title: Stimulant-induced dopamine increases are markedly blunted in active cocaine abusers.
abstract: Dopamine signaling in nucleus accumbens is essential for cocaine reward. Interestingly, imaging studies have reported blunted dopamine increases in striatum (assessed as reduced binding of [(11)C]raclopride to D2/D3 receptors) in detoxified cocaine abusers. Here, we evaluate whether the blunted dopamine response reflected the effects of detoxification and the lack of cocaine-cues during stimulant exposure. For this purpose we studied 62 participants (43 non-detoxified cocaine abusers and 19 controls) using positron emission tomography and [(11)C]raclopride (radioligand sensitive to endogenous dopamine) to measure dopamine increases induced by intravenous methylphenidate and in 24 of the cocaine abusers, we also compared dopamine increases when methylphenidate was administered concomitantly with a cocaine cue-video versus a neutral-video. In controls, methylphenidate increased dopamine in dorsal (effect size 1.4; P<0.001) and ventral striatum (location of accumbens) (effect size 0.89; P<0.001), but in cocaine abusers methylphenidate's effects did not differ from placebo and were similar whether cocaine-cues were present or not. In cocaine abusers despite the markedly attenuated dopaminergic effects, the methylphenidate-induced changes in ventral striatum were associated with intense drug craving. Our findings are consistent with markedly reduced signaling through D2 receptors during intoxication in active cocaine abusers regardless of cues exposure, which might contribute to compulsive drug use.
authors.affiliation: National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
authors.forename: N D
authors.initials: ND
authors.lastname: Volkow
authors.affiliation: National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
authors.forename: D
authors.initials: D
authors.lastname: Tomasi
authors.affiliation: Bioscience Department Brookhaven National Laboratory, Upton, NY, USA.
authors.forename: G-J
authors.initials: GJ
authors.lastname: Wang
authors.affiliation: Bioscience Department Brookhaven National Laboratory, Upton, NY, USA.
authors.forename: J
authors.initials: J
authors.lastname: Logan
authors.affiliation: Bioscience Department Brookhaven National Laboratory, Upton, NY, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Alexoff
authors.affiliation: National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
authors.forename: M
authors.initials: M
authors.lastname: Jayne
authors.affiliation: Bioscience Department Brookhaven National Laboratory, Upton, NY, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Fowler
authors.affiliation: National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA.
authors.forename: C
authors.initials: C
authors.lastname: Wong
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
authors.forename: P
authors.initials: P
authors.lastname: Yin
authors.affiliation: Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY, USA.
authors.forename: C
authors.initials: C
authors.lastname: Du
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000378:metabolism*; D001931:Brain Mapping; D000697:Central Nervous System Stimulants / Q000494:pharmacology*; D003042:Cocaine / Q000008:administration & dosage; D019970:Cocaine-Related Disorders / Q000000981:diagnostic imaging / Q000378:metabolism*; D015331:Cohort Studies; D066249:Craving / Q000187:drug effects / Q000502:physiology; D003463:Cues; D004298:Dopamine / Q000378:metabolism*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage; D006801:Humans; D008297:Male; D008774:Methylphenidate / Q000494:pharmacology*; D008875:Middle Aged; D049268:Positron-Emission Tomography; D020891:Raclopride; D019275:Radiopharmaceuticals; D014741:Video Recording; D014796:Visual Perception / Q000187:drug effects / Q000502:physiology
chemical_list: D000697:Central Nervous System Stimulants; D018765:Dopamine Uptake Inhibitors; D019275:Radiopharmaceuticals; D008774:Methylphenidate; D020891:Raclopride; D003042:Cocaine; D004298:Dopamine