PERSISTENCE OF ALTERED RNA SYNTHESIS IN RAT CEREBRAL CORTEX 12h AFTER A SINGLE ELECTROCONVULSIVE SHOCK

— The effect of electroshock (ECS) on RNA synthesis in nuclei and cytoplasm of rat cerebral cortex was examined using a double label technique by intraventricular injection of [ 3 H] and [ 14 C]orotate. At t h after ECS, the incorporation into nuclear RNA was 80% of the control rate and the appearance of newly synthesized RNA in the cytoplasm was only 27.6%. Analysis on composite polyacrylamide‐agarose gels of purified RNA showed that the 3 H/ 14 C ratio of each gel slice slowly increased with decreasing M.W. of the RNA. This has been interpreted as an inhibition in the rate of processing of nuclear RNA. When the nuclear RNA was subjected to denaturation with 50% dimethyl sulphoxide (DMSO) this effect was enhanced. In a similar experiment, rats were injected, treated to ECS and killed 12 h later. The overall incorporation into nuclear and cytoplasmic RNA was increased to 174%, and 137.5% respectively. Analysis on gels showed very little variation in the 3 H/ 14 C ratio of the steady state levels of nuclear RNA. They compared well with a control experiment where rats were injected with [ 3 H] and [ 14 C]orotate as described above but no ECS was applied to the [ 14 C] labelled animals. However a 1 h pulse label given 11 h after ECS treatment revealed that the rate of incorporation into nuclear RNA still showed a decrease of 81% of the control. The nuclear RYA fractionated on gels clearly showed that the inhibition of the processing rate of nuclear RNA was still occurring. This effect was again magnified on denaturation of the RNA with DMSO. This suggests that ECS may disturb RNA metabolism in nervous tissue for much longer periods than previously realised.