CPP studies with cannabinoids have been largely ineffective at producing positive place preferences and the studies that have shown cannabinoid place preference have done so at various doses and magnitudes depending on the training procedure used across studies. Although very specific dosing parameters are required to produce place preferences for many drugs in the CPP paradigm (Bardo and Bevins 2000; Tzschentke 1998, the ability of cannabinoids, such as THC and the synthetic CB1 receptor high-efficacy agonist CP 55,940, to produce a place preference in rats and mice are particularly sensitive to the timing of injections as well as on the range of doses used (Lepore et al. 1995; Valjent and 2000; Braida et al. 2001; Ghozland et al. 2002). For
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When the schedule of daily injections was changed and a day where no drug or vehicle injection was administered was added in between test sessions (i.e., vehicle, day off, drug, day off, vehicle, day off, drug, etc.), the results were opposite such that THC produced a conditioned place preference at 1.0 mg/kg but place aversions were found at the 2.0 and 4.0 mg/kg doses of THC. These findings indicated that the rewarding effects of THC as assessed under the CPP paradigm might be qualitatively changed by increasing the interval between drug injections due to what the authors referred to as a “postdrug dysphoric rebound.” As a result, the pharmacological properties of THC that may be contributing to this effect may help to explain why THC and synthetic cannabinoids often produce conditioned place aversions, rather than place preferences, in rats and mice using similar dose ranges and standard place-preference conditioning procedures (Lepore et al. 1995; McGregor et al.
When the schedule of daily injections was changed and a day where no drug or vehicle injection was administered was added in between test sessions (i.e., vehicle, day off, drug, day off, vehicle, day off, drug, etc.), the results were opposite such that THC produced a conditioned place preference at 1.0 mg/kg but place aversions were found at the 2.0 and 4.0 mg/kg doses of THC. These findings indicated that the rewarding effects of THC as assessed under the CPP paradigm might be qualitatively changed by increasing the interval between drug injections due to what the authors referred to as a “postdrug dysphoric rebound.” As a result, the pharmacological properties of THC that may be contributing to this effect may help to explain why THC and synthetic cannabinoids often produce conditioned place aversions, rather than place preferences, in rats and mice using similar dose ranges and standard place-preference conditioning procedures (Lepore et al. 1995; McGregor et al.