Serotonin distribution in rat cerebral cortex; radioenzymatic assays with thin-layer chromatography.

Serotonin was measured in six different cortical regions of the rat by a specific and sensitive radioenzymatic assay which includes thin-layer chromatography in the last separation step. The indoleamine was found to be unevenly distributed throughout the cortical regions examined; and the highest concentrations were determined for the prefrontal and the occipito-temporal cortex lateral to the hypothalamus. These results correlate with anatomical and electrophysiological studies which support a modulatory role for the serotonin afferent innervation of the cerebral cortex.