Effect of phenobarbital & 3-methylcholanthrene treatment on thyroid hormones in rat
Khanduja, K.L.; Gupta, M.P.; Pathak, C.M.; Vaidyanathan, S.; Koul, A.; Koul, I.B.; Sharma, R.R.
Indian Journal of Medical Research 86: 375-381
1987
ISSN/ISBN: 0019-5340 PMID: 3428972 Document Number: 297169
Effect of inducers of drug metabolizing enzymes, phenobarbital and 3-methylcholanthrene, on thyroid hormone (T4 and T3) levels in serum and on thyroid hormone metabolism was studied in rats. Levels of thyroid hormones were determined in animals treated with the inducer or carrier after 0, 2, 4, 6 and 8 days of treatment, the animals being fasted overnight. Disappearance of intravenously injected I125-labelled thyroid hormones was investigated after 10 days of treatment. In the liver, arylhydrocarbon hydroxylase and UDP-glucuronyltransferase activities increased significantly by treatment with the inducers. However, serum levels of T4 and T3 decreased only by treating the animals with phenobarbital. Also, only phenobarbital treatment decreased the biological half-life and increased total distribution space without affecting the catabolic rate of T4 and T3. It is suggested that phenobarbital-type inducers of drug metabolism may modify several parameters involved in thyroid physiology.