Melatonin is a highly conserved molecule that regulates day/night rhythms; it is associated with sleep improvement, reactive oxygen species (ROS) scavenging, anti-aging effects, and seasonal and circadian rhythms and has been a hot topic of research for decades. Using single-cell RNA sequencing, a recent study describes a single-cell transcriptome atlas for the rat pineal gland. Based on a more comprehensive analysis of the retrieved data (Mays et al., PLoS One, 2018, 13, e0205883), results from the current study unveiled the underappreciated gene regulatory network behind different cell populations in the pineal gland. More importantly, our study here characterized, for the first time, the day/night activation of autophagy flux in the rat pineal gland, indicating a potential role of autophagy in regulating melatonin synthesis in the rat pineal gland. These findings emphasized a hypothetical role of day/night autophagy in linking the biological clock with melatonin synthesis. Furthermore, ultrastructure analysis of pinealocytes provided fascinating insights into differences in their intracellular structure between daytime and nighttime. In addition, we also provide a preliminary description of cell-cell communication in the rat pineal gland. In summary, the current study unveils the day/night regulation of autophagy in the rat pineal gland, raising a potential role of autophagy in day/night-regulated melatonin synthesis.

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自噬在大鼠松果体中昼夜节律调节的褪黑激素合成中的假设作用

褪黑激素是一种高度保守的分子，可调节昼夜节律；它与睡眠改善、活性氧 (ROS) 清除、抗衰老作用以及季节性和昼夜节律有关，几十年来一直是研究的热门话题。最近的一项研究使用单细胞 RNA 测序描述了大鼠松果体的单细胞转录组图谱。基于对检索到的数据进行更全面的分析（Mays 等人，PLoS One，2018, 13, e0205883），当前研究的结果揭示了松果体中不同细胞群背后未被充分认识的基因调控网络。更重要的是，我们的研究首次表征了大鼠松果体中自噬通量的昼夜激活，表明自噬在调节大鼠松果体褪黑激素合成中的潜在作用。这些发现强调了昼夜自噬在将生物钟与褪黑激素合成联系起来方面的假设作用。此外，松果体细胞的超微结构分析提供了对白天和夜间细胞内结构差异的迷人见解。此外，我们还提供了大鼠松果体中细胞间通讯的初步描述。总之，目前的研究揭示了大鼠松果体中自噬的昼/夜调节，提高了自噬在昼/夜调节的褪黑激素合成中的潜在作用。松果体细胞的超微结构分析提供了对白天和夜间细胞内结构差异的迷人见解。此外，我们还提供了大鼠松果体中细胞间通讯的初步描述。总之，目前的研究揭示了大鼠松果体中自噬的昼/夜调节，提高了自噬在昼/夜调节的褪黑激素合成中的潜在作用。松果体细胞的超微结构分析提供了对白天和夜间细胞内结构差异的迷人见解。此外，我们还提供了大鼠松果体中细胞间通讯的初步描述。总之，目前的研究揭示了大鼠松果体中自噬的昼/夜调节，提高了自噬在昼/夜调节的褪黑激素合成中的潜在作用。