| Abstract: | Abstract— Radioactive hydroxylated phenylethylamines were released in vitro by electrical stimulation of minces of brain tissues from several anatomically discrete areas, while labelled urea and amphetamine were poorly released from all regions. Release of 3H]norepinephrine occurred in the order hypothalamus > caudate nucleus ≥ cerebral cortex, thus in parallel with the distribution of endogenous norepinephrine. In contrast, 3H]tyramine was poorly released from cortical tissues but readily released from minces of caudate nucleus or hypothalamus. 3H]Octopamine was released from all areas, but was most readily released from thecaudatenucleus. Results for cerebral cortex were similar to those for coronal slices or minces of whole brain; release occurred in the order: norepinephrine > octopamine > tyramine in all three preparations. We suggest that certain β-hydroxylated phenolic phenylethyl-amines may be released from norepinephrine- or dopamine-containing nerve endings in the brain, and that their non-β-hydroxylated congeners may be released from neurons in which endogenous amines are not β-hydroxylated. |
