Effects of salmon GnRH and sex steroid hormones on expression of genes encoding growth hormone/prolactin/somatolactin family hormones and a pituitary-specific transcription factor in masu salmon pituitary cells in vitro
Effects of salmon GnRH and sex steroid hormones on expression of genes encoding growth hormone/prolactin/somatolactin family hormones and a pituitary-specific transcription factor in masu salmon pituitary cells in vitro
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DOI：
10.1016/j.ygcen.2005.03.003
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发表时间：
2005-09-01
影响因子：
2.7
通讯作者：
Urano, A
中科院分区：
文献类型：
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作者：
Onuma, T;Ando, H;Urano, A
在生长和成熟的鲑鱼中，生长激素(GH)、催乳素(PRL)和生长抑素(SL)基因的表达是由促性腺激素释放激素(GnRH)类似物在生命周期的特定时期刺激的。因此，GnRH似乎直接和/或间接调节GH、PRL和SL的基因表达，并与性激素等脑垂体-性腺轴结合。因此，在原代培养的马哈鱼四个生殖阶段，观察了鲑鱼促性腺激素释放激素(SGnRH)、雌二醇-17β(E_2)、睾酮和11-酮-睾酮(11kt)对生长激素(GH)、催乳素(PRL)和黄体生成素(SL)mRNAs含量的直接影响。用实时定量聚合酶链式反应检测脑垂体特异性POU同源结构域转录因子(Pit-1)的表达。对照组细胞中GH、PRL和SL的mRNAs含量随性腺成熟而增加，与Pit-1mRNAs的含量一致。1.0 nM的sGnRH提高了产卵前雌体的所有mRNA量，而100 nM的sGnRH在任何生殖阶段都没有观察到显著的影响。性激素在性腺开始成熟前和成熟期均无明显作用。在雄鱼中，雌二醇在产卵前期有降低SL基因表达的趋势。雌鱼在产卵前期，E2和11kT使PRL和SL的mRNAs含量增加，而在产卵期，PRL mRNAs的含量减半。Pit-1mRNA量与PRL和SLmRNAs的量在各个时期的变化趋势一致。100 nM sGnRH可完全消除E_2的作用。结果表明，sGnRH和类固醇激素均直接调节Pit-1的合成，进而调节PRL和SL基因的表达。SGnRH可能通过垂体-性腺轴间接调节GH/PRL/SL家族激素基因，特别是在配子发生的后期。(C)2005 Elsevier Inc.保留所有权利。
Expression of genes encoding growth hormone (GH), prolactin (PRL), and somatolactin (SL) in growing and maturing salmon was stimulated by gonadotropin-releasing hormone (GnRH) analog during particular periods of the life cycle. GnRH therefore appears to directly and/or indirectly regulate gene expression for GH, PRL, and SL in combination with the pituitary-gonadal axis, such as sex steroid hormones. Direct effects of salmon GnRH (sGnRH), estradiol-17 beta (E2), testosterone, and 11-ketotestosterone (11KT) on the amounts of GH, PRL, and SL mRNAs were thus examined using primary pituitary cell cultures of masu salmon at the four reproductive stages. We also determined the amounts of mRNA encoding pituitary specific POU homeodomain transcription factor (Pit-1) by real-time polymerase chain reactions. The amounts of GH, PRL, and SL mRNAs in the control cells elevated with gonadal maturation, coincidently with those of Pit-1 mRNA. sGnRH at 1.0 nM elevated the amounts of all mRNAs examined in the pre-spawning females, whereas significant effects were not observed with 100 nM sGnRH at any reproductive stages. Sex steroid hormones had no significant effects before initiation of gonadal maturation and at the maturing stage. In the males, E2 tended to decrease the amounts of SL mRNA in the pre-spawning stage. In the females, E2 and 11KT increased the amounts of PRL and SL mRNAs in the pre-spawning stage, but halved those of PRL mRNA in the spawning stage. The amounts of Pit-1 mRNA changed coincidently with those of PRL and SL mRNAs at all examined stages. The effects of E2 alone were abolished by 100 nM sGnRH. The present results indicated that both sGnRH and steroid hormones directly modulate synthesis of Pit-1, and further expression of PRL and SL genes. sGnRH may indirectly regulate GH/PRL/SL family hormone genes through the pituitary-gonadal axis, particularly in the late stage of gametogenesis. (c) 2005 Elsevier Inc. All rights reserved.