The influence of experimental hypo- and hyperthyroid states on acute and chronic inflammatory reactions: modified response to non-steroidal anti-inflammatory agents.

ABSTRACT

Hyperthyroid and hypothyroid states were induced in rats by administration of triiodothyronine or surgical thyroparathyroidectomy. The anti-inflammatory activity of Indomethacin, Oxametacine and Phenylbutazone was evaluated in these animals using paw oedema provoked by carrageenan granulomas induced by cotton pellets and polyarthritis induced by Freund complete adjuvant. Our results indicate that the hyperthyroid state leads to a significant inhibition of the acute inflammatory response to carrageenan, while hypothyroidism has no effect. There was a marked increase in the anti-inflammatory activity of Indomethacin and Phenylbutazone in hyperthyroid rats. By contrast, in thyroparathyroidectomised animals the anti-inflammatory effect of these drugs appeared less than in euthyroid rats. The hyperthyroid state slightly inhibited the development of the cotton pellet-induced granuloma, while hypothyroidism enhanced it. Treatment of hypothyroid animals with the anti-inflammatory drugs resulted in a significant decrease in the size of the granuloma. In the hyperthyroid state, the activity of the compounds appeared similar to that detected in euthyroid rats. Neither hyperthyroidism, nor hypothyroidism affected the inflammatory response to mycobacterial adjuvant, or the effect of anti-inflammatory drugs on the response. These results suggest that thyroid hormones may influence, to various degrees the development of acute inflammation due to carrageenan, and chronic inflammation due to implanted cotton pellets. Our results indicate also that hyper- and hypothyroid states can modify the response of the rat to some non-steroidal anti-inflammatory drugs.