[Participation of serotoninergic mechanisms in the regulation of visceral functions during conditioned reflex activity].

In chronic experiments on dogs, a reverse correlation was revealed between the level of positive salivary conditioning and the amount of serotonin in the blood. Administration of 0.2 and 0.4 mg of serotonin into the anterior limbic cortex enhanced conditioning in animals with high initial amount of serotonin in the blood and decreased it in animals with low amount of serotonin in the blood. Subcutaneous administration of serotonin in doses 0.5, 1.0, 2.0 and 5.0 mg/kg augmented the small intestine electrical activity. Subcutaneous administration of the serotonin precursor 5-oxytryptophan (0.5 mg/kg) enhanced both the conditioning and the small intestine electrical activity. An increased level of serotonin in the blood was revealed in neuroses peculiar by a prolonged depression of conditioning.