AJP - Endocrinology and Metabolism, Vol 259, Issue 3 E305-E311, Copyright © 1990 by American Physiological Society
Thermogenic effect of thyroid hormones: interactions with epinephrine and insulin
V. Piolino, K. J. Acheson, M. J. Muller, N. Jeanpretre, A. G. Burger and E. Jequier
Institute of Physiology, Lausanne University Medical School, Switzerland.
The interactions between thyroid hormones, epinephrine, and insulin in the
regulation of energy expenditure were investigated in a group of healthy
young men before and after thyroxine (T4) treatment (300 micrograms/day for
14 days) at basal plasma insulin concentrations and during hypoinsulinemia
with and without epinephrine infusion (0.05 micrograms.kg fat-free
mass-1.min-1). T4 treatment induced moderate hyperthyroidism and increased
resting energy expenditure (RMR). The effect was more pronounced during
short-term hypoinsulinemia, but hypoinsulinemia by itself did not influence
RMR. Epinephrine infusion caused a significant increase in energy
expenditure. The effect was most pronounced at hypoinsulinemia and with T4
treatment. Hypoinsulinemia and T4 treatment were not additive in their
effects. We conclude that basal insulin concentrations mask some of the
thermogenic effects of thyroid hormones and epinephrine. Thus insulin
antagonism may suppress some of the thermogenic actions of thyroid hormones
and epinephrine.
