Nerve growth factor inhibits the expression of nitric oxide synthase in neurones in dissociated cultures of rat dorsal root ganglia.

In dissociated cultures of DRG derived from 15-day-old rats the numbers of neurones expressing immunocytochemically detectable quantities of the neuronal isoform of nitric oxide synthase (nNOS) was determined and the effects of different culture media examined. The availability of NGF in the cultures was found to be a critical determinant of nNOS expression. In a serum-rich media (SRM) supplemented with NGF, 24% of the neurones expressed nNOS compared with 72% in the absence of added NGF and the presence of an antibody to NGF (t-test, P < 0.0001). Cultures grown in a defined media (DM) developed poorly and many neurones died, these cultures also showed poor growth of other cell types. Immunostaining for NGF revealed that some of the non-neuronal cells produce NGF and that this would be predicted to contribute to the survival of the neurones. In cultures in which neurones were dying most of the surviving neurones expressed nNOS suggesting it may have a survival promoting function.