Nitrative stress impairs pro nerve growth factor transport in basal forebrain cholinergic neurons via c-Jun N-terminal kinase activation

In this study, rat BFCNs were cultured in microfluidic chambers, and axonal transport of quantum dot labelled proNGF was analysed via fluorescence microscopy. BFCNs were treated with SIN-1, a peroxynitrite generator, CC401, a JNK inhibitor, or L-NAME, a nitric oxide synthase inhibitor, prior to analysis of axonal transport. JNK activity was quantified via immunocytochemistry. In vitro aging decreased retrograde transport of proNGF. Age-induced proNGF transport deficits were rescued by L-NAME and CC401. L-NAME reduced levels of activated JNK in aged BFCNs, SIN-1 increased JNK activation in young BFCNs, and SIN-1-induced proNGF transport deficits were rescued by CC401. These results indicate that nitrative stress impairs proNGF transport by activating JNK. Interestingly, SIN-1 and L-NAME increased and decreased JNK activation, respectively, in p75NTR exon III knockout BFCNs, indicating that nitrative stress-induced JNK activation occurs independently of p75NTR. Our findings identify mechanisms contributing to loss of proNGF transport in aged BFCNs, which may help to rescue BFCN function and cognition in aging.