Navegando por Assunto "Homeostase"

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Acesso aberto (Open Access)
Efeitos da expansão de volume extracelular sobre o conteúdo de catecolaminas e a ativação neuronal de estruturas do hipotálamo e do tronco cerebral de ratos
(Universidade Federal do Pará, 2007-07-24) OLIVEIRA, Fabíola Raquel Tenório; DINIZ, Domingos Luiz Wanderley Picanço; http://lattes.cnpq.br/9601463988942971; RODRIGUES, José Antunes; http://lattes.cnpq.br/4243976484500835
The fine adjustment of the volume and osmolarity of body fluids is vital to survival. Any variation in the composition of the internal environment, active behavioral mechanisms, neural and hormonal compensatory which control intake and excretion of water and electrolytes in order to maintain homeostasis hydroelectrolytic. Changes in the range of 1-2% in blood osmolarity stimulate the release of arginine vasopressin (AVP) resulting in antidiuresis addition to oxytocin (OT) and atrial natriuretic peptide (ANP) promoting natriuresis. Work done in our laboratory using the experimental model of extracellular volume expansion (EVEC) showed activation of magnocellular OT-neurons located in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) responsible for the secretion of AVP and OT also changed in response this stimulus. The involvement of the sympathetic nervous system in these conditions has been raised. Projections spinal and brainstem (sympathetic) to the hypothalamus could act selectively inhibiting signals for eating and stimulating signals for excretion of water and electrolytes. The role of noradrenergic brainstem this regulation still needs to be better established. Thus, this study aimed to elucidate the role of the sympathetic nervous system (noradrenergic pathway) in the regulation of the changes induced model of EVEC analyzing by high performance liquid chromatography the content of norepinephrine (NE), epinephrine (DA) and serotonin (5 -HT) in brainstem structures such as the nucleus of the solitary tract (NTS), bulb rostral ventrolateral (RVLM), locus coeruleus (LC) and dorsal raphe nucleus (DRN) and hypothalamic structures like SON and PVN. We also seek, by immunocytochemical studies to determine changes in the pattern of neuronal activation by analysis of Fos-HT or Fos-5HT in the above mentioned structures in experimental conditions in which are induced changes in extracellular fluid volume.
Acesso aberto (Open Access)
Fotoperíodo sobre parâmetros fisiológicos relacionados ao estresse em alevinos de tilápia-do-nilo
(2013-10) VERAS, Galileu Crovatto; MURGAS, Luis David Solis; ZANGERONIMO, Márcio Gilberto; ROSA, Priscila Vieira; SOLIS DE LEON, Jonathan Antonio; SALARO, Ana Lúcia
The objective of this study was to evaluate the influence of different photoperiods on physiological parameters related to stress in Nile tilapia fingerlings (Oreochromis niloticus). A completely randomized design with five treatments (0L, 6L, 12L, 18L, 24L) and four replications was used, and the aquarium as the experimental unit. One hundred and sixty tilapia fingerlings, 3.21±0.05g and 4.35±0.07cm were distributed in 20 aquariums of 20L in a recirculation system with temperature controlled at 27 º C and density of eight fish per aquarium. Feeding was performed twice daily with extruded feed containing 40% crude protein, for a period of 75 days. At the end of experimental period, the data of survival, cortisol, glucose and hematocrit were subjected to analysis of variance and, subsequently, in case of significance (P<0.05) a Tukey test 5% was performed to compare means. Manipulation of photoperiod shows no alteration in the homeostasis of juveniles, since there is no difference in survival, blood glucose, hematocrit and plasma cortisol (P>0.05).