MAPK3 and hyperthyroidism: One main finding of this study was that in the period between 1 and 10 days of treatment with high doses of T3 to induce hyperthyroidism in rats, the hearts that showed hypertrophy and functional improvement (i.e., positive inotropic and lusitropic effects) displayed ERK1/2 inhibited cyclically and Akt activated transiently.