Understanding dynorphin and dopamine dynamics during fentanyl exposure

项目总结/摘要 美国目前正处于阿片类药物流行病和非法制造的合成阿片类药物如芬太尼的兴起之中。 是导致吸毒过量死亡人数翻三倍的主要原因为了更好地了解非法芬太尼的使用， 成瘾，我们必须更好地了解内源性阿片功能。kappa上调 阿片受体（KOR）系统及其内源性神经肽强啡肽与成瘾性疾病有关 和痛苦. KOR的激活，特别是在富含多巴胺的大脑区域（中脑核，NAc， 和腹侧被盖区（VTA）产生负性情感状态并降低动机。但我们的 最近的工作沿着其他人的工作表明，强啡肽/KOR系统在NAc壳层中的功能更多， 细致入微我们已经证明，光刺激腹侧NAc壳中的强啡肽能神经元可以驱动 光刺激背侧强啡肽能神经元， NAc外壳驱动奖励样行为和强啡肽释放，对NAc外壳的确切作用的理解有限。 药物暴露中的强啡肽部分是由于缺乏对释放的强啡肽的可靠体内测量 程度.本提案的目的是确定强啡肽释放是否在急性芬太尼 暴露在不同的亚区的NAc和调查强啡肽的预测是至关重要的 情感调节剂和芬太尼诱导的多巴胺释放。强啡肽/KOR在NAc中上调 在强迫性药物服用后，如mRNA和蛋白质水平的增加所示。然而，目前还不知道 如果强啡肽在急性药物暴露后被招募，以及这是否转化为强啡肽的增加， release.在目标1中，我将直接检验这一假设，即背侧和腹侧NAc壳强啡肽的释放是 使用体内微透析和伏安法在急性芬太尼暴露后差异活化。]]虽然 KOR介导的多巴胺抑制主要归因于KOR对多巴胺末梢的直接作用， 腹侧被盖区的NAc、KOR也是情感行为和神经传递的重要调节因子。尽管如此， 从NAc到VTA的强啡肽能投射是否在调节情感和药物方面具有独特的作用， 诱发多巴胺释放。[[在目标2中，我将检验不同的强啡肽表达神经元 从NAc到VTA的投射传递正和负价信号，同时也调节芬太尼- 使用光遗传学，实时位置测试和快速扫描循环测试以双相方式诱导多巴胺释放。 伏安法一旦我们了解了强啡肽信号在急性芬太尼暴露期间是如何被招募的，以及 这种募集调节芬太尼诱发的多巴胺释放，然后我们可以开始研究强啡肽， 慢性芬太尼暴露期间的多巴胺动力学，并确定安全有效的新靶点 缓解非法芬太尼使用和成瘾。]]这一多学科研究金培训计划的成功， 结合活动，以扩大我的科学和职业发展，将促进示范 在研究，合作和教育的机会，由华盛顿大学医学院提供。

PROJECT SUMMARY/ABSTRACT The U.S. is currently amidst an opioid epidemic and the rise of illicitly manufactured synthetic opioids like fentanyl is largely responsible for the tripling of overdose deaths. In order to better understand illicit fentanyl use and addiction, we must develop a better understanding of endogenous opioid function. Upregulation of the kappa opioid receptor (KOR) system and its endogenous neuropeptide dynorphin is implicated in disorders of addiction and pain. Activation of KORs, specifically in brain regions enriched with dopamine (nucleus accumbens, NAc, and ventral tegmental area, VTA), produces negative affective states and decreases motivation. However, our recent work along with others has shown that the function of the dynorphin/KOR system in the NAc shell is more nuanced. We have shown that photostimulation of dynorphinergic neurons in the ventral NAc shell drives aversive-like responses and dynorphin release whereas photostimulation of dynorphinergic neurons in the dorsal NAc shell drives reward-like behavior and dynorphin release, A limited understanding of the precise role of dynorphin in drug exposure is in part due to the lack of reliable in vivo measurements of released dynorphin levels. The goal of this proposal is to determine whether dynorphin release is recruited during acute fentanyl exposure in distinct subregions of the NAc and investigate which dynorphinergic projections are critical modulators of affect and fentanyl-induced dopamine release. Dynorphin/KORs are upregulated in the NAc following compulsive drug taking, as shown by increases in mRNA and protein levels. [[However, it is not known if dynorphin is recruited following acute drug exposure and whether this translates to an increase in dynorphin release. In Aim 1, I will directly test the hypothesis that dorsal and ventral NAc shell dynorphin release is differentially activated following acute fentanyl exposure using in vivo microdialysis and voltammetry.]] Although KOR-mediated dopamine suppression is largely attributed to direct action of KORs on dopamine terminals in the NAc, KORs in the VTA also act as a key regulator of affective behaviors and neurotransmission. Still, it is unclear whether dynorphinergic projections from the NAc to the VTA have a distinct role in modulating affect and drug evoked dopamine release. [[ In Aim 2, I will test the hypothesis that distinct dynorphin-expressing neuronal projections from the NAc to the VTA transmit positive and negative valence signals while also regulating fentanyl- induced dopamine release in a biphasic manner using optogenetics, real-time place testing, and fast-scan cyclic voltammetry. Once we understand how dynorphin signaling is recruited during acute fentanyl exposure and how this recruitment modulates fentanyl evoked dopamine release, we can then begin to investigate dynorphin and dopamine dynamics during chronic contingent fentanyl exposure and identify new targets for safe and effective mitigation of illicit fentanyl use and addiction.]] The success of this multidisciplinary fellowship training plan, which incorporates activities to expand my scientific and career development, will be facilitated by the exemplary opportunities in research, collaboration, and education provided by Washington University School of Medicine.