PDF(Pubmed)
Abstract：
BACKGROUND: Mutations in the X-linked gene cyclin-dependent kinase-like 5 (CDKL5) cause a severe neurological disorder characterised by early-onset epileptic seizures, autism and intellectual disability (ID). Impaired hippocampal function has been implicated in other models of monogenic forms of autism spectrum disorders and ID and is often linked to epilepsy and behavioural abnormalities. Many individuals with CDKL5 deficiency disorder (CDD) have null mutations and complete loss of CDKL5 protein, therefore in the current study we used a Cdkl5-/y rat model to elucidate the impact of CDKL5 loss on cellular excitability and synaptic function of CA1 pyramidal cells (PCs). We hypothesised abnormal pre and/or post synaptic function and plasticity would be observed in the hippocampus of Cdkl5-/y rats.
METHODS: To allow cross-species comparisons of phenotypes associated with the loss of CDKL5, we generated a loss of function mutation in exon 8 of the rat Cdkl5 gene and assessed the impact of the loss of CDLK5 using a combination of extracellular and whole-cell electrophysiological recordings, biochemistry, and histology.
RESULTS: Our results indicate that CA1 hippocampal long-term potentiation (LTP) is enhanced in slices prepared from juvenile, but not adult, Cdkl5-/y rats. Enhanced LTP does not result from changes in NMDA receptor function or subunit expression as these remain unaltered throughout development. Furthermore, Ca2+ permeable AMPA receptor mediated currents are unchanged in Cdkl5-/y rats. We observe reduced mEPSC frequency accompanied by increased spine density in basal dendrites of CA1 PCs, however we find no evidence supporting an increase in silent synapses when assessed using a minimal stimulation protocol in slices. Additionally, we found no change in paired-pulse ratio, consistent with normal release probability at Schaffer collateral to CA1 PC synapses.
CONCLUSIONS: Our data indicate a role for CDKL5 in hippocampal synaptic function and raise the possibility that altered intracellular signalling rather than synaptic deficits contribute to the altered plasticity.
CONCLUSIONS: This study has focussed on the electrophysiological and anatomical properties of hippocampal CA1 PCs across early postnatal development. Studies involving other brain regions, older animals and behavioural phenotypes associated with the loss of CDKL5 are needed to understand the pathophysiology of CDD.
METHODS: To allow cross-species comparisons of phenotypes associated with the loss of CDKL5, we generated a loss of function mutation in exon 8 of the rat Cdkl5 gene and assessed the impact of the loss of CDLK5 using a combination of extracellular and whole-cell electrophysiological recordings, biochemistry, and histology.
RESULTS: Our results indicate that CA1 hippocampal long-term potentiation (LTP) is enhanced in slices prepared from juvenile, but not adult, Cdkl5-/y rats. Enhanced LTP does not result from changes in NMDA receptor function or subunit expression as these remain unaltered throughout development. Furthermore, Ca2+ permeable AMPA receptor mediated currents are unchanged in Cdkl5-/y rats. We observe reduced mEPSC frequency accompanied by increased spine density in basal dendrites of CA1 PCs, however we find no evidence supporting an increase in silent synapses when assessed using a minimal stimulation protocol in slices. Additionally, we found no change in paired-pulse ratio, consistent with normal release probability at Schaffer collateral to CA1 PC synapses.
CONCLUSIONS: Our data indicate a role for CDKL5 in hippocampal synaptic function and raise the possibility that altered intracellular signalling rather than synaptic deficits contribute to the altered plasticity.
CONCLUSIONS: This study has focussed on the electrophysiological and anatomical properties of hippocampal CA1 PCs across early postnatal development. Studies involving other brain regions, older animals and behavioural phenotypes associated with the loss of CDKL5 are needed to understand the pathophysiology of CDD.
摘要：
背景：X连锁基因细胞周期蛋白依赖性激酶样5（CDKL5）的突变会导致严重的神经系统疾病，其特征是早发性癫痫发作，自闭症和智力障碍（ID）。海马功能受损已与自闭症谱系障碍和ID的单基因形式的其他模型有关，并且通常与癫痫和行为异常有关。许多患有CDKL5缺乏症（CDD）的个体具有无效突变和CDKL5蛋白的完全缺失，因此，在本研究中，我们使用Cdkl5-/y大鼠模型来阐明CDKL5丢失对CA1锥体细胞（PC）的细胞兴奋性和突触功能的影响。我们假设在Cdkl5-/y大鼠的海马中会观察到异常的突触前和/或突触后功能和可塑性。
方法：为了允许与CDKL5缺失相关的表型的跨物种比较，我们在大鼠Cdkl5基因的外显子8中产生了功能缺失突变，并使用细胞外和全细胞电生理记录的组合评估了CDLK5缺失的影响，生物化学,和组织学。
结果：我们的结果表明，CA1海马长时程增强（LTP）在从青少年制备的切片中增强，但不是成年人，Cdkl5-/y大鼠。增强的LTP不是由NMDA受体功能或亚基表达的变化引起的，因为它们在整个发育过程中保持不变。此外，Ca2通透性AMPA受体介导的电流在Cdkl5-/y大鼠中没有变化。我们观察到mEPSC频率降低，伴随着CA1PCs基底树突的脊柱密度增加，然而,当在切片中使用最小刺激方案进行评估时,我们没有发现支持沉默突触增加的证据.此外,我们发现配对脉冲比没有变化，与Schaffer侧支到CA1PC突触的正常释放概率一致。
结论：我们的数据表明CDKL5在海马突触功能中的作用，并提高了改变细胞内信号而不是突触缺陷导致可塑性改变的可能性。
结论：本研究集中于出生后早期海马CA1PCs的电生理和解剖学特性。涉及其他大脑区域的研究，需要老年动物和与CDKL5丢失相关的行为表型来了解CDD的病理生理学。
方法：为了允许与CDKL5缺失相关的表型的跨物种比较，我们在大鼠Cdkl5基因的外显子8中产生了功能缺失突变，并使用细胞外和全细胞电生理记录的组合评估了CDLK5缺失的影响，生物化学,和组织学。
结果：我们的结果表明，CA1海马长时程增强（LTP）在从青少年制备的切片中增强，但不是成年人，Cdkl5-/y大鼠。增强的LTP不是由NMDA受体功能或亚基表达的变化引起的，因为它们在整个发育过程中保持不变。此外，Ca2通透性AMPA受体介导的电流在Cdkl5-/y大鼠中没有变化。我们观察到mEPSC频率降低，伴随着CA1PCs基底树突的脊柱密度增加，然而,当在切片中使用最小刺激方案进行评估时,我们没有发现支持沉默突触增加的证据.此外,我们发现配对脉冲比没有变化，与Schaffer侧支到CA1PC突触的正常释放概率一致。
结论：我们的数据表明CDKL5在海马突触功能中的作用，并提高了改变细胞内信号而不是突触缺陷导致可塑性改变的可能性。
结论：本研究集中于出生后早期海马CA1PCs的电生理和解剖学特性。涉及其他大脑区域的研究，需要老年动物和与CDKL5丢失相关的行为表型来了解CDD的病理生理学。
