Inhibitory Effects of Dexmedetomidine and Propofol on Gastrointestinal Tract Motility Involving Impaired Enteric Glia Ca2+ Response in Mice

An ingestible self-propelling device for intestinal reanimation

Postoperative ileus (POI) is the leading cause of prolonged hospital stay after abdominal surgery and is characterized by a functional paralysis of the digestive tract, leading to symptoms such as constipation, vomiting, and functional obstruction. Current treatments are mainly supportive and inefficacious and yield acute side effects. Although electrical stimulation studies have demonstrated encouraging pacing and entraining of the intestinal slow waves, no devices exist today to enable targeted intestinal reanimation. Here, we developed an ingestible self-propelling device for intestinal reanimation (INSPIRE) capable of restoring peristalsis through luminal electrical stimulation. Optimizing mechanical, material, and electrical design parameters, we validated optimal deployment, intestinal electrical luminal contact, self-propelling capability, safety, and degradation of the device in ex vivo and in vivo swine models. We compared the INSPIRE's effect on motility in models of normal and depressed motility and chemically induced ileus. Intestinal contraction improved by 44% in anesthetized animals and up to 140% in chemically induced ileus cases. In addition, passage time decreased from, on average, 8.6 days in controls to 2.5 days with the INSPIRE device, demonstrating significant improvement in motility. Luminal electrical stimulation of the intestine via the INSPIRE efficaciously restored peristaltic activity. This noninvasive option offers a promising solution for the treatment of ileus and other motility disorders.

Molecular mechanisms of cholinergic neurotransmission in visceral smooth muscles with a focus on receptor-operated TRPC4 channel and impairment of gastrointestinal motility by general anaesthetics and anxiolytics

Acetylcholine is the primary excitatory neurotransmitter in visceral smooth muscles, wherein it binds to and activates two muscarinic receptors subtypes, M2 and M3, thus causing smooth muscle excitation and contraction. The first part of this review focuses on the types of cells involved in cholinergic neurotransmission and on the molecular mechanisms underlying acetylcholine-induced membrane depolarisation, which is the central event of excitation-contraction coupling causing Ca2+ entry via L-type Ca2+ channels and smooth muscle contraction. Studies of the muscarinic cation current in intestinal myocytes (mICAT) revealed its main molecular counterpart, receptor-operated TRPC4 channel, which is activated in synergy by both M2 and M3 receptors. M3 receptors activation is of permissive nature, while activation of M2 receptors via Gi/o proteins that are coupled to them plays a direct role in TRPC4 opening. Our understanding of signalling pathways underlying mICAT generation has vastly expanded in recent years through studies of TRPC4 gating in native cells and its regulation in heterologous cells. Recent studies using muscarinic receptor knockout have established that at low agonist concentration activation of both M2 receptor and the M2/M3 receptor complex elicits smooth muscle contraction, while at high agonist concentration M3 receptor function becomes dominant. Based on this knowledge, in the second part of this review we discuss the cellular and molecular mechanisms underlying the numerous anticholinergic effects on neuroactive drugs, in particular general anaesthetics and anxiolytics, which can significantly impair gastrointestinal motility. This article is part of the Special Issue on "Ukrainian Neuroscience".

Dexmedetomidine Has Differential Effects on the Contractility of Equine Jejunal Smooth Muscle Layers In Vitro

α2 agonists are frequently used in horses with colic, even though they have been shown to inhibit gastrointestinal motility. The aim of this study was to determine the effect of dexmedetomidine on small intestinal in vitro contractility during different phases of ischaemia. Experimental segmental jejunal ischaemia was induced in 12 horses under general anaesthesia, and intestinal samples were taken pre-ischaemia and following ischaemia and reperfusion. Spontaneous and electrically evoked contractile activity of the circular and longitudinal smooth muscles were determined in each sample with and without the addition of dexmedetomidine. During a second experiment, tetrodotoxin was added to determine if the effect was neurogenic. We found that the circular smooth muscle (CSM) contractility was not affected by ischaemia, whereas the longitudinal smooth muscle (LSM) showed an increase in both spontaneous and induced contractile activity. The addition of dexmedetomidine caused a decrease in the spontaneous contractile activity of CSM, but an increase in that of LSM, which was not mediated by the enteric nervous system. During ischaemia, dexmedetomidine also mildly increased the electrically induced contractile activity in LSM. These results may indicate a stimulatory effect of dexmedetomidine on small intestinal contractility. However, the influence of dexmedetomidine administration on intestinal motility in vivo needs to be further investigated.

