FGF9: A motoneuron survival factor expressed by medial thoracic and sacralmotoneurons

In the nervous system, fibroblast growth factor-9 (FGF9) is produced mainly by neurons. By whole-mount in situ hybridization, on embryonic rat spinal cord, we observed Fgf9 expression in a subpopulation of motoneurons located in the thoracic and sacral regions of the median motor column that innerva te the axial muscles. Furthermore, FGF9 pre vented death of purified rat an d chicken motoneurons in culture in the same concentration range as FGF2. T he targets of FGF9 are more restricted than that of the other FGFs, however , because conversely to FGF1 or FGF2, FGF9 had only weak or inexistent surv ival effects on chicken ciliary neurons or rat DRG. FGF9 may therefore play a role as an autocrine/paracrine survival factor for motoneurons. J. Neuro sci. Res. 60:1-9, 2000. (C) 2000 Wiley-Liss, Inc.