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

摘要 目前阿片类药物的流行是由处方止痛药的稳步上升推动的，如奥施康定， 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， 羟考酮即使在控释形式中被消耗时也表现出来。的遗传力 阿片类药物成瘾在人类中估计约为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群，因此进行了研究。在这一提议中， 我们的目的是进行遗传图谱研究，以确定影响羟考酮动机的遗传因素， 行为和易受压力，阿片类药物使用障碍的主要危险因素。跟踪临床使用 模式，我们开发了一种操作性口服羟考酮自我给药模型，其中大鼠自愿消耗 口服羟考酮以获得远高于临床处方的剂量。将两个近交系分别进行了比较， 我们建议在本研究中使用的大鼠是从易受应激影响的Wistar京都大鼠中选择性繁殖的。的 抑郁症是一种建立的抑郁症和易受压力影响的动物模型，而WLI则是其 同基因控制我们的初步数据显示， 与WLI菌株相比，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）也存在品系和性别差异。 海马糖皮质激素受体（Nr 3c 1）表达。因此，我们假设， 基因决定的对羟考酮戒断的应激反应驱动羟考酮的应变差异 自我管理和恢复羟考酮寻求。在目标1中，我们将使用降低的复杂度 作图策略，以确定羟考酮和应激反应表型的因果遗传因素。这 高遗传力、菌株对表型的大效应量和现有的遗传标记支持了作图策略。 WLI和WLI菌株的全基因组测序数据（每个菌株的覆盖率约为100倍，约4，400个高 菌株之间的置信多态性）。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WLI之间的分离变体的数量少，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敲入CAG-LSL-Cas9大鼠模型在WLI/WLI上确认致病基因。 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.