[Influence of thyroid states on PGE2 biosynthesis]. / Influenza degli stati tiroidei sulla biosintesi di PGE2.

ABSTRACT

Hyperthyroid and hypothyroid states were induced in the rat by daily injection of 3,3',5-triiodothyronine (T3; 33 microgram/100 g b. wt., ip for 6 days) or by thyroparathyroidectomy, respectively. Control animals underwent only a sham operation or received the T3 vehicle. In these experimental conditions the biosynthesis of PGE2-like substance was determined "in vitro" in the fraction obtained after centrifugation at 80,000xg for 60 min of pooled spleens (5). Assays of PGE2 activity were carried out on rat stomach strip preparations according to Vane (8). In a series of additional experiments the influence of thyroid states on the inhibitory activity exerted by Indomethacin, Oxametacine and Phenylbutazone on PGE2 biosynthesis was also evaluated. The results obtained indicate that the hyperthyroidism induces a significant increase of PGE2 production "in vitro" from added arachidonic acid (100% enhancement above the control values) while thyroparathyroidectomy is unable to interfere with such biosynthetic activity. In addition, the inhibitory effect of Indomethacin, Oxametacine and Phenylbutazone on PGE2 production is not affected by hyperthyroid state whereas hypothyroidism significantly limits the action of the mentioned non-steroid anti-inflammatory agents.