基底外侧杏仁核中SIRT1对小鼠条件奖赏模型中吗啡成瘾记忆的作用

Role of basolateral amygdala SIRT1 in morphine-associated memories in a conditioned reward model in mice

目的:通过建立小鼠吗啡条件奖赏(CR)模型模拟吗啡成瘾记忆的形成、消退和再现,并检测基底外侧杏仁核(BLA)内沉默信息调节因子1(SIRT1)在吗啡成瘾记忆不同阶段的表达。方法:小鼠分为4组:CR-吗啡组;CR-糖水组;naive-吗啡组;naive-糖水组。进行CR训练时,条件性刺激依次为8 s和4 s。训练结束后进行49 d的遗忘,随后再进行一次条件性刺激为4 s的训练。运用RT-PCR、Western Blot检测不同阶段BLA内SIRT1mRNA及蛋白表达。结果:在CR形成期,吗啡组正确鼻触总时间显著低于糖水组(P <0. 01)。当加大训练难度将条件性刺激缩短为4 s时,吗啡组正确鼻触时间占比发生逆转,呈现高于糖水组的趋势。与naive-吗啡组比较,CR-吗啡组小鼠SIRT1 mRNA表达量显著升高(P <0. 001);遗忘后再次测试,CR-吗啡组小鼠前壁红外碰触次数升高(P <0. 001),并更趋向于停留在托盘处等待信号出现,CR-糖水组无效鼻触时间显著升高(P <0. 001)。遗忘后CR-吗啡组正确鼻触时间由24. 8%上升到27. 6%,CR-糖水组由20. 6%下降至16. 7%(P <0. 001)。结论:在条件记忆形成期,吗啡可提高条件记忆的强度,并加强困难条件下的觅药行为。BLA内SIRT1可能对成瘾记忆形成及巩固发挥重要调控作用。

Objective: A conditioned rewarding (CR) was used to stimulate the formation of morphine addiction, withdrawal, and relapse, and to detect the expression of silent information regulator 1 ( SIRT1 ) in the basolateral amygdala (BLA) at different stages of morphine addiction memory. Methods: Mice were divided into 4 groups: CR-morphine group;CR-sucrose group;naive-morphine group;naive-sucrose group. CR training was performed in an order of 8 s and 4 s of the conditioned stimuli, respectively. Following a 49 day of extinction, CR test at 4 s was performed in each group of mice. The mRNA and protein expression of SIRT1 in BLA were detect by RT-PCR and Western Blot. Results: In the CR formation stage, the correct response time in the CR-morphine group was significantly lower than that in the CR-sucrose group ( P <0. 01 ). When the stimulation was shortened to 4 s to increase the training difficulty, the proportion of correct response time in the morphine-group was reversed, which was higher than that in the sucrosegroup. Compared with the naive-morphine group, CR-morphine group showed increased SIRT1 mRNA expression (P < 0. 001). After extinction, the CR-morphine mice showed increased number of infrared beam counts ( P < 0. 001) and tended to stay at the tray waiting for the signal to appear. In the CR-sucrose mice group, ineffective response time was higher than that in the CR-morphine mice (P <0.001 ). After the extinction, the correct response time increased from 24. 8% to 27. 6% in the CR-morphine group, and decreased from 20. 6% to 16. 7% in the CR-sucrose group ( P < 0. 001 ). Conclusion: In the period of formation of conditional memory, morphine can enhance the intensity of conditional memory and strengthen the drug seeking behavior under difficult conditions. SIRT1 in BLA may play an important regulatory role in the formation and consolidation of addictive memory.