Expression of a leptin receptor in immortalized gonadotropin-releasing hormone-secreting neurons
Expression of a leptin receptor in immortalized gonadotropin-releasing hormone-secreting neurons
复制标题
DOI：
10.1210/en.140.4.1581
复制
发表时间：
1999-04-01
期刊：
影响因子：
4.8
通讯作者：
Motta, M
中科院分区：
文献类型：
--
作者：
Magni, P;Vettor, R;Motta, M
瘦素由脂肪细胞分泌，通过激活特异性受体（OB-R）调节食物摄入和能量平衡。最近的证据表明，它也参与控制生殖过程，可能作用于中央和外围目标。特别是，它已被证明，瘦素可能间接刺激GnRH释放下丘脑片段通过作用于interneurons碰撞GnRH分泌神经元。在本研究中，通过使用永生化的GnRH分泌细胞系GT 1 -7，瘦素可能以直接的方式另外调节GnRH分泌神经元的活性。通过RT-PCR分析来自GT 1 -7细胞的总RNA来检测OB-R信使RNA（mRNA）（长形式）的存在。如免疫细胞化学和Western印迹分析所示，OB-R蛋白也在这些细胞中表达。后者揭示了一个单一的免疫反应OB-R的存在下，约130 kDa的大小。为了研究这些受体的功能，评估了瘦素处理对GT 1 -7细胞中GnRH分泌和基因表达的影响。在静态条件下，暴露于低浓度的瘦素（30分钟后10（-12）M; 60分钟后10 M）刺激GnRH释放。选择10（-1）μ M剂量研究动态条件下瘦素对GnRH分泌的影响。为此，将GT 1 -7细胞置于灌流系统中;用瘦素（10-12 hi）处理60 min刺激GnRH释放，而脉冲频率没有变化。与此相反，10（-12）-10（-10）M的leptin作用1、3、6和24 h对GT 1 -7细胞中GnRH基因的表达没有影响。目前的结果表明GT 1 -7细胞具有OB-Rs，瘦素可能直接影响其功能。结合已有的研究结果，提示瘦素可能通过中枢和外周多水平的作用参与生殖过程的调控。
Leptin is secreted by adipocytes and regulates food intake and energy balance through the activation of specific receptors (OB-R). Recent evidence suggests that it is also involved in the control of reproductive processes, by possibly acting on central and peripheral targets. In particular, it has been shown that leptin may indirectly stimulate GnRH release from hypothalamic fragments by acting on interneurons impinging on GnRH-secreting neurons. The possibility that leptin might additionally modulate the activity of GnRH-secreting neurons in a direct way has been addressed in the present study, by using the immortalized GnRH-secreting cell line GT1-7. The presence of OB-R messenger RNA (mRNA) (long form) was detected by RT-PCR analysis of total RNA from GT1-7 cells. An OB-R protein is also expressed in these cells, as shown by immunocytochemistry and by Western blot analysis. The latter has revealed the presence of a single immunoreactive OB-R with an approximate size of 130 kDa. To study the functionality of these receptors, the effect of leptin treatment on GnRH secretion and gene expression in GT1-7 cells were evaluated. Under static conditions, GnRH release was stimulated by exposure to low concentrations of leptin (10(-12) M after 30 min; 10 M after 60 min). The 10(-1)2 M dose was selected for studying the effect of leptin on GnRH secretion under dynamic conditions. To this purpose, GT1-7 cells were placed in a perifusion system; treatment with leptin (10-12 hi) for 60 min stimulated GnRH release with no changes of pulse frequency. On the contrary, exposure to leptin (10(-12)-10(-10) M) for 1, 3, 6, and 24 h did not affect GnRH gene expression in GT1-7 cells. The present results indicate that GT1-7 cells possess OB-Rs and that leptin may directly affect their function. Taken together with the available reports, these findings suggest that leptin might participate in the regulation of reproductive processes by acting at multiple levels, both centrally and peripherally.