Developmental and Reproductive Biology Graduate Program, Institute for Biogenesis Research, University of Hawaii John A. Burns School of Medicine, Honolulu, Hawaii 96813.
Toxicol Sci. 2018 Oct 1;165(2):372-388. doi: 10.1093/toxsci/kfy143.
Fluoxetine is one of the most commonly prescribed antidepressants in the selective serotonin reuptake inhibitor (SSRI) class. Epidemiologic studies have suggested a link between maternal fluoxetine use during pregnancy and an increased incidence of birth defects. However, the mechanisms by which fluoxetine adversely impacts embryonic developments are unknown. Here, we used the mouse P19C5 embryoid body (EB) as a 3D morphogenesis model to investigate the developmental toxicity of fluoxetine. Morphological and molecular changes in P19C5 EBs replicate the processes of axial elongation and patterning seen in early embryos, and these changes are specifically and sensitively altered by exposure to developmental toxicants. Treatment with fluoxetine, or its major metabolite, norfluoxetine, adversely affected EB morphogenesis at concentrations of 6 µM and above. Treatment with other serotonin reuptake inhibitors or serotonin itself did not impair EB morphogenesis, suggesting that the adverse effects of fluoxetine are independent of serotonin signaling. Gene expression analyses showed that various key developmental regulators were affected by fluoxetine, particularly those involved in mesodermal differentiation. Reporter assays demonstrated that fluoxetine inhibited canonical Wnt signaling, and that the pharmacologic activation of canonical Wnt signaling partially alleviated the morphogenetic effects of fluoxetine. Fluoxetine also exhibited cytostatic effects independently of inhibition of the serotonin transporter or canonical Wnt signaling. These results suggest that the SSRI-independent actions of fluoxetine, namely inhibition of canonical Wnt signaling and reduction of cellular proliferation, are largely responsible for the observed adverse morphogenetic impacts. This study provides mechanistic insight for further investigations on the teratogenicity of fluoxetine.
氟西汀是选择性 5-羟色胺再摄取抑制剂（SSRI）类中最常被开的抗抑郁药之一。流行病学研究表明，母亲在怀孕期间使用氟西汀与出生缺陷发生率增加之间存在关联。然而，氟西汀如何对胚胎发育产生不利影响的机制尚不清楚。在这里，我们使用小鼠 P19C5 类胚体（EB）作为三维形态发生模型来研究氟西汀的发育毒性。P19C5 EB 的形态和分子变化复制了早期胚胎中所见的轴向伸长和模式形成过程，这些变化可被发育毒性物质特异性和敏感地改变。浓度为 6µM 及以上的氟西汀或其主要代谢物去甲氟西汀处理会对 EB 形态发生产生不利影响。其他 5-羟色胺再摄取抑制剂或 5-羟色胺本身处理并不会损害 EB 形态发生，这表明氟西汀的不良影响与 5-羟色胺信号无关。基因表达分析表明，各种关键发育调节剂受到氟西汀的影响，特别是那些参与中胚层分化的调节剂。报告基因检测表明，氟西汀抑制经典 Wnt 信号，而经典 Wnt 信号的药理学激活部分缓解了氟西汀的形态发生效应。氟西汀还表现出独立于 5-羟色胺转运体或经典 Wnt 信号抑制的细胞停滞作用。这些结果表明，氟西汀的 SSRI 非依赖性作用，即对经典 Wnt 信号的抑制和细胞增殖的减少，在很大程度上是导致观察到的不良形态发生影响的原因。这项研究为进一步研究氟西汀的致畸性提供了机制上的见解。
