Dysregulation of Protein Synthesis in Fragile X Syndrome

在2012年融资期间，我们处理了以下问题： 我们测量了15名男性受试者（18-24岁）与完整的脆性X突变和12名年龄匹配的健康志愿者的rCPS。由于他们的损伤，有必要在深度镇静下研究FXS受试者。我们用异丙酚作为镇静剂。每个健康志愿者被研究两次，一次清醒，一次在丙泊酚镇静下，我们发现在整个大脑或在任何10个区域检查的rCPS没有差异。与我们的假设相反，与镇静对照组相比，丙泊酚镇静下的FXS受试者在全脑、小脑、额叶和顶叶皮质中的rCPS在统计学上显著降低。 我们认为丙泊酚可能对FXS受试者的rCPS产生不同的影响，从而掩盖了rCPS的基线升高，我们在Fmr 1 KO小鼠模型中检查了这种可能性。我们在成年Fmr 1基因敲除小鼠中的研究表明，丙泊酚导致整个大脑的rCPS广泛且显著降低，而在WT小鼠中的影响非常有限，幅度较小。我们观察到，用改变神经元和可能的突触活性的药物治疗也改变了Fmr 1 KO小鼠的rCPS，这对FXS治疗策略的发展具有影响。 报告这些结果的手稿正在审查中。 我们研究了未处理或用含锂食物处理的WT和Fmr 1 KO小鼠，这些小鼠在断奶时开始并在整个实验期间维持。 在8至12周龄之间，对小鼠进行以下行为测试：旷场、社会互动、高架十字迷宫、高架零迷宫和被动回避。在13周时，制备大脑用于高尔基染色和内侧前额叶皮质中树突棘形态学分析。 在不同的小鼠组中，我们在12周龄时测量了rCPS。 我们发现，与未经处理的WT相比，未经处理的Fmr 1 KO小鼠多动，焦虑减少，社交互动受损，被动回避测试缺陷。Fmr 1基因敲除小鼠内侧前额叶皮质的树突棘较长，数量增加。锂治疗改善了多动和逆转受损的社会互动和学习缺陷。锂治疗也使一般性焦虑水平和树突棘形态正常化。此外，锂长期治疗逆转了在Fmr 1 KO小鼠中发现的rCPS增加，并且对WT小鼠中的rCPS几乎没有影响。 与WT相比，未处理的Fmr 1 KO小鼠中rCPS增加主要见于边缘系统和下丘脑，而锂的作用发生在整个大脑中。 我们扩展了我们的研究，以检查海马体中锂处理对影响翻译的一些信号通路的影响。 我们的结果表明，无论是对PI 3 K/Akt或ERK 1/2通路的影响不能完全解释我们的研究的基础条件下对rCPS的影响。 这些研究的结果发表在International Journal of Neuropsychopharmacology（Liu等人，2011）和Neurobiology of Disease（Liu等人，2012年）。

During the 2012 funding period, we addressed the following: We measured rCPS in 15 male subjects (18-24 y) with the full fragile X mutation and 12 age-matched healthy volunteers. Because of their impairments it was necessary to study FXS subjects under deep sedation. We used propofol as the sedating agent. Each healthy volunteer was studied twice, once awake and once under propofol-sedation, and we found no differences in rCPS in whole brain or in any of the 10 regions examined. Contrary to our hypothesis, FXS subjects under propofol-sedation had statistically significantly reduced rCPS in whole brain, cerebellum, frontal and parietal cortex compared with sedated controls. We considered the possibility that propofol could have a disparate effect on rCPS in FXS subjects thereby masking a baseline elevation in rCPS, and we examined this possibility in the Fmr1 KO mouse model. Our study in adult Fmr1 KO mice showed that propofol results in widespread and significantly decreased rCPS throughout the brain whereas effects in WT mice were very circumscribed and smaller in magnitude. Our observation that treatment with a drug that alters neuronal and possibly synaptic activity also alters rCPS in Fmr1 KO mice has implications for the development of therapeutic strategies for FXS. A manuscript reporting these results is under review. We studied WT and Fmr1 KO mice untreated or treated with lithium-containing chow commenced at weaning and maintained throughout the experiment. Between 8 and 12 weeks of age, mice were subjected to the following behavioral tests: open field, social interaction, elevated plus maze, elevated zero maze and passive avoidance. At 13 weeks, brains were prepared for Golgi staining and analysis of dendritic spine morphology in medial prefrontal cortex. In separate groups of mice treated identically we measured rCPS at 12 weeks of age. We found that compared with untreated WT, untreated Fmr1 KO mice were hyperactive and had reduced anxiety, impaired social interactions, and deficits on the passive avoidance test. Dendritic spines in medial prefrontal cortex were longer and increased in number in Fmr1 KO mice. Lithium treatment ameliorated the hyperactivity and reversed impaired social interaction and learning deficits. Lithium treatment also normalized general anxiety levels and dendritic spine morphology. Moreover, chronic treatment with lithium reversed the increased rCPS found in Fmr1 KO mice and had little, if any, effect on rCPS in WT mice. Increased rCPS in the untreated Fmr1 KO mice compared with WT were found primarily in the limbic system and hypothalamus, whereas the effects of lithium occurred throughout the brain. We extended our studies to examine in hippocampus the effects of lithium treatment on some of the signaling pathways that influence translation. Our results indicate that neither effects on the PI3K/Akt nor the ERK 1/2 pathway can fully account for the effects on rCPS under the basal conditions of our study. Results of these studies were published in International Journal of Neuropsychopharmacology (Liu et al., 2011) and Neurobiology of Disease (Liu et al., 2012).