孕期地塞米松暴露对子代海马发育的神经毒性窗：剂量-时间-疗程依赖性研究

Neurotoxic Window of Prenatal Dexamethasone Exposure on Offspring Hippocampal Development: A Dose-Time-Duration Dependency Study

关键词:  孕期用药  地塞米松  毒性窗  海马  神经发育

Key words:  pregnancy medication  dexamethasone  toxicity window  hippocampus  neurodevelopment

摘要:

目的 探讨孕期地塞米松暴露的关键参数（剂量、时间窗、疗程）对子代海马发育与功能的特异性影响。方法 建立昆明鼠妊娠期皮下注射地塞米松模型，系统模拟临床暴露场景：设定剂量梯度（低0.2 mg/kg、中0.4 mg/kg、高0.8 mg/kg）、给药时间窗（孕中期GD14-15、孕晚期GD16-17）及疗程方案（单疗程[GD14-15/GD16-17]、多疗程[GD14-17]），并以生理盐水为对照。对GD18胎鼠海马进行组织学观察、神经元增殖/凋亡检测、胶质细胞标志物（S100b、Gfap、Iba1、Trem2）及关键信号通路分子（Sox2、Notch1）表达分析。结果 与对照组相比，孕晚期地塞米松暴露可显著损害海马形态结构，抑制神经元增殖、促进凋亡，并显著下调星形胶质细胞标志物S100b、Gfap表达，而小胶质细胞标志物Iba1、Trem2无明显变化。此外，孕期地塞米松暴露可剂量、时间及疗程依赖性地抑制胎海马中调控神经祖细胞增殖的关键信号通路Sox2和Notch1，且损伤程度表现为孕晚期 > 孕中期、高剂量 > 中/低剂量、多疗程 > 单疗程，其中孕晚期高剂量多疗程组损伤最为显著。结论 研究表明，孕期地塞米松暴露，尤其是孕晚期、高剂量及多疗程方案，可通过抑制Sox2和Notch信号通路，显著损害胎鼠海马发育。该结果为临床优化地塞米松用药策略及评估胎儿神经发育毒性风险提供了重要的实验与理论依据。

Abstract:

OBJECTIVE To investigate the specific effects of key parameters of prenatal dexamethasone exposure (dose, time window, and treatment course) on offspring hippocampal development and function. METHODS A subcutaneous dexamethasone injection model was established in pregnant Kunming mice to systematically simulate clinical exposure scenarios. Gradient doses (low: 0.2 mg/kg; medium: 0.4 mg/kg; high: 0.8 mg/kg), administration windows (mid-gestation, GD14-15; late gestation, GD16-17), and treatment courses (single course [GD14-15 or GD16-17] and multiple courses [GD14-17]), with saline-treated mice serving as controls. On GD18, fetal hippocampi were analyzed by histological assessment, neuronal proliferation/apoptosis assays, immunodetection of glial markers (S100b, Gfap, Iba1, Trem2), and evaluation of key signaling molecules (Sox2, Notch1). RESULTS Compared with the control group, late-gestation dexamethasone exposure significantly impaired hippocampal morphology, inhibited neuronal proliferation, promoted apoptosis, and markedly downregulated the astrocyte markers S100b and Gfap, while microglial markers Iba1 and Trem2 remained unchanged. Furthermore, prenatal dexamethasone exposure suppressed the expression of the key signaling pathways Sox2 and Notch1, which regulate neural progenitor cell proliferation, in a dose, timing, and course dependent manner. The degree of impairment followed the pattern: late gestation > mid-gestation, high dose > medium/low dose, and multiple courses > single course, with the most severe damage observed in the high-dose, multiple-course group during late gestation. CONCLUSION These findings demonstrate that prenatal dexamethasone exposure-particularly high-dose, repeated administration during late pregnancy-can significantly impair fetal hippocampal development by disrupting the Sox2 and Notch signaling pathways. This study provides important experimental and theoretical evidence for optimizing the clinical use of dexamethasone during pregnancy and assessing its neurodevelopmental toxicity risks in the fetus.