nucleus accumbens, appears to mediate the function of another transcription factor, ΔFosB (Kelz et al., 1999). The latter has been termed a “molecular switch for addiction,” as it parallels sensitization to drugs (Nestler, 2001), and is generally an important component of neuronal plasticity (McClung et al., 2004) involved in addiction pathogenesis. Importantly, CREB inhibits drug reward, whereas ΔFosB enhances it (Nestler, 2001). Under non-novelty conditions amphetamine induces c-Fos in striatal neurons positive for dopamine D1 receptor mRNA; under conditions of novelty c-Fos is induced in both D1 and D2 neurons (Badiani et al., 1999).
