Regional differences in the high affinity uptake or 3H-dopamine and 3H-norepinephrine in synaptosome rich homogenates of cat brain.

The uptake of ³H-dopamine and ³H-norepinephrine into synaptosome rich fractions of cat brain was studied. Following kinetic analysis of the high affinity uptake mechanism, the five areas investigated could be divided into two distinct groups: (1) the dorsal caudate nucleus and the septal region which showed a greater affinity for dopamine than for norepinephrine and (2) the hypothalamus, prefrontal and cerebellar cortex which showed equal affinities for both dopamine and norepinephrine. The distribution of monoamine oxidase activity did not correspond with the affinities for norepinephrine or dopamine but choline acetyltransferase activity was higher in areas which showed a preference for dopamine. A high affinity uptake system for 5-hydroxytryptamine was also observed in the septal region.