Abstract
Highly purified preparations of human thyrotropin [TSH], follitropin [follicle stimulating hormone, FSH] and choriogonadotropin [human chorionic gonadotropin, HCG] were evaluated for their ability to stimulate lipolysis in isolated rat adipocytes. TSH was the most active of all, while FSH showed some activity. LH and HCG were essentially inactive. The isolated subunits of TSH were inactive, and 60-100% activity was regenerated upon recombination. Lipolytic activity is intrinsic to human TSH. The hybrid of human LH .alpha. + TSH .beta. was considerably less active than the natural recombinant (TSH .alpha. + .beta.), possibly indicating the presence of some differences in the .alpha. subunits.