Endocrine control of the distribution of basic fibroblast growth factor, insulin-like growth factor-I and transforming growth factor-beta 1 mRNAs in adult rat adrenals using non-radioactive in situ hybridization.

This study located the particular cell types involved in the synthesis of growth factors in adult female rat adrenal glands. Non-isotopic in situ hybridization was used and the cellular localizations of the mRNAs of basic fibroblast growth factor (bFGF), IGF-I, and transforming growth factor-beta 1 (TGF-beta 1) were studied in adrenals from control animals and from those treated with ACTH or subjected to dietary sodium restriction. The adrenal medulla was the richest source of both bFGF and IGF-I mRNA in both control and experimental rat adrenals. In the cortex, bFGF and IGF-I mRNAs were found mainly in the zona fasciculata in control animals, although some transcription was also detected in the zona reticularis and zona glomerulosa. Both ACTH and sodium restriction activated bFGF and IGF-I gene expression in the zona glomerulosa. Since cellular proliferation and differentiation occur primarily in the outer cortex, the data are consistent with the view that bFGF and IGF-I act as an autocrine/paracrine mitogen and differentiation regulator respectively in the rat adrenal cortex. Very small amounts of TGF-beta 1 mRNA were detected, predominantly in the zona fasciculata of control rats. There were no observable differences in amounts and localization of TGF-beta 1 mRNA between the adrenals of control rats and those treated with ACTH for 1 day. TGF-beta 1 mRNA was very weak or undetectable in the adrenals from rats treated with ACTH for three and five days or from sodium-restricted rats.(ABSTRACT TRUNCATED AT 250 WORDS)