ROLE OF NEUROTRANSMITTERS, PROSTAGLANDINS AND GLUCOSE ON PRECURSOR INCORPORATION INTO 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 labeling from [3H]uridine; atropine abolished this effect. NaF, at 1 and 5 mM, pregressively 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 labeling from [3H]uridine. This effect was not inhibited by dinitrophenol. Prostaglandins (E1, A1, F1α and F2α) assayed in concentrations between 5 and 25 μg/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 stimulate PB125I formation.