Abstract
Evidence from in vitro studies supports the concept that growth factors are involved in the function of endocrine organs. We studied the effects of target endocrine organs (thyroid, adrenals, and gonads) on levels of basic fibroblast growth factor (FGF-2) messenger ribonucleic acid (mRNA) in the anterior pituitary and the hypothalamus of male rats using RNase protection assays. Castration significantly reduced the levels of FGF-2 mRNA in the anterior pituitary, but not in the hypothalamus. This decrease was restored by testosterone administration. The regulation of pituitary FGF-2 mRNA involves a specific hormone, i.e. testosterone, since neither adrenalectomy nor chemical thyroidectomy affects the expression of the gene for FGF-2.