Lipolytic activity of gonadotropins and their subunits

Abstract

The lipolytic activity of highly purified gonadotropins (LH, FSH, PMSG and hCG) and the related glycoprotein, TSH, was evaluated in rat adipose cells. It was found that LH, FSH and TSH were able to stimulate glycerol release. hCG and PMSG, tested at similar dose levels, were not active. The pituitary gonadotropins and TSH displayed a dose-response relationship similar to that for ACTH except that much higher concentrations were required. A varying degree of potency was noted among the different LH molecules studied: bovine > human > ovine. All gonadotropins tested were inactive in rabbit adipose cells. The α and β subunits of ovine LH were tested and found to possess 5 and 2% activity, respectively, compared to native LH. Recombination of the subunits yielded 40% activity. The potency of hormones possessing sialic acid (human LH, ovine FSH, PMSG and hCG) was unaffected following the removal of sialic acid with neuraminidase.