Thyroid hormone regulation of poly(adenylate) polymerase activities in neuronal nuclei of developing rat brain cortex

Neuronal and glial cell-enriched nuclei were prepared from developing rat brain cortex to study the effect of thyroxine on nuclear poly(A) polymerase. Long-term thyroxine treatment stimulated the activity of the chromatin-associated enzyme of neuronal nuclei without significantly affecting that of glial nuclei. The nuclear content of poly(A)-containing RNA in neuronal nuclei was also increased by thyroxine administrations. A single dose of thyroxine enhanced both the chromatin-bound and the free, nucleoplasmic form of neuronal poly(A) polymerase in hypothyroid rats aged 12 days. The results suggest that thyroid hormones may regulate both transcriptional and post-transcriptional events in target cell nuclei.