The Roles And Mechanisms Of Hippocampus And Amygdala PKM? In Morphine Addiction In Rats

Objective:Drug addiction is a chronic relapsing encephalopathy.The memory associated with psychological dependence of addictive drug is strong and durable.Furthermore,the addictive memory is difficult to fade with time,leading to high relapse rate.Limbic system participates in the process of drug addiction,and PKM zeta is closely related to the memory and LTP.We speculated that the amygdala PKM? may participate in the process of morphine addictive memory.Microinjection of ZIP(a specific inhibitors of PKM?)in brain might erase the addictive memory,promote the extinction and reduce the relapse rate.To test this hypothesis,we used conditioned place preference to establish the models of morphine addiction,extinction and reinstatement.Then,the expressions of PKM? and p-PKM? in the process of addiction were examined by using the methods of molecular biology.Third,effects of the PKM? specific inhibitor ZIP on morphine extinction and reinstatement were explored by microinjection of ZIP in the hippocampus and amygdala.Lastly,the expression of acetylated histone H3 was examined by western blot.The research could enrich the mechanisms of morphine addiction and relapse and provide new targets for the treatment of opioid addiction.Method:1.SD rats between 200g-300 g were used in the experiments.Conditioned place preference was used to establish morphine addiction,extinction and reinstatement models.Western Blot was applied to examine the expression of PKM? and phosphorylated PKM? in the hippocampus and the amygdala during morphine addiction.2.The surgery of hippocampus or amygdala stereotaxic intubation was did for microinjection.After 5~7 days' recovery,rats was injected with morphine to establish addiction model by using conditioned place preference.Then preference value was examined 3h after microinject of ZIP into hippocampus or amygdala.3.After morphine extinction,preference value was measured after half dose of morphine reinstatement in both ZIP group and saline group.4.Expressions of H3 histone acetylation in the hippocampus were tested by using western blot in morphine addictive rats.Results:1.The expressions of PKM? and phosphorylated PKM? both in the hippocampus and the amygdala were significantly increased.2.Microinjection of ZIP in hippocampus or amygdala promoted the extinction of morphine addiction and the effect was sustained.3.Microinjection of ZIP in hippocampus or amygdala inhibited half-dose morphine reinstatement after extinction.4.Western blot showed the expression of H3 histone acetylation increase in the hippocampus after morphine addiction.Conclusion:PKM? is involved in addiction memory process.Microinjection of the PKM zeta specific inhibitor ZIP in the hippocampus or the amygdala accelerates the extinction of addiction,and erases the addictive memory,and inhibits relapse in rats.