Expression of hepatic mRNAs for insulin-like growth factors-I and -II during the development of hypothyroid rats

Abstract

ABSTRACT The effect of thyroid status on the expression of insulin-like growth factors-I and -II mRNAs in the liver of developing rats has been investigated. Northern blot analyses of the specific mRNA demonstrated the presence of four IGF-II mRNA species which were strongly expressed in fetal liver and progressively declined after birth, becoming undetectable after week 3. This decrease was markedly delayed in the liver of hypothyroid rats. In addition, expression of IGF-I mRNA, absent in fetal liver, began during week 1 after birth and progressively increased with age. This increase was markedly delayed in the liver of hypothyroid rats. The data suggest that thyroid hormones regulate rat development via the co-ordinate expression of hepatic IGF-II and IGF-I mRNAs. Journal of Endocrinology (1991) 131, 367–372