Effect of Glibenclamide on Thyroid Hormone Metabolism in Rats

Summary

This study was undertaken to elucidate the effect of glibenclamide, one of sulfonylurea drugs, on thyroid hormone metabolism in vivo and on the conversion of thyroxine (T₄) to 3,5,3′-triiodothyronine (T₃) in the isolated perfused rat liver and kidney. Glibenclamide (0.2 mg/kg body weight) was intraperitoneally administered to normal and streptozotocin-induced (50 mg/kg) diabetic rats for 14 days. The liver and kidney of normal rats were perfused for 30 minutes with a synthetic medium containing 20 μg/dl T₄ and glibenclamide (200 or 400 ng/ml), and production of T₃ in the tissues was measured by radioimmunoassay.

Serum T₄ and T₃ levels in control and streptozotocin-induced diabetic rats were not changed by daily intraperitoneal glibenclamide administration.

The production of T₃ (111 ± 40 and 95 ± 16 ng/g/30 min, mean ± SD) and the conversion rate of T₄ to T₃ (11.1 ± 2.9 and 10.2 ± 2.3%) in the liver perfused with glibenclamide (200 and 400 ng/ml) were not significantly different from those in controls (109 ± 41 ng/g/30 min and 12.8 ± 5.4%). And those (120 ± 33 and 99 ± 19 ng/g/30 min, and 3.5 ± 0.6 and 2.5 ± 0.4%) in the kidney perfused with glibenclamide (200 and 400 ng/ml) were similar to those in controls (98 % 33 ng/g/30 min and 3.0 ± 1.5%).

These results suggest that glibenclamide had no effect on thyroid hormdne metabolism in vivo and in vitro in rats.

Key-Words

Serum T ₄ - Serum T ₃ - Conversion of T ₄ to T ₃ - Perfused Rat Liver - Perfused Rat Kidney