Subcellular distribution of rRNA and poly(A) RNA in hippocampal neurons in culture

In situ hybridization was used to assess the subcellular distribution of rRNA and poly(A) RNA in hippocampal neurons maintained in culture. Labeling produced with ³⁵S-labeled probes to either rRNA or poly(A) was heaviest over the cell body with lighter, patchy labeling of proximal dendrites. In contrast, ³H-labeled probes labeled dendrites throughout their length, and the ratio of dendritic to cell body labeling was higher with ³H-labeled probes. There was no detectable labeling of axons of mature neurons with either probe. The pattern of hybridization produced by ³⁵S-labeled oligonucleotide probes to rRNA varied depending on the concentration of the oligonucleotide. These studies provide the first detailed study of the subcellular distribution of rRNA and poly(A) RNA in neurons, and highlight technical issues to consider when evaluating results of hybridizations carried out with ³⁵S- and ³H-labeled probes on cells in culture.