Clinical data, fresh feces and intestinal mucosal tissues of patients with diarrheal IBS were collected. High performance liquid chromatography, immunohistochemistry and immunofluorescence were used to study the amino acid levels in feces of patients with IBS, the expression of taste receptors in intestinal mucosa, and the correlation between symptoms of abdominal pain and diarrhea and the expression of taste receptors, so as to obtain the conclusion that "intestinal amino acid perception abnormalities exist in patients with IBS. And correlated with clinical symptoms."

Inclusion Criteria:

• Patients with IBS who meet the Rome IV diagnostic criteria:

  1. that is, recurrent abdominal pain, with symptoms occurring at least 1 day per week or at least 3 days per month on average in the last 3 months, combining 2 or more of the following:

     1. related to defecation;
     2. accompanied by changes in the frequency of bowel movements;
     3. Accompanied by changes in fecal characteristics (appearance). (Symptoms appeared at least 6 months before diagnosis, and above diagnostic criteria were met in the last 3 months) 2. Age ≥18 years old.

Exclusion Criteria:

• 1. History of celiac disease and other organic intestinal diseases, metabolic diseases (thyroid dysfunction, diabetes, etc.); (2) Serious neurological, mental and psychological diseases, or accompanied by serious organ dysfunction; 3. Abdominal surgery; 4. Pregnant, possible pregnant and lactating patients; 5. History of colonoscopy in the past 1 year; 6. Declined to participate in the study.

Patients with irritable bowel syndrome who met all inclusion and exclusion criteria and corresponding healthy controls admitted to the gastroenterology Department of the Second Affiliated Hospital of Xi 'an Jiaotong University