Lateral parabrachial nucleus and serotonergic mechanisms in the
control of salt appetite in rats.
Menani, Jose Vanderlei, Robert L. Thunhorst, 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 2:0217R, 1995.
This study investigated the effects of bilateral injections of
serotonergic receptor agonist and antagonist into the lateral
parabrachial nucleus (LPBN) on the ingestion of water and 0.3 M NaCl
induced by intracerebroventricular (icv) angiotensin II (ANG II) or
by combined subcutaneous (sc) injections of the diuretic, furosemide
(FURO), and the angiotensin-converting enzyme inhibitor, captopril
(CAP). Rats had stainless steel cannulas implanted bilaterally into
the LPBN and into the left lateral ventricle (LV). Bilateral LPBN
pretreatment with the serotonergic 5HT1/5HT2 receptor antagonist,
methysergide, (4 [mu]g/200 nl each site) increased 0.3 M NaCl and
water intakes induced by icv ANG II (50 ng/1 [mu]l) and 0.3 M NaCl
intake induced by sc FURO + CAP. Pretreatment with bilateral LPBN
injections of a serotonergic 5HT2A/2C receptor agonist, DOI, (5
[mu]g/200 nl) significantly reduced 0.3 M NaCl intake induced by sc
FURO + CAP. Pretreatment with methysergide or DOI into the LPBN
produced no significant changes in the water intake induced sc FURO +
CAP. These results suggest that serotonergic mechanisms associated
with the LPBN may have inhibitory roles in water and sodium ingestion
in rats.
Received 3 May 1995; accepted in final form 25 July 1995.
APS Manuscript Number R265-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 10 August 1995.