Key result
Water ingestion attenuates angiotensin II-induced noradrenaline release in the median preoptic nucleus of rats.
Why the study?
The study was conducted to investigate the role of noradrenergic systems in the median preoptic nucleus in the drinking response caused by microinjection of angiotensin II into the subfornical organ in awake rats.
Does microinjection of angiotensin II into the subfornical organ increase noradrenaline release in the median preoptic nucleus in male Wistar rats?
Does microinjection of angiotensin II into the subfornical organ increase noradrenaline release in the median preoptic nucleus in male Wistar rats?
p-value: p=<0.001
Water ingestion attenuates the release of noradrenaline in the median preoptic nucleus induced by angiotensin II activation of the subfornical organ in rats, suggesting the noradrenergic system mediates the dipsogenic response.
Should not yet change practice; hypothesis-generating for noradrenergic mediation of angiotensin II-induced thirst.
The present study was carried out to investigate the role of noradrenergic systems in the median preoptic nucleus (MnPO) in the drinking response caused by microinjection of angiotensin II (ANG II) into the subfornical organ (SFO) in the awake rat. Extracellular levels of noradrenaline (NA) in the region of theMnPO were monitored with in vivo microdialysis methods. Injections of ANG II (10^<-6> M,50 nl) into the SFO significantly increased NA release in the MnPO area. The increase in the NA release induced by the ANG II injection was significantly reduced by water ingestion. In urethane-anesthetized rats, injections of ANG II into the SFO produced an elevation in mean arterial pressure (M.A.P.). Intravenous infusions of metaraminol (5μg), on the other hand, slightly suppressed the release of NA in the MnPO area that accompanied an elevation in M.A.P. These results suggest that the noradrenergic system in the MnPO may be involved in the dipsogenic response induced by ANG II acting at the SFO.
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田中 et al. (2007) studied Healthy (animal model) (n=42). Angiotensin II (ANG II) microinjection and water intake vs. Saline vehicle or ANG II without water intake was evaluated on Noradrenaline (NA) release in the median preoptic nucleus (MnPO) area (p=<0.001). Water ingestion significantly attenuated the enhanced noradrenaline release in the median preoptic nucleus area induced by angiotensin II microinjection into the subfornical organ in rats.
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