GROWTH AND SURVIVAL FACTORS OF SPINAL MOT ONEURONS

The development of motoneurons in the spinal cord is strongly dependen t on their interactions with their target tissue, skeletal muscle, and with other cells of the central nervous system. The molecular nature of these interactions has remained obscure for many years. However, ov er the last few years, known growth factors have been shown to have bi ological activity on the survival of motoneurons, at least in culture. The factors that have been studied are members of the FGF family (fib roblast growth factors), the TGF-beta family (transforming growth fact or-beta), CNTF (ciliary neurotrophic factor) and CDF-LIF (cholinergic development factor-leukaemia inhibitory factor). There are also strong reasons to suppose that at least one member of the neurotrophin famil y (the family that contains Nerve Growth Factor) is involved in motone uron development. A more detailed analysis of the biological role of e ach of these factors should not only enlighten us as to the importance of cell-cell interactions in development of the motoneuron, but also open the way to attempts to slow motoneuron death in pathological situ ations, either in animals or in man.