Paraventricular noradrenergic systems participate in angiotensin II-induced drinking.
The present study was designed to examine the role of noradrenergic systems in the hypothalamic paraventricular nucleus (PVN) in the drinking response induced by microinjection of angiotensin II (ANG II) into the subfornical organ (SFO) in the awake rat. Intracerebral microdialysis techniques were utilized to quantify the extracellular concentration of noradrenaline (NA) in the region of the PVN. Injections of ANG II (10(-6)M, 0.2 microl) into the SFO significantly increased NA release in the PVN area. The increase in the NA concentration caused by the ANG II injection was significantly attenuated by water ingestion. In urethane-anesthetized rats, injections of ANG II into the SFO elicited an elevation in mean arterial pressure (MAP). On the other hand, intravenous injections of the alpha-agonist metaraminol (5 microg) slightly decreased the release of NA in the PVN area that accompanied an elevation in MAP. These results show that the noradrenergic system in the PVN area may be involved in the dipsogenic response induced by ANG II acting at the SFO.
Ushigome
Akihiko
A
Department of Physiology, Saitama Medical School, Morohongo, Moroyama, Iruma-gun, Saitama 350-0495, Japan.
Tanaka
Junichi
J
Kariya
Katsuhide
K
Nomura
Masahiko
M
D000804:Angiotensin II / Q000008:administration & dosage / Q000378:metabolism*; D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004326:Drinking / Q000502:physiology*; D007267:Injections; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013356:Subfornical Organ / Q000378:metabolism
D000804:Angiotensin II; D009638:Norepinephrine