Comparative and quantitative study of L-dopa decarboxylase mRNA in rat neuronal and non-neuronal tissues.

The L-DOPA decarboxylase mRNA levels were determined by a sensitive S1 nuclease method in four organs and one tumor of adult rat. S1 mapping analysis, with probes corresponding to the mRNA coding region, showed that this region is conserved in all L-DOPA decarboxylase mRNA of neuronal and non-neuronal tissues. The mRNA was not very abundant; its representation varies approximately from 0.00035% of total RNA in the mid brain to 0.013% of total mRNA in the pheochromocytoma. A strong correlation between mRNA level and enzyme amount was observed (correlation coefficient = 0.99). The results indicate that the level of mRNA is a primary factor determining the L-DOPA decarboxylase level.