Melatonin Controls Photoperiodic Changes in Tanycyte Vimentin and Neural Cell Adhesion Molecule Expression in the Djungarian Hamster (Phodopus sungorus)
Melatonin Controls Photoperiodic Changes in Tanycyte Vimentin and Neural Cell Adhesion Molecule Expression in the Djungarian Hamster (Phodopus sungorus)
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DOI：
10.1210/en.2011-1039
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发表时间：
2011-10-01
期刊：
影响因子：
4.8
通讯作者：
Klosen, Paul
中科院分区：
文献类型：
--
作者：
Bolborea, Matei;Laran-Chich, Marie-Pierre;Klosen, Paul
保加利亚仓鼠在夜间分泌松果体褪黑激素，显示出与季节同步的性腺大小的光周期变化。在短光周期（SP）中，性腺大小退化，循环性类固醇水平下降。因此，大脑受到褪黑激素和性类固醇的季节性变化的影响。伸长细胞是位于第三脑室室管膜内的特化胶质细胞。它们向脑膜或中基底下丘脑的血管发送信号。此外，已知它们局部调节中隆起的GnRH释放并显示季节性结构变化。鞣质细胞形态的季节性变化可能通过褪黑激素或性类固醇介导。因此，我们分析了光周期、褪黑激素和性类固醇对1)免疫组化对伸长细胞vimentin表达的影响，2)对神经细胞粘附分子（NCAM）和多唾液酸作为脑可塑性标志物的表达的影响。同样，SP中伸长细胞及其过程中含有较低量的NCAM。这些由SP暴露引起的变化不能通过补充睾酮恢复到长光周期（LP）水平。同样，去势不影响LP细胞vimentin和NCAM的表达。相比之下，下午晚些时候注射褪黑素，在LP仓鼠中模拟sp样褪黑素峰值，降低了vimentin和NCAM的表达。因此，伸长细胞中vimentin和NCAM表达的季节性变化是由褪黑素调节的，独立于性类固醇的季节性变化。（内分泌学152:3871-3883,2011）
The Djungarian hamster displays photoperiodic variations in gonadal size synchronized to the seasons by the nightly secretion of the pineal hormone melatonin. In short photoperiod (SP), the gonads regress in size, and circulating sex steroids levels decline. Thus, the brain is subject to seasonal variations of both melatonin and sex steroids. Tanycytes are specialized glial cells located in the ependymal lining of the third ventricle. They send processes either to the meninges or to blood vessels of the medio-basal hypothalamus. Furthermore, they are known to locally modulate GnRH release in the median eminence and to display seasonal structural changes. Seasonal changes in tanycyte morphology might be mediated either through melatonin or sex steroids. Therefore, we analyzed the effects of photoperiod, melatonin, and sex steroids 1) on tanycyte vimentin expression by immunohistochemistry and 2) on the expression of the neural cell adhesion molecule (NCAM) and polysialic acid as markers of brain plasticity. Vimentin immunostaining was reduced in tanycyte cell bodies and processes in SP. Similarly, tanycytes and their processes contained lower amounts of NCAM in SP. These changes induced by SP exposure could not be restored to long photoperiod (LP) levels by testosterone supplementation. Likewise, castration in LP did not affect tanycyte vimentin or NCAM expression. By contrast, late afternoon melatonin injections mimicking a SP-like melatonin peak in LP hamsters reduced vimentin and NCAM expression. Thus, the seasonal changes in vimentin and NCAM expression in tanycytes are regulated by melatonin independently of seasonal sex steroid changes. (Endocrinology 152: 3871-3883, 2011)