mucosa, plays an important role in the regulation of gastrointestinal (GI) motility. In the present study, we first determined the cDNA and amino acid sequences of motilin in the Japanese quail and studied the distribution of motilin-producing cells in the gastrointestinal tract. We also examined the motilin-induced contractile properties of quail GI tracts using an in vitro organ bath, and then elucidated the mechanisms of motilin-induced contraction in the proventriculus and duodenum of the quail. Mature quail motilin was composed of 22 amino acid residues, which showed high homology with chicken (95.4%), human (72.7%), and dog (72.7%) motilin. Immunohistochemical analysis showed that motilin-immunopositive cells were present in the mucosal layer of the duodenum (23.4±4.6cells/mm(2)), jejunum (15.2±0.8cells/mm(2)), and ileum (2.5±0.7cells/mm(2)), but were not observed in the crop, proventriculus, and colon. In the organ bath study, chicken motilin induced dose-dependent contraction in the proventriculus and small intestine. On the other hand, chicken ghrelin had no effect on contraction in the GI tract. Motilin-induced contraction in the duodenum was not inhibited by atropine, hexamethonium, ritanserin, ondansetron, or tetrodotoxin. However, motilin-induced contractions in the proventriculus were significantly inhibited by atropine and tetrodotoxin. These results suggest that motilin is the major stimulant of GI contraction in quail, as it is in mammals and the site of action of motilin is different between small intestine and proventriculus.

The effects of camicinal, a novel motilin agonist, on gastro-esophageal function in healthy humans-a randomized placebo controlled trial

BACKGROUND

A proportion of patients with foregut dysmotility fail to respond to standard interventions. Motilin agonists may be beneficial in this group. We aimed to determine the effect of camicinal, a novel motilin agonist, on gastrointestinal physiology in healthy volunteers.

METHODS

Healthy male subjects were randomly assigned to receive a single dose of 125 mg camicinal or placebo in a double-blind cross-over design. Esophageal function and reflux indices were assessed using high-resolution manometry (pre and 1.5-h post dose) and 24-h ambulatory multichannel intraluminal impedance/pH. After a standardized meal, subjects ingested a wireless motility capsule from which compartmental transit times and motility indices were derived. Subjects were restudied with the alternate intervention after 7 days.

KEY RESULTS

The study subjects (12 male, mean age 47.4 years, range 22-55) tolerated the drug well, except one who exhibited mild abdominal pain on both placebo and camicinal. In comparison to placebo, gastric emptying time (GET) was accelerated following camicinal (-115.4 min, 95% confidence interval -194.4, -36.4, p = 0.009). No effect was demonstrable on esophageal function, small bowel, colonic, or whole bowel transit times and motility indices. With camicinal, as part of a post hoc analysis, there was a trend association between the percentage reduction in GET and total number of acidic reflux events (r = 0.56, p = 0.09).

CONCLUSIONS & INFERENCES

Camicinal decreases GET and was generally well-tolerated. In health, the direct effects of camicinal are on accelerating GET with a potential secondary benefit of reducing reflux events, which warrant further exploration in patient cohorts.

Improvements in safety and recovery following cystectomy: reassessing the role of pre-operative bowel preparation and interventions to speed return of post-operative bowel function

For radical cystectomy, historical practice trends have favored the use of preoperative bowel preparations to reduce complications, including surgical site infections, ileus, and anastomotic leaks. However, emerging data has questioned this practice. Postoperative cystectomy care also remains in flux, as new pharmacologic agents that may potentiate earlier return of bowel function are studied. We review the current literature with regards to preoperative and postoperative cystectomy bowel management.