Simultaneous indirect activity measurements of GH and PRL genes in the same, living mammosomatotrope

Dynamic intracellular processes in endocrine cells are usually controlled b y the coordinated modulation of two or more functionally related genes. Att empts to gain a more complete understanding of these processes would be fac ilitated greatly by a method enabling activity measurements of two genes at the same time. Here we describe how we developed such a system and used it to determine indirectly whether individual, living pituitary cells could c oncurrently express both the growth hormone (GH) and prolactin (PRL) genes. Our results demonstrate that coexpression of these genes is indeed possibl e. Moreover, our findings provide a general paradigm for future "real-time" analysis of other interrelated genes involved in the regulation of endocri ne processes.