RESUMO
Immunohistochemical methods for the demonstration of tyrosine hydrolase (TH) and neuronal form of nitric oxide synthase (nNOS) were used to study the distribution of catecholaminergic and nitroxidergic vasomotor neurons respectively, in the nuclei of the medulla oblongata and the pons of 12 Wistar rats. Most often the expression of TG was found in neurons located in the nucleus and several reticular nuclei (gigantocellular, paragigantocellular, caudal pons nucleus), but the proportion of immunoreactive neurons did not exceed 8-14%. In the other nuclei (reticular parvocellular nucleus and oral pons nucleus, spinal nucleus of the trigeminal nerve) the value of this parameter ranged from 1 to 3%. In a large group of nuclei with proven vasomotor function such neurons were constantly not detected. In the structures with high content of catecholaminergic neurons, nNOS-positive cells were found, as a rule, in fewer numbers than in the nuclei with a limited number of TH-positive neurons.