The orexin-1 receptor antagonist SB-334867 reduces amphetamine-evoked dopamine outflow in the shell of the nucleus accumbens and decreases the expression of amphetamine sensitization.
Orexin-expressing neurons are present in hypothalamic nuclei and send projections toward mesolimbic regions such as the nucleus accumbens (NAc), a key brain region implicated in the processing of the motivational significance of reinforcers. Recent evidence found that activation of the orexin system can lead to a state of hyperarousal that may facilitate drug craving or contribute to vulnerability to drug relapse. This study aimed at assessing the effects of the orexin-1 receptor antagonist SB-334867 [1-(2-methylbenzoxazol-6-yl)-3-[1,5]naphthyridin-4-yl-urea hydrochloride] on amphetamine-induced dopamine (DA) release in the shell subregion of the NAc by means of in vivo microdialysis in freely moving rats. Since behavioral sensitization is thought to play a role in the maintenance of compulsive drug use, we also tested the effect of SB-334867 on the expression of sensitization to the locomotor activating effects of amphetamine. Acute administration of SB-334867 (30 mg/kg SC) significantly reduced the acute effects of amphetamine (1 mg/kg IP) on extracellular DA levels in the NAc shell. The expression of amphetamine sensitization was also significantly reduced by acute SB-334867 treatment. Altogether our findings show that selective orexin-1 antagonism both reduces the acute effects of amphetamine on DA outflow in the NAc shell and decreases the expression of locomotor sensitization to the repeated, intermittent administration of amphetamine.
Quarta
Davide
D
Department of Biology, Neurosciences CEDD, GlaxoSmithKline Medicines Research Centre, Verona, Italy. davide.2.quarta@gsk.com
Valerio
Enzo
E
Hutcheson
Daniel M
DM
Hedou
Gael
G
Heidbreder
Christian
C
D000661:Amphetamine / Q000037:antagonists & inhibitors*; D019969:Amphetamine-Related Disorders / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D000818:Animals; D001583:Benzoxazoles / Q000494:pharmacology; D004298:Dopamine / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000037:antagonists & inhibitors; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008297:Male; D017551:Microdialysis; D009287:Naphthyridines; D009434:Neural Pathways / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D009479:Neuropeptides / Q000378:metabolism; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism* / Q000503:physiopathology; D064446:Orexin Receptors; D000068797:Orexins; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012201:Reward; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D014508:Urea / Q000031:analogs & derivatives / Q000494:pharmacology
C420062:1-(2-methylbenzoxazol-6-yl)-3-(1,5)naphthyridin-4-yl urea; D001583:Benzoxazoles; D018765:Dopamine Uptake Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D009287:Naphthyridines; D009479:Neuropeptides; D064446:Orexin Receptors; D000068797:Orexins; D043562:Receptors, G-Protein-Coupled; D018013:Receptors, Neuropeptide; D014508:Urea; D000661:Amphetamine; D004298:Dopamine