The neurochemical features of intranuclear neurons of the medulla oblongata in normo- and hypertensive rats

Resumo

We studied the distribution of cells that express neuronal NO-synthase (NO-neurons), heme oxygenase- 2 (HO-neurons), and tyrosine hydroxylase (CA-neurons) in the solitary tract nucleus and the giantcell reticular nucleus of normotensive Wistar rats and the time course of changes in the enzyme contents and number of respective cells for 20 weeks after modeling of renovascular hypertension (RVH) in these rats. The earliest and strongest changes in these indices were revealed in NO-neurons of the solitary tract nucleus at weeks 4–6 of RVH. Significant modifications of the respective indices were observed in HO-neurons at weeks 10–12 of RVH only; however, they were 1.5–3 fold less expressed as compared to NO-neurons. A significant increase in the number of cells and enzyme content in CA-neurons were found at weeks 8–10 of RVH in the giant-cell reticular nucleus. Similar alterations were observed in CA-neurons of the solitary tract nucleus; however, they did not differ from the control level. These features of the time course of changes in intranuclear neurons during the development of RVH resulted in neurochemical reorganization of the vasomotor center, which evokes alterations of blood circulation and maintenance of the arterial pressure at a new higher level.