Alteration of the pattern of hippocampal nerve cell RNA labelling during training in rats.

RNA synthesis in the CA3 region of brain hippocampus was studied in rats trained to a handedness reversal task. The newly synthesized RNA, labelled by intraventricular injection of radioactive orotic acid, was extracted and analyzed by micromethods. The result was following. In the trained animals the incorporation of the labelled precursor into RNA, corrected by the pool radioactivity, was almost double in comparison with the controls. In the trained animals there was a stimulation of the incorporation in the high molecular weight (greater than 18S) RNA region and in two specific low molecular weight regions: 8-9 and 16-17S. Taking in account previous results of other authors, these data appear to imply a stimulation of brain mRNA synthesis as a result of training.