Neonatal hypothyroidism: Enhanced incorporation of precursors into cerebral RNA [formula omitted] and normalizing effect of a semi-acute injection of thyroxine

Abstract

The incorporation of radioactivity from intracisternally injected (6− 14C) orotic acid into cerebral RNA and precursor pool was markedly elevated in 25 day-old hypothyroid rats compared to controls. Similar results were achieved with (2− 14C) uridine as the isotopic precursor. The increase in specific radioactivity of cerebral ribosomal RNA and the purified nucleotide precursor pool was essentially restored to normal by a single injection of L-thyroxine at 22 days of age (72 hours prior to sacrifice). The results are compatible with an increased intracellular uptake (transport) of RNA precursors and reflect the participation of thyroid hormones in the regulation of events at the membrane during brain development.