Nitroxidergic nerve fibers of intracerebral vessels.

Light and electron histochemical methods were used to study the structure and distribution of neurons containing NADPH diaphorase and their processes in the parietal area of the cortex in rats. Most neurons were found to be characterized by tight associations with intracerebral vessels. The smallest distances between the axon plasmalemma and the smooth myocytes of intracerebral arteries in the cerebral cortex were at least 0.3-0.5 microm. Neuron bodies were located at functionally important locations of vessels (sites at which subsidiary vessels branched off, the origins of arterioles), and their processes accompanied vessels, densely entwining the vessels with their branches. Neurons whose dendrites contacted the bodies or process of above- or below-lying neurons often sent nerve conductors to arteries, veins, or capillaries. Thus, nitroxidergic neurons or groups of these neurons may monitor the state of the circulation at different points in the vascular bed, functioning as local nerve centers.