Acupuncture at HT7 suppresses morphine self-administration at high dose through GABA system

In the previous study, acupuncture at HT7 has shown to attenuate the self-administration of morphine at a low dose (0.1mg/kg). In this study, it was further investigated whether acupuncture at HT7 could attenuate the morphine self-administration at a high dose (0.5mg/kg). Male Sprague-Dawley rats weighing 270-300g were used. After surgery of catheterization, animals were trained to self-administer morphine solution (0.5mg/kg) using daily 1h session under fixed ratio 1 schedule for 3 weeks. Animals that had shown stable morphine-taking (establish baseline: variation less than 20% of the mean of three consecutive days) were subjected to the acupuncture treatment. Bicuculline and SCH 50911 were used to investigate the possible relation between the effect of acupuncture and the GABA receptor system. Acupuncture at HT7, but not at control acupoint, LI5, suppressed spontaneous morphine-taking behavior significantly. In addition, the effect of acupuncture was blocked by both GABA receptor antagonists. The results of this study suggest that acupuncture at HT7 suppresses morphine-taking behavior through the mediation of GABA receptor system.