宇宙輻射劑量或可改變宇航員大腦和行為

一項新的研究為將來計劃飛往火星的宇航員們帶來了壞消息：在深空任務中遭受的宇宙輻射劑量足以改變大腦和行為。其作用是暫時性的，而且到目前為止僅在小鼠身上被觀察到；然而研究人員已經開始了解在通常關注的癌症之外，輻射如何造成其它健康危害。

來源 BMC 中國

本文發表在 BioMed Central 旗下系列期刊BMC Genomics上，原文標題：

56Fe照射對認知以及海馬體DNA甲基化和基因表達的短期和長期影響

相關視頻如下

背景：

宇航員在深太空中執行長期的空間任務時會暴露於56Fe離子下，這可能會造成重大的健康危害的。我們先前的研究表明，在用56Fe離子照射的2個月齡的小鼠中，海馬體（一種認知功能的關鍵結構）參與的物體辨認功能會受到影響。本文中，我們研究了用56Fe離子照射的6個月齡小鼠的物體辨認；此類小鼠的生物學年齡與宇航員的典型年齡更加相關。此外，由於介導56Fe離子對海馬體功能的有害作用的機理尚不清楚，因此我們檢測了伴隨基因表達變化而變化的海馬體網路，這些變化包括了突觸可塑性和記憶、基因表達、以及胞嘧啶甲基化（5mC）和羥甲基化（5hmC）的表觀遺傳等多種變化。我們評估了在早期（2周）和晚期（20周）時間點，全身56Fe離子照射對依賴于海馬體的記憶能力和海馬體網路穩定性的影響，以及這些影響是否與海馬體DNA甲基化（5mC和5hmC）和基因表達的表觀遺傳變化相關。

結果：

在2周時間點，物體辨認和網路穩定性在0.1和0.4 Gy劑量照射後受損，但在0.2Gy劑量照射後不受影響。在20周時間點，在所使用的任何照射劑量下，沒有觀察到物體辨認或網路穩定性的損傷。與這種模式一致，與2周時間點相比，在20周時間點5hmC基因類別的途徑的顯著性較低，儘管還未被消除。類似地，在2周時間點觀察到5mC基因途徑有顯著的變化，但在20周時間點沒有觀察到明顯的基因類別。僅5hmC的變化與基因表達的變化相關。

結論：

暴露於56Fe離子後在海馬體中的劑量和時間依賴性的表觀基因組重塑是與行為變化相關的。

版權聲明：

本文歸 BioMed Central 所有，中文內容僅供參考，一切內容以英文原版為主。

相關論文信息

題目Short- and long-term effects of 56Fe irradiation on cognition and hippocampal DNA methylation and gene expression

作者Soren Impey Timothy Jopson, Carl Pelz, Amanuel Tafessu, Fatema Fareh, Damian Zuloaga, Tessa Marzulla, Lara-Kirstie Riparip, Blair Stewart, Susanna Rosi, Mitchell S. Turker and Jacob RaberEmail authorView ORCID ID profile

刊期BMC Genomics 201617:825

發表日期Published: 24 October 2016

摘要

Background

Astronauts are exposed to 56Fe ions that may pose a significant health hazard during and following prolonged missions in deep space. We showed previously that object recognition requiring the hippocampus, a structure critical for cognitive function, is affected in 2-month-old mice irradiated with 56Fe ions. Here we examined object recognition in 6-month-old mice irradiated with 56Fe ions, a biological age more relevant to the typical ages of astronauts. Moreover, because the mechanisms mediating the detrimental effects of 56Fe ions on hippocampal function are unclear, we examined changes in hippocampal networks involved in synaptic plasticity and memory, gene expression, and epigenetic changes in cytosine methylation (5mC) and hydroxymethylation (5hmC) that could accompany changes in gene expression. We assessed the effects of whole body 56Fe ion irradiation at early (2 weeks) and late (20 weeks) time points on hippocampus-dependent memory and hippocampal network stability, and whether these effects are associated with epigenetic changes in hippocampal DNA methylation (both 5mC and 5hmC) and gene expression.

Results

At the two-week time point, object recognition and network stability were impaired following irradiation at the 0.1 and 0.4 Gy dose, but not following irradiation at the 0.2 Gy dose. No impairments in object recognition or network stability were seen at the 20-week time point at any irradiation dose used. Consistent with this pattern, the significance of pathways for gene categories for 5hmC was lower, though not eliminated, at the 20-week time point compared to the 2-week time point. Similarly, significant changes were observed for 5mC gene pathways at the 2-week time point, but no significant gene categories were observed at the 20-week time point. Only the 5hmC changes tracked with gene expression changes.

Conclusions

Dose- and time-dependent epigenomic remodeling in the hippocampus following 56Fe ion exposure correlates with behavioral changes.

BioMed Central隸屬於Springer Nature出版集團，是世界上開放獲取出版的先鋒，發表生物、醫學領域的最新科研成果。目前擁有300多本開放獲取期刊，其中近200本擁有影響因子。期刊Genome Biology(IF: 11.313)、BMC Biology(IF: 6.967)、BMC Medicine(IF: 8.005)、Genome Medicine(IF: 5.7)為旗下4本旗艦刊，頗受科研人員的歡迎。同時，擁有多本與中國科研機構合辦的期刊，廣受中國作者好評。