Involvement of enteric glial cells in colonic motility in a rat model of irritable bowel syndrome with predominant diarrhea

The enteric nervous system (ENS) is one of the important systems that regulate gastrointestinal function. The ENS is made up of enteric glial cells (EGCs) and neurons. For a long time, it was believed that the function of EGCs was only to give structural support to neurons. However, recent evidence indicates EGCs are involved in most gut functions, including the development and plasticity of the ENS, epithelial barrier, and motility. However, it remains unclear whether EGCs have the potential to modify colonic motility following irritable bowel syndrome (IBS) with predominant diarrhea (IBS-D). This study aimed to investigate changes in EGCs during IBS-D and assessed the effects of manipulating EGCs. An IBS-D rat model was constructed using acetic acid and restraint stress, and DL-fluorocitric acid (FC), an inhibitor of EGCs, was administered. The changes in EGCs and colonic motility were studied by employing techniques comprising morphological, molecular biological and functional experiments. The results showed significant activation of EGCs in the myenteric plexus (MP) of the IBS-D-induced rat colon with accelerated colonic motility. FC significantly reduced the activation of EGCs and colonic motility caused by acetic acid and restraint stress. Hypercontraction of the colon caused by IBS-D may be associated with activation of EGCs in the MP of the colon and this was prevented by FC. Therefore, regulating colon hypercontraction through interference with the activation of EGCs has significant prospects for clinical application to alleviate diarrhea in patients with IBS-D.

Effect of anaesthetic maintenance with isoflurane or propofol on ease of endoscopic duodenal intubation in dogs

OBJECTIVE

To compare the ease of endoscopic duodenal intubation (EDI) in dogs during maintenance of general anaesthesia with isoflurane or propofol infusion.

STUDY DESIGN

Prospective, randomized, partially blinded clinical trial.

ANIMALS

A total of 22 dogs undergoing upper gastrointestinal tract endoscopy to include EDI were recruited.

METHODS

Dogs were randomly assigned isoflurane (ISO; n = 10) or propofol (PROP; n = 11) for maintenance of general anaesthesia. Following anaesthetic premedication with intramuscular medetomidine (0.005 mg kg^-1) and butorphanol (0.2 mg kg^-1), general anaesthesia was induced with propofol, to effect, maintained with 1.5% (vaporizer setting) isoflurane in 100% oxygen or 0.2 mg kg^-1 minute^-1 propofol. The dose of both agents was adjusted to maintain general anaesthesia adequate for the procedure. Degree of sedation 20 minutes post-anaesthetic premedication, propofol induction dose, anaesthetist and endoscopist training grade, animal's response to endoscopy, presence of gastro-oesophageal and duodenal-gastric reflux, spontaneous opening of the lower oesophageal and pyloric sphincters, antral movement and time to achieve EDI were recorded. EDI was scored 1 (immediate entry with minimal manoeuvring) to 4 (no entry after 120 seconds) by the endoscopist, blinded to the agent in use. Data were tested for normality (Shapiro-Wilk test) and differences between groups analysed using independent t test, Mann-Whitney U test and Fisher's exact test as appropriate.

RESULTS

There were no significant differences between groups for EDI score [median (interquartile range): 2 (3) ISO, 2 (3) PROP] or time to achieve EDI [mean ± standard deviation: 52.50 ± 107.00 seconds (ISO), 70.00 ± 196.00 seconds (PROP)]. Significantly more dogs responded to passage of the endoscope into the oesophagus in group PROP compared with group ISO (p = 0.01).

CONCLUSIONS AND CLINICAL RELEVANCE

Maintenance of general anaesthesia with either isoflurane or propofol did not affect EDI score or time to achieve EDI.

Inhibition of platelet activation suppresses reactive enteric glia and mitigates intestinal barrier dysfunction during sepsis

Background

Intestinal barrier dysfunction, which is associated with reactive enteric glia cells (EGCs), is not only a result of early sepsis but also a cause of multiple organ dysfunction syndrome. Inhibition of platelet activation has been proposed as a potential treatment for septic patients because of its efficacy in ameliorating the organ damage and barrier dysfunction. During platelet activation, CD40L is translocated from α granules to the platelet surface, serving as a biomarker of platelet activation a reliable predictor of sepsis prognosis. Given that more than 95% of the circulating CD40L originate from activated platelets, the present study aimed to investigate if inhibiting platelet activation mitigates intestinal barrier dysfunction is associated with suppressing reactive EGCs and its underlying mechanism.

Methods

Cecal ligation and puncture (CLP) was performed to establish the sepsis model. 24 h after CLP, the proportion of activated platelets, the level of sCD40L, the expression of tight-junction proteins, the intestinal barrier function and histological damage of septic mice were analyzed. In vitro, primary cultured EGCs were stimulated by CD40L and LPS for 24 h and EGCs-conditioned medium were collected for Caco-2 cells treatment. The expression of tight-junction proteins and transepithelial electrical resistance of Caco-2 cell were evaluated.

