gamma-Aminobutyric acid type A receptors and alcoholism - Intoxication, dependence, vulnerability, and treatment

Context: Alcohol facilitates gamma-aminobutyric acid (GABA) function, and GABA type A (GABA(A)) receptor facilitating agents suppress alcohol withdrawal symptoms. Advances in molecular neuroscience, genetics, and neuroimaging provide new insights into the role of brain GABA systems in short- and long-term alcohol effects. Objective: To review the role of brain GABA systems in alcohol response, alcohol dependence, alcoholism vulnerability, and alcoholism pharmacotherapy. Design: Literature review. Results: Alcohol increases GABA release, raises neurosteroid levels, and may potently enhance the function of a GABA(A) receptor subclass that shows high affinity for GABA and neurosteroids, relative insensitivity to benzodiazepines, low chloride conductance, and an extra-synaptic location. Variation in GABA(A) receptor subunit genes may contribute to the vulnerability to alcoholism, particularly in the context of environmental risk factors. Alcohol dependence is associated with timedependent changes in brain GABA(A) receptor density and subunit gene expression levels that contribute to a withdrawal-related deficit in GABA(A) receptor function. However, cortical GABA levels are not reduced during acute withdrawal. Benzodiazepine-assisted detoxification enhances a phasic component of GABA function. However, novel treatments target the tonic component of GABA neurotransmission mediated by benzodiazepine-insensitive GABA(A) receptors. Smoking attenuates withdrawal-related disturbances in brain GABA function, perhaps contributing to comorbid nicotine and alcohol dependence. The GABA systems show recovery with long-term sobriety. Conclusions: Recent research deepens our understanding of the role of GABA systems in alcohol action, alcohol dependence, and the vulnerability to alcoholism. Also, GABA(A) receptor subtype-selective treatments merit exploration for reducing withdrawal symptoms and drinking in alcohol-dependent individuals.