Iopanoic acid

Cell experiment:

Rat pituitary fragments are superfused by Medium-199. After a 90 min equilibration period, the superfusion is continued for 135 min with or without inclusion into the superfusion medium of 3,5,3'-triiodothyronin (T3) 10-7 M, triiodothyroacetic acid (TRIAC) (stock solution 10-4 M in 20% methanol, final concentrations 10-8 to 10-6 M), Iopanoic acid (stock solution 10-3 M in 0.2 M NaOH, final concentrations 10-7 to 10-5 M), or potassium iodide 10-7 to 10-4 M. The superfusion is followed by a 6-min pulse of thyrotropin-releasing-hormone (TRH)[2].

Animal experiment:

Wistar rats initially weighing 180 to 200 g are used. The administration of Iopanoic acid (IOP) is started at day 18 of gestation. Pregnant rats are injected subcutaneously with 10 mg of Iopanoic acid every 12 h, from day 18 of gestation to 12 h before they are killed on the morning of day 20 or 22 of gestation. Control animals receive the vehicle solution with identical timing. Iopanoic acid effectiveness in decreasing interscapular brown adipose tissue (IBAT) nuclear 3,5,3'-triiodothyronin (T3) is assessed by Iopanoic acid (IOP) administration to adult male rats (220 to 250 g body weight) following the same dose and time schedule as in pregnant dams during two days. Caesarean sections are performed at 18 (only untreated animals), 20 and 22 days of gestation. Fetuses are killed by decapitation, and IBAT, brain, and liver are removed. Tissue samples are immediately frozen in liquid nitrogen with the exception of brown fat from several 22 day-old fetuses, which is directly homogenized in 0.25 M sucrose for mitochondria isolation[1].

References:

[1]. Tuca A, et al. Inhibition of iodothyronine 5'-deiodinase by iopanoic acid does not block nuclear T3 accumulation during rat fetal development. Pediatr Res. 1994 Jan;35(1):91-5.
[2]. Szabolcs I, et al. Effects of triiodothyronine, triiodothyroacetic acid, iopanoic acid and iodide on the thyrotropin-releasing hormone-induced thyrotropin release from superfused rat pituitary fragments. Acta Endocrinol (Copenh). 1991 Oct;125(4):427-34.