TGF-beta 2 attenuates the injury-induced death of mature motoneurons

The distributions of transforming growth factor-betas (TGF-betas) and their receptors suggest that the TGF-betas regulate motoneuron survival. This hy pothesis was tested by avulsing the hypoglossal nerve of adult rats and per fusing either TGF-beta2 or vehicle adjacent to the hypoglossal nucleus. By 4 weeks, half of the avulsed motoneurons had died. Infusion of 6 ng of TGF- beta2 adjacent to the avulsed motor nucleus caused a significant attenuatio n of this death. This dose of TGF-beta2 is low compared to that used with G DNF or BDNF in previous studies of avulsed motoneurons, indicating that TGF -beta2 may be one of the more potent survival factors for adult motoneurons . TGF-beta2 was, however, unable to prevent or reduce the axotomy-induced d own regulation of choline acetyltransferase. Other motoneuron survival fact ors also have a narrow-spectrum of actions, suggesting that the homeostasis of motoneurons is regulated by a cocktail of growth factors with distinct but partially overlapping actions. (C) 2000 Wiley-Liss, Inc.