Integrative genomics reveals pathogenic mediator of valproate-induced neurodevelopmental outcomes.

Prenatal exposure to the anti-seizure drug sodium valproate (VPA) is associated with an increased risk of adverse postnatal neurodevelopmental outcomes, including lowered intellectual ability, autism spectrum disorder and attention-deficit hyperactivity disorder. In this study, we aimed to clarify the molecular mechanisms underpinning the neurodevelopmental consequences of gestational VPA exposure using integrative genomics. First, we assessed the effect of gestational VPA on fetal brain gene expression using a validated rat model of valproate teratogenicity that mimics the human scenario of chronic oral valproate treatment during pregnancy at doses which are therapeutically relevant to the treatment of epilepsy. Two different rat strains were studied - inbred Genetic Absence Epilepsy Rats from Strasbourg (GAERS), a model of genetic generalized epilepsy, and inbred Non-Epileptic Control (NEC) rats. Female rats were fed standard chow or VPA mixed in standard chow for 2 weeks prior to conception and then mated with same-strain males. In the VPA-exposed rats maternal oral treatment was continued throughout pregnancy. Fetuses were extracted via C-section on gestational day 21 (one day prior to birth) and fetal brains were snap frozen and genome-wide gene expression data generated. We found that gestational VPA exposure via chronic maternal oral dosing was associated with substantial drug-induced differential gene expression in the pup brains, including dysregulated splicing, and observed that this occurred in the absence of evidence for significant neuronal gain or loss. The set of genes down-regulated by VPA in the pup brains were significantly enriched for pathways related to neurodevelopment and synaptic function, and significantly enriched for heritability to human intelligence, schizophrenia and bipolar disorder. Our results provide a mechanistic link between chronic fetal VPA exposure and adverse neurodevelopmental outcomes mediated by VPA-induced transcriptional dysregulation.产前暴露于抗癫痫药物丙戊酸钠（sodium valproate，VPA）与不良产后神经发育结局风险升高相关，包括智力低下、自闭症谱系障碍及注意缺陷多动障碍。 本研究旨在通过整合基因组学方法，阐明妊娠期VPA暴露所引发神经发育结局的潜在分子机制。 首先，本研究采用经过验证的丙戊酸钠致畸性大鼠模型，模拟人类妊娠期间以癫痫治疗相关治疗剂量长期口服丙戊酸钠的场景，以此评估妊娠期VPA暴露对胎儿脑组织基因表达的影响。本研究选用两种近交系大鼠品系：遗传性全面性癫痫模型——斯特拉斯堡遗传性失神癫痫大鼠（Genetic Absence Epilepsy Rats from Strasbourg，GAERS），以及非癫痫对照（Non-Epileptic Control，NEC）大鼠。 在受孕前2周，雌性大鼠喂食标准饲料或混有VPA的标准饲料，随后与同品系雄性大鼠交配。对于VPA暴露组大鼠，母鼠的口服给药将持续整个妊娠周期。在妊娠第21天（分娩前1天）通过剖宫产术获取胎鼠，将胎鼠脑组织快速冷冻后开展全基因组基因表达谱检测。 本研究发现，通过母鼠长期口服给药实现的妊娠期VPA暴露，可导致幼鼠脑组织出现显著的药物诱导性差异基因表达，包括剪接失调；同时观察到，该现象未伴随显著的神经元数量增减相关证据。幼鼠脑组织中被VPA下调的基因集合，显著富集于神经发育与突触功能相关通路，同时显著富集于与人类智力、精神分裂症及双相情感障碍相关的遗传力特征。 本研究结果揭示了慢性胎儿期VPA暴露与不良神经发育结局之间的机制性关联，该关联由VPA诱导的转录失调所介导。