基底外侧杏仁核至伏隔核环路对丙泊酚成瘾的调控及机制

Increasing studies have reported that propofol has a high potential for abuse and addiction, however, the underlying molecular mechanisms remain unclear. The neural circuit from basolateral amygdala (BLA) to nucleus accumbens (NAc) was demonstrated to be pivotal in regulating drug addiction through N-methyl-D-aspartate receptors (NMDAR) and dopamine D1 receptors (D1R) in the NAc, by regulating the downstream signal pathway of extracelluar signal-regulated kinase (ERK)/ cyclic-AMP response element binding protein (CREB)/Fos. Our previous research suggested that D1R in the NAc was implicit in modulating propofol self-administration behavior in rats under an operant conditioning paradigm, and our preliminary experiment results indicated that the propofol self-administration behaviors in rats significantly decreased after blocking the activity of the unilateral BLA and the contralateral NAc, or inhibiting NMDAR in the NAc shell (NASh). Whereas, the propofol self-administration behavior was promoted after the rats were treated with D1R agonist in the NASh. Moreover, the expressions of p-CREB (phosphorylated CREB) and c-fos in the NAc were also examined by western blot, and we found that the changes of the expressions of p-CREB and c-fos paralleled with the propofol self-administration behaviors in rats. Thus, we hypothesized that the circuit of BLA-to-NAc modulated propofol addiction, which may act through the NMDAR-D1R/ERK/CREB/Fos signal pathway in the NAc. In this study, we will employ optogenetics, small interfering RNA (siRNA), agonists and antagonists, patch-clamp technique and the transgenic mice of Drd1a-tdTomat to further examine the hypothesis. Our study would provide preclinical and mechanistic evidence of propofol addiction prevention and treatment if funded.

越来越多证据表明丙泊酚具有成瘾性，但其机制未明。基底外侧杏仁核（BLA）至伏隔核（NAc）的神经环路是调控药物成瘾的关键，并可能通过NAc的NMDA受体（NMDAR）与D1受体（D1R）共同调控下游的ERK/CREB/Fos通路发挥作用。申请者及课题组研究证实NAc的D1R调控大鼠丙泊酚成瘾，预实验发现抑制一侧BLA和对侧NAc活性、拮抗NAc壳区的NMDAR或激动D1R分别抑制和促进了大鼠丙泊酚自身给药行为，且分别下调和上调NAc区p-CREB和c-fos蛋白表达。据此提出假说：BLA-NAc环路调控大鼠丙泊酚成瘾，并可能通过NAc的NMDAR-D1R/ERK/CREB/Fos通路发挥作用。本项目拟采用光遗传学方法、siRNA方法、激动剂和拮抗剂方法、膜片钳方法和利用Drd1a-tdTomato转基因小鼠证明上述假说。本研究可为丙泊酚成瘾的机制研究提供新思路，为药物成瘾的防治提供新靶点。

丙泊酚成瘾具有成瘾性，但机制未明。基底外侧杏仁核（BLA）至伏隔核（NAc）环路是调控药物成瘾的关键，可能通过NAc的NMDA受体（NMDAR）与D1受体（D1R）共同调控下游ERK/CREB/Fos通路发挥作用。基于申请者前期研究和预实验结果，我们提出假说：BLA-NAc环路调控大鼠丙泊酚成瘾，并可能通过NAc区NMDAR-D1R/ERK/CREB/Fos通路发挥作用。我们采用膜片钳技术对比正常大鼠（未成瘾）和丙泊酚成瘾大鼠NAc-shell（NASh）兴奋性突触后电流（EPSC）的频率和幅度、以及动作电位（APs）变化，发现丙泊酚成瘾大鼠NASh区EPSC频率、幅度以及APs个数均较未成瘾大鼠显著升高，提示NASh突触前和突触后机制、该区的神经元兴奋性均调控大鼠丙泊酚成瘾。双侧BLA注射腺相关病毒AAV-Camk2α-ChR2-EYFP和AAV-Camk2α-NpHR3.0-EYFP，采用体内光遗传方法刺激，分别促进和抑制了大鼠丙泊酚自身给药行为，证实BLA-NASh环路调控大鼠丙泊酚成瘾。定位NASh注射以下受体拮抗剂：AMPA受体（AMPAR，NBQX）、D1R（SCH23390）、ERK1/2（U0126）均显著抑制大鼠丙泊酚自身给药行为，但NMDAR拮抗剂AP-5促进大鼠丙泊酚自身给药行为。但NASh注射NBQX可抑制激活的BLA-NASh环路对大鼠丙泊酚自身给药行为的促进作用，提示NASh区AMPAR在BLA-NASh环路对大鼠丙泊酚成瘾的调控中发挥关键作用。NBQX可显著抑制NAc区GluA2、NR2B和D1R表达，对GluA1、NR2A、以及p-ERK1/2和p-CREB表达无显著影响，提示AMPAR通过GluA2和NR2B调控大鼠丙泊酚成瘾，D1R可能发挥介导作用，但不通过下游ERK1/2-CREB通路。此外，以上药物对大鼠自发活动均无显著影响。