Sandström J, Broyer A, Zoia D, Schilt C, Greggio C, Fournier M, Do K Q, Monnet-Tschudi F
Swiss Centre for Applied Human Toxicology (SCAHT), Switzerland; Department of Physiology, University of Lausanne, CH-1005 Lausanne, Switzerland.
Department of Physiology, University of Lausanne, CH-1005 Lausanne, Switzerland.
Neurotoxicology. 2017 May;60:116-124. doi: 10.1016/j.neuro.2017.04.010. Epub 2017 Apr 30.
Exposure to environmental toxicants during vulnerable windows of brain development is suspected to raise the prevalence for neurological dysfunctions at later stages in life. Differentiation processes and changes in morphology, as well as a lack of physiological barriers, might be reasons that render a developing brain more susceptible to neurotoxicants than an adult. However, also the intrinsic capacity of cells to combat toxicant induced cellular stress might differ between the immature- and mature brain. In order to study whether this intrinsic protection capacity differs between immature and maturated brain cells we chose to study the maturation-dependent adverse effects of the known neurotoxicant Paraquat Dichloride (PQ) in 3D rat brain cell cultures. This in vitro system consists of the major brain cell types - neurons, astrocytes, oligodendrocytes and microglia - and over the time in vitro cultured cells undergo differentiation and maturation into a tissue-like organization. PQ was applied repeatedly over ten days in the sub-micromolar range, and effects were evaluated on neurons and glial cells. We observed that despite a higher PQ-uptake in mature cultures, PQ-induced adverse effects on glutamatergic-, GABAergic- and dopaminergic neurons, as assessed by gene expression and enzymatic activity, were more pronounced in immature cultures. This was associated with a stronger astrogliosis in immature- as compared to mature cultures, as well as perturbations of the glutathione-mediated defense against oxidative stress. Furthermore we observed evidence of microglial activation only in mature cultures, whereas immature cultures appeared to down-regulate markers for neuroprotective M2-microglial phenotype upon PQ-exposure. Taken together our results indicate that immature brain cell cultures have less intrinsic capacity to cope with cellular stress elicited by PQ as compared to mature cells. This may render immature brain cells more susceptible to the adverse effects of PQ.
在大脑发育的脆弱窗口期接触环境毒物被怀疑会增加日后生活中神经功能障碍的患病率。分化过程、形态变化以及缺乏生理屏障可能是发育中的大脑比成人大脑更容易受到神经毒物影响的原因。然而，未成熟大脑和成熟大脑中细胞对抗毒物诱导的细胞应激的内在能力也可能不同。为了研究这种内在保护能力在未成熟和成熟脑细胞之间是否存在差异，我们选择在三维大鼠脑细胞培养物中研究已知神经毒物百草枯二氯化物（PQ）的成熟依赖性不良影响。这个体外系统由主要的脑细胞类型——神经元、星形胶质细胞、少突胶质细胞和小胶质细胞组成，随着时间的推移，体外培养的细胞会分化并成熟为类似组织的结构。在亚微摩尔范围内，PQ在十天内反复应用，并评估其对神经元和神经胶质细胞的影响。我们观察到，尽管成熟培养物中PQ的摄取量更高，但通过基因表达和酶活性评估，PQ对谷氨酸能、γ-氨基丁酸能和多巴胺能神经元的不良影响在未成熟培养物中更为明显。这与未成熟培养物中比成熟培养物更强的星形胶质细胞增生有关，以及谷胱甘肽介导的抗氧化应激防御的扰动。此外，我们仅在成熟培养物中观察到小胶质细胞激活的证据，而未成熟培养物在接触PQ后似乎下调了神经保护性M2小胶质细胞表型的标志物。综上所述，我们的结果表明，与成熟细胞相比，未成熟脑细胞培养物应对PQ引起的细胞应激的内在能力较弱。这可能使未成熟脑细胞更容易受到PQ的不良影响。
