title: Postsynaptic alpha 2-noradrenergic receptors mediate feeding induced by paraventricular nucleus injection of norepinephrine and clonidine.
abstract: This study examines the feeding response induced by hypothalamic noradrenergic stimulation, in terms of the type and synaptic position of its mediating receptor. Tests with norepinephrine or the alpha 2 receptor agonist clonidine, injected into the area of the paraventricular nucleus (PVN), revealed a potent feeding response in satiated animals. This response by either agonist was blocked, in a dose-dependent fashion, by local injection of the alpha 2-noradrenergic antagonists, rauwolscine and yohimbine. It was also blocked by the general antagonist, phentolamine. In contrast, it was unaffected by hypothalamic injection of the alpha 1-noradrenergic antagonists, prazosin and corynanthine. These results indicate that feeding elicited by noradrenergic stimulation in the region of the PVN is mediated through alpha 2-type receptors. These alpha 2 receptors appear to be located postsynaptically, since the effectiveness of clonidine in eliciting eating was undisturbed by prior injection of the catecholamine synthesis inhibitor, alpha-methyl-p-tyrosine.
mesh_terms: D000818:Animals; D003000:Clonidine / Q000494:pharmacology*; D007267:Injections; D008297:Male; D009638:Norepinephrine / Q000494:pharmacology*; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D011224:Prazosin / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D014363:Tryptamines / Q000378:metabolism; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D014363:Tryptamines; D015016:Yohimbine; C015293:indopan; D003000:Clonidine; D009638:Norepinephrine; D011224:Prazosin