Effects of serotonin on the physiology of the rabbit small intestine

Serotonin has been shown to alter the intestinal transport of ions and inte stinal motility. These effects may interfere with each other, modulating th e whole physiology of the intestine. We have previously shown that serotoni n also alters the transport of nutrients. Thus, the aims of the present wor k were to determine the possible interference between the secretagogue effe ct of serotonin and the mechanism by which serotonin inhibits the absorptio n of nutrients, and to study the effect of serotonin on the digestive activ ity of nutrients of the brush border membrane jejunum enterocyte in the rab bit. The results show that the secretagogue effect of serotonin neither aff ects the inhibitory effect of serotonin on the intestinal absorption of the nutrients, nor affects the activity of Na+/K+-ATPase. The activity of sucr ase and aminopeptidase N was also not affected by serotonin in the rabbit j ejunum. Finally, we also studied different parameters of the motility in th e rabbit small intestine. Serotonin seemed to stimulate the motility of the rabbit small intestine by increasing integrated mechanical activity and to ne of muscle fibers in duodenum, jejunum, and ileum. In conclusion, seroton in might alter or modulate the whole intestinal physiology.