In vitro 3H-serotonin (5-HT) synthesis and release in BALBc and C57BL mice. II. Cell body areas

"In vitro" 3H-5-HT and 3H-5-HIAA, newly synthesized from 3H-TRP, are measured in the brainstem, the anterior raphe nuclei and the locus coeruleus of C57BL and BALBc mice. As found for the caudate nucleus and the hippocampus, higher synthesis and release are determined in C57BL than in BALBc, for the locus coeruleus and more globally, for the brainstem. But these differences disappear when the study is carried on the raphe dorsalis and the raphe centralis nuclei. Therefore the serotonergic activity could be independently regulated at the level of cell bodies and at those of terminals. However, the 5-HT metabolism of NRD of BALBc mice could be submitted to a specific autoinhibition which could explain a lower 5-HT synthesis and release at the corresponding terminal level, compared to C57BL.