Department of Neuroscience, The Scripps Research Institute, La Jolla, CA, USA.
Addict Biol. 2018 Sep;23(5):1117-1129. doi: 10.1111/adb.12568. Epub 2017 Sep 22.
Repeated cycles of alcohol [ethanol (EtOH)] intoxication and withdrawal dysregulate excitatory glutamatergic systems in the brain and induce neuroadaptations in the medial prefrontal cortex (mPFC) that contribute to cognitive dysfunction. The mPFC is composed of subdivisions that are functionally distinct, with dorsal regions facilitating drug-cue associations and ventral regions modulating new learning in the absence of drug. A key modulator of glutamatergic activity is the holoenzyme calcium/calmodulin-dependent protein kinase II (CaMKII) that phosphorylates ionotropic glutamate receptors. Here, we examined the hypothesis that abstinence from chronic intermittent EtOH (CIE) exposure dysregulates CaMKII activity in the mPFC to impair cognitive flexibility. We used an operant model of strategy set shifting in male Long-Evans rats demonstrating reduced susceptibility to trial omissions during performance in a visual cue-guided task versus albino strains. Relative to naïve controls, rats experiencing approximately 10 days of abstinence from CIE vapor exposure demonstrated impaired performance during a procedural shift from visual cue to spatial location discrimination. Phosphorylation of CaMKII subtype α was upregulated in the dorsal, but not ventral mPFC of CIE-exposed rats, and was positively correlated with perseverative-like responding during the set shift. The findings suggest that abstinence from CIE exposure induces an undercurrent of kinase activity (e.g. CaMKII), which may promote aberrant glutamatergic responses in select regions of the mPFC. Given the role of the mPFC in modulating executive control of behavior, we propose that increased CaMKII subtype α activity reflects a dysregulated 'top-down' circuit that interferes with adaptive behavioral performance under changing environmental demands.
反复的酒精(乙醇)摄入和戒断周期会扰乱大脑中的兴奋性谷氨酸能系统,并在大脑前额皮质(mPFC)中诱导神经适应,从而导致认知功能障碍。mPFC 由功能不同的分区组成,背侧区域促进药物线索关联,腹侧区域在没有药物的情况下调节新的学习。谷氨酸能活动的关键调节剂是全酶钙/钙调蛋白依赖性蛋白激酶 II(CaMKII),它磷酸化离子型谷氨酸受体。在这里,我们假设慢性间歇性乙醇(CIE)暴露戒断会扰乱 mPFC 中的 CaMKII 活性,从而损害认知灵活性。我们使用雄性长耳大鼠的操作性策略转换模型,该模型在视觉线索引导任务中表现出相对于白化品系对试验遗漏的敏感性降低。与未接受处理的对照组相比,经历约 10 天 CIE 蒸气暴露戒断的大鼠在从视觉线索到空间位置辨别程序转换期间表现出认知灵活性受损。CaMKII 亚型 α的磷酸化在 CIE 暴露大鼠的背侧 mPFC 中上调,但在腹侧 mPFC 中没有上调,并且与定势转换期间的持续性样反应呈正相关。这些发现表明,CIE 暴露戒断会引起激酶活性(例如 CaMKII)的暗流,这可能会促进 mPFC 中某些区域的异常谷氨酸能反应。鉴于 mPFC 在调节行为的执行控制中的作用,我们提出增加的 CaMKII 亚型 α 活性反映了失调的“自上而下”回路,该回路干扰了在不断变化的环境需求下的适应性行为表现。