Cellular dopamine is increased following exposure to a factor derived from immortalized striatal neurons [corrected]

A factor obtained from an immortalized hybrid monoclonal cell line (X61) of striatal origin is capable of increasing the dopamine content of hybrid, monoclonal cells expressing a dopaminergic phenotype (MN9D) and of aggregate cultures containing primary dopaminergic neurons. The factor is a protein smaller than 100 kDa and appears to be different than a number of other trophic agents with effects on the dopaminergic neuron. The effect on dopamine content appears to be specific to centrally-derived neuronal elements; the protein having no effect on the dopamine content of PC12 cells. Given that parkinsonian symptoms are only apparent following degeneration of a substantial portion of the mesencephalic dopaminergic cell population, activity capable of increasing dopamine content of the surviving cells may represent an interesting candidate therapeutic agent.