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Symptom severity linked to serotonin concentrations in functional constipation, IBS
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Platelet-depleted plasma concentrations of serotonin were linked to symptom severity and rectal insensitivity in patients with functional constipation and IBS with constipation in a recent study.
Researchers evaluated serotonin concentrations in platelet-depleted plasma (PDP) collected from women with IBS with constipation (IBS-C; n=23) and functional constipation (FC; n=11) and healthy controls. (n=23) Abdominal and bowel-related symptoms were assessed at baseline, and 5-hydroxytryptamine (5-HT) was measured after fasting and meals.
Abdominal and bowel movement-associated symptoms were more pronounced in the IBS-C and FC groups compared with controls, while IBS-C patients had more severe symptoms than FC patients. Symptoms increased after meal ingestion in the IBS-C group (P<.001).
No significant differences were observed in PDP 5-HT concentrations between groups when fasting (P=.1), but patients with IBS-C had lower concentrations than FC patients after meals (P<.05). When fasting and postprandial concentrations were combined, FC patients had higher concentrations than those with IBS-C (P=.026), and numerically higher concentrations compared with controls (P=.1).
Oro-cecal transit was similar for all groups, while IBS-C and FC patients had longer colonic transit time (P=.001 or less). Sensory thresholds for first and stool sensations did not differ, but pain thresholds were lower in the IBS-C group than the FC group (P<.05).
An inverse correlation was observed between serotonin concentration and defecation frequency in the IBS-C and FC groups (r=–0.4; P=.03), while a correlation between stool threshold and frequency approached statistical significance (r=–0.3; P=.1). Serotonin concentration also correlated with pain threshold (r=0.4; P=.02) and neared significance with stool threshold (r=0.5; P=.06).
“Elevated platelet-depleted plasma 5-HT concentration associates with reduced visceral sensation and bowel frequency,” researcher Lesley A. Houghton, PhD, director of research, gastroenterology and hepatology, at Mayo Clinic in Jacksonville, Fla., told Healio.com. “Reduced bowel frequency associates with a more insensitive rectum, thus bowel frequency in patients with constipation more associates with visceral sensitivity than GI transit. … This is the first study to show such associations, and only the second to say IBS-C may be symptomatically indistinguishable compared with functional constipation.”
Disclosure: The researchers report no relevant financial disclosures.
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