Cerebellum plus locus coeruleus in tissue culture II: Development and metabolism of catecholamines

In contrast to locus coeruleus neurons in vivo, dopamine was the predominant catecholamine synthesized, stored, and released by neonatal mouse locus coeruleus cultures which included target cerebellar tissue, and norepinephrine was present in these cultures only at very low levels. Developmentally, norepinephrine increased slightly in the explants during the first 4 days in vitro and declined thereafter to barely detectable levels, whereas dopamine began to rise after 4 days and reached maximal levels by 7 days. Dopamine β‐hydroxylase was present in these cultures throughout maturation. These results suggest that the high ratio of dopamine to norepinephrine in locus coeruleus cultures cannot be attributed to the absence of appropriate target tissue or to a lack of the enzyme, dopamine β‐hydroxylase.