The pathophysiology of functional dyspepsia is still unclear but several peptides have been indicated in the etiological factors in FD. Ghrelin and leptin are involved in regulation of appetite and gut motility and serotonin is a typical neurotransmitter related with sensory and motor functions of gut. On the other hand, transient receptor potential vanilloid receptor 1 (TRPV1) has been proposed to be involved with functional gastrointestinal disorder, and expression of this receptor could be regulated by nerve growth factor (NGF) or glial cell-line derived neurotrophic factor (GDNF). The investigators aimed to determine whether expressions of ghrelin,leptin, serotonin,TRPV1,GDNF and NGF in blood or gastric mucosa of FD patients are different from those in healthy controls, and whether some changes of their expression correlate with certain dyspeptic symptoms. The investigators also investigated the effect of H. pylori infection by comparing their expressions before and one year after H. pylori eradication.

Inclusion Criteria:

• Subjects who completed upper GI endoscopy and questionnaire about gastrointestinal symptoms

Exclusion Criteria:

• Daily user of NSAID or anticoagulants
• with concomitant systemic diseases such as diabetes mellitus or any malignancy
• Participants with major depression, psychosis, eating disorder
• Participants with typical reflux symptom
• Patients with Benign gastric ulcer or duodenal ulcer
• Patients with past gastrointestinal surgery

Patients who had epigastric pain or discomfort with normal upper endoscopy and no evidence for explaining these symptoms were prospectively enrolled in Seoul National University Bundang Hospital. All participants underwent esophagogastroduodenoscopy. During endoscopy, biopsies were taken from both antrum and body for histological evaluation, determining H. pylori infection status.

Participants were divided into control and patients according to the Rome III criteria. Patients group were subclassified into 3 categories; PDS (postprandial distress syndrome), EPS(epigastric pain syndrome) or mixed (PDS+EPS)