Inhibiting P13K p110B to block cocaine-induced habits and drug seeking

摘要 磷脂酰肌醇3-激酶(PI3K)是一种膜相关信号复合体，可磷酸化肌醇磷脂， 调节神经元发育、存活和可塑性的第二信使。2002年，Izzo et al.已报告 脑室抑制PI3K阻断可卡因诱导的精神运动敏化的表达 (自然神经学)。随后的研究表明，反复接触可卡因可以增加大脑中PI3K的活性 内侧前额叶皮质(MPFC)。然而，mPFC PI3K和可卡因之间的因果关系- 诱发的行为后遗症仍未得到证实。我们将直接操作PI3K亚基p110β来 减少可卡因后刺激引起的习惯。 P110β是PI3K的四个催化亚基之一，在整个出生后高度表达 发展阶段和成年阶段。我们发现，编码p110β的Pik3cb的减少在整个 MPFC阻断刺激诱导的习惯和可卡因暴露后的运动敏感化 青春期或青壮年。这是在人类身上进行大量药物试验的时期。在AIM 1，我们将使用病毒介导的基因沉默来确定特定的mPFC亚区负责 Pik3cb抑制的“保护性”后果。 反复接触可卡因的一个广泛报道的后果是多巴胺受体失衡。 介导的信号，有利于D2家族Gs偶联的系统，而不是D2家族的Gi偶联系统。D1 刺激激活PI3K，这可能是心理刺激剂加强基于习惯的机制 行为。DRD1在mPFC中的过表达降低了下游纹状体中D2的表达， 提示可卡因后mPFC D1介导的信号的正常化可能与纹状体D2有关 系统。在目标2中，我们将检验这样的假设，即在mPFC中抑制Pik3cb会产生一个允许的 背内侧纹状体D2依赖的目标定向反应策略的环境。 可卡因可诱导mPFC内依赖活性的树突棘增殖。同时，抑制 PI3K p110β可使脆性X综合征模型树突棘异常增殖正常化。因此， 抑制p110β可以纠正可卡因诱导的脊髓形成。此外，PI3K p110δ和γ调节 RhoA GTPase依赖的神经元收缩和NMDA受体依赖的长期抑郁， 分别进行了分析。在目标3中，我们将检验抑制p110β和δ将纠正树突棘的假设。 可卡因后的密度和阻断习惯，而p110γ抑制可能加剧可卡因的影响。 我们的发现表明，p110β阻断赋予可卡因一定的行为弹性。建议数 研究将明确解剖机制和细胞结构后果。从以下方面获得的知识 这些实验可以推进药物使用障碍的治疗策略，因为亚单位具有选择性 与广谱PI3K阻滞剂相比，抑制剂可能具有更有利的临床特征。

SUMMARY PI3-kinase (PI3K) is a membrane-associated signaling complex that phosphorylates phosphoinositides, second messengers that regulate neuronal development, survival, and plasticity. In 2002, Izzo et al. reported that intraventricular PI3K inhibition blocks the expression of cocaine-induced psychomotor sensitization (Nature Neurosci.). Subsequent studies indicated that repeated cocaine exposure can increase PI3K activity in the medial prefrontal cortex (mPFC). Nevertheless, causal relationships between mPFC PI3K and cocaine- induced behavioral sequelae remain unconfirmed. We will directly manipulate the PI3K subunit p110β to mitigate stimulus-elicited habits following cocaine. p110β is one of the four PI3K catalytic subunits, and it is highly expressed throughout postnatal development and in adulthood. We find that reduction of Pik3cb, encoding p110β, broadly throughout the mPFC blocks stimulus-elicited habits and locomotor sensitization following cocaine exposure during adolescence or young adulthood. These are periods of considerable drug experimentation in humans. In Aim 1, we will use viral-mediated gene silencing to identify specific mPFC subregions responsible for the “protective” consequences of Pik3cb inhibition. One widely-reported consequence of repeated cocaine exposure is an imbalance in dopamine receptor- mediated signaling, favoring D1-family Gs-coupled, at the expense of D2-family Gi-coupled, systems. D1 stimulation activates PI3K and is a likely mechanism by which psychostimulants strengthen habit-based behavior. Overexpression of Drd1 in the mPFC decreases D2 expression in the downstream striatum, suggesting that normalization of mPFC D1-mediated signaling following cocaine could engage striatal D2 systems. In Aim 2, we will test the hypothesis that Pik3cb inhibition in the mPFC creates a permissive environment for dorsomedial striatal D2-dependent goal-directed response strategies. Cocaine can induce activity-dependent dendritic spine proliferation in the mPFC. Meanwhile, inhibiting PI3K p110β can normalize aberrant dendritic spine proliferation in models of Fragile X Syndrome. Thus, inhibiting p110β could conceivably correct cocaine-induced spinogenesis. Further, PI3K p110δ and γ regulate RhoA GTPase-dependent neuronal contraction and NMDA receptor-dependent long-term depression, respectively. In Aim 3, we will test the hypothesis that inhibiting p110β and δ will correct dendritic spine densities and block habits following cocaine, while p110γ inhibition could exacerbate cocaine’s influence. Our findings indicate that p110β blockade confers certain behavioral resiliencies to cocaine. The proposed studies will crystallize anatomical mechanisms and cyto-structural consequences. Knowledge gained from these experiments could advance treatment strategies for drug use disorders, given that subunit-selective inhibitors may have more favorable clinical profiles than broad-spectrum PI3K blockade.