Interaction between neuropeptide Y and noradrenaline on central catecholamine neurons.
Despite their widespread occurrence in the central nervous system, interactions between co-localized transmitters and their receptors remain poorly understood. Noradrenergic neurons of the nucleus locus coeruleus contain the peptide co-transmitter neuropeptide Y (refs 1,2). In locus coeruleus cells, stimulation of alpha2-adrenoceptors 3,4 or opioid mu-receptors 5,6 increases a potassium conductance and thereby leads to hyperpolarization and inhibition of spontaneous firing. Coupling between these receptors and the inward rectifying K+ channels involves a pertussis toxin-sensitive GTP-binding protein (Gi or Go)7. Here we investigate whether the neuropeptide Y and alpha2-receptors of locus coeruleus neurons interact with one another. When administered alone, neuropeptide Y reduces the discharge of action potentials, probably by increasing the permeability of the membrane to potassium ions through the activation of a G protein; this effect is reduced in the presence of alpha2-adrenoceptor antagonists. Moreover, the peptide selectively increases the hyperpolarizing effect of alpha2-agonists, but does not enhance responses to opioid mu-agonists. We suggest that noradrenaline and its co-transmitter neuropeptide Y stimulate separate receptors, which influence each other in a specific way.
Illes
P
P
Department of Pharmacology, University of Freiburg, FRG.
Regenold
J T
JT
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000316:Adrenergic alpha-Agonists / Q000494:pharmacology; D000818:Animals; D000068438:Brimonidine Tartrate; D004745:Enkephalins / Q000494:pharmacology; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006153:Guanosine Diphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D008125:Locus Coeruleus / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D009478:Neuropeptide Y / Q000502:physiology*; D009638:Norepinephrine / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D011957:Receptors, Opioid / Q000502:physiology; D017450:Receptors, Opioid, mu; D013873:Thionucleotides / Q000494:pharmacology; D015016:Yohimbine / Q000494:pharmacology
D000316:Adrenergic alpha-Agonists; D004745:Enkephalins; D009478:Neuropeptide Y; D011810:Quinoxalines; D011942:Receptors, Adrenergic, alpha; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; D013873:Thionucleotides; D006153:Guanosine Diphosphate; D015016:Yohimbine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D000068438:Brimonidine Tartrate; C023427:guanosine 5'-O-(2-thiodiphosphate); D006160:Guanosine Triphosphate; D009638:Norepinephrine