Distribution of NOS-Containing Neurons in Different Regions of the Solitary Complex in Normo- and Hypertensive Rats

In genetically normo- and hypertensive rats, we studied the distribution of nitric oxide synthase (NOS)-containing neurons within the region of the afferent input from arterial baroreceptors to the solitary complex. A high density of NOS-containing neurons was observed mostly in the commissural and dorsolateral nuclei at the level of the area postrema and in the dorsal parts of the intermediate and medial nuclei, at the level of the obex. The number of NOS-containing neurons exerting an inhibitory effect on the baroreflex and the level of sympathetic tone in hypertensive rats was found to be smaller in the dorsolateral nucleus at the level of the area postrema. This peculiarity can cause disinhibition of sympathoactivating neurons in the rostral ventrolateral medulla and enhancement of efferent supraspinal signals coming to sympathetic preganglionic spinal neurons.