Effect of CART55-102 protein vaccine on morphine analgesia and tolerance / 第二军医大学学报

ABSTRACT

Objective: To study the effect of cocaine- and amphetamine-regulated transcript (CART) protein vaccine on morphine analgesia and tolerance. Methods: The expression plasmid pGEX-4T3-CART was constructed by gene cloning. The CART protein was purified by glutathione s-transferase (GST)-affinity chromatography. The experiment included 6 groups blank control, normal saline (NS) GST + Freund's adjuvant, and CART protein vaccine (5 μg, 10 μg and 20 μg) groups. After immunization for twice, all groups were tested in hot plate. Morphine analgesia effect was evaluated through s. c. injection with 6 mg/kg morphine solution, calculated by MPE%. Then morphine tolerance model was established, and the tolerance to morphine was tested by s. c. injection with 6 mg/kg morphine 12 h after the last injection. Results: CART vaccine itself had no pronounced effect on the pain threshold (P>0.05). CART vaccine at 10 μg significantly depressed the analgesic effect of morphine analgesia (P<0.05). Compared with NS group, vaccine groups showed a potential antagonizing tolerance effect, especially in the 10 μg group, with the MPE% significantly increased (P<0. 05). Conclusion: CART vaccine itself has no influence on the pain response; however, it can impair the analgesia effect of morphine and can antagonize the analgesia tolerance to morphine.