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This Article Full Text Full Text (PDF) All Versions of this Article: 89/5/541    most recent expphysiol.2004.027243v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Durlo, F. V. Articles by Antunes-Rodrigues, J. Search for Related Content PubMed PubMed Citation Articles by Durlo, F. V. Articles by Antunes-Rodrigues, J. Related Collections Neuroendocrinology/Endocrinology

¹ Departamento de Patologia Clínica, Universidade de Campinas, UNICAMP, CEP 13083-970 Campinas, Sao Paulo, Brazil² Departamento de Clínica Medica³ Departamento de Fisiologia, Faculdade de Medicina de Ribeirao Preto, USP, 14049-900 Ribeirao Preto, Sao Paulo, Brazil

The present study evaluated the effect of acute extracellular volume expansion (EVE) induced by intravenous injection of isotonic (0.15 M NaCl) or hypertonic saline (0.3 M NaCl) on prolactin, corticosterone, vasopressin, oxytocin and atrial natriuretic peptide (ANP) secretion. Male Wistar rats were treated with bromocriptine, sulpiride or dexamethasone. After isotonic and hypertonic EVE, the control group showed a significant increase in the plasma concentrations of prolactin, corticosterone, ANP and oxytocin. The increase in ANP and oxytocin levels in response to hypertonic EVE was more pronounced than to isotonic EVE. Bromocriptine and sulpiride treatments did not modify corticosterone, ANP and oxytocin responses to either isotonic or hypertonic EVE. The increases in prolactin and oxytocin, but not ANP, were blocked in dexamethasone pretreated rats. In conclusion, isotonic or hypertonic EVE induced an increase in the plasma concentrations of prolactin, corticosterone, ANP and oxytocin. The increases in ANP and oxytocin were independent of plasma concentrations of prolactin. The increases in prolactin and oxytocin were blocked by the inhibition of the hypothalamo–pituitary–adrenal (HPA) axis by dexamethasone. However, dexamethasone did not alter the increase in ANP secretion induced by isotonic or hypertonic EVE. Therefore, prolactin might participate in regulation of the hydroelectrolytic balance in mammals; however, in the present study, there was no evidence for direct interaction with ANPergic and oxytocinergic systems. In addition, the responses of prolactin and oxytocin induced by isotonic or hypertonic EVE are modulated by the HPA axis.

(Received 15 January 2004; accepted after revision 24 May 2004; first published online 7 June 2004)
Corresponding author M. Castro: Departamento de Clinica Medica, Faculdade de Medicina de Ribeirao Preto, USP, Avenue Bandeirantes 3900, 14049-900 Ribeirao Preto, Sao Paolo, Brazil. Email: castrom{at}fmrp.usp

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