Basal Forebrain Neuronal Loss in Mice Lacking Neurotrophin Receptor p75

There is substantial evidence from in vitro studies that nerve growth factor (NGF) ex-erts an important influence on the develop-ment and survival of central neurons (1). The effects of NGF are thought to be me-diated through the high-affinity tyrosine receptor kinase trkA and the low-affinity p75 receptor (2). Several studies suggest that the p75 receptor initiates an apoptotic signal that leads to neuronal death (3). The role of NGF in the development and survival of central neurons in intact systems is less clear. The use of null mu-tant mice provides a useful strategy for delineating the role of specific receptor