title: Metabolic correlates of toluene abuse: decline and recovery of function in adolescent animals.
abstract: BACKGROUND
  Children and adolescents will readily abuse household products that contain solvents such as toluene. It is likely that reinforcing exposures to toluene alter brain glucose metabolism.
  
  
  OBJECTIVE
  Using an animal model of drug reinforcement, we sought to identify a metabolic signature of toluene abuse in the adolescent rodent brain. Small animal PET (microPET), in combination with the glucose analog radiotracer, (18)FDG, were used to evaluate the metabolic consequences of inhaled toluene.
  
  
  METHODS
  The exposure protocol paralleled our previously established method for assessing the conditioned reinforcing effects of toluene (5,000 ppm) using the conditioned place preference (CPP) paradigm. Animals were scanned at baseline and 2 h after the last exposure. Follow-up (18)FDG scans occurred 1 day, 3 weeks, and 2 months later.
  
  
  RESULTS
  After six pairings, 38% of the animals preferred the toluene paired chamber and 25% were averse. The immediate metabolic effect in toluene-exposed animals was a 20% decline in whole brain (18)FDG uptake. Twenty-four hours following the last exposure, the whole brain decline was 40%, and 2 months later, the decline was 30% of pretoluene levels. A region-by-region analysis demonstrated significant additional decreases in the pons, cerebellum, striatum, midbrain, temporal cortex, and hippocampus. Two months after toluene cessation, regions of complete metabolic recovery were the thalamus and cerebellum; however, the temporal cortex did not recover.
  
  
  CONCLUSIONS
  Brain uptake of (18)FDG appears to be a useful tool for examining the metabolic impact of toluene abuse, which include a profound decline followed by region-specific recovery after cessation.
authors.affiliation: Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973, USA. wynne@bnl.gov
authors.forename: Wynne K
authors.initials: WK
authors.lastname: Schiffer
authors.forename: Dianne E
authors.initials: DE
authors.lastname: Lee
authors.forename: David L
authors.initials: DL
authors.lastname: Alexoff
authors.forename: Rich
authors.initials: R
authors.lastname: Ferrieri
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Brodie
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Dewey
mesh_terms: D000818:Animals; D001921:Brain / Q000000981:diagnostic imaging / Q000187:drug effects / Q000378:metabolism*; D001931:Brain Mapping; D004195:Disease Models, Animal; D019788:Fluorodeoxyglucose F18; D019570:Inhalation Exposure / Q000009:adverse effects*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012054:Reinforcement, Psychology; D012997:Solvents / Q000633:toxicity*; D019966:Substance-Related Disorders / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism* / Q000523:psychology; D014050:Toluene / Q000633:toxicity*; D014055:Tomography, Emission-Computed
chemical_list: D012997:Solvents; D019788:Fluorodeoxyglucose F18; D014050:Toluene