Repeated exposure to amphetamine during adolescence alters inhibitory tone in the medial prefrontal cortex following drug re-exposure in adulthood

Kush Paul, Shuo Kang, Charles L. Cox, Joshua M. Gulley

Research output: Contribution to journalArticlepeer-review

Abstract

Behavioral sensitization following repeated amphetamine (AMPH) exposure is associated with changes in GABA function in the medial prefrontal cortex (mPFC). In rats exposed to AMPH during adolescence compared to adulthood, there are unique patterns of sensitization that may reflect age-dependent differences in drug effects on prefrontal GABAergic function. In the current study, we used a sensitizing regimen of repeated AMPH exposure in adolescent and adult rats to determine if a post-withdrawal AMPH challenge would alter inhibitory transmission in the mPFC in a manner that depends on age of exposure. Male Sprague-Dawley rats were treated with saline or 3 mg/kg AMPH (i.p.) during adolescence [postnatal day (P) 27-P45] or adulthood (P85- P103) and were sacrificed either at similar ages in adulthood (~P133; experiment 1) or after similar withdrawal times (3-4 weeks; experiment 2). Spontaneous inhibitory postsynaptic currents (sIPSCs) were recorded in vitro from deep layer pyramidal cells in the mPFC using the whole-cell configuration. We found no effect of AMPH pre-exposure on baseline sIPSC frequency. Subsequent application of AMPH (25 μM) produced a stable increase in sIPSC frequency in controls, suggesting that AMPH increases inhibitory tone in the mPFC. However, AMPH failed to increase sIPSCs in adolescent- or adult-exposed rats. In experiment 2, where withdrawal period was kept similar for both exposure groups, AMPH induced a suppression of sIPSC activity in adolescent-exposed rats. These results suggest that sensitizing treatment with AMPH during adolescence or adulthood dampens inhibitory influences on mPFC pyramidal cells, but potentially through different mechanisms.

Original languageEnglish (US)
Pages (from-to)9-13
Number of pages5
JournalBehavioural Brain Research
Volume309
DOIs
StatePublished - Aug 1 2016

Keywords

  • Adolescence
  • Amphetamine
  • GABA
  • Medial prefrontal cortex
  • Whole-cell recording

ASJC Scopus subject areas

  • Behavioral Neuroscience

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