Effects of calcium channel antagonists on the reinforcing properties of morphine, ethanol and cocaine as measured by place conditioning.

Morphine, ethanol and cocaine were examined in place conditioning paradigm. After initial preferences were determined, animals were conditioned with morphine (5 mg/kg), ethanol (1 g/kg) and cocaine (5 mg/kg) alone or combinations of these drugs plus some calcium antagonists: nifedipine (5 and 10 mg/kg) and verapamil (5 and 10 mg/kg). Nifedipine prevented the ability of morphine and cocaine, but not of ethanol, to produce a place preference. Our results suggest that substances which can influence calcium distribution are involved in the rewarding actions of some drugs-morphine and cocaine. Dihydropyridine, a calcium channel antagonists might be clinically useful for the treatment of morphine and cocaine abuse.