Reduced complexity mapping of oxycodone self-administration and stress responsiveness in rats

摘要 目前的阿片类药物流行是由处方止痛药的稳步上升推动的，如奥施康定，它是 羟考酮控释片。尽管临床和动物研究都发现， 药物作用的开始影响成瘾的发展，特别是滥用的可能性 羟考酮即使在控释剂中被摄入时也表现出来。的遗传性 据估计，人类对阿片成瘾的比例约为0.5。然而，很少有人类遗传学研究 由于难以聚集必要的大量研究人员，已经进行了一些研究。在这份提案中， 我们的目标是进行基因定位研究，以确定影响羟考酮动机的遗传因素。 行为和对压力的脆弱性，这是阿片类药物使用障碍的主要风险因素。遵循临床用法 模式，我们开发了一种可操作性的口服羟考酮自我给药模型，在该模型中，大鼠自愿消耗 口服羟考酮以获得远高于临床处方的剂量。WMI和WLI近交系 我们打算在这项研究中使用的大鼠是从应激敏感的Wistar京都大鼠中选择性地培育出来的。这个 WMI是抑郁症和压力易感性的既定动物模型，而WLI则是其 等基因对照。我们的初步数据显示，在 WMI与WLI菌株进行比较。我们还发现，女性的羟考酮摄入量高于男性。 基础血浆皮质酮(CORT)和稳态血浆皮质酮(CORT)也存在应变和性别差异 海马糖皮质激素受体(NR3C1)的表达。因此，我们假设 对羟考酮停药的基因决定的应激反应驱动羟考酮的品系差异 寻求羟考酮的自我管理和恢复。在目标1中，我们将使用降低的复杂性 确定羟考酮和应激反应表型的致病遗传因素的作图策略。这 遗传力高，菌株对表型的影响大，存在 WMI和WLI菌株的全基因组测序数据(每株覆盖约100倍，高约4,400 菌株之间的可信度多态)。在目标2中，我们将使用系统识别候选基因 遗传学方法。WLI和WMI之间的分离变体数量很少，这极大地促进了这一目标。 在目标3中，我们将使用已建立的WMI/WLI上的敲打CAG-LSL-Cas9大鼠模型来确认原因基因 遗传背景。

Abstract The current opioid epidemic is fueled by the steady rise of prescription painkillers, such as OxyContin, which is a controlled-release tablet of oxycodone. Although both clinical and animal studies have found that the rate of onset of drug action influences the development of addiction, the exceptionally strong abuse liability of oxycodone was manifested even when it was consumed in the controlled-release from. The heritability of opioid addiction has been estimated to be approximately 0.5 in humans. However, few human genetics studies have been conducted due to the difficulty in assembling the necessary large study population. In this proposal, we aim to conduct a genetic mapping study to identify genetic factors influencing oxycodone-motivated behaviors and vulnerability to stress, a major risk factor of opioid use disorder. To follow the clinical use pattern, we developed an operant oral oxycodone self-administration model, where rats voluntarily consume oral oxycodone to obtain doses that are well above clinical prescriptions. The WMI and WLI inbred strains of rats we propose to use in this study were selectively bred from the stress-vulnerable Wistar Kyoto rat. The WMI is an established animal model of depression and vulnerability to stress, while the WLI serves as its isogenic control. Our preliminary data showed higher levels of oxycodone intake and oxycodone seeking in the WMI compared to the WLI strains. We also found that females have higher oxycodone intake than males. There were also strain and sex differences in basal plasma corticosterone (CORT) and steady-state hippocampal glucocorticoid receptor (Nr3c1) expression. We therefore hypothesized that genetically-determined stress response to oxycodone withdrawal drives the strain differences in oxycodone self-administration and reinstatement of oxycodone seeking. In Aim 1, we will use a reduced complexity mapping strategy to identify the causal genetic factors for oxycodone and stress response phenotypes. This mapping strategy is supported by the high heritability, large effect size of strain on phenotypes, and existing whole genome sequencing data for the WMI and WLI strains ( ~100x coverage per strain, with ~4,400 high confidence polymorphisms between strains). In Aim 2, we will identify candidate genes using a systems genetics approach. The low number of segregating variants between WLI and WMI greatly facilitates this goal. In Aim 3, we will confirm causal genes using an established knockin CAG-LSL-Cas9 rat model on the WMI/WLI genetic background.