Abstract
Glutamatergic system has an important role in cocaine-seeking behavior. Studies have reported that chronic exposure to cocaine induces downregulation of glutamate transporter-1 (GLT-1) and cystine/glutamate exchanger (xCT) in the central reward brain regions. Ceftriaxone, a beta-lactam antibiotic, restored GLT-1 expression and consequently reduced cue-induced reinstatement of cocaine-seeking behavior. In this study, we investigated the reinstatement to cocaine (20 mg/kg, i.p.) seeking behavior using a conditioned place preference (CPP) paradigm in male alcohol-preferring (P) rats. In addition, we investigated the effects of Ampicillin/Sulbactam (AMP/SUL) (200 mg/kg, i.p.), a beta-lactam antibiotic, on cocaine-induced reinstatement. We also investigated the effects of AMP/SUL on the expression of glial glutamate transporters and metabotropic glutamate receptor 1 (mGluR1) in the nucleus accumbens (NAc) core and shell and the dorsomedial prefrontal cortex (dmPFC). We found that AMP/SUL treatment reduced cocaine-triggered reinstatement. This effect was associated with a decrease in locomotor activity. Moreover, GLT-1 and xCT were downregulated in the NAc core and shell, but not in the dmPFC, following cocaine-primed reinstatement. However, cocaine exposure increased the expression of mGluR1 in the NAc core, but not in the NAc shell or dmPFC. Importantly, AMP/SUL treatment normalized GLT-1 and xCT expression in the NAc core and shell; however, the drug normalized mGluR1 expression in the NAc core only. Additionally, AMP/SUL increased the expression of GLT-1 and xCT in the dmPFC as compared to the water naive group. These findings demonstrated that glial glutamate transporters and mGluR1 in the mesocorticolimbic area could be potential therapeutic targets for the attenuation of reinstatement to cocaine-seeking behavior.