THE MULTIFUNCTIONALITY OF FGF-2 IN THE ADRENAL-MEDULLA

Chromaffin cells of the adrenal medulla and their tumor counterparts, the pheochromocytoma (PC12) cells, are well-established model systems in neurobiology. The development of sympathoadrenal progenitor cells t o chromaffin cells can be studied with regard to developmental signals which trigger the differentiation. With regard to potential treatment s of neurological disorders like Parkinson's disease chromaffin cell g rafting can be used as one therapeutical approach. The beneficial effe ct of chromaffin cell grafts is possibly not only related to the relea se of dopamine but may also be linked to the release of growth factors . One of the growth factors that is synthesized by chromaffin and PC12 cells is basic fibroblast growth factor (FGF-2). The experimental dat a available so far, are in agreement with different functional roles o f FGF-2. This article summarizes the putative physiological functions of FGF-2 in the adrenal medulla. Three differential functional roles o f FGF-2 are discussed: (1) as a differentiation factor for sympathoadr enal progenitor cells; (2) as a target-derived neurotrophic factor for preganglionic sympathetic neurons which innervate adrenal medullary c ells; (3) as an auto-/paracrine factor in the adrenal medulla.