[Changes in spatial relationships between catecholamine- and nitroxidergic neurons in the nuclei of the caudal brain stem in the development of hypertension]. / Izmenenie prostranstvennykh vzaimootnoshenii katekholamin- i nitroksidergicheskikh neironov v iadrakh kaudal'noi chasti stvola mozga pri razvitii arterial'noi gipertenzii.

AIM: To obtain the data on the spatial relationships between catecholamine (TH-positive) and nitroxidergic (nNOS-positive) neurons in vasomotor nuclei of the medulla in different periods of hypertension development. MATERIAL AND METHODS: The experiment was performed on male Wistar rats (n=45) with induced renovascular hypertension (RVH). TH and nNOS in neurons of solitary tract nuclei, reticular small-and giant cell nuclei were detected using immunohistochemical methods. RESULTS AND CONCLUSION: The most early and severe changes in the intensity of reaction and amount of nNOS-positive neurons were noted in the solitary tract nucleus. Significant changes in the quantitative parameters of TH-positive neurons in RVH were identified only in the reticular giant cell nucleus but they appeared later and were less expressed compared to nNOS-positive cells. This resulted in the changes of spatial relationships between two types of neurons and remodeling of the bulbar region of the cardiovascular center.

Topochemistry of Internuclear and Intranuclear Interneurons of the Vasomotor Area in the Medulla Oblongata of Hypertensive Rats.

Immunohistochemical examination with the antiserum against neuronal NO synthase and cystathionine ß-synthase was used to study the following two pools of interneurons in Wistar rats at various periods after the development of renovascular hypertension: intranuclear interneurons (lying in the projection of the solitary nucleus, reticular gigantocellular nucleus, and parvocellular nucleus) and 2 groups of internuclear interneurons (small interneurons, area 50-300 µ(2); and large interneurons, area above 350 µ(2)). Intranuclear and internuclear interneurons probably play a role in the central mechanisms of hemodynamics regulation. These interneurons differ by not only in topochemical parameters, but also functional properties (different resistances to BP changes). Intranuclear interneurons are characterized by high sensitivity of the gas transmitter systems to a continuous increase in BP, which results in remodeling and dysfunction of the bulbar part of the cardiovascular center. Large internuclear interneurons demonstrate a strong reaction to BP rise, which confirms their involvement into hemodynamics regulation. By contrast, small internuclear interneurons retain their characteristics in arterial hypertension and probably perform an integrative function.

Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP

Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.

Numerosas formas de evidência experimental obtidas nos últimos 37 anos demonstraram inequivocamente que a medula oblongata contém os principais circuitos responsáveis pela geração e manutenção do tono vasomotor e a regulação da pressão arterial. A visão atual que possuímos destes circuitos deriva em grande parte dos estudos de Pedro Guertzenstein, um estudante e mais tarde Professor de Fisiologia da UNIFESP e seus colaboradores. Nesta revisão nós sumarizamos os seus principais resultados assim como a nossa colaboração para uma melhor compreensão da regulação da pressão arterial em condições normais e patológicas.