Results

In vivo, inhibiting platelet activation with cilostazol mitigated the intestinal barrier dysfunction, increased the expression of ZO-1 and occludin and improved the survival rate of septic mice. The efficacy was associated with reduced CD40L⁺ platelets proportion, decreased sCD40L concentration, and suppressed the activation of EGCs. Comparable results were observed upon treatment with compound 6877002, a blocker of CD40L-CD40-TRAF6 signaling pathway. Also, S-nitrosoglutathione supplement reduced intestinal damage both in vivo and in vitro. In addition, CD40L increased release of TNF-α and IL-1β while suppressed the release of S-nitrosoglutathione from EGCs. These EGCs-conditioned medium reduced the expression of ZO-1 and occludin on Caco-2 cells and their transepithelial electrical resistance, which could be reversed by CD40-siRNA and TRAF6-siRNA transfection on EGCs.

Conclusions

The inhibition of platelet activation is related to the suppression of CD40L-CD40-TRAF6 signaling pathway and the reduction of EGCs activation, which promotes intestinal barrier function and survival in sepsis mice. These results might provide a potential therapeutic strategy and a promising target for sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00562-w.

Inhibition of platelet activation suppresses reactive enteric glia and mitigates intestinal barrier dysfunction during sepsis

Background

Intestinal barrier dysfunction, which is associated with reactive enteric glia cells (EGCs), is not only a result of early sepsis but also a cause of multiple organ dysfunction syndrome. Inhibition of platelet activation has been proposed as a potential treatment for septic patients because of its efficacy in ameliorating the organ damage and barrier dysfunction. During platelet activation, CD40L is translocated from α granules to the platelet surface, serving as a biomarker of platelet activation a reliable predictor of sepsis prognosis. Given that more than 95% of the circulating CD40L originate from activated platelets, the present study aimed to investigate if inhibiting platelet activation mitigates intestinal barrier dysfunction is associated with suppressing reactive EGCs and its underlying mechanism.

Methods

Cecal ligation and puncture (CLP) was performed to establish the sepsis model. 24 h after CLP, the proportion of activated platelets, the level of sCD40L, the expression of tight-junction proteins, the intestinal barrier function and histological damage of septic mice were analyzed. In vitro, primary cultured EGCs were stimulated by CD40L and LPS for 24 h and EGCs-conditioned medium were collected for Caco-2 cells treatment. The expression of tight-junction proteins and transepithelial electrical resistance of Caco-2 cell were evaluated.

Results

In vivo, inhibiting platelet activation with cilostazol mitigated the intestinal barrier dysfunction, increased the expression of ZO-1 and occludin and improved the survival rate of septic mice. The efficacy was associated with reduced CD40L⁺ platelets proportion, decreased sCD40L concentration, and suppressed the activation of EGCs. Comparable results were observed upon treatment with compound 6,877,002, a blocker of CD40L–CD40–TRAF6 signaling pathway. Also, S-nitrosoglutathione supplement reduced intestinal damage both in vivo and in vitro. In addition, CD40L increased release of TNF-α and IL-1β while suppressed the release of S-nitrosoglutathione from EGCs. These EGCs-conditioned medium reduced the expression of ZO-1 and occludin on Caco-2 cells and their transepithelial electrical resistance, which could be reversed by CD40-siRNA and TRAF6-siRNA transfection on EGCs.

Conclusions

The inhibition of platelet activation is related to the suppression of CD40L-CD40-TRAF6 signaling pathway and the reduction of EGCs activation, which promotes intestinal barrier function and survival in sepsis mice. These results might provide a potential therapeutic strategy and a promising target for sepsis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-022-00556-8.

Impact of intravenous dexmedetomidine on gastrointestinal function recovery after laparoscopic hysteromyomectomy: a randomized clinical trial

