Accumulation of different c-erbA transcripts during rat brain development and in cortical neurons cultured in a synthetic medium.

1. Accumulation of different c-erbA transcripts was studied, during rat brain maturation and in cortical neurons differentiating in a serum-free medium, by quantitative Northern blot hybridization. 2. The alpha and beta forms of c-erbA mRNAs exhibit different patterns of accumulation, with a precocious increase in the alpha forms compared with the beta forms both in vivo and in culture. 3. erbA alpha 2 mRNA (2.6 kb) is by far the predominant form, with a maximum at birth (PO). 4. The accumulation patterns of both alpha and beta forms show discrete differences in isolated neurons compared to brain cortices; in particular the pattern of alpha 2 mRNA accumulation in culture suggests its predominant localization to neurons. 5. The presence of T3 in the culture medium does not have significant effects on the level of any of erbA mRNAs. 6. Possible implications and relationships with neuronal terminal differentiation are discussed.