PARACRINE COMMUNICATION IN THE ANTERIOR-PITUITARY AS STUDIED IN REAGGREGATE CELL-CULTURES

The classical image of the endocrine system is that secretory function of a gland is regulated from outside that gland by other organs. Focu sed on the pituitary gland, hormone secretion by the anterior lobe is under control of peptides and biogenic amines produced by the hypothal amus. About a decade ago, our group launched the new idea that functio ning of the anterior pituitary (AP) is also regulated from within, i.e ., that the constituent cell types inter-communicate to control hormon e secretion. Extensive in vitro research has now provided a body of ev idence that paracrine communication plays an important role, not only in regulation of hormone secretion but also in development, growth, an d differentiation of the AP [reviewed in Denef(1994) The Pituitary Gla nd, pp. 351-378]. It further revealed that crosstalk between the cells is mediated by local, paracrine, factors. The main objective of our r esearch is to identify those factors, their actions and the producing and target cell type(s) in order to unravel the paracrine communicatio n network that is functional in the AP. Equally important, we set the step towards in vivo examination of the results obtained in vitro usin g transgenic mice. In the present article, we will review the technolo gy used, three examples of AP cell-to-cell interactions studied, and w e will discuss the value of transgenic animal models in the study of A P paracrine communication. (C) 1997 Wiley-Liss, Inc.