Adrenal activity during repeated long-access cocaine self-administration is required for later CRF-Induced and CRF-dependent stressor-induced reinstatement in rats

Neuropsychopharmacology. 2011 Jun;36(7):1444-54. doi: 10.1038/npp.2011.28. Epub 2011 Mar 16.

Abstract

Understanding the neurobiological processes that contribute to the establishment and expression of stress-induced regulation of cocaine use in addicted individuals is important for the development of new and better treatment approaches. It has been previously shown that rats self-administering cocaine under long-access conditions (6 h daily) display heightened susceptibility to the reinstatement of extinguished cocaine seeking by a stressor, electric footshock, or i.c.v. administration of the stressor-responsive neuropeptide, corticotropin-releasing factor (CRF). This study tested the hypothesis that adrenal responsiveness during earlier long-access cocaine self-administration (SA) is necessary for the establishment of later CRF-dependent stress-induced reinstatement. Reinstatement by footshock, but not a cocaine challenge (10 mg/kg, i.p.) following long-access SA, was blocked by i.c.v. administration of the CRF receptor antagonist, α-helical CRF(9-41) (10 μg). Elimination of SA-induced adrenal responses through surgical adrenalectomy and diurnal corticosterone replacement (ADX/C) before 14 days of SA under long-access conditions had minimal impact on cocaine SA, but blocked later footshock-induced reinstatement. By contrast, ADX/C after SA, but before extinction and reinstatement testing, failed to reduce footshock-induced reinstatement. Likewise, ADX/C before 14 days long-access SA prevented later reinstatement by i.c.v. CRF (0.5 or 1.0 μg). However, significant CRF-induced reinstatement was observed when rats underwent ADX/C following SA, but before extinction and reinstatement testing, although a modest but statistically nonsignificant reduction in sensitivity to CRF's reinstating effects was observed. Taken together, these findings suggest that adrenal-dependent neuroadaptations in CRF responsiveness underlie the increased susceptibility to stress-induced relapse that emerges with repeated cocaine use.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenalectomy
  • Analysis of Variance
  • Animals
  • Behavior, Animal
  • Cocaine / administration & dosage*
  • Conditioning, Operant / drug effects*
  • Conditioning, Operant / physiology
  • Corticosterone / blood
  • Corticotropin-Releasing Hormone / metabolism*
  • Corticotropin-Releasing Hormone / pharmacology
  • Dopamine Uptake Inhibitors / administration & dosage*
  • Extinction, Psychological / drug effects
  • Male
  • Peptide Fragments / pharmacology
  • Rats
  • Rats, Sprague-Dawley
  • Reinforcement Schedule
  • Reinforcement, Psychology*
  • Self Administration

Substances

  • Dopamine Uptake Inhibitors
  • Peptide Fragments
  • Corticotropin-Releasing Hormone
  • corticotropin releasing hormone (9-41)
  • Cocaine
  • Corticosterone