Hypothalamic growth hormone-releasing hormone (GHRH) deficiency: Targeted ablation of GHRH neurons in mice using a viral ion channel transgene
Hypothalamic growth hormone-releasing hormone (GHRH) deficiency: Targeted ablation of GHRH neurons in mice using a viral ion channel transgene
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DOI：
10.1210/me.2004-0223
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发表时间：
2005-05-01
影响因子：
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通讯作者：
Robinson, ICAF
中科院分区：
文献类型：
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作者：
Le Tissier, PR;Carmignac, DF;Robinson, ICAF
GHRH过量的动物和临床模型表明，GHRH为垂体生长激素提供了重要的营养驱动。我们采用了一种新的方法来沉默或消融GHRH神经元，使用流感病毒M2蛋白((H3A)M2)的一个修改的H37A变体。在哺乳动物细胞中，(H37A)M2形成一种高电导的单价阳离子通道，可被抗病毒药物金刚乙胺阻断。具有针对GHRH神经元的(H37A)M2表达的转基因小鼠在断奶后出现侏儒症，下丘脑GHRH转录本可以通过RT-PCR检测到，但不能通过原位杂交和免疫细胞化学检测到，这表明(H37A)M2的表达已经沉默或消融了几乎所有的GHRH细胞。GHRH-M2小鼠表现出明显的垂体前叶发育不良并伴有GH缺乏，尽管GH细胞仍然存在。GHRH-M2小鼠也缺乏催乳素，但没有TSH。GHRH-M2小鼠静脉注射GHRH可引起明显的GH反应，而注射GHRP-6则无此反应。GHRH-M2小鼠每日两次注射GHRH(100 mg/d)，连续7d后，其脑垂体GH含量增加，但PRL含量无明显变化。金刚乙胺治疗未能恢复生长或脑垂体GH含量。我们的结果表明GHRH神经元对生长激素和催乳素的产生以及正常生长的重要性。
Animal and clinical models of GHRH excess suggest that GHRH provides an important trophic drive to pituitary somatotrophs. We have adopted a novel approach to silence or ablate GHRH neurons, using a modified H37A variant of the influenza virus M2 protein ((H3A)M2). In mammalian cells, (H37A)M2 forms a high conductance monovalent cation channel that can be blocked by the antiviral drug rimantadine. Transgenic mice with (H37A)M2 expression targeted to GHRH neurons developed postweaning dwarfism with hypothalamic GHRH transcripts detectable by RT-PCR but not by in situ hybridization and immunocytochemistry, suggesting that expression of (H37A)M2 had silenced or ablated virtually all the GHRH cells. GHRH-M2 mice showed marked anterior pituitary hypoplasia with GH deficiency, although GH cells were still present. GHRH-M2 mice were also deficient in prolactin but not TSH. Acute iv injections of GHRH in GHRH-M2 mice elicited a significant GH response, whereas injections of GHRP-6 did not. Twice daily injections of GHRH ( 100 mu g/d) for 7 d in GHRH-M2 mice doubled their pituitary GH but not PRL contents. Rimantadine treatment failed to restore growth or pituitary GH contents. Our results show the importance of GHRH neurons for GH and prolactin production and normal growth.