Long-lasting effects of electroconvulsive shock on the pattern of poly(A)-RNA synthesis in rabbit cerebral cortex

Alteration of RNA synthesis in vitro in intact cerebral cortex nuclei induced by convulsions in seizure-susceptible El mice

We examined the effects of convulsive seizures on in vitro RNA synthesis by cerebral cortex nuclei in El mice. The rate of incorporation of [3H]uridine-5'-triphosphate by intact nuclei during seizures was decreased to 47.4% compared with the rate during the interictal period, but gradually recovered. During the 30-min period after onset of seizures, the rate of RNA synthesis was significantly lower in El mice than in identically stimulated ddY mice. Seizures in El mice had no effect on liver RNA synthesis, suggesting that the alteration of RNA polymerase activity is specific to the brain. Analysis of gel electrophoresis of polyadenylated RNA synthesized in the presence of ammonium sulphate revealed a marked decrease in high-molecular weight RNA species 15 min after seizures in El mice compared with the pattern in nonstimulated ddY mice. This shift from high- to low-molecular weight RNA species was not attributable to RNase activity, but it appeared to be related RNA polymerase.

Labeling of non poly(A) associated RNA in the rabbit cerebral cortex 24 hours after a single electroconvulsive shock

The labeling pattern of non poly(A) associated (poly(A)-)RNA of rabbit cerebral cortex was studied 24 hr after a single electroconvulsive shock (ECS). The animals were injected subarachnoidally with [3H]uridine and sacrificed 1 hr later. The fractionation pattern of labeled nuclear poly(A)-RNA in the cerebral cortex of ECS treated animals was identical to that of the controls. However, microsomal poly(A)-RNA from the treated animals showed an increased labeling of 18S ribosomal RNA. Also 28S RNA displayed a higher labeling but the effect was not statistically significant. These results indicate a more efficient production of ribosomal RNA in the late post-ECS period which might be in relationship with an increased activity of brain protein synthesis machinery.