VA San Diego Healthcare System, San Diego, CA, 92161, USA.
Departments of Molecular Medicine and Neuroscience, Scripps Research, La Jolla, CA, 92037, USA.
Neuropharmacology. 2021 Mar 1;185:108438. doi: 10.1016/j.neuropharm.2020.108438. Epub 2020 Dec 15.
Alterations in the function of prefrontal cortex (PFC) and hippocampus have been implicated in underlying the relapse to alcohol seeking behaviors in humans and animal models of moderate to severe alcohol use disorders (AUD). Here we used chronic intermittent ethanol vapor exposure (CIE), 21d protracted abstinence following CIE (21d AB), and re-exposure to one vapor session during protracted abstinence (re-exposure) to evaluate the effects of chronic ethanol exposure on basal synaptic function, neuronal excitability and expression of key synaptic proteins that play a role in neuronal excitability in the medial PFC (mPFC) and dentate gyrus (DG). CIE consistently enhanced excitability of layer 2/3 pyramidal neurons in the mPFC and granule cell neurons in the DG. In the DG, this effect persisted during 21d AB. Re-exposure did not enhance excitability, suggesting resistance to vapor-induced effects. Analysis of action potential kinetics revealed that altered afterhyperpolarization, rise time and decay time constants are associated with the altered excitability during CIE, 21d AB and re-exposure. Molecular adaptations that may underlie increases in neuronal excitability under these different conditions were identified. Quantitative polymerase chain reaction of large-conductance potassium (BK) channel subunit mRNA in PFC and DG tissue homogenates did not show altered expression patterns of BK subunits. Western blotting demonstrates enhanced phosphorylation of Ca⁺/calmodulin-dependent protein kinase II (CaMKII), and reduced phosphorylation of glutamate receptor GluN2A/2B subunits. These results suggest a novel relationship between activity of CaMKII and GluN receptors in the mPFC and DG, and neuronal excitability in these brain regions in the context of moderate to severe AUD.
前额叶皮层（PFC）和海马体功能的改变与人类和中度至重度酒精使用障碍（AUD）动物模型中复饮酒精寻求行为的潜在机制有关。在这里，我们使用慢性间歇乙醇蒸气暴露（CIE）、CIE 后 21 天延长禁欲期（21dAB）以及在延长禁欲期期间重新暴露于一次蒸气接触（重新暴露）来评估慢性乙醇暴露对基底突触功能、神经元兴奋性和关键突触蛋白表达的影响，这些蛋白在 PFC 中间区（mPFC）和齿状回（DG）中发挥调节神经元兴奋性的作用。CIE 一致增强了 mPFC 中 2/3 层锥体神经元和 DG 中颗粒细胞神经元的兴奋性。在 21dAB 期间，这种影响持续存在。重新暴露并没有增强兴奋性，这表明对蒸气诱导的效应具有抗性。动作电位动力学分析表明，改变后的超极化、上升时间和衰减时间常数与 CIE、21dAB 和重新暴露期间的改变兴奋性有关。鉴定了可能导致不同条件下神经元兴奋性增加的分子适应。PFC 和 DG 组织匀浆中大电导钾（BK）通道亚基 mRNA 的定量聚合酶链反应未显示 BK 亚基的表达模式改变。Western blot 显示 Ca²⁺/钙调蛋白依赖性蛋白激酶 II（CaMKII）的磷酸化增强，谷氨酸受体 GluN2A/2B 亚基的磷酸化减少。这些结果表明，在中度至重度 AUD 背景下，mPFC 和 DG 中 CaMKII 和 GluN 受体的活性与这些脑区的神经元兴奋性之间存在新的关系。
