Avaliação da dinâmica neuronal do núcleo paraventricular do hipotálamo durante o desenvolvimento pós-natal em cutia (Dasyprocta aguti - Linnaeus, 1766.)

Abstract

The hypothalamus is a central nervous system (CNS) region, composed of several nuclei responsible for maintaining homeostasis. Among many hypothalamic nuclei there is the Paraventricular nucleus (PVN), which is one of the centers responsible for the autonomic and endocrine regulation of the organism. PVN is an important pre-autonomic center that assists in the regulation of the sympathetic nervous system, acting at the regulation of several systems, including the cardiovascular system. Changes in this nucleus may be related to cardiovascular complications, such as hypertension and heart failure. Therefore, with aging, there may be changes in PVN that can trigger cardiac changes in the elderly. Thus, we analyzed the PVN of agouti (Dasyprocta agouti) in different ages in order to observe the neuronal dynamics in the nucleus during the postnatal development. For this, three-dimensional morphoquantitative analysis (stereological analysis) of the PVN was performed, based on Cavalieri’s principle, together with the volume density (Vv) analysis of the nucleus neurons based on Delesse’s principle, quantification of number of neurons by optical dissector and average neuronal volume per nucleator. These analyzes were performed in 11 male agoutis, divided into four age groups: G1- Neonate (n = 2); G2- Young (n = 2); G3- Adult (n = 3) and G5-Senile (n = 4). In the PVN of the agouti two magnocellular regions and six parvocellular regions were observed. Quantitative analysis showed that the PVN of senile animals, when compared to neonates, shows a 317% increase in total nucleus volume and 291% increase in total volume occupied by non-neuronal components. It also showed that the number of young and senile neurons, when compared with neonates, had a 114% increase. For adults, when compared with neonates, had a 109% increase. Therefore, our data indicate that PVN of senile agouti presents hypertrophy and may be associated with neuronal hyperplasia when compared to neonates.