Duodenal epithelial transport in functional dyspepsia: Role of serotonin

Figure 1 Basal slope conductance of duodenal mucosa as measured in a modified air-suction Ussing chamber. Conductance, in millisiemens per square cm (mS/cm²), is significantly higher in healthy controls (n = 18) compared to patients with functional dyspepsia (FD) (n = 15), P = 0.005 vs FD. mean ± SE.

Figure 2 Dose-response of 5-hydroxytryptamine-induced short circuit current. Addition of 5-hydroxytryptamine (5-HT) in cumulative concentrations by steps of a factor three from 3 to 243 μmol/L on the serosal side of duodenal biopsies mounted in an Ussing chamber resulted in an increased short circuit (μA/cm²), in both functional dyspepsia patients (n = 8) and healthy controls (n = 9), with significantly lower values in the dyspeptic group (P < 0.001 for the overall difference) (mean ± SE). SCC: Short circuit current.

Figure 3 Paraformaldehyde-fixed duodenal tissue from a patient with functional dyspepsia. The tissue was stained immunohistochemically using a polyclonal antibody against 5-hydroxytryptamine (5-HT). There are many 5-HT immunoreactive cells in the surface epithelium, both in the crypts and the villi. The biopsy has an intact surface epithelium without signs of mechanical damage (magnification ×220).

Figure 4 Gene expression (mRNA) levels differed significantly in duodenal mucosa from functional dyspepsia patients compared to healthy controls. A: HTR3E; B: HTR7; C: SLC4A6; D: TPH1. Empty bars represent patients (n = 10 for HTR3E, SLC4A6 and TPH1, and n = 8 for HTR7) and filled bars represent controls (n = 16 for SLC4A6 and TPH1, n = 15 for HTR3E and n = 13 for HTR7). All levels were measured by quantitative real-time polymerase chain reaction and expressed as mean fold change ± SE relative to the values obtained for a control sample arbitrarily chosen as a reference. P < 0.05, P < 0.01 vs control group.