Fisheries Research Institute of Karatsu, Faculty of Agriculture, Kyushu University, Saga 847-0132, Japan.
Laboratory of Marine Biology, Faculty of Agriculture, Kyushu University, Fukuoka 819-0395, Japan.
Gen Comp Endocrinol. 2020 Jun 1;292:113442. doi: 10.1016/j.ygcen.2020.113442. Epub 2020 Feb 18.
Leptin transmits information about energy stored in the periphery to the reproductive axis and is an essential signal for puberty initiation in mammals; however, to date, few studies have focused on the direct effects of leptin stimulation on reproductive factors in fish. This study demonstrated the effect of leptin stimulation on important reproductive factors and ovarian development in the marine teleost chub mackerel (Scomber japonicus). We prepared recombinant leptin and conducted functional analyses through in vitro bioassays using primary pituitary cells, long-term leptin treatment administered to pre-pubertal females, and intracerebroventricular (ICV) administration. The results showed that leptin stimulation strongly induced gonadotropin (follicle-stimulating hormone: FSH and luteinizing hormone: LH) secretion from pituitary cells collected from pre-pubertal females, and that long-term leptin treatment significantly promoted ovarian development and triggered pubertal onset. Furthermore, ICV administration of leptin did not affect kisspeptin gene expression but significantly upregulated gonadotropin-releasing hormone 1 (gnrh1), fshb and lhb gene expression in sexually immature females. These results strongly suggest leptin as an important signal for reproductive-axis activation in chub mackerel.
瘦素将外周储存的能量信息传递给生殖轴，是哺乳动物青春期启动的重要信号；然而，迄今为止，很少有研究关注瘦素刺激对鱼类生殖因子的直接影响。本研究证明了瘦素刺激对海洋鲐（Scomber japonicus）重要生殖因子和卵巢发育的影响。我们制备了重组瘦素，并通过体外生物测定使用来自青春期前雌性的初级垂体细胞进行了功能分析，以及脑室内（ICV）给药。结果表明，瘦素刺激强烈诱导来自青春期前雌性采集的垂体细胞中促性腺激素（卵泡刺激素：FSH 和促黄体生成素：LH）的分泌，并且长期瘦素处理显著促进卵巢发育并引发青春期开始。此外，ICV 给予瘦素不会影响 kisspeptin 基因表达，但会显著上调性未成熟雌性中的促性腺激素释放激素 1（gnrh1）、fshb 和 lhb 基因表达。这些结果强烈表明瘦素是鲐鱼生殖轴激活的重要信号。
