Regulation of binge-like ethanol intake by arcuate POMC projection neurons

摘要 内源性阿片系统与奖励、强化和激励作用密切相关。 阿片受体拮抗剂纳曲酮和阿片受体拮抗剂纳曲酮和阿片受体拮抗剂的临床疗效 纳美芬可减少酒精摄入量、复发倾向和渴求。动物研究表明， 乙醇能激活大脑内的各种阿片肽环路，包括大脑的 大脑中皮质边缘奖赏回路和杏仁核。最近我们收集了多条证据 这表明乙醇激活了下丘脑弓状核(ArcN)内的一组神经元 表达前阿片黑素皮质素，可产生多种生物活性神经肽，包括- 内啡肽。利用膜片钳电生理学，我们观察到浴中施加乙醇(5-40 mM) 增加记录的ArcN POMC神经元~35%的放电频率。同样，使用FosB 免疫组织化学，我们证明了暴饮式酒精摄入大约激活了ArcN的一个子集 POMC神经元，其中大多数合成-内啡肽与-MSH。逆行追踪发现了狂欢- 与酒精摄入一样，酒精摄入主要激活投射到杏仁核的ArcN POMC神经元，激活的神经元较少 投射到腹侧被盖区(VTA)或伏隔核(NAC)的神经元。令人惊讶的是，化学发生 未划分亚群的ArcN POMC神经元的调制对酒精摄入量无影响。然而， 我们推测，这些效应的缺乏是由于一些ArcN激活的非特异性性质造成的 包含子电路的POMC神经元。暴饮式酒精摄入量的基线性别差异被观察到，其中 雌性小鼠比雄性小鼠消耗更多的乙醇，我们观察到ER是 定位于ArcN POMC神经元上的初级女性性激素受体与ER、或孕酮的比较 感受器。总之，这些观察结果导致了我们的总体假设，即ArcN POMC神经元 向中脑边缘奖赏系统区域的投射调节性别依赖患者的暴饮式酒精摄入量 途径主要是通过ER依赖机制。为了验证这一假设，我们制定了以下公式 既相互关联又相互独立的具体目标。在目标1中，我们将确定乙醇对 ArcN POMC投射神经元的神经生理学特性。在目标2中，我们将确定 特定ArcN POMC传出投射神经元对暴饮式酒精摄入的化学调控。 最后，在目标3中，我们将确定ER在狂欢样乙醇调节POMC神经元中的作用 摄取和与中脑多巴胺神经元的潜在相互作用。总之，这些研究将阐明具体的 阿片类回路和调节暴饮式酒精摄入的机制，这将指导改善 治疗酒精使用障碍的神经调节和/或药理学方法。

ABSTRACT The endogenous opioid system is strongly implicated in the rewarding, reinforcing, and motivational effects of ethanol, as evidenced by the established clinical efficacy of the opioid receptor antagonists naltrexone and nalmefene in reducing ethanol intake, relapse propensity, and craving. Animal studies have demonstrated that ethanol activates various opioid peptide-containing circuits within the brain, including regions of the mesocorticolimbic reward circuitry and amygdala. Recently we have generated multiple lines of evidence indicating that ethanol activates a subset of neurons within the arcuate nucleus (ArcN) of the hypothalamus expressing pro-opiomelanocortin (POMC), which gives rise to numerous bioactive neuropeptides including - endorphin. Using patch clamp electrophysiology, we observed that bath application of ethanol (5-40 mM) increases the firing frequency of ~35% of recorded ArcN POMC neurons. Similarly, using FosB immunohistochemistry, we demonstrated that binge-like ethanol intake activates approximately a subset of ArcN POMC neurons, the majority of which synthesize -endorphin vs. -MSH. Retrograde tracing revealed binge- like ethanol intake primarily activates ArcN POMC neurons projecting to the amygdala, with fewer activated neurons projecting to the ventral tegmental area (VTA) or nucleus accumbens (NAc). Surprisingly, chemogenetic modulation of ArcN POMC neurons without subpopulation delineation had no effect on ethanol intake. However, we speculate that these lack of effects were due to the non-specific nature of activation of a number of ArcN POMC neuron containing subcircuits. Baseline sex differences in binge-like ethanol intake were observed, where female mice consumed significantly more ethanol than their male counterparts, and we observed that ER is the primary female sex hormone receptor located on ArcN POMC neurons as compared to ER or progesterone receptors. Together, these observations have led to our overarching hypothesis that ArcN POMC neuron projections to regions of the mesolimbic reward system regulate binge-like ethanol intake in a sex-dependent manner primarily via ER dependent mechanisms. To test this hypothesis, we have formulated the following inter-related yet independent Specific Aims. In Aim 1, we will determine the effects of ethanol on the neurophysiological properties of ArcN POMC projection neurons. In Aim 2, we will determine the effects of chemogenetic modulation of specific ArcN POMC efferent projection neurons on binge-like ethanol intake. Finally, in Aim 3, we will determine the role of ER on POMC neurons in the regulation of binge-like ethanol intake and potential interactions with midbrain dopamine neurons. Together, these studies will elucidate specific opioid circuits and mechanisms regulating binge-like ethanol intake, which will guide the improvement of neuromodulatory and/or pharmacological approaches for the treatment of alcohol use disorders.