Role of Microglia in Prenatal ethanol exposure-induced Impairment of Endocannabinoid Signaling

产前酒精暴露(PE)可导致胎儿酒精谱系障碍(FASD)，由多种因素组成 认知/行为缺陷，包括学习障碍、注意力和执行功能缺陷， 上瘾风险增加，以及情绪障碍。FASD是最可预防的神经发育障碍， 然而，发病率仍然很高，在美国和世界上至少有2%-5%。因此，开发有效的 干预是FASD研究的一个重要目标。 包括未成熟突触在内的持续性突触功能障碍是介导 FASD的认知/行为缺陷。目前，这些效应的潜在机制尚不清楚。我们 研究表明，在成年期，PE导致小胶质细胞激活和异常的内源性大麻素(ECB)信号。 小胶质细胞和ECB信号在突触的成熟、维持和调节中都起着关键作用 大脑的功能。此外，据报道，激活的小胶质细胞释放的ECB增加 对抗神经炎症。我们还观察到，减少小胶质细胞的激活与 使PE动物的ECB信号、突触功能和行为正常化。这些观察结果导致了我们 中心假设PE诱导的持续性小胶质细胞激活导致紧张性ECB信号异常，这是 导致突触成熟/功能障碍和行为缺陷的长期损害。这 假设将使用腹侧被盖区多巴胺(VTA DA)神经元作为模型来验证 因为这些神经元是研究ECB信号和突触的极好方法 功能。此外，持续的小胶质细胞激活、异常的紧张性ECB信号和突触受损 在VTA中观察到了成熟/功能障碍。PE诱导的VTA DA突触功能障碍 神经元也与明确定义的行为缺陷相关--成瘾风险增加。一共有三个 具体目标利用多学科方法系统地验证中心假说。 目标1将彻底描述强直性ECB中PE所致损伤的剂量和性别效应 信号、突触成熟/稳态和小胶质细胞激活。目标2将检验PE- 诱导异常的紧张性ECB信号是由激活的小胶质细胞合成/释放ECB增加引起的。 目的3将验证这样的假设，即减少PE动物的小胶质细胞激活可以恢复突触 功能障碍和行为缺陷。 拟议的研究结果将导致对细胞机制的重要理解。 调节PE持续的细胞和认知/行为缺陷。研究结果还填补了一个知识空白。 关于PE如何影响神经元/小胶质细胞的相互作用，这是一个新的令人兴奋的研究领域。最后， 方法采用各种方法，旨在减少小胶质细胞的激活，以挽救细胞和行为 由PE引起的缺陷。因此，结果可以很容易地转化为FASD的干预策略。

Prenatal ethanol exposure (PE) leads to fetal alcohol spectrum disorders (FASD), which consist of many cognitive/behavioral deficits including learning disabilities, attention and executive function deficits, increased addiction risk, and mood disorders. FASD is the most preventable neurodevelopmental disorder, yet the prevalence is still high which is at least 2-5% in the US and the world. Therefore, developing effective interventions is an important goal for FASD research. Persistent synaptic dysfunctions including immature synapses are critical cellular mechanisms mediating cognitive/behavioral deficits in FASD. Currently, the underlying mechanisms for these effects are not clear. We have shown PE leads to microglial activation and aberrant endocannabinoid (eCB) signaling during adulthood. Both microglia and eCB signaling play a critical role in the maturation, maintenance, and regulation of synaptic functions in the brain. Furthermore, increased eCB release from activated microglia has been reported to counter neuroinflammation. We have also observed that reducing microglial activation is associated with normalized eCB signaling, synaptic functions, and behaviors in PE animals. These observations lead to our central hypothesis that PE-induced persistent microglial activation leads to aberrant tonic eCB signaling, which contributes to long-lasting impairments in synaptic maturation/dysfunctions and behavioral deficits. This hypothesis will be verified using the ventral tegmental area dopaminergic (VTA DA) neurons as a model system because these neurons represent an excellent approach for studying eCB signaling and synaptic functions. Furthermore, persistent microglial activation, aberrant tonic eCB signaling, and impaired synaptic maturation/dysfunctions have been observed in the VTA. The PE-induced synaptic dysfunctions of VTA DA neurons are also associated with a clearly defined behavioral deficit - increased addiction risk. There are three Specific Aims utilizing multidisciplinary approaches to systematically verify the central hypothesis. Aim 1 will thoroughly characterize the dose and sex effects of PE-induced impairments in tonic eCB signaling, synaptic maturation/homeostasis, and microglial activation. Aim 2 will test the hypothesis that PE- induced aberrant tonic eCB signaling is caused by increased eCB synthesis/release from activated microglia. Aim 3 will test the hypothesis that reducing microglial activation in PE animals can restore synaptic dysfunctions and behavioral deficits. The results of the proposed studies will lead to important understanding in the cellular mechanisms mediating the persistent cellular and cognitive/behavioral deficits of PE. The results also fill a knowledge gap regarding how PE impacts the neuron/microglia interaction, a new exciting area of research. Lastly, the approach employs various methods aiming at reducing microglial activation to rescue cellular and behavioral deficits induced by PE. Therefore, the results can be readily translated to intervention strategies for FASD.