Central oxytocin and atrial natriuretic peptide receptors mediate
osmotic inhibition of salt appetite in rats.
Blackburn, Ruth E., Willis K. Samson, R. Jerrold Fulton, Edward M.
Stricker, and Joseph G. Verbalis.
Departments of Medicine and Neuroscience, University of Pittsburgh,
Pittsburgh, PA 15261, Department of Physiology, University of North
Dakota, Grand Forks, ND 58202, Inland Laboratories, Dallas, TX
75207
APStracts 2:0060R, 1995.
These studies evaluated the involvement of central oxytocin (OT) and
atrial natriuretic peptide (ANP) receptors in the osmotic inhibition
of hypovolemia-induced salt appetite. Rats were pretreated centrally
with the A chain of the cytotoxin ricin conjugated to OT (rAOT) or
ANP (rAANP), to selectively inactivate cells bearing these respective
receptors, or with the unconjugated A chain (rA) as a control.
Hypovolemia was induced with subcutaneous colloid injections, and
rats then were given either 2 M mannitol, which raises plasma
osmolality but lowers plasma sodium, or 1 M NaCl, which raises both.
Hypertonic mannitol inhibited saline ingestion in rA-treated control
rats but stimulated ingestion in rAOT- and rAANP-treated rats,
whereas hypertonic NaCl blunted saline ingestion in rA- and rAOT
-treated rats but stimulated ingestion in rAANP-treated rats.
Angiotensin II-induced saline intake was similarly potentiated in
rAOT- and rAANP-treated rats, indicating that this treatment also
activates central inhibitory OT and ANP pathways. These data suggest
that central ANP receptors mediate both Na+- and osmolality-induced
inhibition of NaCl ingestion, whereas central OT receptors primarily
mediate osmolality-induced inhibition of NaCl ingestion in rats.
Received 2 May 1994; accepted in final form 15 February 1995.
APS Manuscript Number R233-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 7 March 1995.