Effects of long-acting thyroid stimulator and prostaglandin antagonists on adenyl cyclase activity in isolated bovine thyroid cells

Abstract

We studied the effects of long-acting thyroid stimulator [LATS] and two unrelated compounds reported to be prostaglandin antagonists, 7-oxa-13-prostynoic acid [PY 1] and polyphloretin phosphate [PPP] on adenyl cyclase activity in isolated bovine thyroid cells [ITC]. LATS-IgG stimulated ITC adenyl cyclase in a dose-related manner; the time-course of LATS-induced cyclase activation was comparable to that observed with thyrotropin [TSH] [onset at 5 min, maximal at 7.5 to 10 min]. PY 1, 5 μg/ml [≌ 1.4 × 10 −5M] and PPP, 5 μg/ml [≌ 3.3 × 10 −8M], significantly inhibited the stimulatory effects of prostaglandin E 2, TSH and LATS on ITC adenyl cyclase but did not modify basal cyclase activity. PPP, 0.5 mg, inhibited the effects of both TSH and LATS on mouse thyroid radioiodine release in vivo in an apparently competitive manner but did not modify dibutyryl cyclic AMP effects thereon. These studies suggest that activation of a prostaglandin receptor site may be an early step in the action of both LATS and TSH on thyroid.