RATIONALE: Opioid and cannabinoid CB(1) receptor antagonists reduce the motivation to consume alcohol when taken individually but their effectiveness in combination is not yet known. OBJECTIVE: The effects of naloxone/naltrexone and SR 141716 alone and in combination were examined on beer consumption in rats. METHODS: In a progressive ratio paradigm rats were trained to lick at a tube for either beer (4.5% ethanol v/v) or near-beer (beer containing <0.5% ethanol v/v) under a progressive ratio schedule of reinforcement. They were then tested with naloxone (0.3, 0.6 or 1.2 mg/kg i.p.), SR 141716 (0.15, 0.3 or 0.6 mg/kg i.p.) and their combination. In a continuous access paradigm, other rats were given beer or near-beer in their home cages for several weeks and the effects of repeated (4 day) administration of naltrexone (0.3, 0.6 or 1.2 mg/kg), SR 141716 (0.15, 0.3 or 0.6 mg/kg) and their combination were assessed. RESULTS: In the progressive ratio paradigm SR 141716, naloxone and their combination were more effective in reducing the break points for beer rather than near-beer. The two lowest dose combinations produced a synergistic reduction in break points. The highest dose combination reduced break points for both beer and near-beer and effects were more additive than synergistic. In the continuous access paradigm, the low doses of the drugs selectively reduced beer consumption in a synergistic fashion with higher doses having a less selective and more additive effect. CONCLUSIONS: The combined, low dose treatment has possible clinical efficacy in treating alcohol craving in humans.
RATIONALE: Opioid and cannabinoid CB(1) receptor antagonists reduce the motivation to consume alcohol when taken individually but their effectiveness in combination is not yet known. OBJECTIVE: The effects of naloxone/naltrexone and SR 141716 alone and in combination were examined on beer consumption in rats. METHODS: In a progressive ratio paradigm rats were trained to lick at a tube for either beer (4.5% ethanol v/v) or near-beer (beer containing <0.5% ethanol v/v) under a progressive ratio schedule of reinforcement. They were then tested with naloxone (0.3, 0.6 or 1.2 mg/kg i.p.), SR 141716 (0.15, 0.3 or 0.6 mg/kg i.p.) and their combination. In a continuous access paradigm, other rats were given beer or near-beer in their home cages for several weeks and the effects of repeated (4 day) administration of naltrexone (0.3, 0.6 or 1.2 mg/kg), SR 141716 (0.15, 0.3 or 0.6 mg/kg) and their combination were assessed. RESULTS: In the progressive ratio paradigm SR 141716, naloxone and their combination were more effective in reducing the break points for beer rather than near-beer. The two lowest dose combinations produced a synergistic reduction in break points. The highest dose combination reduced break points for both beer and near-beer and effects were more additive than synergistic. In the continuous access paradigm, the low doses of the drugs selectively reduced beer consumption in a synergistic fashion with higher doses having a less selective and more additive effect. CONCLUSIONS: The combined, low dose treatment has possible clinical efficacy in treating alcohol craving in humans.
Authors: Simona Perra; Giuliano Pillolla; Miriam Melis; Anna Lisa Muntoni; Gian Luigi Gessa; Marco Pistis Journal: Psychopharmacology (Berl) Date: 2005-10-15 Impact factor: 4.530