Production of prolactin is very tissue-specific – the gene is present in all cells, but in the rat it is expressed only in the anterior pituitary gland, while in man it is also expressed at low levels in the decidualized endometrium. Much of the work on rat prolactin gene expression has been greatly facilitated by the availability of the rat pituitary tumour-derived GH cell line (including the GH1, GH3 and GH4 cell subclones) which produces both prolactin and growth hormone. In contrast, much less is so far known about the regulation of the human prolactin gene, due in part to the lack of readily available human pituitary tissue for in-vitro studies.
An increasing amount is known about hormonal and intracellular regulation of prolactin mRNA production, which has been reviewed elsewhere (Davis, Belayew & Sheppard, 1989). However, some of the most impressive and important recent advances have been