Chunk #34 — 2. Neural substrates for the negative emotional state associated with addiction — 2.3. Neuropharmacological studies of the aversive stimulus effects of drug withdrawal
Another candidate for the aversive effects of drug withdrawal is dynorphin. Much evidence shows that dynorphin is increased in the nucleus accumbens in response to dopaminergic activation and, in turn, that overactivity of the dynorphin systems can decrease dopaminergic function. κ opioid agonists are aversive (Land et al., 2008; Pfeiffer et al., 1986), and cocaine, opioid, and ethanol withdrawal is associated with increased dynorphin in the nucleus accumbens and/or amygdala (Spangler et al., 1993; Lindholm et al., 2000; Rattan et al., 1992).
