Cellular and Circuit Mechanisms Responsible for Dynorphin Actions in mPFC

项目摘要：kappa阿片受体(KOR)在人类体内的药理激活引发了以下报道 烦躁不安和认知障碍。激动剂或应激诱导的强啡肽释放对啮齿动物KOR的激活 已被证明会产生厌恶情绪，增加焦虑样行为，增加药物的奖励作用 滥用(如可卡因、安非他命、海洛因、乙醇和尼古丁)，增加成瘾药物的自我给药，以及 恢复已绝迹的寻毒行为。导致这些的细胞和分子机制 强啡肽依赖的、促成瘾的行为还没有完全被理解，更好的理解可能会提示 治疗压力相关疾病的新治疗方法，包括复吸药物。之前 该奖项支持的研究表明，KOR激活在中缝背侧、腹侧被盖和 应激诱导腹侧纹状体释放强啡肽或药物KOR激动剂产生 5-羟色胺能p38丝裂原激活增强小鼠对可卡因条件性位置偏爱 和多巴胺能神经元来调节兴奋性和5-羟色胺的运输。最近的研究支持这一点 该研究继续确定强啡肽在前额叶皮层内侧的分子和细胞位置。 (MPFC)和KOR对大脑这些部位神经元回路功能的调节机制。研究 在本申请中提出的将继续建立在这一坚实的基础上，通过表征蜂窝和 强啡肽/KOR诱导mPFC认知障碍的分子机制我们建议 为了解决三个问题：在MPFC中突触前和突触后KOR的个体贡献是什么 在操作型延迟交替任务中控制行为？需要什么行为刺激才能唤起 强啡肽在mPFC中的释放？强啡肽释放和KOR激活对神经细胞兴奋性有何影响 MPFC神经元？我们的背景研究证实，药物性KOR激活会扰乱表现 在延迟交替操作任务中，这种效应可以被KOR的局部失活所阻断 拮抗剂(NorBNI)或通过病毒介导的PFC Kors基因切除(AAV-Cre in the PFC) 雄鼠)。KOR激活对雌性动物延迟交替行为的影响尚不清楚。 应激诱导的内源性强啡肽在PFC中的释放也破坏了延迟交替中的表现 任务，但不同形式的行为应激的有效性尚未确定。KOR表示在 PFC回路的突触前和突触后成分，但各自对控制的贡献延迟 交替表现目前还不清楚。初步结果显示纳洛酮在体内有沉淀 吗啡依赖雄性小鼠戒断后可引起mPFC中强啡肽的释放，这表明 强啡肽介导的认知障碍可能是阿片类药物戒断状态的一个组成部分。建议数 研究将进一步促进我们对kappa选择性配体在糖尿病中的治疗潜力的理解。 治疗慢性疼痛和药物成瘾。

Project Summary: Pharmacological activation of kappa opioid receptors (KOR) in humans elicits reports of dysphoria and cognitive disruption. KOR activation in rodents by agonists or by stress-evoked dynorphin release has been shown to produce aversion, increase anxiety-like behaviors, increase the rewarding effects of drugs of abuse (e.g. cocaine, amphetamine, heroin, ethanol & nicotine), increase addictive drug self-administration, and reinstate extinguished drug-seeking behaviors. The cellular and molecular mechanisms responsible for these dynorphin-dependent, pro-addictive behaviors are not fully understood, and a better understanding may suggest new therapeutic approaches to the treatment of stress-related diseases including relapse to drug use. Prior studies supported by this award demonstrated that KOR activation in the dorsal raphe, ventral tegmentum and ventral striatum by stress-induced release of dynorphin or pharmacological KOR agonist administration produces aversion in mice and potentiates cocaine conditioned place preference by activating p38 MAPK in serotonergic and dopaminergic neurons to regulate excitability and serotonin transport. Recent studies supported by this award continued to define the molecular and cellular sites of dynorphin action in the medial prefrontal cortex (mPFC) and mechanisms of KOR regulation of neuronal circuit function at each of these sites in brain. Studies proposed in the present application will continue to build on this strong foundation by characterizing cellular and molecular mechanisms responsible for dynorphin / KOR induced cognitive disruption in the mPFC. We propose to address three questions: What are the individual contributions of pre- and postsynaptic KORs in the mPFC in controlling behavior in an operant delayed alternation task? What are the behavioral stimuli required to evoke dynorphin release in mPFC? What are the effects of dynorphin release and KOR activation on excitability of mPFC neurons? Our background studies establish that pharmacological KOR activation disrupts performance in the delayed alternation operant task, and this effect can be blocked by local KOR inactivation by a KOR antagonist (norBNI) or by virally-mediated genetic excision of PFC KORs (AAV-Cre in the PFC of floxed KOR male mice). The effects of KOR activation on delayed alternation performance in females are not yet known. Stress-induced release of endogenous dynorphins in PFC also disrupt performance in the delayed alternation task, but the efficacy of different forms of behavioral stress have not yet been established. KOR is expressed on both pre- and postsynaptic components of the PFC circuit, but the respective contributions to controlling delayed alternation performance are not yet understood. Preliminary results demonstrate that naloxone precipitated withdrawal in morphine dependent male mice evokes dynorphin release in mPFC, and this suggests that dynorphin-mediated disruption of cognition may be a component of the opioid abstinent state. The proposed studies would further advance our understanding of the therapeutic potential of kappa selective ligands in the treatment of chronic pain and drug addiction.