Department of Cell Biology, King Faisal Specialist Hospital & Research Centre, Riyadh, Saudi Arabia.
PLoS One. 2018 Mar 21;13(3):e0194416. doi: 10.1371/journal.pone.0194416. eCollection 2018.
Aspartame (L-aspartyl phenylalanine methyl ester) is a non-nutritive sweetener (NNS) approved for use in more than 6000 dietary products and pharmaceuticals consumed by the general public including adults and children, pregnant and nursing mothers. However a recent prospective study reported a doubling of the risk of being overweight amongst 1-year old children whose mothers consumed NNS-sweetened beverages daily during pregnancy. We have previously shown that chronic aspartame (ASP) exposure commencing in utero may detrimentally affect adulthood adiposity status, glucose metabolism and aspects of behavior and spatial cognition, and that this can be modulated by developmental N-methyl-D-aspartate receptor (NMDAR) blockade with the competitive antagonist CGP 39551 (CGP). Since glucose homeostasis and certain aspects of behavior and locomotion are regulated in part by the NMDAR-rich hypothalamus, which is part of the hypothalamic-pituitary-adrenal- (HPA) axis, we have elected to examine changes in hypothalamic and adrenal gene expression in response to ASP exposure in the presence or absence of developmental NMDAR antagonism with CGP, using Affymetrix microarray analysis.
Using 2-factor ANOVA we identified 189 ASP-responsive differentially expressed genes (DEGs) in the adult male hypothalamus and 2188 in the adrenals, and a further 23 hypothalamic and 232 adrenal genes significantly regulated by developmental treatment with CGP alone. ASP exposure robustly elevated the expression of a network of genes involved in hypothalamic neurosteroidogenesis, together with cell stress and inflammatory genes, consistent with previous reports of aspartame-induced CNS stress and oxidative damage. These genes were not differentially expressed in ASP mice with CGP antagonism. In the adrenal glands of ASP-exposed mice, GABA and Glutamate receptor subunit genes were amongst those most highly upregulated. Developmental NMDAR antagonism alone had less effect on adulthood gene expression and affected mainly hypothalamic neurogenesis and adrenal steroid metabolism. Combined ASP + CGP treatment mainly upregulated genes involved in adrenal drug and cholesterol metabolism.
ASP exposure increased the expression of functional networks of genes involved in hypothalamic neurosteroidogenesis and adrenal catecholamine synthesis, patterns of expression which were not present in ASP-exposed mice with developmental NMDAR antagonism.
阿斯巴甜（L-天冬氨酰苯丙氨酸甲酯）是一种非营养性甜味剂（NNS），已被批准用于 6000 多种供普通大众（包括成人和儿童、孕妇和哺乳期妇女）食用的饮食产品和药品中。然而，最近一项前瞻性研究报告称，在怀孕期间每天饮用含 NNS 甜味剂的饮料的母亲所生的 1 岁儿童超重的风险增加了一倍。我们之前曾表明，宫内开始的慢性阿斯巴甜（ASP）暴露可能会对成年后的肥胖状态、葡萄糖代谢以及行为和空间认知的某些方面产生不利影响，而这种影响可以通过发育性 N-甲基-D-天冬氨酸受体（NMDAR）阻断剂 CGP 39551（CGP）来调节。由于葡萄糖稳态和某些行为和运动的某些方面受富含 NMDAR 的下丘脑调节，而下丘脑是下丘脑-垂体-肾上腺轴（HPA）的一部分，因此我们选择使用 Affymetrix 微阵列分析来检查 ASP 暴露后下丘脑和肾上腺基因表达的变化，以及存在或不存在发育性 NMDAR 拮抗作用时 CGP 的变化。
使用 2 因素方差分析，我们在成年雄性下丘脑鉴定出 189 个 ASP 反应性差异表达基因（DEGs）和 2188 个肾上腺基因，以及单独用 CGP 发育性处理显著调节的 23 个下丘脑和 232 个肾上腺基因。ASP 暴露强烈上调了参与下丘脑神经甾体生成的基因网络的表达，以及细胞应激和炎症基因，这与先前报道的阿斯巴甜诱导的中枢神经系统应激和氧化损伤一致。在具有 CGP 拮抗作用的 ASP 小鼠中，这些基因没有差异表达。在暴露于 ASP 的小鼠的肾上腺中，GABA 和谷氨酸受体亚基基因是上调最明显的基因之一。单独的发育性 NMDAR 拮抗作用对成年期基因表达的影响较小，主要影响下丘脑神经发生和肾上腺类固醇代谢。ASP+CGP 联合治疗主要上调了参与肾上腺药物和胆固醇代谢的基因。
ASP 暴露增加了参与下丘脑神经甾体生成和肾上腺儿茶酚胺合成的功能基因网络的表达，而这些表达模式在具有发育性 NMDAR 拮抗作用的 ASP 暴露小鼠中不存在。
