A modified method for the measurement of dopamine beta-hydroxylase

Neurotransmitter enzyme activities in neurons purified by bulk-isolation

Neurons, purified by bulk-isolation procedures from 10 day-old rat brain, are 80-90% homogeneous. Contaminants are primarily blood vessels and occasional oligodendroglia. All sizes and shapes of neurons are obtained, as they are isolated from all areas of the brain, except the cerebellum. Neurotransmitter enzyme activities involved in the metabolism of catecholamines, acetylcholine, and GABA are found at twice the level in these purified neurons when compared to that found in whole brain tissue. However, acetycholinesterase is found at a similar activity as in whole brain tissue, suggesting its localization in other cell types as well. Thus purified rat neurons are a good model system for studying neuronal function.

Alterations of catecholamine enzymes in several brain regions of victims of sudden infant death syndrome

Dopamine-beta-Hydroxylase (DBH) activity is decreased and tyrosine hydroxylase activity is increased in three brain regions (hypothalamus, putamen, and caudate nucleus) from victims of Sudden Infant Death Syndrome (SIDS) when compared to values in the same regions from infants dying of known causes. No stastically significant difference was detected in tyrosine hydroxylase activity in the thalamus and brain stem although DBH was 20% lower in the former region of the SIDS victims. Two other enzymes of biogenic amine metabolism, catechol-o-methyl transferase and Dopa-decarboxylase, were essentially the same in both groups. These data are consistent with the hypothesis that an alteration in the central nervous system may be a factor in the pathophysiology of SIDS.