Central interactions between noradrenaline and neuropeptide Y in the rat: implications for blood pressure control.
Neuropeptide Y (NPY) and noradrenaline are co-localised in central neurones and both transmitters exert cardiovascular effects. Using microdialysis and push-pull techniques to measure transmitter release in vivo, and microinjection studies, we examined the role(s) of central noradrenaline and NPY in blood pressure regulation in the hypothalamus and nucleus tractus solitarius (NTS) of the rat. Hypothalamic noradrenaline release was increased following haemorrhage and reduced after phenylephrine infusion. Ageing is associated with markedly reduced NPY concentrations in the hypothalamus. 18-month old animals showed a reduced ability to release both NPY and noradrenaline to a potassium depolarisation stimulus. NTS administration of NPY induced dose-dependent decreases in blood pressure and heart rate. The depressor but not the bradycardic response was attenuated by prior administration of yohimbine. NTS microinjection of 23 pmol NPY induced similar cardiovascular effects in spontaneously hypertensive and Wistar Kyoto rats. NPY and noradrenaline appear to interact at several sites in the brain known to be important for blood pressure control.
Morris
M J
MJ
Department of Pharmacology, University of Melbourne, Parkville, Victoria, Australia.
Hastings
J A
JA
Pavia
J M
JM
D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology; D000375:Aging / Q000502:physiology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006973:Hypertension / Q000188:drug therapy / Q000503:physiopathology; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology; D009478:Neuropeptide Y / Q000008:administration & dosage / Q000378:metabolism / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism / Q000502:physiology*; D010656:Phenylephrine / Q000008:administration & dosage; D051381:Rats; D011918:Rats, Inbred SHR; D017207:Rats, Sprague-Dawley; D017552:Solitary Nucleus / Q000187:drug effects / Q000502:physiology; D015016:Yohimbine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D000317:Adrenergic alpha-Antagonists; D009478:Neuropeptide Y; D010656:Phenylephrine; D015016:Yohimbine; D009638:Norepinephrine