Taken together, findings from the present study suggest that catastrophic thinking exerts an influence on oesophageal pain sensitivity, but not necessarily on the magnitude of acid-induced oesophageal sensitization. WHAT DOES THIS STUDY ADD?: Catastrophizing is associated with heightened pain sensitivity in the oesophagus. This was substantiated by assessing responses to noxious stimulation of the oesophagus using an experimental paradigm mimicking features and symptoms experienced by patients with gastro-oesophageal reflux disease (GORD).
Background/AimsTo employ an experimental model of opioid-induced bowel dysfunction in healthy human volunteers, and evaluate the impact of opioid treatment compared to placebo on gastrointestinal (GI) symptoms and motility assessed by questionnaires and regional GI transit times using the 3-dimensional (3D)-Transit system. MethodsTwenty-five healthy males were randomly assigned to oxycodone or placebo for 5 days in a double blind, crossover design. Adverse GI effects were measured with the bowel function index, gastrointestinal symptom rating scale, patient assessment of constipation symptom questionnaire, and Bristol stool form scale. Regional GI transit times were determined using the 3D-Transit system, and segmental transit times in the colon were determined using a custom Matlab ® graphical user interface. ResultsGI symptom scores increased significantly across all applied GI questionnaires during opioid treatment. Oxycodone increased median total GI transit time from 22.2 to 43.9 hours (P < 0.001), segmental transit times in the cecum and ascending colon from 5.7 to 9.9 hours (P = 0.012), rectosigmoid colon transit from 2.7 to 9.0 hours (P = 0.044), and colorectal transit time from 18.6 to 38.6 hours (P = 0.001). No associations between questionnaire scores and segmental transit times were detected. ConclusionsSelf-assessed GI adverse effects and increased GI transit times in different segments were induced during oxycodone treatment. This detailed information about segmental changes in motility has great potential for future interventional head-to-head trials of different laxative regimes for prevention and treatment of constipation.(J Neurogastroenterol Motil 2016;22:282-291)
Aims The present study investigated expression and overall function of transient receptor potential vanilloid-1 (TRPV1) on trigeminal ganglion (TG) neurons and satellite glial cells (SGCs) in a whole-organ culture model to provide further information on association of TG with craniofacial nociception. Methods For TRPV1 receptor expression on neurons and SGCs, immunohistochemistry was performed on 24 cultured trigeminal ganglia isolated from male adult Sprague–Dawley rats. For the functional assay, the cultured trigeminal ganglia were treated with graded concentrations of capsaicin (0.1 μM, 1 μM, or 10 μM) or vehicle (0.1% ethanol in DMEM) and glutamate release was measured by a competitive enzyme-linked immunosorbent assay (ELISA). Samples were taken at 5, 15, and 30 min. Data from the functional assay were analyzed by two-way repeated measures ANOVA and Tukey post hoc test. Results The preliminary results confirmed the expression of TRPV1 mainly on small (46.6%) and medium (44.2%) sized neurons. In addition, expression of TRPV1 on SGCs was shown. Functionality test of the whole-organ demonstrated a significant increase in glutamate concentration, 30 min after application of 10 μM capsaicin (31.69 ± 6.73 μM) in comparison with vehicle (9.83 ± 2.53 μM) and 0.1 μM capsaicin (11.59 ± 7.04 μM) (p < 0.01). Conclusions This preliminary study demonstrated the expression of TRPV1 on trigeminal neurons and SGCs in the whole-organ model. Furthermore, capsaicin-evoked glutamate release from the whole-organ culture was detectable under controlled conditions and provided a potential platform for further investigation on TRPV1 stimulation and pharmacological modulation in relation to craniofacial nociception.
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