Involvement of peripheral alpha2A adrenoceptor in the acceleration of gastrointestinal transit and abdominal visceral pain induced by intermittent deprivation of REM sleep.

Many studies have associated sleep alterations with the severity of irritable bowel syndrome (IBS) symptoms, but the direct pathophysiological relationship has not been clarified. In addition, alterations in noradrenergic signaling have been implicated in the pathophysiology of IBS, and alpha2-adrenoceptors are potential treatment targets. We have previously shown that acceleration of gastrointestinal transit (GIT) elicited by intermittent rapid eye movement (REM) sleep deprivation stress may fulfill the profile of a model of IBS. Moreover, we showed hypernoradrenergic function in the brain of sleep-deprived mice. On the other hand, acetic acid-induced writhes indicate visceral pain features of IBS model animals. In this study, using mice, we investigated whether intermittent REM sleep deprivation stress causes changes in acetic acid-induced writhing and whether the number of writhes and GIT are improved by administration of the hydrophilic clonidine analogue, ST-91. Mice were deprived of REM sleep intermittently using the small-platform method (20h/day) for 3days. The intermittent REM sleep deprivation stress elicited acceleration of GIT and the increased number of writhes was significantly improved by ST-91 treatment. The ID50 values of ST-91 on the GIT in cage-control mice and intermittent REM sleep-deprived mice were 0.24 and 0.70mg/kg, respectively. In addition, the ID50 values of ST-91 on the writhes in cage-control mice and intermittent REM sleep-deprived mice were 0.52 and 0.73mg/kg, respectively. Further, the expression of alpha2A-adrenoceptor was decreased in the distal ileum of intermittent REM sleep-deprived mice compared to that in cage-control mice. Moreover, the effects of ST-91 on GIT and writhes in cage-control and intermittent REM sleep-deprived mice were decreased by the administration of BRL44408 (6mg/kg, i.p.), a selective alpha2A-adrenoceptor antagonist, and not by the administration of imiloxan (3mg/kg, i.p.), or JP-1302 (3mg/kg, i.p.), selective alpha2B-and alpha2C-adrenoceptor antagonists, respectively. These results suggest that the increase in GIT and writhes induced by intermittent REM sleep deprivation stress may serve as a model of diarrhea and visceral pain symptoms in IBS. Further, the onset of these symptoms may be related to the hypofunction of peripheral alpha2A-adrenoceptor.

Orally administered Bifidobacterium triggers immune responses following capture by CD11c(+) cells in Peyer's patches and cecal patches.

We have investigated the immunomodulatory mechanisms of Bifidobacterium pseudocatenulatum JCM7041 (Bp) as model of probiotics following oral administration to mice. This study was conducted with the aim of clarifying the mechanism of immunomodulation induced by oral administration of probiotic bacteria through elucidation of the detailed mechanism of transfer of orally administered bacterial cells within the body and the interaction between bacterial cells and cells of the immune tissues. We observed the localization of Bp in mice following oral administration, showing that Bp was surrounded by CD11c(+) cells in Peyer's patches (PP) and cecal patches (CP). These results indicated that Bp might induce CD11c(+) cell-mediated immune responses directly. Furthermore, IL-10 and IL-12p40 production by Thy1.2(-) cells, including CD11c(+) cells, increased significantly. Production of IL-10 and IL-12p40 by bone marrow-derived dendritic cells (BMDC) was significantly increased by Bp stimulation. These results suggest that oral administration of Bp induces immune responses directly following capture by CD11c(+) dendritic cells (DCs). Subsequently, we observed oral administration of Bp for 1 week induced IgA and IgA-associated cytokine production by CP and PP cells, suggesting that Bp induced DC-mediated immune responses on CP as well as PP.

Safety evaluation of probiotic bifidobacteria by analysis of mucin degradation activity and translocation ability.

Although probiotic-containing nutrient formulas for infants and toddlers have become very popular, some adverse effects related to translocation of probiotic strains have been reported. We assessed the safety of probiotic bifidobacteria that have been used in clinical investigations and proven to have beneficial effects, by analyzing mucin degradation activity and translocation ability. Mucin degradation activities of three probiotic bifidobacteria strains; Bifidobacterium longum BB536, Bifidobacterium breve M-16V and Bifidobacterium infantis M-63, were evaluated by three in vitro tests comprising growth in liquid medium, SDS-PAGE analysis of degraded mucin residues, and degradation assay in Petri dish. All test strains and control type strains failed to grow in the liquid medium containing mucin as the only carbon source, although good growth was obtained from fecal sample. In the SDS-PAGE analyses of mucin residues and observation of mucinolytic zone in agar plate, the three test strains also showed no mucin degradation activity as the type strains, although fecal sample yielded positive results. In another study, a high dose of B. longum BB536 was administered orally to conventional mice to examine the translocation ability. No translocation into blood, liver, spleen, kidney and mesenteric lymph nodes was observed and no disturbance of epithelial cells and mucosal layer in the ileum, cecum and colon was detected, indicating that the test strain had no translocation ability and induced no damage to intestinal surface. These results resolve the concern about bacterial translocation when using bifidobacteria strains as probiotics, which have been tested in various clinical trials, supporting the continuous use of these probiotic strains without anxiety.