In vitro activity: Serotonin stimulates acid–base transport by the anterior stomach region of the midgut in vitro. The function of this stimulation is assumed to be maintenance of optimal conditions for digestion and absorption of nutrients rather than regulation of hemolymph acid–base homeostasis.

Cell Assay: For macrophage culture, peritoneal cavity cells are collected from WT and IL-13-/- mice with or without dextran sodium sulfate (DSS) treatment and cultured. Cells are plated at a concentration of 3.0×106 cells per millilitre, and treated with either lipopolysaccharides (LPS); (100 ng/mL) or Serotonin hydrochloride (10-10 M) for 24 hours. The culture supernatant are collected and stored in -80°C until determination of cytokine levels using protein array system