Postoperative intestinal ileus is common after laparoscopic surgery, the incidence of those after hysterectomy was 9.2%. Anesthesia is one of the independent risk factors of postoperative ileus. Dexmedetomidine has been widely used in perioperative anesthesia and previous reports suggested that intraoperative dexmedetomidine may be associated with the improvement of gastrointestinal function recovery after abdominal surgery. We hypothesized that dexmedetomidine could improve gastrointestinal function recovery after laparoscopic hysteromyomectomy. Participants in elective laparoscopic hysteromyomectomy were enrolled with a single dose of 0.5 μg kg⁻¹ dexmedetomidine or the same volume of placebo intravenously administered for 15 min, followed by continuous pumping of 0.2 μg kg⁻¹ h⁻¹ of corresponding drugs until 30 min before the end of surgery. The primary outcome was the time to first flatus. Secondary outcomes were the time to first oral feeding and the first defecation, the occurrence of flatulence, pain score and postoperative nausea and vomiting until 48 h after the surgery. Eventually, 106 participants (54 in dexmedetomidine group and 52 in placebo group) were included for final analysis. The time to first flatus (SD, 25.83 [4.18] vs 27.67 [3.77], P = 0.019), oral feeding time (SD, 27.29 [4.40] vs 28.92 [3.82], P = 0.044), the time to first defecation (SD, 59.82 [10.49] vs 63.89 [7.71], P = 0.025), abdominal distension (n%, 12 (22.2) vs 21 (40.4), P = 0.044), PONV at 24 h (n%, 10 (18.5) vs 19 (36.5), P = 0.037), NRS 6 h (3.15(0.68) vs 3.46 (0.87), P = 0.043) and NRS 12 h (3.43 (0.88) vs 3.85 (0.85), P = 0.014) of dexmedetomidine group were significantly shorter than those of the placebo group. Intraoperative dexmedetomidine reduced the time to first flatus, first oral feeding, and first defecation. These results suggested that this treatment may be a feasible strategy for improving postoperative gastrointestinal function recovery in patients undergoing laparoscopic hysteromyomectomy.

Preventive strategies for feeding intolerance among patients with severe traumatic brain injury: A cross-sectional survey

Objectives

This study aimed to investigate the application status of preventive measures for feeding intolerance in patients with severe traumatic brain injury (STBI) in China and analysis the differences and their causes.

Methods

A cross-sectional survey was conducted. From December 2019 to January 2020, ICU nurses and physicians of 89 hospitals in China were surveyed by using a questionnaire on preventive strategies for feeding intolerance in patients with STBI. The questionnaire included two parts: the general information of participants (10 items) and application of preventive measures for feeding intolerance in STBI patients (18 items).

Results

Totally 996 nurses and physicians completed the questionnaire. Among various methods, gastrointestinal symptoms(85.0%) and injury severity (71.4%) were mostly used to assess gastrointestinal functions and risk of feeding intolerance among STBI patients, respectively. Initiating enteral nutrition (EN) within 24–48 h (61.5%), nasogastric tubes (91.2%), 30°–45° of head-of-bed elevation (89.5%), continuous feeding by pump (72.9%), EN solution temperature of 38–40 °C (65.5%), <500 ml initial volume of EN solution (50.0%), monitoring gastric residual volume with a syringe (93.7%), and assessing gastric residual volume every 4 h (51.5%) were mostly applied for EN delivery among STBI patients. Prokinetic agents (73.3%), enema (73.6%), probiotics (79.0%), antacid agents (84.1%), and non-nutritional preparations as initial EN formula (65.6%) were commonly used for preventing feeding intolerance among STBI patients.

Conclusions

The survey showed that nurses and clinicians in China have a positive attitude towards preventive strategies for feeding intolerance. However, some effective new technologies and methods have not been timely applied in clinical practice. We suggest that managers, researchers, clinicians, nurses, and other health professionals should collaborate to explore effective and standard preventive strategies for feeding intolerance among patients with STBI.

Dexmedetomidine Versus Propofol for Patients With Sepsis Requiring Mechanical Ventilation: A Systematic Review and Meta-Analysis

Purpose: This meta-analysis was performed to access the influence of dexmedetomidine versus propofol for adult patients with sepsis undergoing mechanical ventilation. Materials and Methods: NCBI PUBMED, Cochrane Library, Embase, China National Knowledge Internet (CNKI), and China Biological Medicine (CBM) were searched. Revman 5.3 and Stata software (version 12.0, Stata Corp LP, College Station, TX, United States) were used for meta-analysis. Results: Fifteen studies were included, and the data from the included studies were incorporated into the meta-analysis. Also, the result shows that compared with propofol, dexmedetomidine does not reduce 28-day mortality [risk ratios (RR) =0.97, 95% confidence interval (CI) =0.83-1.13, p = 0.70]. However, our analysis found that dexmedetomidine could reduce intensive care unit (ICU) stays {standard mean difference (SMD): -0.15; 95% CI: [-0.30-(-0.01)], p = 0.03}, duration of mechanical ventilation {SMD: -0.22; 95% CI: [-0.44-(-0.01)], p = 0.043}, sequential organ failure assessment (SOFA) {SMD: -0.41; 95% CI: [-0.73-(-0.09)], p = 0.013}, levels of interleukin-6 (IL-6) at 24 h (SMD: -2.53; 95% CI: -5.30-0.24, p = 0.074), and levels of CK-MB at 72 h {SMD: -0.45; 95% CI: [-0.83-(-0.08)], p = 0.017}. Conclusions: This meta-analysis (MA) suggests that in terms of 28-day mortality, sepsis patients with the treatment of dexmedetomidine did not differ from those who received propofol. In addition, more high-quality trials are needed to confirm these findings. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/#recordDetails, identifier CRD42021249780.