title: Peer influences on drug self-administration: social facilitation and social inhibition of cocaine intake in male rats.
abstract: BACKGROUND
  One problem facing animal models of intravenous drug self-administration, particularly those examining social manipulations, is that subjects must be removed from the home environment and separated from cagemates during testing. This represents a limitation of animal models because it fails to capture the complex social environments in which drug use often occur.
  
  
  OBJECTIVE
  The aim of this study was to examine intravenous cocaine self-administration in isolated and socially housed rats, with the caveat that the socially housed subjects lived together 24 h/day, including during daily self-administration sessions. As a secondary aim, the study examined the impact of a companion that also self-administered cocaine versus a companion without access to cocaine.
  
  
  METHODS
  Male rats were obtained at weaning and reared in isolated or pair-housed conditions for 6 weeks. Rats were then implanted with intravenous catheters and transferred to custom-built operant conditioning chambers that served as home cages for the remainder of the study. For some socially housed subjects, both rats had simultaneous access to cocaine; for others, only one rat of the pair had access to cocaine.
  
  
  RESULTS
  Cocaine self-administration was facilitated in socially housed rats if both members of the pair had access to cocaine; however, cocaine self-administration was inhibited if only one rat of the pair had access to cocaine.
  
  
  CONCLUSIONS
  These data indicate that the self-administration behavior of a peer, not merely the presence of a peer, determines whether cocaine self-administration is facilitated or inhibited by social contact.
authors.affiliation: Department of Psychology, Program in Neuroscience, Davidson College, Box 7037, Davidson, NC 28035-7037, USA. masmith@davidson.edu
authors.forename: Mark A
authors.initials: MA
authors.lastname: Smith
mesh_terms: D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D003216:Conditioning, Operant; D006799:Housing, Animal; D007262:Infusions, Intravenous; D008297:Male; D023421:Models, Animal; D010379:Peer Group; D051381:Rats; D020318:Rats, Long-Evans; D012646:Self Administration; D012931:Social Environment; D012932:Social Facilitation; D012934:Social Isolation / Q000523:psychology*
chemical_list: D003042:Cocaine