Martinez-Chavez Carlos C, Minghetti Matteo, Migaud Herve
Institute of Aquaculture, University of Stirling, Stirling, UK.
Gen Comp Endocrinol. 2008 Apr 1;156(2):224-33. doi: 10.1016/j.ygcen.2008.01.019. Epub 2008 Feb 10.
The Kiss1/GPR54 system has recently been shown to play a key role in the onset of puberty in mammals. Growing evidence suggests that this system is also conserved across vertebrates although very few studies so far have been performed in lower vertebrates. The aims of this study were firstly in the teleost Nile tilapia to screen tissues for GPR54 expression levels, secondly to measure the expression patterns of GPR54 and GnRH I receptor (rGnRH I) in whole brains during the onset of puberty and finally to determine the effects of continuous illumination (LL) on receptor expression levels. Results confirmed that GPR54 was predominantly expressed in the brain and pituitary of adult tilapia. Furthermore, a significant increase of GPR54 gene expression was found in tilapia brains at 11 weeks post hatch (wph) followed by rGnRH I at 13 wph just prior to the histological observation of vitellogenic oocytes and active spermatogenesis in ova and testes at 17 wph. These results suggest a correlation between the increase of GPR54 expression in the brain and the onset of puberty. Finally, a significant effect of LL was observed on GPR54 expression levels which were characterized by a delayed surge with significantly lower levels than those of control fish. The current study not only suggests a link between the Kiss1/GPR54 system and the onset of puberty in a tropical batch spawning teleost that would be a highly conserved feature across vertebrates but also that the transcriptional mechanisms regulating GPR54 expression could be directly or indirectly influenced by light.
Kiss1/GPR54系统最近被证明在哺乳动物青春期启动过程中起关键作用。越来越多的证据表明，尽管目前在低等脊椎动物中进行的研究很少，但该系统在整个脊椎动物中也是保守的。本研究的目的，一是在硬骨鱼尼罗罗非鱼中筛选GPR54表达水平的组织，二是测量青春期启动期间全脑中GPR54和促性腺激素释放激素I受体（rGnRH I）的表达模式，最后确定持续光照（LL）对受体表达水平的影响。结果证实，GPR54主要在成年罗非鱼的脑和垂体中表达。此外，在孵化后11周（wph）的罗非鱼脑中发现GPR54基因表达显著增加，随后在13 wph时rGnRH I表达增加，紧接着在17 wph时在卵子和睾丸中观察到卵黄生成卵母细胞和活跃精子发生的组织学变化。这些结果表明，脑中GPR54表达的增加与青春期启动之间存在相关性。最后，观察到LL对GPR54表达水平有显著影响，其特征是激增延迟，水平显著低于对照鱼。当前的研究不仅表明Kiss1/GPR54系统与热带分批产卵硬骨鱼的青春期启动之间存在联系，这在整个脊椎动物中是一个高度保守的特征，而且调节GPR54表达的转录机制可能直接或间接受光的影响。
