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(Reference retrieved automatically from Google Scholar through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Glucocorticoid modulation of neuronal activity and hormone secretion induced by blood volume expansion

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Author(s):
Ruginsk‚ SG ; Oliveira‚ FRT ; Margatho‚ LO ; Vivas‚ L. ; Elias‚ LLK ; Antunes-Rodrigues‚ J.
Total Authors: 6
Document type: Journal article
Source: Experimental Neurology; v. 206, n. 2, p. 192-200, 2007.
Abstract

The present study evaluated the involvement of glucocorticoid in the activation of vasopressinergic and oxytocinergic neurons of hypothalamic nuclei and plasma levels of vasopressin (AVP), oxytocin (OT), atrial natriuretic peptide (ANP) and corticosterone (CORT) in response to both isotonic and hypertonic blood volume expansion (BVE). Rats were subjected to isotonic (0.15 M NaCl, 2 ml/100 g b.w., i.v.) or hypertonic (0.30 M NaCl, 2 ml/100 g b.w., i.v.) BVE with or without pre-treatment with dexamethasone (1 mg/kg, i.p.). Results showed that isotonic BVE increased OT, ANP and CORT, and decreased AVP plasma levels. On the other hand, hypertonic BVE enhanced AVP, ANP, OT, and CORT plasma concentrations. Both hypertonic and isotonic BVE induced an increase in the number of Fos-OT double-labeled magnocellular neurons in the PVN and SON. Pre-treatment with dexamethasone reduced OT secretion, as well as Fos-OT immunoreactive neurons in response to both isotonic and hypertonic BVE. We also observed that dexamethasone pre-treatment had no effect on AVP secretion in response to hypertonic BVE, although this effect was associated with a blockade of Fos expression in the vasopressinergic magnocellular neurons in the PVN and SON. In conclusion, these data suggest that, not only the rapid OT release from storages, but also the oxytocinergic cellular activation induced by BVE are modulated by glucocorticoids. However, this pattern of response was not observed for AVP cells, suggesting that dexamethasone is not likely to influence rapid release of AVP but seems to modulate the activation of these neurons in response to hypertonic BVE. (c) 2007 Elsevier Inc. All rights reserved. (AU)

FAPESP's process: 03/00327-8 - Integrative studies of the body fluid homeostasis: physiological and molecular aspects of the neuroendocrine control and clinical and experimental evaluation
Grantee:José Antunes Rodrigues
Support Opportunities: Research Projects - Thematic Grants