Ramosetron (5 μg oral, once daily for 12 weeks) improved stool consistency in male patients with IBS-D, compared with placebo. These study results, along with the pharmacologic profile of ramosetron, indicate that increased stool consistency is the best end point for studies of ramosetron in patients with IBS-D. Clinicaltrials.gov No, NCT01225237.

In a randomized, placebo-controlled study of 576 women with IBS-D, 2.5 μg ramosetron per day reduced symptoms and increased stool consistency and QOL. Clinicaltrials.gov no: NCT01870895.

Neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) belong to a family of structurally related peptides which have numerous functions in both neural and endocrine signaling. By homology screening, we cloned a novel gene sharing the highest homology with the NPY Y1 receptor gene from humans, rabbits, and several other species. This novel gene of rabbit encodes a functional NPY/PYY receptor, designated Y2b, which prefers NPY 13-36 rather than [Leu 31 ,Pro 34 ]NPY despite its higher identity with the Y1 receptor. Although, at low levels, mRNA was detected in the tissues and brain regions, including hypothalamus. Further, sequence data revealed that this gene is the orthologue of the recently cloned mouse novel NPY receptor, Y5. However, our study demonstrates that the receptor function of this gene has been inactivated in primates by a frameshift mutation occurring early in primate evolution. This novel NPY receptor represents the first neurotransmitter receptor identified that has universally lost its receptor function in primate species. Interestingly, despite its inactivation in humans, the transcripts were abundantly detected in the heart and skeletal muscle, suggesting a novel function of the human gene.Neuropeptide Y (NPY), 1 peptide YY (PYY), and pancreatic polypeptide (PP) belong to a family of structurally related 36-amino acid peptides which have functions in both neural and endocrine signaling. These peptides exert their actions via receptors on the targeted neurons and peripheral cells. Several receptor subtypes have been defined by their ability to bind NPY, PYY, PP, and derivatives of these peptides. Earlier studies classified this receptor family into at least three receptor subtypes, Y1, Y2, and Y3 (1). The existence of additional receptors were also proposed, "atypical" Y1 receptor (mediating the feeding response of NPY in hypothalamus), PP-preferring receptor (exerting PP activity), and PYY-preferring receptor (2, 3). Molecular cloning studies have revealed the structure of Y1, Y2, and Y4/PP1 receptors (4 -9). These are all heptahelix (seven-transmembrane regions) receptors which couple to G-proteins. The Y4/PP1 receptor has higher affinity for PP than PYY and NPY, suggesting this receptor to be a member of PP receptors.As yet unknown members of this NPY receptor family are expected to be identified by molecular cloning. Very recently, during the course of the present work, the cloning and characterization of mouse Y5 (10) and rat Y5 (11) receptors was reported. The mouse Y5 receptor has significant homology with the Y1 receptor, but the rat Y5 receptor has little identity with the previously cloned NPY receptors, showing that these receptors are not species orthologues, despite having the same name, Y5. In the present report, we describe the cloning of a novel gene sharing the highest homology with the Y1 receptor from humans, rabbits, and several other species. Our study revealed that this novel gene is the orthologue of the mouse Y5 receptor gene (10) and encodes functional ...

BackgroundAbdominal bloating is a common symptom in patients with irritable bowel syndrome with constipation (IBS-C). However, it is not included among the required items in the Rome III diagnostic criteria for IBS. Little is known about an impact of abdominal bloating seen in patients with IBS-C. Using a large population-based sample, the aim of the present study was to investigate what is the most bothersome symptom in subjects with IBS-C.MethodsAn Internet survey of 30,000 adults drawn from the general public throughout Japan was conducted to identify subtypes of IBS using the Rome III diagnostic questionnaire. Consecutively, the screened subjects with IBS-C and the same number of age- and sex-matched non-IBS subjects who were randomly selected as controls were asked to answer a questionnaire on the degree of anxiety they experienced in their daily lives, thoughts about bowel habit, and their dominant gastrointestinal symptoms together with exacerbation factors (for IBS-C only).ResultsThe screening survey showed that the prevalence of overall IBS was 16.5 % (female 17.4 %, male 15.5 %) and that 2.8 % met the criteria for IBS-C, 4.5 % for IBS with diarrhea (IBS-D) and 8.2 % for mixed IBS (IBS-M). Seven hundred and fifty-nine of 835 (90.9 %) subjects with IBS-C and 746 of 830 (89.9 %) control subjects completed the consecutive questionnaire. IBS-C subjects felt a higher degree of anxiety in their daily lives (p < 0.01) and considered bowel habit to be an indicator of health (p < 0.01) to a greater extent than control subjects. In IBS-C, the degree of anxiety was significantly associated with abdominal discomfort (p < 0.01), pain (p < 0.01) and bloating (p = 0.02), but not with the frequency of bowel habit (p > 0.1). Abdominal bloating was the most bothersome symptom (27.5 %), which was more likely to occur after a meal (52.2 %), at work/school (29.2 %) and during times of stress (26.8 %). Only 4.5 % of IBS-C subjects reported abdominal pain as the ‘most bothersome’ symptom.ConclusionsA large population-based Internet survey suggests that abdominal bloating has a great impact on the daily lives of subjects diagnosed with IBS-C. Not only bowel movement/abdominal pain but also abdominal bloating should be evaluated in patients with IBS-C.Electronic supplementary materialThe online version of this article (doi:10.1186/s13030-016-0070-8) contains supplementary material, which is available to authorized users.

This study suggests that a linaclotide dose of 0.5 mg may be appropriate in Japanese patients with IBS-C.