Sensitization and cannabinoid cross-sensitization to methamphetamine antiaggressive effects is not developed in morphine treatment design in mice
| Authors | |
|---|---|
| Year of publication | 2004 |
| Type | Article in Periodical |
| Magazine / Source | Fundamental & Clinical Pharmacology |
| MU Faculty or unit | |
| Citation | |
| Field | Pharmacology and pharmaceutical chemistry |
| Keywords | cannabinoid; methamphetamine; morphine; sensitization |
| Description | Repeated drug administration leading to a progressively enhanced response, a phenomenon termed sensitization, may be involved in the development and maintenance of drug addiction and also relapse to drug-taking behaviour in weaned addicts. There also is data available showing a cross-sensitization between different types of drugs of abuse. The present study observed behavioural sensitization to the psychostimulant methamphetamine (MET), the opioid morphine (MO) and cross-sensitization with cannabinoid methanandamide (CA) to both of them in mice. The model of agonistic behaviour in singly-housed male mice on paired interactions with non-aggressive group-housed partners was used to analyze behavioural changes in 15 acts of 4 categories: sociable, timid, aggressive and locomotor. Both MET and MO produce dose-dependent antiaggressive effects in singly-housed mice; MET increased while MO decreased locomotor activities. The sensitization to these effects of MET was clearly demonstrated when after the pre-treatment with 5 daily MET doses the challenge dose was given 5 days later, was suppressed by pretreatment with MET+cannabinoid antagonist AM 251, and cross-sensitization was present after the pretreatment with CA. In the same experimental design neither sensitization nor CA cross-sensitization to the antiaggressive efficacy of MO was registered. These results suggest an interaction between the endocannabinoid system and methamphetamine brain mechanisms, and support further the hypothesis that repeated use of cannabis may facilitate progression to the consumption of psychostimulants. The parallel was not confirmed with morphine. |
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