Effect of raphe lesions on brain serotonin in the cat

A quantitative study of the regional distribution of serotonin (5-HT) in the forebrain, was performed in adult cats, following brainstem lesions. Seven to 10 days survival times were used to avoid nonspecific variations of the amine levels, as were observed in chronic preparations. Significant decreases of 5-HT levels were found after lesions of the nucleus centralis superior (CS), in hypothalamus, preoptic area, amygdala and hippocampus. After lesions of the nucleus dorsalis raphe (Dr), significant 5-HT decreases were also found in the hypothalamus and hippocampus. There was no change of 5-HT levels after lesions placed in the lateral midbrain, pontine tegmentum, or caudal pontine raphe, contrary to that was reported for chronic lesioned cats. These results suggest that CS and Dr may integrate different serotonergic subsystems and, probably, each one of these subsystems is related to specific functional phenomena.