Structural interactions between NOS-positive neurons and blood vessels in the hippocampus

The anatomical relationship between nitric oxide synthase (NOS)-positive neurons and blood vessels was examined in the hippocampus of the rat. NADPH-diaphorase histochemistry was used to identify NOS-positive neurons by light-microscopy. A close association of somatic, dendritic and axonal processes of NOS-positive neurons with cerebral blood vessels was observed. These findings suggest the possibility of neurovascular signaling by local NOS-containing neurons, through direct vascular innervation by terminals generating nitric oxide, and paracrine signaling from closely apposed somatic and dendritic neuronal elements.