HTR4 and irritable bowel syndrome: It may be related to anti-inflammation for acupuncture in patients with IBS, since acupuncture has been reported to reduce inflammation by inhibiting the transient receptor potential vanilloid-1 channel in peripheral intestinal sensory neurons [52], downregulating 5-hydroxytryptamine 3 receptor (5-HT3R) expression within the serotonin pathway, increasing 5-HT4R expression, influencing the activity of receptors and neurotransmitters in peripheral sensory endings [17, 53–55].