Concentration of serotonin in intestine and factors affecting its release

The concentration of serotonin in the female chicken intestine (10.79 mug/g wet tissue) was significantly higher than in the male (7.98 mug/g). The release of serotonin from an isolated perfused intestine was studied. The intestine continually releases serotonin at the rate of 10 ng per g/min. A number of substances, including glycine, epinephrine, and acetylcholine, caused a significant release of serotonin, with acetylcholine having the greatest effect. Histamine or electrical stimulation did not affect the release of serotonin.