title: Disrupted social development enhances the motivation for cocaine in rats.
abstract: BACKGROUND
  Early social experiences are of major importance for behavioural development. In particular, social play behaviour during post-weaning development is thought to facilitate the attainment of social, emotional and cognitive capacities. Conversely, social insults during development can cause long-lasting behavioural impairments and increase the vulnerability for psychiatric disorders, such as drug addiction.
  
  
  OBJECTIVE
  The aim of this study was to investigate whether a lack of social experiences during the juvenile and early adolescent stage, when social play behaviour is highly abundant, alters cocaine self-administration in rats.
  
  
  METHODS
  Rats were socially isolated from postnatal days 21 to 42 followed by re-socialization until adulthood. Cocaine self-administration was then assessed under a fixed ratio and progressive ratio schedule of reinforcement. Next, cue, cocaine and stress-induced reinstatement of cocaine seeking was determined following extinction of self-administration.
  
  
  RESULTS
  Early social isolation resulted in an enhanced acquisition of self-administration of a low dose (0.083 mg/infusion) of cocaine, but the sensitivity to cocaine reinforcement, assessed using a dose-response analysis, was not altered in isolated rats. Moreover, isolated rats displayed an increased motivation for cocaine under a progressive ratio schedule of reinforcement. Extinction and reinstatement of cocaine seeking was not affected by early social isolation.
  
  
  CONCLUSIONS
  Early social isolation causes a long-lasting increase in the motivation to self-administer cocaine. Thus, aberrations in post-weaning social development, such as the absence of social play, enhance the vulnerability for drug addiction later in life.
authors: Department of Translational Neuroscience, Brain Center Rudolf Magnus, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Petra J J
authors: PJ
authors: Baarendse
authors: Jules H W
authors: JH
authors: Limpens
authors: Louk J M J
authors: LJ
authors: Vanderschuren
mesh_terms: D058669:Adrenergic alpha-2 Receptor Antagonists / Q000494:pharmacology; D000375:Aging; D000818:Animals; D003042:Cocaine / Q000008:administration & dosage*; D003463:Cues; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D058999:Drug-Seeking Behavior / Q000187:drug effects / Q000502:physiology*; D005108:Extinction, Psychological / Q000187:drug effects / Q000502:physiology; D008297:Male; D009042:Motivation / Q000502:physiology*; D051381:Rats; D012055:Reinforcement Schedule; D012646:Self Administration; D012919:Social Behavior; D012934:Social Isolation; D013315:Stress, Psychological / Q000503:physiopathology; D015016:Yohimbine / Q000494:pharmacology
chemical_list: D058669:Adrenergic alpha-2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors; D015016:Yohimbine; D003042:Cocaine