Brain-specific src oncogene mRNA mapped in rat brain by in situ hybridization.

Brain src protooncogene is expressed in two forms, one identical to message in other tissues, and one containing an 18-nucleotide insert specific to brain. We have mapped mRNA for the two forms of src in rat brain with selective antisense oligonucleotide probes to the brain (src+) and peripheral (src-) forms. Fetal rat src mRNA levels were much higher in the central nervous system than any peripheral organ. In adult brain, src+ mRNA level was highest in the internal granular layer of the olfactory bulb, pyramidal cells of the hippocampus, granule cells of the dentate gyrus, and cerebellar granule cells. src+ and src- levels were similar in hindbrain, but src+ levels were higher than those of src- in forebrain. These distributions suggest that src+ may play roles in a number of neural processes, possibly including neuronal plasticity.