title: Escalation of i.v. cocaine intake in peri-adolescent vs. adult rats selectively bred for high (HiS) vs. low (LoS) saccharin intake.
abstract: BACKGROUND
  Adolescence marks a period of increased vulnerability to the development of substance use disorders. High sweet preference is a genetically mediated behavioral trait that also predicts vulnerability to substances of abuse. Previous research has shown that while adolescent rats selectively bred for high (HiS) saccharin intake acquire cocaine self-administration at the same rate as adult HiS rats, adolescent rats bred for low saccharin intake (LoS) acquire cocaine self-administration faster than adult LoS rats.
  
  
  OBJECTIVE
  This study was conducted to investigate the interaction of the addiction vulnerability factors of peri-adolescence and saccharin preference on cocaine intake using an animal model of escalation of cocaine consumption over 6-h/day sessions.
  
  
  METHODS
  Peri-adolescent and adult HiS and LoS female rats self-administered i.v. cocaine (0.4 mg/kg/inf) during short-access (2-h/day) sessions for 2 days. Next, a long-access (6-h/day) period (LgA) commenced and lasted 16 days. Following LgA, session length was returned to 2-h/day for a second short access phase.
  
  
  RESULTS
  LoS peri-adolescent rats escalated cocaine intake over the LgA period and consumed more drug than LoS adult rats; however, peri-adolescent and adult HiS rats consumed similar amounts of cocaine during this period. Additionally, adult HiS rats self-administered more cocaine than adult LoS rats during the LgA period, while there was no phenotypic difference between the rat lines during peri-adolescence for the LgA period. During the first short-access phase, peri-adolescent rats self-administered more cocaine than adult rats.
  
  
  CONCLUSIONS
  These results emphasize the importance of adolescent drug abuse prevention by illustrating that phenotypic protection from addiction may not be expressed until adulthood.
authors.affiliation: Department of Psychiatry, University of Minnesota Medical School, MMC 392, Minneapolis, MN 55455, USA. holt0324@umn.edu
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Holtz
authors.forename: Marilyn E
authors.initials: ME
authors.lastname: Carroll
mesh_terms: D000367:Age Factors; D000818:Animals; D016739:Behavior, Addictive; D001522:Behavior, Animal; D003042:Cocaine / Q000008:administration & dosage*; D019970:Cocaine-Related Disorders / Q000453:epidemiology; D005260:Female; D007275:Injections, Intravenous; D051381:Rats; D017207:Rats, Sprague-Dawley; D012439:Saccharin / Q000008:administration & dosage*; D012646:Self Administration; D013997:Time Factors
chemical_list: D012439:Saccharin; D003042:Cocaine