Ayers-Ringler J1, Qiu Y1, Oliveros A1, Hinton D2, and Choi DS1,2,3
1Department of Molecular Pharmacology and Experimental Therapeutics, 2Neurobiology of Disease Program, 3Department of Psychiatry and Psychology, Mayo Clinic College of Medicine, Rochester, Minnesota, USA.
Alcohol withdrawal symptom (AWS) is a medical emergency associated with high mortality rates. The neurobiological mechanisms underlying AWS are complex, but generally involve neuroadaptation triggered by the chronic presence of alcohol, a CNS depressant, which leads to hyperexcitability upon termination of ethanol intake. This hyperexcitability is mediated by disruption in the balance between inhibitory GABAergic and excitatory glutamatergic neurotransmission, and is marked by reduced levels of GABA and GABA receptor insensitivity as well as over-activation of glutamatergic neurotransmission. Hyper-glutamatergic states comprise a critical consequence of and potential contributor to AWS in humans, which we replicated in rodent models in our lab. In this study, we employed label-free proteomic analysis to determine changes in protein expression within the striatum during chronic ethanol use and early withdrawal. The striatum is composed primarily of medium spiny GABAergic neurons, which signaling from glutamatergic and dopaminergic nerve terminals and astrocytes. We identified more than 5,000 proteins from both the dorsal (caudate and putamen) and ventral (nucleus accumbens) striatum. We found significant changes following chronic intermittent ethanol exposure and acute (8 h) withdrawal compared to ethanol naïve and ethanol exposure groups respectively. Our bioinformatics revealed that glutamate signaling is an essential component of AWS. Especially, we found that striatal EAAT2 expression is significantly reduced during alcohol withdrawal. We validated that EAAT2 expression is significantly reduced 8 h after ethanol withdrawal following 4 days of chronic ethanol exposure in the vapor chamber. In summary, our novel proteomic approach elucidates a role of EAAT2 and glutamate levels in the striatum during ethanol withdrawal in mice.