Enhancement of behavioral sensitization, anxiety-like behavior, and hippocampal and frontal cortical CREB levels following cocaine abstinence in mice exposed to cocaine during adolescence

PLoS One. 2013 Oct 21;8(10):e78317. doi: 10.1371/journal.pone.0078317. eCollection 2013.

Abstract

Adolescence has been linked to greater risk-taking and novelty-seeking behavior and a higher prevalence of drug abuse and risk of relapse. Decreases in cyclic adenosine monophosphate response element binding protein (CREB) and phosphorylated CREB (pCREB) have been reported after repeated cocaine administration in animal models. We compared the behavioral effects of cocaine and abstinence in adolescent and adult mice and investigated possible age-related differences in CREB and pCREB levels. Adolescent and adult male Swiss mice received one daily injection of saline or cocaine (10 mg/kg, i.p.) for 8 days. On day 9, the mice received a saline injection to evaluate possible environmental conditioning. After 9 days of withdrawal, the mice were tested in the elevated plus maze to evaluate anxiety-like behavior. Twelve days after the last saline/cocaine injection, the mice received a challenge injection of either cocaine or saline, and locomotor activity was assessed. One hour after the last injection, the brains were extracted, and CREB and pCREB levels were evaluated using Western blot in the prefrontal cortex (PFC) and hippocampus. The cocaine-pretreated mice during adolescence exhibited a greater magnitude of the expression of behavioral sensitization and greater cocaine withdrawal-induced anxiety-like behavior compared with the control group. Significant increases in CREB levels in the PFC and hippocampus and pCREB in the hippocampus were observed in cocaine-abstinent animals compared with the animals treated with cocaine in adulthood. Interestingly, significant negative correlations were observed between cocaine sensitization and CREB levels in both regions. These results suggest that the behavioral and neurochemical consequences of psychoactive substances in a still-developing nervous system can be more severe than in an already mature nervous system.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Anxiety / chemically induced*
  • Anxiety / metabolism
  • Behavior, Animal / drug effects*
  • Cocaine / adverse effects*
  • Cocaine-Related Disorders / metabolism
  • Conditioning, Psychological / drug effects
  • Cyclic AMP Response Element-Binding Protein / metabolism*
  • Exploratory Behavior / drug effects*
  • Hippocampus / drug effects*
  • Hippocampus / metabolism
  • Learning / drug effects
  • Male
  • Mice
  • Motor Activity / drug effects
  • Prefrontal Cortex / drug effects*
  • Prefrontal Cortex / metabolism
  • Risk-Taking

Substances

  • Creb1 protein, mouse
  • Cyclic AMP Response Element-Binding Protein
  • Cocaine

Grant support

The work was funded by the following: Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.