Etiological mechanism of lifestyle-related diseases caused by disordered daily rhythms

固醇调节元件结合蛋白-1（SREBP-1）是一种在脂质生物合成中起关键作用的转录因子，其基因的表达在标准饮食喂养的小鼠肝脏中每日光/暗周期的黑暗喂养期达到峰值，在高碳水化合物、高脂肪和高蛋白饮食的光禁食期达到峰值，这强调了营养素在塑造每日节律中的重要性。鸟氨酸循环（氨解毒酶系统）的基因表达在高蛋白饮食的进食期达到峰值，在低蛋白（高碳水化合物）饮食的禁食后期至早期进食期达到峰值，这表明在进食期和禁食期的表达都被激活，因为氨解毒需要氨基酸降解。

Expression of the gene for sterol regulatory element-binding protein-1 (SREBP-1), a transcription factor pivotal in lipid biosynthesis, achieved a peak in the dark feeding period of the daily light/dark cycle in the liver of mice fed with a standard diet, and a peak in the light fasting period with high-carbohydrate, high-fat, and high-protein diets, underlining the importance of nutrients in shaping the daily rhythm. Expression of genes for the ornithine cycle, an enzyme system for ammonia detoxification, achieved a peak in the feeding period with a high-protein diet, and a peak in the late fasting to early feeding periods with a low-protein (high-carbohydrate) diet, suggesting activation of the expression both in the feeding and fasting periods because of requirement for detoxifying ammonia derived form amino acid degradation.