Effects of administration of glucagon on the plasma and hepatic contents of the thyroid hormones in the lizardPodarcis sicula

Abstract

Plasma levels of glycemia, 3,5,3'-triiodo-L-thyronine (T3), L-thyroxine (T4), thyroid stimulating hormone (TSH), and insulin were assayed in adult male specimens of Podarcis sicula after treatment with glucagon. The hepatic contents of T3, T4, and 5'-T4 ORDII-monodeiodinase activity were also determined. In treated specimens, plasma T3, T4, insulin, and glycemia levels were higher than in the control group, while no difference in plasma TSH was observed between control and treated specimens. Glucagon increased the hepatic contents of T3, T4, and 5'-T4 ORDII-monodeiodinase activity. The data obtained confirm the results of a previous study demonstrating that, in this lizard, glucagon treatment induces activation of the thyroid gland.