Effects of central oxytocin receptor blockade on water and saline intake, mean arterial pressure, and c-Fos expression in rats.
Central injection of ANG II has been proposed to have dual effects on salt appetite including a direct stimulatory effect and an indirect inhibitory effect through an activation of central oxytocinergic neurons. The inhibition was demonstrated by pretreating rats with central ornithine vasotocin (OVT; oxytocin antagonist) 30 min before a central ANG II injection. The OVT pretreatment produced a large increase in ANG II-induced saline intake. The present paper reports a failure to replicate that influential experiment. However, we also report for the first time that OVT by itself: 1) provokes drinking of both water and saline solution with a latency almost as short as that produced by ANG II; 2) produces a mild pressor response; and 3) increases c-Fos expression in the organum vasculosum laminae terminalis (OVLT) and the median preoptic nucleus (MnPO). Oxytocin activity may provide an inhibitory control of drinking responses as has been suggested, but the inhibition is tonic and includes both water and saline drinking. Inhibition of this tonic activity may stimulate drinking by increasing neural activity in the OVLT and MnPO.
Fitts
Douglas A
DA
Department of Psychology, University of Washington, Seattle, Washington 98195-1525, USA. dfitts@u.washington.edu
Thornton
Simon N
SN
Ruhf
Alexandra A
AA
Zierath
Dannielle K
DK
Johnson
Alan Kim
AK
Thunhorst
Robert L
RL
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D002628:Chemoreceptor Cells / Q000187:drug effects / Q000502:physiology*; D004326:Drinking / Q000187:drug effects / Q000502:physiology*; D007276:Injections, Intraventricular; D008297:Male; D009951:Ornipressin / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012462:Saline Solution, Hypertonic / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D014662:Vasoconstrictor Agents / Q000494:pharmacology*; D014868:Water Deprivation / Q000502:physiology
D016760:Proto-Oncogene Proteins c-fos; D012462:Saline Solution, Hypertonic; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D009951:Ornipressin; D012965:Sodium Chloride; D010100:Oxygen