Targeting PDZ to unravel early anesthetic exposure-produced cognitive dysfunction

描述(由申请人提供)：先前的临床队列研究和动物研究表明，早期接触麻醉药是日后发生脑血管意外的重要危险因素。 学习障碍。然而，其潜在的分子机制尚不清楚。一系列证据表明，海马神经发生和突触发生受损可能参与了早期麻醉导致长期认知损害的机制，突触支架蛋白PSD-95 PDZ结构域介导的蛋白相互作用和突触活动参与了海马神经发生和突触发生的调节。我们以前的研究已经证明，PDZ结构域介导的蛋白质相互作用可以被临床上相关浓度的吸入麻醉药破坏。最近，我们发现出生后(PND)7天的大鼠暴露在异氟醚中会减少海马神经发生，抑制树突棘的发育和突触的可塑性，并损害学习和记忆功能。这些结果表明，PDZ相互作用的破坏和PDZ结构域介导的突触功能可能在早期麻醉暴露所致的长期认知损害的发病机制中起重要作用。我们假设，新生大鼠早期吸入麻醉药会抑制神经发生，并通过扰乱发育中的海马区突触PDZ相互作用和PDZ结构域介导的突触功能而干扰突触发生，从而产生长期的神经认知功能障碍。为了解决这一假说，我们将确定突触PDZ相互作用和PDZ结构域介导的突触功能是否参与了异氟醚抑制神经发生和突触再生的潜在机制(目标1)；我们将确定吸入麻醉剂异氟醚介导的PDZ结构域破坏对体外培养的海马神经元(AM 2)的细胞生物学效应；我们将进一步确定突触PDZ相互作用的中断和PDZ结构域介导的突触功能受损是否有助于早期麻醉暴露后的长期认知功能障碍(目标3)。这项拟议的研究将为阐明早期麻醉暴露是否通过抑制PDZ相互作用调节的海马神经发生和突触发生而导致长期认知损害提供关键证据。这些数据将为新生儿麻醉剂神经毒性的发病机制提供新的线索。这项建议的总体目标是证明突触PDZ相互作用和PDZ结构域介导的突触功能在早期麻醉暴露所产生的长期认知损害中的作用。

DESCRIPTION (provided by applicant): Previous clinical cohort studies and animal studies have shown that early exposure to anesthetics is a significant risk factor for later development of learning disabilities. However, the underlying molecular mechanism is unclear. Several lines of evidence have indicated that impaired hippocampal neurogenesis and synaptogenesis may be involved in the mechanisms by which early anesthetic exposure produces long-term cognitive impairment, and that synaptic scaffolding protein PSD-95 PDZ domain-mediated protein-protein interactions and synaptic activities are involved in the regulation of neurogenesis and synaptogenesis in the hippocampus. Our previous studies have demonstrated that PDZ domain-mediated protein interactions are disrupted by clinically relevant concentrations of inhaled anesthetics. Recently, we showed that exposing postnatal day (PND) 7 rats to isoflurane diminishes hippocampal neurogenesis, inhibits dendritic spine development and synaptic plasticity, and impairs learning and memory function. These results suggest that the disruption of PDZ interactions and PDZ domain-mediated synaptic function may play important roles in the pathogenesis of early anesthetic exposure-produced long-term cognitive impairment. We hypothesize that early exposure of neonatal rats to inhaled anesthetics inhibits neurogenesis and interferes with synaptogenesis by disrupting synaptic PDZ interactions and PDZ domain-mediated synaptic function in the developing hippocampus, thereby producing long-term neurocognitive dysfunction. To address this hypothesis, we will determine whether synaptic PDZ interactions and PDZ domain-mediated synaptic function contribute to the mechanism underlying isoflurane suppression of neurogenesis and inhibition of synaptogenesis (Aim 1); we will determine the cell biological effects of inhaled anesthetic isoflurane-mediated PDZ domain disruption in developing hippocampal neurons in vitro (Am 2); we will further determine whether the disruption of synaptic PDZ interactions and the impairment of PDZ domain-mediated synaptic function contributes to long-term cognitive impairment after early anesthetic exposure (Aim 3). The proposed studies will provide critical evidence to clarify whether early anesthetic exposure produces long-term cognitive impairment by inhibiting PDZ interaction-regulated hippocampal neurogenesis and synaptogenesis. The data will shed new light on the pathogenesis of neonatal anesthetic neurotoxicity. The overall goal of this proposal is to demonstrate the roles of synaptic PDZ interactions and PDZ domain-mediated synaptic function in early anesthetic exposure- produced long-term cognitive impairment.