In vitro 3H-serotonin (5-HT) synthesis and release in BALBc and C57BL mice. I. Terminal areas.

"In vitro," 3H-5-HT and 3H-5-HIAA newly synthesized from 3H-TRP are measured in the caudate nucleus and the hippocampus of C57BL and BALBc mice. Higher synthesis, utilization and release are to be found in C57BL than in BALBc strain. In the hippocampus of C57BL this higher synthesis is due both to higher tryptophan hydroxylase activity and to higher tryptophan uptake ability. But in the caudate nucleus the initial accumulation of tryptophan is similar in both strains. Finally the two forms of monoamine oxidase (A and B) show also similar activities in both strain. These data will be compared to those obtained at the nerve cell body level in the paper (II).