Acute administration of ethanol to experimental animals is associated with changes in various neurotransmitter systems in the PFC. Several studies have examined these effects using outbred strains of rats. For example, µ-opioid receptors were upregulated in frontal cortex 2 h after intragastric administration of 2.5 g/kg ethanol (Mendez et al., 2001). In Wistar rats, ethanol (1 g/kg) increased the extracellular levels of 5-HT as measured by in vivo microdialysis (Langen et al., 2002). One day of exposure to an ethanol-containing liquid diet decreased CB1 receptor levels in rat PFC (Rubio et al., 2009). Measures of the immediate-early gene Fos have been measured in rat PFC neurons following acute administration of ethanol to gauge its effects on activity. Ethanol increased Fos staining with apparently equal increases in both GABAergic and glutamatergic neurons (Leriche et al., 2008). In contrast to these results, spontaneous spike activity of prefrontal neurons in Sprague-Dawley rats as measured by in vivo multi-array electrodes (Fig. 5) was decreased in a dose-dependent manner by ethanol (Tu et al., 2007). The differences between the results of the Fos and spike
