Disinhibition of nucleus accumbens neurons by the dopamine D2 receptor agonist LY-141865: prevented by 6-OHDA pretreatment.
Intravenous administration of LY-141865, a specific dopamine (DA) D2 receptor agonist, caused a biphasic increase/decrease in the firing rate of cells in the rat nucleus accumbens (NAc). 6-Hydroxydopamine injected directly into the medial forebrain bundle, through which the ascending DA fibers pass, prevented the initial rate increase of NAc neurons produced by low doses of LY-141865. In contrast, pretreatment of rats with 5,7-dihydroxytryptamine did not alter the biphasic response of NAc neurons to LY-141865. These results, together with previous findings that D2 autoreceptors are much sensitive to DA and DA agonists, strongly support the hypothesis that the initial rate-increase caused by low doses of LY-141865 is the result of disinhibition.
Hu
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Department of Psychiatry and Behavioral Sciences, S.U.N.Y., Stony Brook 11794.
Wang
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D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004873:Ergolines / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006892:Hydroxydopamines / Q000494:pharmacology*; D008474:Medial Forebrain Bundle / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects*; D009714:Nucleus Accumbens / Q000502:physiology*; D016627:Oxidopamine; D019257:Quinpirole; D011954:Receptors, Dopamine / Q000502:physiology*; D017448:Receptors, Dopamine D2; D012686:Septal Nuclei / Q000502:physiology*
D004873:Ergolines; D006892:Hydroxydopamines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D015116:5,7-Dihydroxytryptamine; D016627:Oxidopamine