The role of delta-opioid receptor subtypes in cocaine- and methamphetamine-induced place preferences.

The effects of delta-receptor antagonists on cocaine- and methamphetamine-induced place preferences were examined in rats. Cocaine- and methamphetamine-induced place preferences were significantly attenuated by naltrindole (NTI: a non-selective delta-opioid receptor antagonist). Furthermore, naltriben (NTB: a selective delta 2-opioid receptor antagonist), but not 7-benzylidenenaltrexone (BNTX: a selective delta 1-opioid receptor antagonist), attenuated the cocaine- and methamphetamine-induced place preferences. These results suggest that delta-opioid receptors, particularly delta 2-opioid receptors, may be involved in the reinforcing effects of cocaine and methamphetamine.