Inhibition of RNA and protein synthesis in isolated cerebellar cells by in vitro and in vivo methyl mercury

Abstract

Cerebellar perikarya isolated from neonatal rats were exposed to 0–20 μM methyl mercury to simultaneously compare the effect on RNA and protein synthesis. Although 50% inhibition was found at ∼8 μM for both [³H]uridine and [³H]phenylalanine incorporation, lower concentrations of methyl mercury produced 10–15% greater inhibition of RNA than protein synthesis. In vivo methyl mercury experiments also indicated a greater sensitivity of RNA synthesis in isolated cerebellar perikarya. The observed inhibition of RNA synthesis was not caused by a defect in cellular [³H]uridine uptake or by increased degradation of RNA. Both of these activities were altered by less than 10% at concentrations of methyl mercury that produced greater than 60% inhibition of RNA synthesis. Experiments showing that the specific activity of cerebellar cell RNA synthesis peaks and remains high between 4 and 10 d of age, whereas the specific activity of protein synthesis declines rapidly emphasize the potential importance of transcriptional perturbation in neonatal rats.