Expressão do fator de transcrição nuclear kB (NF-kB) em neurônios ocitocinérgicos de ratos submetidos à sobrecarga salina : influência da dexametasona

• Autor(a) principal: Santos, Patricia Rabelo dos
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFS
• Texto Completo: https://ri.ufs.br/handle/riufs/4004
• topic: Fisiologia; Ocitocina; Dexametasona; Equilíbrio hidro-eletrolítico; P65/RelA; Sobrecarga salina; Núcleo supra-óptico; Núcleo paraventricular; Paraventricular nucleus; Oxytocin; Dexamethasone; Salt loading; Supraoptic nucleus; CIENCIAS BIOLOGICAS::FISIOLOGIA

The hypothalamic-neurohypophysial system is the main system through which the brain maintains homeostasis of bodily fluids. Specifically, the supraoptic (SON) and paraventricular (PVN) hypothalamic nuclei are directly involved with hydroelectrolytic equilibrium and are specialized in the synthesis and secretion of vasopressin and oxytocin (OT). Changes in the milieu intérieur are conceived as stressors by the central nervous system (CNS) and are modulated by the hypothalamic-pituitary-adrenal axis (HPA). Nuclear transcription factor kappa B (NF-κB) mediates immunosuppressant and anti-inflammatory of glucocorticoids. Thus, the aim of this study was to verify the expression profile of component p65 of the NF-κB classical pathway in SON and PVN oxytocinergic neurons in response to dehydration, glucocorticoid treatment, and in normal conditions. Methods: Wistar rats (250-300g) were maintained in controlled environment with temperature (23 ± 2ºC), light/dark cycle of 12 hours and water and food specific for rodents ad labitum until the beginning of experimental period. All procedures were approved by Ethical Comitee of Research with Animals from UFS (Protocol # 60/2012). Animals were grouped into Control (water ad libitum for 4 days, n = 6-7); Control + Dexa (water ad libitum and treated with dexamethasone, n = 6-7); SL4 (salt overloading ad libitum, 1.8% NaCl for 4 days, n = 6-7); SL4 + Dexa (salt overloading ad libitum, 1.8% NaCl for 4 days and dexamethasone, n = 6-7). Dexamethasone (10 mg/kg i.p.) was administered 12 and 2 hours before perfusion and removal of brains for OT/p65 immunofluorescence, or before sacrifice for blood sampling and angiotensin II (ANGII) dosage. We applied two-way ANOVA and Bonferroni posthoc test to analyze behavioral and hormonal dosage data. Results obtained from imunohistochemestry for evaluation of oxytocin and/or p65 neuronal activity, were subjected to qualitative evaluation. We verified SL4 animals ingested more fluid than control, on second (p<0.01), third (p<0.01) and forth (p<0.001) experimental day. SL4 also increased plasmatic concentration of ANGII (p<0.01). Qualitative analysis of double labeling OT/p65 on PVN and SON revealed a weak immunoreactivity for oxytocin on SL4 and SL4 + Dexa groups, when compared to control and Control + Dexa groups. Was observed expression of p65 subunit of NF-κB in all hypothalamic studied areas, with predominant cytoplasmic imunoreactivity in all groups. These data demonstrate that p65 subunit of NF-κB are present in oxytocinergic neurons from the most important hypothalamic areas that integrates the stress axis (HPA) and hidroelectrolyte balance (SHNH). More studies are necessary to clarify the real participation of NF-κB intracellular pathway evoked by intracellular dehydration on endocrines and behavioral hidroelectrolyte adjustments.