title: Chronic treatment with monoamine oxidase-B inhibitors decreases cocaine reward in mice.
abstract: OBJECTIVE
  Whether monoamine oxidase inhibitors (MAOIs) can be used to suppress the reinforcing effect of cocaine remains unknown. This study was undertaken to examine effects of a long-term dosing regimen with selective MAOIs on cocaine and food reward.
  
  
  METHODS
  Since single dose of clorgyline (2 mg/kg), deprenyl (1 mg/kg), and pargyline (10 mg/kg) did not acutely affect mouse locomotor activity, these doses were chosen to treat the male C57BL/6j mice on a daily basis.
  
  
  RESULTS
  Fourteen consecutive days of pretreatments with clorgyline, deprenyl, or pargyline (one injection per day) did not affect natural reward-supported operant behavior, since acquisition of the lever pressing responses for food pellets under an FR-1 protocol did not differ among these drug- and saline-treated mice. Likewise, 24 consecutive days of pretreatments with clorgyline did not alter acquisition of the cocaine (0.3 mg/kg per infusion)-supported operant responses under an FR-1 protocol. In contrast, 24 days of pretreatments with deprenyl and pargyline abolished the cocaine-supported operant responses under a similar protocol. Twenty-four days of clorgyline treatment enhanced serotonin contents in striatum, nucleus accumbens, and frontal cortex. Frontal cortical 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacidic acid concentrations were decreased following 24 days of pretreatments with deprenyl and pargyline. These changes were not evident in mice pretreated with clorgyline.
  
  
  CONCLUSIONS
  We suggest that long-term treatments with MAO-B inhibitors may decrease cocaine-supported operant responses in cocaine-naïve mice by selectively decreasing frontal cortical metabolism of dopamine and serotonin.
authors.affiliation: Institute of Behavioral Medicine, National Cheng Kung University College of Medicine, Tainan, Taiwan, 70101, Republic of China.
authors.forename: Ming-Che
authors.initials: MC
authors.lastname: Ho
authors.forename: Chianfang G
authors.initials: CG
authors.lastname: Cherng
authors.forename: Yen-Ping N
authors.initials: YP
authors.lastname: Tsai
authors.forename: Chih-Yuan
authors.initials: CY
authors.lastname: Chiang
authors.forename: Jia-Ying
authors.initials: JY
authors.lastname: Chuang
authors.forename: Shu-Fang
authors.initials: SF
authors.lastname: Kao
authors.forename: Lung
authors.initials: L
authors.lastname: Yu