Effects of Cocaine Exposure on Astrocytic Glutamate Transporters and Relapse-Like Ethanol-Drinking Behavior in Male Alcohol-Preferring Rats

Alcohol Alcohol. 2020 Apr 16;55(3):254-263. doi: 10.1093/alcalc/agaa010.


Aim: Glutamate has been considered as neurotransmitter that is critical in triggering relapse to drugs of abuse, including ethanol and cocaine. Extracellular glutamate concentrations are tightly regulated by several mechanisms, including reuptake through glutamate transporters. Glutamate transporter type 1 (GLT-1) is responsible for clearing the majority of extracellular glutamate. The astrocytic cystine/glutamate antiporter (xCT) regulates also glutamate homeostasis. In this study, we investigated the effects of cocaine exposure and ampicillin/sulbactam (AMP/SUL), a β-lactam antibiotic known to upregulate GLT-1 and xCT, on relapse-like ethanol intake and the expression of astrocytic glutamate transporters in mesocorticolimbic brain regions.

Methods: Male alcohol-preferring (P) rats had free access to ethanol for 5 weeks. On Week 6, rats were exposed to either cocaine (20 mg/kg, i.p.) or saline for 12 consecutive days. Ethanol bottles were then removed for 7 days; during the last 5 days, either AMP/SUL (100 or 200 mg/kg, i.p.) or saline was administered to the P rats. Ethanol bottles were reintroduced, and ethanol intake was measured for 4 days.

Results: Cocaine exposure induced an alcohol deprivation effect (ADE), which was associated in part by a decrease in the expression of GLT-1 and xCT in the nucleus accumbens (NAc) core. AMP/SUL (100 mg/kg, i.p.) attenuated the ADE, while AMP/SUL (200 mg/kg, i.p.) reduced ethanol intake during 4 days of ethanol re-exposure and upregulated GLT-1 and xCT expression in the NAc core, NAc shell and dorsomedial prefrontal cortex (dmPFC).

Conclusion: This study suggests that these astrocytic glutamate transporters might be considered as potential targets for the treatment of polysubstance abuse.

MeSH terms

  • Alcohol Drinking / metabolism
  • Alcohol Drinking / psychology*
  • Amino Acid Transport System X-AG / drug effects*
  • Amino Acid Transport System X-AG / metabolism
  • Animals
  • Astrocytes / drug effects*
  • Astrocytes / metabolism
  • Blotting, Western
  • Brain / drug effects
  • Brain / metabolism
  • Cocaine / adverse effects*
  • Excitatory Amino Acid Transporter 1 / metabolism
  • Excitatory Amino Acid Transporter 2 / drug effects
  • Excitatory Amino Acid Transporter 2 / metabolism
  • Male
  • Rats
  • Recurrence


  • Amino Acid Transport System X-AG
  • Excitatory Amino Acid Transporter 1
  • Excitatory Amino Acid Transporter 2
  • Slc1a3 protein, rat
  • Cocaine