REGIONAL DISTRIBUTION OF ENZYMES ASSOCIATED WITH NEUROTRANSMISSION BY MONOAMINES, ACETYLCHOLINE AND GABA IN THE HUMAN BRAIN

Abstract— The activities of tyrosine hydroxylase (T-OH). DOPA decarboxylase (DDC). dopamine-β-hydroxylase (DβH). monoamine oxidase (MAO), choline acetyltransferase (ChAT), acetylcholinesterase (AChE), l -glutamic acid decarboxylase (GAD) and the concentrations of DNA and RNA were measured in 13–20 areas of post-mortem brain tissue from neurologically and psychiatrically normal individuals. Emphasis has been put on regional distribution rather than establishing normal values and detailed comparisons have been made with previously published work on the normal human brain. Despite expressing all results relative to an internal reference point there was substantial inter-brain variability. There was no apparent relation between age, sex, medication, cause of death or time lag between death and dissection and any of the enzyme activities. Enzyme activities were fairly evenly distributed throughout cerebral cortex whereas clear differences existed along the rostro-caudal axis of the brain. It is hoped that this paper, with its companion paper on amine and metabolite concentrations, will be useful as a reference work for investigators of the chemical pathology of the human brain.