Localization and characterization of phenylethanolamine N-methyl transferase in the brain of various mammalian species

The distribution of PNMT activity in various regions and nuclei of the rat, monkey and human brain was investigated. The distribution of PNMT activity in the rat brain correlates with the distribution of PNMT immunofluorescence. The PNMT activity in the primate brain is more widely distributed than in the rat brain. High and intermediate enzyme activity values were found in the same regions of the primate brain as in the rat brain. Intermediate or low levels were also found in various other regions of the primate brain, e.g., basal ganglia, amygdala, septum, habenula. The brain PNMT has the same substrate specificity and similar kinetic properties as the adrenal enzyme. Immunotitration studies revealed cross-reactivity between the homologous adrenal and brain PNMT.