Green light inhibits GnRH‐I expression by stimulating the melatonin‐GnIH pathway in the chick brain
Green light inhibits GnRH‐I expression by stimulating the melatonin‐GnIH pathway in the chick brain
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DOI：
10.1111/jne.12468
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发表时间：
2017-05
影响因子：
3.2
通讯作者：
L. Zhang;F. Chen;J. Cao;Y. Dong;Z. Wang;M. Hu;Y. Chen
中科院分区：
文献类型：
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作者：
L. Zhang;F. Chen;J. Cao;Y. Dong;Z. Wang;M. Hu;Y. Chen
为研究单色光对鸡下丘脑促性腺激素释放激素（GnRH）表达的影响机制，将192只初孵雏鸡分为完整、假手术和松果体切除组，采用发光二极管系统分别照射白色（WL）、红色（RL）、绿色（GL）和蓝色（BL）光2周。在GL完整组中，与WL、RL和BL暴露的鸡相比，下丘脑中GnRH-I的mRNA和蛋白水平、苍白连合核GnRH-I免疫反应（-ir）细胞的平均细胞面积和平均细胞光密度（OD）分别降低13.2%-34.5%、5.7%-39.1%和9.9%-17.3%。GL降低了这些与GnRH-I表达相关的因子，在松果体切除的鸟类中未观察到GL的作用。然而，与WL相比，暴露于GL的雏鸡的下丘脑促性腺激素抑制激素（GnIH）和GnIH受体（GnIHR）的mRNA和蛋白水平、室旁巨细胞GnIH-ir细胞的平均细胞面积和平均细胞OD以及血浆褪黑素浓度分别增加18.6%-49.2%、21.1%-60.0%和8.6%-30.6%，RL和BL完整组。血浆褪黑素浓度与GnRH-I蛋白呈负相关，与GnIH和GnIHR蛋白呈正相关。下丘脑中GnRH-I和GnIHR的蛋白表达均呈负相关。松果体切除后，GnRH-I表达增加，而血浆褪黑素浓度、GnIH和GnIHR表达降低，WL、RL、GL和BL组之间无显著差异。双标记免疫荧光显示，GnIH轴突终末位于GnRH-I神经元附近，一些GnRH-I神经元与GnIHR共表达，GnIH神经元与褪黑素受体亚型醌还原酶2共表达。这些结果表明，绿色光通过增加鸡脑中的褪黑激素分泌和刺激褪黑激素受体-GnIH-GnIH受体途径来抑制GnRH-I表达。
To study the mechanism by which monochromatic light affects gonadotrophin‐releasing hormone (GnRH) expression in chicken hypothalamus, a total of 192 newly‐hatched chicks were divided into intact, sham‐operated and pinealectomy groups and exposed to white (WL), red (RL), green (GL) and blue (BL) lights using a light‐emitting diode system for 2 weeks. In the GL intact group, the mRNA and protein levels of GnRH‐I in the hypothalamus, the mean cell area and mean cell optical density (OD) of GnRH‐I‐immunoreactive (‐ir) cells of the nucleus commissurae pallii were decreased by 13.2%‐34.5%, 5.7%‐39.1% and 9.9%‐17.3% compared to those in the chicks exposed to the WL, RL and BL, respectively. GL decreased these factors related to GnRH‐I expression and the effect of GL was not observed in pinealectomised birds. However, the mRNA and protein levels of hypothalamic gonadotrophin‐inhibitory hormone (GnIH) and GnIH receptor (GnIHR), the mean cell area and mean cell OD of the GnIH‐ir cells of the paraventricularis magnocellularis, and the plasma melatonin concentration in the chicks exposed to GL were increased by 18.6%‐49.2%, 21.1%‐60.0% and 8.6%‐30.6% compared to the WL, RL and BL intact groups, respectively. The plasma melatonin concentration showed a negative correlation with GnRH‐I protein and a positive correlation with GnIH and GnIHR proteins. Protein expression of both GnRH‐I and GnIHR showed a negative correlation in the hypothalamus. After pinealectomy, GnRH‐I expression increased, whereas plasma melatonin concentration, GnIH and GnIHR expression decreased, and there were no significant differences among the WL, RL, GL and BL groups. Double‐labelled immunofluorescence showed that GnIH axon terminals were near GnRH‐I neurones, some GnRH‐I neurones coexpressed with GnIHR and GnIH neurones coexpressed with melatonin receptor subtype quinone reductase 2. These results demonstrate that green light inhibits GnRH‐I expression by increasing melatonin secretion and stimulating melatonin receptor‐GnIH‐GnIH receptor pathway in the chick brain.