Target miRNA information.

Melatonin is a pineal hormone synthesized exclusively at night, in several organisms. Its action on sperm is of particular interest, since they transfer genetic and epigenetic information to the offspring, including microRNAs, configuring a mechanism of paternal epigenetic inheritance. MicroRNAs are known to participate in a wide variety of mechanisms in basically all cells and tissues, including the brain and the sperm cells, which are known, respectively, to present 70% of all identified microRNAs and to transfer these molecules to the embryo. MicroRNAs from sperm have been associated with modulation of embryonic development and inheritance of psychiatric symptoms, including autism. Given that microRNAs and melatonin are ubiquitous molecules with important roles in the organism, the aim of this study was to investigate the expression of specific microRNAs in sperm, brain and cerebellum of pinealectomized rats. For this study, Wistar rats had their pineal gland removed at 60 post-partum. Part of these rats received exogenous melatonin until the day of the euthanasia. The control group did not receive any treatment or manipulation. The sperm, hypothalamus, prefrontal cortex and cerebellum were collected for analysis of microRNA expression by RT-qPCR. The results suggest that melatonin absence caused by pinealectomy increases the expression of the target microRNAs in the sperm. Although the data suggest an alteration (increase or decrease depending on the region and microRNA) of expression levels of some microRNAs in the brain and cerebellum of pinealectomized rats, the differences were not statistically significant. This seems to be a consequence of the intragroup variation. Melatonin administration restored the levels of the target microRNAs in the sperm. Additional studies are needed to understand the impact of the alterations of microRNA expression to the pinealectomized rats as well as to their descendants.褪黑素（Melatonin）是一类仅在夜间于多种生物体内合成的松果体激素（pineal hormone）。其对精子（sperm）的作用尤为受关注，因为精子可将遗传信息与表观遗传信息（epigenetic information）传递给后代，其中包括微小RNA（microRNAs），由此构成父本表观遗传遗传的机制。已知微小RNA广泛参与几乎所有细胞与组织中的多种生理过程，涵盖大脑与精子细胞（sperm cells）；其中，大脑与精子细胞分别含有已鉴定微小RNA总量的70%，且可将此类分子传递至胚胎。精子来源的微小RNA已被证实与胚胎发育调控以及包括自闭症（autism）在内的精神症状遗传相关。鉴于微小RNA与褪黑素均为在生物体内广泛分布且发挥重要功能的分子，本研究旨在探究松果体切除大鼠（pinealectomized rats）的精子、大脑及小脑中特定微小RNA的表达水平。本研究选取的Wistar大鼠于产后60天时摘除松果体；其中部分大鼠每日注射外源性褪黑素直至安乐死当日；对照组大鼠未接受任何处理或干预。研究人员采集了大鼠的精子、下丘脑（hypothalamus）、前额叶皮层（prefrontal cortex）及小脑（cerebellum），通过逆转录实时定量PCR（RT-qPCR）分析其中的微小RNA表达水平。结果显示，松果体切除术导致的褪黑素缺失会提升精子中靶标微小RNA的表达水平。尽管数据显示松果体切除大鼠的大脑及小脑中部分微小RNA的表达水平发生了改变（上调或下调取决于脑区与微小RNA种类），但上述差异均无统计学显著性，这一现象可能源于组内变异。外源性褪黑素补充可恢复精子中靶标微小RNA的表达水平。未来仍需开展更多研究，以阐明微小RNA表达改变对松果体切除大鼠及其后代的影响。