Forebrain angiotensin type 1 receptors (at1) and parabrachial
serotonin in the control of nacl and water intake.
Colombari, Debora S. A., Jose Vanderlei Menani, and Alan Kim Johnson.
Departments of Psychology and Pharmacology and the Cardiovascular
Center, University of Iowa, Iowa City, IA 52242-1407, USA, and
Department of Physiology, School of Dentistry, Paulista State
University, Araraquara, SP 14801-903, Brazil
APStracts 3:0188R, 1996.
This study investigated the roles of serotonin (5HT) receptors in the
lateral parabrachial nucleus (LPBN) and brain angiotensin Type 1
(AT1) receptors in the intake of 0.3 M NaCl and water induced by
angiotensin II (ANG II). Rats were implanted with stainless steel
cannulas for injections into the subfornical organ (SFO) and into the
LPBN. Bilateral LPBN pretreatment with the non-selective serotonergic
5HT1/5HT2 receptor antagonist, methysergide, (4 symbol 109 \f
"Symbol" g/200 nl) markedly enhanced 0.3 M NaCl intake induced by
injections of ANG II (20 ng/200 n1) into the SFO. Pretreatment of the
SFO with the AT1 receptor antagonist, losartan, (1 g/200 nl) blocked
the intake of 0.3 M NaCl induced by ANG II in combination with LPBN
methysergide injections. These results suggest that serotonergic
mechanisms associated with the LPBN inhibit the expression of salt
appetite induced by ANG II injections into the SFO. In addition, the
results indicate that the enhanced NaCl intake generated by central
administration of ANG II in the presence of LPBN 5HT blockade is
mediated by brain AT1 receptors.
Received 20 September 1995; accepted in final form 8 May 1996.
APS Manuscript Number R589-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 May 96