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, 52 (5), 663-70

Increased Platelet Depleted Plasma 5-hydroxytryptamine Concentration Following Meal Ingestion in Symptomatic Female Subjects With Diarrhoea Predominant Irritable Bowel Syndrome

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Increased Platelet Depleted Plasma 5-hydroxytryptamine Concentration Following Meal Ingestion in Symptomatic Female Subjects With Diarrhoea Predominant Irritable Bowel Syndrome

L A Houghton et al. Gut.

Abstract

Background: Meal ingestion is often associated with exacerbation of gastrointestinal symptoms in subjects with irritable bowel syndrome (IBS). Furthermore, recent preliminary data suggest that 5-hydroxytryptamine (5-HT) concentration in platelet poor plasma is elevated following meal ingestion in some subjects with diarrhoea predominant IBS (d-IBS) compared with healthy subjects, although it is not known whether this is related to postprandial symptomatology.

Aim: To expand on previous data by evaluating a larger number of subjects but also to assess plasma 5-hydroxyindole acetic acid (5-HIAA) concentrations, 5-HT turnover, platelet 5-HT stores, and any relationship to symptomatology.

Methods: We assessed platelet depleted plasma 5-HT and 5-HIAA concentrations for two hours (60 minute intervals) under fasting conditions, and then for a further four hours (30 minute intervals) after a standard carbohydrate meal (457 kcal), together with fasting platelet 5-HT concentrations in 39 female subjects with d-IBS (aged 19-52 years; mean age 33) and 20 healthy female volunteers (aged 20-46 years, mean age 28). IBS symptomatology, in particular abdominal pain and bloating, and urgency to defecate were assessed throughout the study

Results: When related to fasting levels, there was no statistically significant difference in postprandial plasma 5-HT concentrations between d-IBS and healthy subjects. However, when fasting levels were not taken into consideration, d-IBS subjects exhibited higher postprandial plasma 5-HT concentrations compared with healthy subjects (p=0.040). Furthermore, d-IBS subjects who exhibited postprandial symptomatology had higher levels of postprandial plasma 5-HT, whether assessed with respect to fasting baseline levels (p=0.069) or not (p=0.047), compared with d-IBS subjects who did not report postprandial symptomatology. This appeared to be associated with a concomitant increase in plasma 5-HIAA (p=0.161) but reduction in turnover (p=0.058). Lastly, d-IBS subjects had higher platelet concentrations of 5-HT than healthy subjects (p=0.009).

Conclusions: These data suggest that postprandial symptomatology may be associated with increased platelet depleted plasma 5-HT concentrations in female subjects with d-IBS. In addition, the presence of increased platelet stores of 5-HT may act as a useful marker for the diagnosis and management of d-IBS.

Figures

Figure 1
Figure 1
Profile of overall symptom score with respect to meal ingestion (t=0) in female diarrhoea predominant irritable bowel syndrome (d-IBS) subjects with (+) and without (−) postprandial symptoms, and in healthy female subjects. Data are means and 95% confidence interval.
Figure 2
Figure 2
Profiles of 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) concentrations and turnover with respect to meal ingestion (t=0) in female subjects with diarrhoea predominant irritable bowel syndrome (d-IBS) and healthy female subjects. Data are geometric means and 95% confidence interval.
Figure 3
Figure 3
Individual plots of values for fasting concentrations of platelet depleted plasma 5-hydroxytryptamine (5-HT) in female subjects with diarrhoea predominant irritable bowel syndrome (d-IBS), and healthy subjects.
Figure 4
Figure 4
Individual plots of values for area under the postprandial 5-hydroxytryptamine (5-HT) concentration/time curve (not referenced to fasting levels) in female subjects with diarrhoea predominant irritable bowel syndrome (d-IBS) with (+) and without (−) postprandial symptoms and in healthy subjects.
Figure 5
Figure 5
Profiles of 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) concentrations and turnover with respect to meal ingestion (t=0) in female subjects with diarrhoea predominant irritable bowel syndrome (d-IBS) with (+) and without (−) postprandial symptoms. Data are geometric means and 95% confidence interval.
Figure 6
Figure 6
Profiles of 5-hydroxytryptamine (5-HT) and 5-hydroxyindole acetic acid (5-HIAA) concentrations and turnover with respect to meal ingestion (t=0) in female subjects with diarrhoea predominant irritable bowel syndrome (d-IBS) with (+) and without (−) worsening of postprandial symptomatology. Data are geometric means and 95% confidence interval.
Figure 7
Figure 7
Individual plots of values for platelet 5-hydroxytryptamine (5-HT) concentration in female subjects with diarrhoea predominant irritable bowel syndrome (d-IBS) and healthy subjects.

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