Biochemical and histofluorescence studies of catecholamines in superior cervical ganglia in organ culture.

The metabolism of catecholamines in rat superior cervical ganglia in organ culture was examined by biochemical and histofluorescence methods. Pronounced increases in both norepinephrine and dopamine content were observed in the cultured ganglia. Norepinephrine levels were more than doubled after 12 hours in culture and reached a maximum after 24 hours. The greatest increase in norepinephrine concentration occurred in the region of the postganglionic nerve trunks and was correlated with an accumulation of intense catecholamine fluorescence in the stumps of the severed postganglionic nerves. Since the rate of norepinephrine synthesis was unaltered, the increase in norepinephrine levels in cultured ganglia appears to be a result of blocked axoplasmic transport of this amine out of the ganglia. The dopamine content of the cultured preparations was not altered after 24 hours but increased rapidly thereafter and attained a maximum at 48 hours. The changes in dopamine did not parallel the changes in norepinephrine either in time course or distribution. The elevated levels of dopamine were accompanied by an increased rate of dopamine synthesis. It is suggested that the increased dopamine content in cultured ganglia is the result of an enhanced synthesis of this amine by specific dopaminergic cells.