The role of serotonin in mucociliary transport system in the ciliated epithelium of frog palatine mucosa.
The effects of serotonin (5-hydroxytryptamine, 5-HT) on mucociliary transport and mucus secretion were investigated pharmacologically. The presence of 5-HT in the ciliated epithelium of frog palatine mucosa was examined chromatographically. Mucociliary transport was accelerated by the application of 10(-6) M 5-HT. Mucus secretion was also stimulated significantly by 5-HT (30 mg/kg). 5-HT in the mucosa was detected by a chromatographic technique when a large amount of 5-HT precursor, 5-hydroxytryptophan (5-HTP), was given previously. Phenylhydrazine was used as MAO inhibitor. When phenylhydrazine (20 mg/kg) was given before 5-HTP, 5-HT was markedly concentrated in the mucosa. Radioactive 5-HT was also detected in the mucosa after incubation with [14C]5-HTP. One hour after systemic administration of [3H]5-HTP, a large number of silver grains appeared in the autoradiograms of some epithelial cells. These results suggest the possibility that epithelial cells with the ability to synthesize 5-HT from 5-HTP exist in ciliated epithelium. A possible functional relationship is proposed between the regulation of mucociliary transport with mucus secretion and 5-HT-containing cells.
D006916:5-Hydroxytryptophan / Q000378:metabolism; D000818:Animals; D001345:Autoradiography; D001692:Biological Transport / Q000187:drug effects; D002923:Cilia / Q000187:drug effects* / Q000378:metabolism; D004848:Epithelium / Q000187:drug effects; D005260:Female; D008297:Male; D009092:Mucous Membrane / Q000187:drug effects; D009093:Mucus / Q000378:metabolism; D010159:Palate / Q000187:drug effects*; D011892:Rana catesbeiana; D011898:Ranidae; D012701:Serotonin / Q000032:analysis / Q000494:pharmacology*
D012701:Serotonin; D006916:5-Hydroxytryptophan