Adolescent cocaine self-administration induces habit behavior in adulthood: sex differences and structural consequences

Transl Psychiatry. 2016 Aug 30;6(8):e875. doi: 10.1038/tp.2016.150.

Abstract

Adolescent cocaine use increases the likelihood of drug abuse and addiction in adulthood, and etiological factors may include a cocaine-induced bias towards so-called 'reward-seeking' habits. To determine whether adolescent cocaine exposure indeed impacts decision-making strategies in adulthood, we trained adolescent mice to orally self-administer cocaine. In adulthood, males with a history of escalating self-administration developed a bias towards habit-based behaviors. In contrast, escalating females did not develop habit biases; rather, low response rates were associated with later behavioral inflexibility, independent of cocaine dose. We focused the rest of our report on understanding how individual differences in young-adolescent females predicted long-term behavioral outcomes. Low, 'stable' cocaine-reinforced response rates during adolescence were associated with cocaine-conditioned object preference and enlarged dendritic spine head size in the medial (prelimbic) prefrontal cortex in adulthood. Meanwhile, cocaine resilience was associated with enlarged spine heads in deep-layer orbitofrontal cortex. Re-exposure to the cocaine-associated context in adulthood energized responding in 'stable responders', which could then be reduced by the GABAB agonist baclofen and the putative tyrosine receptor kinase B (trkB) agonist, 7,8-dihydroxyflavone. Together, our findings highlight resilience to cocaine-induced habits in females relative to males when intake escalates. However, failures in instrumental conditioning in adolescent females may precipitate reward-seeking behaviors in adulthood, particularly in the context of cocaine exposure.

MeSH terms

  • Age Factors
  • Animals
  • Baclofen / pharmacology
  • Behavior, Animal / drug effects*
  • Cocaine / administration & dosage
  • Cocaine / pharmacology*
  • Conditioning, Psychological
  • Decision Making / drug effects*
  • Dendritic Spines / drug effects*
  • Dendritic Spines / pathology
  • Dopamine Uptake Inhibitors / administration & dosage
  • Dopamine Uptake Inhibitors / pharmacology*
  • Female
  • Flavones / pharmacology
  • GABA-B Receptor Agonists / pharmacology
  • Male
  • Mice
  • Prefrontal Cortex / drug effects*
  • Prefrontal Cortex / pathology
  • Receptor, trkB / agonists
  • Reward
  • Self Administration

Substances

  • 6,7-dihydroxyflavone
  • Dopamine Uptake Inhibitors
  • Flavones
  • GABA-B Receptor Agonists
  • Receptor, trkB
  • Baclofen
  • Cocaine