Role of neurotransmitters, prostaglandins and glucose on precursor incorporation into the RNA of thyroid slices.

The present studies were performed in order to investigate the role of neurotransmitters, prostaglandins and glucose on [3H] uridine incorporation into total RNA in beef thyroid slices. Carbamylcholine strongly stimulated RNA labelling from [3H uridine; atropine abolished this effect. NaF, at 1 and 5 mM, progressively increased this parameter while norepinephrine caused a similar effect at 10(-3) but not at 10(-6) M. Phentolamine (1 mM) blocked the stimulatory action of TSH; propranolol and atropine did not. Glucose at concentrations between 4 and 24 mM caused a progressive increase in RNA labelling from [3H] uridine. This effect was inhibited by dinitrophenol. Prostaglandins (E1, A1, F1alpha and F2alpha) assayed in concentrations between 5 and 25 microgram/ml, with or without caffeine, had no effect on RNA labelling. Moreover, neither aspirin nor indomethacin inhibited TSH stimulation. Under similar experimental conditions, PGE1 did simulate PB125I formation.