The gamma aminobutyric acid, GABA, neurotransmitter is the predominant inhibitory neurotransmitter in the central nervous system and is a reasonable target for candidate gene studies on alcoholism. Not only are GABA receptors present in the mesolimbic dopamine pathway (Johnson and North 1992; Steffensen et al. 1998), widely believed to play a role in the development of addiction, but studies using both rodent and human brain samples have shown that long-term ethanol exposure, as well as ethanol withdrawal, causes alterations in GABA(A) receptor subunit expression (Lewohl et al. 1997; Mitsuyama et al. 1998; Dodd et al. 1992; Devaud et al. 1996; Grobin et al. 1998; Matthews et al. 1998; Devaud et al. 1997). GABA can also modulate emotion and response to stress, further implicating this neurotransmitter system in drug behaviors (Herman et al. 2004; Martijena et al. 2002).
