Protein and RNA synthesis in cerebral microvessels: a radioautographic study

The distribution of protein and ribonucleic acid (RNA) synthesized by telencephalon slices was determined by radioautography at the light microscope level. Previous studies had shown that, in telencephalon slices, the cells associated with the cerebral microvasculature were synthesizing protein at very high rates compared to other cerebral cells such as neurons. In this study, therefore, particular emphasis was placed on the distribution of newly synthesized protein and RNA among the various cell types of the microvasculature. Rat telencephalon slices were incubated with either [3H] leucine or [3H] uridine for 1 h. The 3H-protein that was found in association with microvessels was present in endothelial cells, pericytes and smooth muscles cells. There was also extensive labeling of cellular processes adjacent to the abluminal side of the basement membrane and extending as far as 15 micrometer from the lumen. The latter processes may have been astrocyte glial projections. All [3H] RNA found associated with microvessels was, however, restricted to endothelial cells and pericytes. This data is discussed in relation to the induction of a 71,000 dalton protein which occurs within minutes of the preparation of tissue slices, and requires the synthesis of new RNA.