Salt loading reduces hypothalamic noradrenaline release after noxious stimuli.
Salt loading reduces neuroendocrine responses to stressful stimuli. Noxious stimuli facilitate noradrenaline release in the hypothalamus and, as a result, activate oxytocin neurones. Here, we examined effects of salt loading upon plasma oxytocin concentrations and noradrenaline release in the hypothalamus after footshocks. Male rats were allowed to drink 2% NaCl for 7 days. Salt loading reduced the footshock-induced increase in plasma oxytocin concentrations and noradrenaline release in the supraoptic nucleus (SON). Acute administration of hypertonic saline also attenuated the footshock-induced noradrenaline increase in the supraoptic nucleus. In contrast, salt loading did not significantly change activation of A1 catecholaminergic neurones in the medulla oblongata, as measured by expression of Fos protein. These data suggest that salt loading presynaptically suppresses noradrenaline release in the hypothalamus and oxytocin release into the blood after footshocks.
Takayanagi
Yuki
Y
Department of Physiology, Jichi Medical School, Kawachi-gun, Tochigi-ken 329-0498, Japan.
Nishimori
Katsuhiko
K
Onaka
Tatsushi
T
D000284:Administration, Oral; D000818:Animals; D004558:Electric Stimulation / Q000009:adverse effects; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism*; D010121:Oxytocin / Q000378:metabolism*; D010146:Pain / Q000209:etiology / Q000378:metabolism* / Q000517:prevention & control*; D051381:Rats; D017208:Rats, Wistar; D012965:Sodium Chloride / Q000008:administration & dosage*
D012965:Sodium Chloride; D010121:Oxytocin; D009638:Norepinephrine