Dipartimento di Scienze del Mare, Università Politecnica delle Marche, Ancona, Italy.
PLoS One. 2011;6(5):e19978. doi: 10.1371/journal.pone.0019978. Epub 2011 May 25.
Most organisms modulate their reproductive activity responding to day length by the nocturnal release of melatonin by the pineal gland. This hormone is also responsible for synchronizing reproduction with specific external environment stimuli in order to optimize reproductive success.The aim of this study was to establish the effect of melatonin on zebrafish reproduction.Adult females were daily exposed, via water, to two different doses (100 nM and 1 µM) of melatonin. Melatonin led to an increase of the Gonado Somatic Index (GSI) associated with the increase of eggs production, and the raise of gene and protein levels of vitellogenin (VTG) and estradiol receptor α (ERα) in the liver. The ability of melatonin to increase fecundity was consistent with a significant increase of gene transcription of kiss 1, kiss 2, gnrh3, in the brain, and lh in the pituitary, while in the ovary (in class IIIB follicles), with a significant decrease of two genes codifying for intra-ovarian regulators of premature oocyte maturation, the tgfβ1 and the bmp15. The reduction in the expression of these two genes was concomitant with the increase of lhr and a modulation of mprα and mprβ gene transcription, whose proteins are involved in oocyte maturation. Melatonin also exerted a direct action on follicles as shown by the increase of the oocytes undergoing to germinal vesicle break down (GVBD) and modulated mpr α and β gene expression in the in vitro exposure.These data highlight the effects of melatonin in promoting zebrafish reproduction exerting its effects either in the brain-pituitary and in the gonads.
大多数生物体通过松果体在夜间释放褪黑素来调节生殖活动，以响应日长。这种激素还负责将生殖与特定的外部环境刺激同步，以优化生殖成功。本研究旨在确定褪黑素对斑马鱼生殖的影响。成年雌性鱼每天通过水暴露于两种不同剂量（100 nM 和 1 µM）的褪黑素。褪黑素导致性腺体指数（GSI）增加，与卵子产量增加有关，以及肝脏中卵黄蛋白原（VTG）和雌激素受体 α（ERα）基因和蛋白水平升高。褪黑素增加生育能力的能力与脑内 kiss1、kiss2、gnrh3 基因转录的显著增加一致，垂体中的 lh 也增加，而在卵巢（在 IIIB 级卵泡中），编码两个内源性卵母细胞成熟调节剂的基因显著减少，即 tgfβ1 和 bmp15。这两个基因的表达减少伴随着 lhr 的增加以及 mprα 和 mprβ 基因转录的调节，其蛋白质参与卵母细胞成熟。褪黑素还对卵泡发挥直接作用，如卵母细胞经历生发泡破裂（GVBD）的增加以及体外暴露时 mprα 和 mprβ 基因表达的调节所示。这些数据强调了褪黑素在促进斑马鱼生殖中的作用，无论是在脑垂体还是在性腺中。
