Although the Arc gene was identified under the GO category ‘regionalization’ (Table 2), this gene was one of the most cited genes both detected as significantly changed in the present study (its gene expression was increased 1.5-fold in the CA group, Table 1) and implicated in substance abuse for morphine (Ammon et al., 2003), amphetamine (Gonzalez-Nicolini and McGinty, 2002), cocaine (Freeman et al., 2002; Samaha et al., 2004) and nicotine (Schochet et al., 2005; Samaha et al., 2005). Arc is an immediate early gene found in soma and dendrites and is involved in, or associated with, synaptic modification and learning/memory (e.g., Guzowski et al., 2006). In a recent study (Pandey et al., 2008), the BDNF-Arc signaling pathway has been implicated in both alcohol dependence and the comorbid expression of anxiety with alcohol abuse.
