Further studies on effects of thyroid-stimulating hormone on thyroid glucose oxidation.

Previously we have reported that thyroid-stimulating hormone stimulates glucose-l-C4 oxidation in thyroid slices in vitro and that this effect appeared to be secondary to an increase in nicotinamide adenine dinucleotide phosphate levels in the tissue (l-3). Although the effect of thyroid-stimulating hormone on glucose oxidation in vitro was apparent within 5 minutes of its addition to the thyroid slice, experiments in viva with guinea pigs indicated that intraperitoneal thyroid-stimulating hormone had to be administered for at least 48 hours before glucose oxidation in the thyroid gland was increased (2). The absence of an immediate effect in viva was difficult to reconcile with the rapid action of the hormone in vitro. Further studies have been done to clarify this discrepancy as well as to elucidate the mechanism of action of TSH.1 Experiments have also been performed to evaluate the role of the TPN concentration in the thyroid slice on the oxidation of glucose-l-U4 to C1402. The results of these experiments serve as the basis for this report.