Neurotrophins and neurotrophin signal transduction in cholinergic neurons of the mouse forebrain.

Nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4/5 (NT-4) are neurotrophins and bind to the p75 NGF receptor (p75NGFR). Previously our laboratory suggested that p75NGFR induced apoptosis in a subpopulation of cholinergic forebrain neurons during postnatal development. We attempted to identify in vivo (i) the putative p75NGFR "neurocidal", or death-inducing ligand that induced apoptotic cell death of these neurons; (ii) the intracellular signaling pathways activated by p75NGFR during developmental apoptotic cell death and following injury in cholinergic forebrain neurons; and (iii) the role of p75NGFR in the potential atrophy or maintenance of cholinergic medial septum neurons during aging.