Butyrate inhibits visceral allodynia and colonic hyperpermeability in rat models of irritable bowel syndrome

Lipopolysaccharide (LPS) or repeated water avoidance stress (WAS) induces visceral allodynia and gut hyperpermeability via corticotropin-releasing factor (CRF) and proinflammatory cytokines, which is a rat irritable bowel syndrome (IBS) model. As butyrate is known to suppress the release of proinflammatory cytokine, we hypothesized that butyrate alleviates these colonic changes in IBS models. The visceral pain was assessed by electrophysiologically measuring the threshold of abdominal muscle contractions in response to colonic distention. Colonic permeability was determined by measuring the absorbance of Evans blue in colonic tissue. Colonic instillation of sodium butyrate (SB; 0.37−2.9 mg/kg) for 3 days inhibited LPS (1 mg/kg)-induced visceral allodynia and colonic hyperpermeability dose-dependently. Additionally, the visceral changes induced by repeated WAS (1 h for 3 days) or CRF (50 µg/kg) were also blocked by SB. These effects of SB in the LPS model were eliminated by compound C, an AMPK inhibitor, or GW9662, a PPAR-γ antagonist, NG-nitro-L-arginine methyl ester, a NO synthesis inhibitor, naloxone or sulpiride. SB attenuated visceral allodynia and colonic hyperpermeability in animal IBS models. These actions may be AMPK and PPAR-γ dependent and also mediated by the NO, opioid and central dopamine D2 pathways. Butyrate may be effective for the treatment of IBS.

Preliminary heritability of complete rotation large colon volvulus in Thoroughbred broodmares

Large colon volvulus (LCV) is a life-threatening form of colic that occurs when the large colon rotates 360° or more on its axis, resulting in colonic distention and ischaemia. Any horse can suffer from LCV, but the risk is greatest for periparturient Thoroughbred broodmares; the objective of this study was to estimate the heritability of LCV in these horses. The criteria for classification as an LCV case were being a Thoroughbred broodmare from one of three farms in central Kentucky and having had surgical correction for LCV. Controls were identified as Thoroughbred broodmares present on the same farms with no history of surgical colic. Thirty-nine cases and 191 controls were identified. Age of the LCV cases at the time of incident was significantly younger than that of the controls at the time of the study (P<0.0001). A total of 2223 horses were present when the five-generation pedigrees of the 230 study horses were combined. Heritability of LCV was estimated at 0.311±0.383 from the fit of a logit sire model with binomial data including year of birth and farm as fixed effects. Further data on broodmares from these and other farms will help to improve this estimate, which suggests the LCV is moderately heritable.

Explosive Vomiting Associated with Proximal Colonic Distention during a Difficult Propofol-Assisted Colonoscopy

We present a case of explosive vomiting associated with the extensive manipulation of the proximal colon during a difficult colonoscopy procedure. The cause of vomiting in this case may have been multifactorial; however, proximal colonic distention was the most likely factor because the onset of vomiting coincided with proximal colonic manipulation and happened without any prodromal signs, coughing, and airway obstruction. Propofol, the sedative most commonly administered to the patient during colonoscopy, allows for a deep state of sedation, and consequently extensive colonic distention and scope manipulation. Colonic distention may lead to a higher risk of vomiting. We reviewed the neurocircuitry associated with vomiting and discussed why proximal colonic distention may increase the risk of vomiting. We emphasize vigilance during the manipulation of the proximal colon because vomiting increases the potential for aspiration pneumonitis and pneumonia in patients under deep propofol sedation with attenuated airway responses.