Activation of the subfornical organ enhances extracellular noradrenaline concentrations in the hypothalamic paraventricular nucleus in the rat.
Experiments were carried out to investigate whether angiotensinergic efferent pathways from the subfornical organ (SFO) regulate the noradrenergic system in the region of the hypothalamic paraventricular nucleus (PVN). Intracerebral microdialysis techniques were utilized to quantify the extracellular content of noradrenaline (NA) in the PVN area. In urethane-anaesthetized male rats, electrical stimulation (5-20 Hz, 600 microA) of the SFO significantly increased the NA concentration in the region of the PVN, and the increase was significantly prevented by pretreatment with the angiotensin II (ANG II) antagonist saralasin (Sar, 5 microg), into the third ventricle (3V). Injections of ANG II (5 microg) into the 3V significantly enhanced NA release in the PVN area. These results suggest that the angiotensinergic pathways from the SFO to the PVN may act to enhance NA release in the region of the PVN.
Tanaka
J
J
Department of Human Development, Naruto University of Education, Takashima, Naruto-cho, Naruto, Tokushima, Japan. tanakaj@naruto-u.ac.jp
Hayashi
Y
Y
Sakamaki
K
K
Okumura
T
T
Nomura
M
M
D000804:Angiotensin II / Q000494:pharmacology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D004558:Electric Stimulation; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012504:Saralasin / Q000494:pharmacology; D013356:Subfornical Organ / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000806:Angiotensin-Converting Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D012504:Saralasin; D009638:Norepinephrine