Lubiprostone ameliorates the cystic fibrosis mouse intestinal phenotype

<p>Abstract</p> <p>Background</p> <p>Cystic fibrosis (CF) is caused by mutations in the <it>CFTR </it>gene that impair the function of CFTR, a cAMP-regulated anion channel. In the small intestine loss of CFTR function creates a dehydrated, acidic luminal environment which is believed to cause an accumulation of mucus, a phenotype characteristic of CF. CF mice have small intestinal bacterial overgrowth, an altered innate immune response, and impaired intestinal transit. We investigated whether lubiprostone, which can activate the CLC2 Cl^-channel, would improve the intestinal phenotype in CF mice.</p> <p>Methods</p> <p><it>Cftr^tm1UNC</it>(CF) and wildtype (WT) littermate mice on the C57BL/6J background were used. Lubiprostone (10 μg/kg-day) was administered by gavage for two weeks. Mucus accumulation was estimated from crypt lumen widths in periodic acid-Schiff base, Alcian blue stained sections. Luminal bacterial load was measured by qPCR for the bacterial 16<it>S </it>gene. Gastric emptying and small intestinal transit in fasted mice were assessed using gavaged rhodamine dextran. Gene expression was evaluated by Affymetrix Mouse430 2.0 microarray and qRT-PCR.</p> <p>Results</p> <p>Crypt width in control CF mice was 700% that of WT mice (<it>P </it>< 0.001). Lubiprostone did not affect WT crypt width but, unexpectedly, increased CF crypt width 22% (<it>P </it>= 0.001). Lubiprostone increased bacterial load in WT mice to 490% of WT control levels (<it>P </it>= 0.008). Conversely, lubiprostone decreased bacterial overgrowth in CF mice by 60% (<it>P </it>= 0.005). Lubiprostone increased gastric emptying at 20 min postgavage in both WT (<it>P </it>< 0.001) and CF mice (<it>P </it>< 0.001). Lubiprostone enhanced small intestinal transit in WT mice (<it>P </it>= 0.024) but not in CF mice (<it>P </it>= 0.377). Among other innate immune markers, expression of mast cell genes was elevated 4-to 40-fold in the CF intestine as compared to WT, and lubiprostone treatment of CF mice decreased expression to WT control levels.</p> <p>Conclusions</p> <p>These results indicate that lubiprostone has some benefits for the CF intestinal phenotype, especially on bacterial overgrowth and the innate immune response. The unexpected observation of increased mucus accumulation in the crypts of lubiprostone-treated CF mice suggests the possibility that lubiprostone increases mucus secretion.</p

Lubiprostone stimulates small intestinal mucin release

<p>Abstract</p> <p>Background</p> <p>Lubiprostone is a synthetic bicyclic fatty acid derivative of prostaglandin E1 (PGE₁) used for chronic constipation. The best known action of lubiprostone is simulation of Cl^- dependent fluid secretion. In a mouse model of the genetic disease cystic fibrosis, we previously showed that in vivo administration of lubiprostone resulted in greater mucus accumulation in the small intestine. The aim of this study was to directly test whether lubiprostone stimulates intestinal mucin release.</p> <p>Methods</p> <p>Mucin release was measured by mounting segments (4-5 cm) of mouse proximal-mid small intestine in an organ bath, allowing access to the perfusate (luminal) and the bath (serosal) solutions. Nifedipine (10^-6 M) and indomethacin (10^-5 M) were included in all solutions to inhibit smooth muscle activity and endogenous prostaglandin production, respectively. The tissue was equilibrated under flow for 30 min, using the perfusate collected during the final 10 min of the equilibration period to measure unstimulated release rate. Stimulus was then added to either the perfusate or the bath and the perfusate was collected for another 30 min to measure the stimulated mucin release rate. Mucin in perfusates was quantified by periodic acid-Schiff's base dot-blot assay, using purified pig gastric mucin as a standard.</p> <p>Results</p> <p>When applied luminally at 1 μM lubiprostone was ineffective at stimulating mucin release. When added to the serosal solution, 1 μM lubiprostone stimulated mucin release to ~300% of the unstimulated rate. As a positive control, serosal 1 μM prostaglandin E2 increased mucin release to ~400% of the unstimulated rate.</p> <p>Conclusions</p> <p>These results support the idea that lubiprostone has prostaglandin-like actions on the intestine, which includes stimulation of mucin release. Stimulation of mucin release by lubiprostone may be protective in gastrointestinal conditions where loss of mucus is believed to contribute to pathogenesis. Thus, in addition to chronic constipation, there is greater potential for the therapeutic applications of lubiprostone.</p

Mindfulness and problem gambling: a review of the literature

This article reviews the literature with respect to mindfulness and its potential for reducing the severity of problem gambling behaviour. Interest in the role of mindfulness as a treatment for problem gambling has gained the attention of researchers across Australia, the United States, and Canada. However, the literature is limited and current studies have severe methodological limitations. Despite this issue, investigations have revealed that dispositional mindfulness is related to less severe problem gambling outcomes and that psychological distress, overconfidence and risk willingness, myopic focus on reward and ego involvement may act as mediators in this relationship. Moreover, the literature indicates that the inverse relationship between dispositional mindfulness and psychological distress may be mediated by factors such as values clarification; emotional, cognitive, and behavioural flexibility; non-attachment; emotion dysregulation/distress intolerance; thought suppression; and rumination. This article discusses the theoretical and clinical implications of these relationships with respect to mindfulness-based interventions for problem gambling. It is recommended that the approach be considered with cautious optimism