significantly reduced GABA responses in oocytes injected with a 2:2:1 ratio and a 6:2:1 ratio of subunits, while not affecting current amplitude of oocytes injected with 0.5:2:1 ratios. This result suggests that the effect is specific to particular subunit ratios and not due to non-specific effects of ethanol on the membrane or viability of the cells. In oocytes, either trafficking or posttranslational modifications may be occurring and may be mechanistically related. For example, it has been previously shown that GABAA receptors are internalized in a subunit-specific manner in oocytes after stimulation with PMA, a protein kinase C activator (Chapell et al. 1998; Filippova et al. 2000). Although there is no direct evidence that GABAA subunits are phosphorylated in vivo after ethanol treatment, it has been hypothesized that chronic ethanol may increase phosphorylation of GABAA subunits and alter expression, function or trafficking (Kumar, Fleming, and Morrow 2004).
