夜晚光照影響腸道的基因表現

Abstract

視網膜上的內生感光神經節細胞(ipRGCs)能感知環境的光線，除了能調控哺乳動物的生理時鐘，也影響周邊組織的生理週期並調節多種賀爾蒙的恆定。近期在小鼠模型上的研究顯示，不正常的日夜週期會引起肥胖、胰島素抗性和的腸道菌相的改變，然而目前造成上述結果的生理機制仍大部分未知。實驗室先前的研究顯示，長期夜晚接受微弱光線(dLAN)照射的小鼠腸道菌相組成改變，並使其表現週期紊亂。在此研究中，我們比較飼養在正常光週期(LD)與夜晚接受微弱光線(dLAN)照射兩週的小鼠其小腸基因表現，並探討哪些基因的表現受到環境光線影響，進而影響其代謝機制和腸道菌相間的交互關係。研究結果顯示，夜晚接受微弱光照小鼠的腸道免疫基因和對抗發炎反應的基因表現表現較高，也有許多蛋白質和脂質消化吸收的基因表現偏高，例如MMP10與Iglv3。然而遭受夜晚光照而升高的生理時鐘基因(Bmal)，然而在裡用6-OJDA阻絕交感神經後，遭受夜晚光照小鼠的Bmal表現量與正常光照週期小鼠的小腸基因表現量相比有顯著上升。總結本篇研究顯示，遭受夜晚光照的小鼠會經由交感神經引發小腸的發炎反應，但腸道生理時鐘的調控不透過交感神經。

Recent studies have shown that intrinsically photosensitive retinal ganglion cells (ipRGCs) in the retina could transmit environmental light information to influence mammalian circadian central clocks at the suprachiasmatic nucleus (SCN) as well as peripheral circadian oscillations and several physiological hormone homeostases. In previous research, disruption of the normal light-dark cycle causes obesity, insulin resistance, and abnormal gut microbiota oscillation in mice. However, how environmental light influences the gut microbiota and host metabolism remains unknown. In this study, we performed a transcriptome analysis of mouse intestine tissue housed under normal light-dark cycle or dim light at night (dLAN) to investigate the genes regulated by environmental light. We observed the up-regulation of genes such as MMP10 and Iglv3, which are involved in immune response and inflammatory under dLAN condition. Besides, the energy balance relative genes such as protein and fats absorption, and circadian related genes such as Nr1d1 and Bmal show higher expression after 2-3 weeks of dLAN treatment. Specifically, Bmal expression is higher in the duodenum under dLAN whether the sympathetic nerve was eliminated or not. Our result suggested that dim light at night induced small intestine inflammation in mice through the sympathetic nervous system.