Drinking attenuates the noradrenaline release in the lateral hypothalamic area induced by angiotensin II activation of the subfornical organ in rats.
Experiments were conducted to investigate the role of noradrenergic systems in the lateral hypothalamus area (LHA) in the water intake caused by injection of angiotensin II (ANG II) into the subfornical organ (SFO) in rats. Intracerebral microdialysis techniques were utilized to quantify the extracellular content of noradrenaline (NA) in the LHA. Microinjection of ANG II into the SFO significantly increased NA release in the LHA when water was not available for drinking. The increase in the release of NA in the LHA was significantly attenuated by water intake. In urethane-anesthetized rats, injections of ANG II into the SFO significantly enhanced the release of NA in the LHA that accompanied an elevation in mean arterial pressure (MAP). Intravenous administration of the alpha-agonist metaraminol, on the other hand, significantly decreased the NA release in the LHA that accompanied an increase in MAP, suggesting that the enhanced NA release in the LHA caused by ANG II into the SFO may be not mediated by increasing in arterial pressure. These results show the involvement of the noradrenergic systems in the LHA in the dipsogenic response induced by angiotensinergic activation of the SFO.
Tanaka
Junichi
J
Department of Curriculum, Teaching and Memory, Naruto University of Education, Takashima, Naruto-cho, Tokushima, Japan. tanakaj@naruto-u.ac.jp
Kariya
Katsuhide
K
Nomura
Masahiko
M
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004326:Drinking / Q000502:physiology*; D005110:Extracellular Space; D007026:Hypothalamic Area, Lateral / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008680:Metaraminol / Q000494:pharmacology; D017551:Microdialysis / Q000379:methods; D009638:Norepinephrine / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013356:Subfornical Organ / Q000187:drug effects*; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000494:pharmacology*
D000316:Adrenergic alpha-Agonists; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D008680:Metaraminol; D009638:Norepinephrine