Neuronal nitric oxide synthase and nerve growth factor expression in the enteric nervous system.

The role of nitric oxide (NO) in various systems of the body has gained prominence since the last decade. The dual role of NO either as a toxic or protective molecule depends on the concentrations of NO being produced, the isoform of NO synthase involved and the type of cell in which NO produced. The protective roles of NO appear to be mediated via cross talk between neurotrophic pathways. In view of this, in this paper, the role of NO in the enteric system is discussed with respect to neuronal nitric oxide synthase expression in neurons associated with the gut and the nerve growth factor and its receptor, tyrosine kinase A expression in the lamina epithelialis.