Local pretreatment with the cannabinoid CB1 receptor antagonist AM251 attenuates methamphetamine intra-accumbens...

The endocannabinoid system is a potential target for therapeutic intervention of substance abuse. Cannabinoid CB1 receptor antagonist decreases intravenous methamphetamine self-administration in animal models. This study examined whether the nucleus accumbens (NAcc) is a site of interaction between methamphetamine and the CB1 receptor antagonist AM251. Male Sprague-Dawley rats were trained to lever press and then were surgically implanted with a guide cannula into the right NAcc. Rats were allowed one week to recover and then AM251 (0.1 or 1.0 microg/microL) was reverse dialyzed directly into the NAcc prior to methamphetamine (10 microg/microL) intra-accumbens self-administration. AM251 (1.0 microg/microL) reduced methamphetamine self-administration while AM251 (0.1 microg/microL) had an intermediary effect. The mechanism of self-administration attenuation is not known but could be mediated by AM251 affecting the negative feedback from the NAcc to the ventral tegmental area (VTA). This study provides evidence that the endocannabinoid system is involved with rewarding effects of methamphetamine and suggests a possible therapeutic intervention for methamphetamine abuse.