基底外侧杏仁核至伏隔核环路在大鼠丙泊酚依赖中的作用

Effect of basolateral amygdala to nucleus accumbens circuit on propofol dependence in rats

目的探讨基底外侧杏仁核(BLA)至伏隔核(NAc)环路在大鼠丙泊酚自身给药行为中的作用及相关分子机制。方法①通过丙泊酚自身给药行为训练将大鼠分为丙泊酚依赖大鼠和丙泊酚非依赖大鼠,Western印迹法检测2种大鼠NAc内谷氨酸能α-氨基-3-羟基-5-甲基-4-异叶恶唑丙酸受体(AMPAR)的亚基GluA1和GluA2蛋白表达水平。②24只丙泊酚依赖大鼠随机分为对照组、NBQX(AMPAR拮抗剂)0.25,0.5和1μg组,在连续14 d丙泊酚自身给药行为训练后,第15天测试前30 min于NAc内注射生理盐水或NBQX,观察NBQX对大鼠丙泊酚自身给药行为的影响。③24只丙泊酚依赖大鼠随机分为增强型黄绿色荧光蛋白(eYFP)组、eYFP+NBQX组、光敏感通道蛋白(ChR2)-eYFP组和ChR2-eYFP+NBQX组。其中eYFP组和eYFP+NBQX组在BLA区注射腺相关病毒载体(AAV)-钙调蛋白依赖激酶Ⅱα(CaMKⅡα)-eYFP,ChR2-eYFP组和ChR2-eYFP+NBQX组在BLA区注射AAV-CaMKⅡα-ChR2-eYFP。在病毒表达4周后,进行连续14 d丙泊酚自身给药行为训练,于第15天测试前30 min,eYFP组和ChR2-eYFP组在NAc区给予生理盐水,而eYFP+NBQX组和ChR2-eYFP+NBQX组在NAc区给予NBQX 0.5μg,并在测试期间蓝光刺激BLA-NAc环路,观察兴奋BLA-NAc环路对大鼠丙泊酚觅药行为的影响。结果①与丙泊酚非依赖组相比,丙泊酚依赖组大鼠有效鼻触次数明显增加(P<0.05)。Western印迹结果显示,丙泊酚依赖大鼠较丙泊酚非依赖大鼠NAc GluA1和GluA2蛋白表达水平明显增高(P<0.05)。②与对照组相比,NBQX 0.5和1μg组大鼠有效鼻触次数显著减少(P<0.01)。③与eYFP组相比,ChR2-eYFP组大鼠有效鼻触次数显著增加(P<0.01),与eYFP+NBQX组相比,ChR2-eYFP+NBQX组大鼠有效鼻触次数显著增加(P<0.01)。结论兴奋BLA-NAc环路可增加大鼠丙泊酚自身给药行为,该作用可能由NAc区AMPAR介导。

OBJECTIVE To investigate the role of the basolateral amygdala(BLA)to the nucleus accumbens(NAc)circuit in propofol self-administration in rats and the related mechanisms.METHODS①SD rats were randomly divided into the propofol addicted group and the propofol non-addicted group via propofol self-administration training,and the expressions of GluA1 and GluA2[the subunits of glutamatergicα-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors(AMPAR)]in NAc of rats were detected by Western blotting.②Twenty-four propofol addicted rats were randomly divided into 4 groups:control group,NBQX(AMPAR antagonist)0.25,0.5 and 1μg groups.After 14 days of propofol self-administration training,rats were injected with saline or different doses of NBQX via intra-NAc 30 min before the last training to observe the change of propofol seeking behavior.③Twenty-four propofoladdicted rats were randomly divided into the enhanced yellow fluorescent protein(eYFP)group,eYFP+NBQX group,channelrhodopsin-2(ChR2)-eYFP group and ChR2-eYFP+NBQX group.AAV-CaMK Ⅱα-eYFP was injected into BLA in the eYFP group and eYFP+NBQX group.AAV-CaMK Ⅱα-ChR2-eYFP was injected into BLA in the ChR2-eYFP group and ChR2-eYFP+NBQX group.After 4 weeks of virus injection,rats received 14 days of training in propofol self-administration.On the 15th day,rats were given saline(eYFP and ChR2-eYFP group)or NBQX 0.5μg(eYFP+NBQX and ChR2-eYFP+NBQX group)via intra-NAc 30 min prior to the test before blue light stimulation from the BLA to the NAc circuit was performed during the test to observe the change of propofol seeking behavior.RESULTS①Compared with the propofol non-addicted rats,the number of effective nasal contacts in propofol-addicted rats was significantly increased(P<0.05).Western blotting results indicated that the expressions of GluA1 and GluA2 in NAc of propofol-addicted rats were increased more significantly than in propofol non-addicted ones(P<0.05).②Compared with the control group,NBQX 0.5 and 1μg could significantly attenuate the propofol self-administration behavior in rats(P<0.01).②Compared with the eYFP group,propofol self-administration behavior in the ChR2-eYFP group was enhanced(P<0.01).Compared with the eYFP+NBQX group,ChR2-eYFP+NBQX group could enhance propofol self-administration behavior in rats(P<0.01).CONCLUSION Exciting the BLA to NAc circuit can enhance propofol self-administration behavior in rats,and the mechanism may be related to AMPAR in NAc.