Sensitive periods, development, and substance abuse

描述（由申请人提供）：药物使用通常始于青春期中期，但当它发生在青春期早期/童年后期时，药物使用与显著的终身成瘾风险相关。识别有风险的个体对于早期干预/预防至关重要，并且可能对长期减少成瘾有最大的影响。然而，这种方法需要了解风险的机制，并且证据应该是因果关系，而不是像以前的研究那样是相关的。此外，这种认识需要扩展到未成熟的雌性，在那里对神经变化和药物敏感性知之甚少。在这里，我们建议利用我们大量的初步数据，利用高度新颖和创新的方法来显示以下内容：a)相对于年轻和年老的大鼠，在青春期雄性大鼠中观察到边缘前额叶皮层（plPFC）谷氨酸能神经元D1多巴胺受体表达升高，并且与该年龄对药物相关线索的敏感性增加有关；b) plPFC中慢病毒载体（CamKII.D1）谷氨酸神经元上D1受体的基因工程升高增加了对可卡因相关信号的偏好；c)基因工程D1受体在GABA和谷氨酸神经元（Synapsin.D1）上的表达不增强药物线索敏感性；D)幼年大鼠寻求新奇与对可卡因相关环境的偏好相关（r=0.87）；e) D1多巴胺受体在血流模式中产生年龄依赖性变化，这很可能反映了D1受体在谷氨酸和GABA神经元上的分布。在一系列与# PA-07-226高度一致的研究中，我们建议使用这两种病毒载体来增加(a)或降低(b)对药物相关线索的敏感性，实验表明D1受体在谷氨酸神经元上的位置是风险机制（Aim I）。这些相同的动物也将表明，由于plPFC内谷氨酸神经元上的D1受体，原始的、强烈的药物线索关联更难以消除，并更强烈地恢复（Aim I）。目的II将确定幼年动物的求新行为是否可以作为一种行为指标来识别增加的药物线索敏感性，以及这与D1受体的关系。同时运行的Aim IV将使用CamKII。D1病毒和新颖性寻求确定药物omri是否可以通过独特的血流模式识别这种风险的生物标志物。目的III将确定在初始药物暴露时更温和的环境（例如，家庭-笼子）是否可以减少在以后生活中其他更突出的环境中的药物寻求。总之，这些研究将确定单个生物标志物如何预测药物使用风险并影响药物滥用的持久风险。

DESCRIPTION (provided by applicant): Substance use typically begins in mid-adolescence, but when it occurs earlier in adolescence/late childhood, drug use is associated with significant, life-long addiction liability. Identification of at-risk individuals is vital for early intervention/prevention and may have the greatest impact on reducing addiction long-term. However, this approach requires an understanding of the mechanism of risk and the proof should be causal, and not correlational, as in previous studies. In addition, this understanding needs to be extended to immature females, where extreme little is know about neural changes and drug sensitivity. Here, we propose to build on our substantial preliminary data that utilizes highly novel and innovative approaches to show the following: a) elevated D1 dopamine receptor expression on glutamatergic neurons in the prelimbic prefrontal cortex (plPFC) is observed in adolescent male rats relative to younger and older rats, and is associated with increased sensitivity to drug-associated cues at this age; b) gene engineered elevations in D1 receptors on glutamate neurons with a lentiviral vector (CamKII.D1) in the plPFC increases preferences to cocaine-associated cues; c) gene engineered D1 receptor expression on both GABA and glutamate neurons (Synapsin.D1) does not enhance drug-cue sensitivity; d) novelty-seeking in juvenile rats correlates with preferences for cocaine-associated environments (r=0.87); e) D1 dopamine receptors produce age-dependent changes in blood flow patterns that most likely reflect the distribution of D1 receptors on glutamate and GABA neurons. In a set of studies that are highly consistent with # PA-07-226, we propose to use these two viral vectors to increase (a) or decrease (b) sensitivity to drug-related cues to experimentally show that D1 receptor location on glutamate neurons is the risk mechanism (Aim I). These same animals will also show that the original, strong drug-cue associations are more difficult to extinguish and reinstate more strongly as a result of D1 receptors on glutamate neurons within the plPFC (Aim I). Aim II will determine whether novelty-seeking in juvenile animals can serve as an behavioral metric to identify increased drug-cue sensitivity and how this relates to D1 receptors. Aim IV, which runs concurrently, will use the CamKII.D1 virus and novelty-seeking to determine whether pharmacoMRI can identify this biomarker of risk through unique blood flow patterns. Aim III will determine whether a more benign environment at the time of initial drug exposure (e.g., home- cage) can reduce drug-seeking in other more salient environments later in life. Together, these studies will determine how a single biomarker predicts risk for substance use and influence enduring risk of drug abuse. PUBLIC HEALTH RELEVANCE: The goal of the proposed research is to determine whether elevated expression of the D1 dopamine receptor in the prefrontal cortex contributes to vulnerability to substance use in developing animals and can serve as a biomarker for early detection. D1 dopamine receptors are transiently over-expressed on specific neurons (e.g., glutamate) during adolescence, which is hypothesized to underlie enhanced vulnerability to cocaine at this stage. Here, we will use gene engineering to manipulate D1 receptor expression to conclusively show that this receptor underlies increased sensitivity to the initial formation of cocaine-associations and their maintenance, which may be detected by behavioral screening early and/or detected with pharmacoMRI and associated blood flow changes.