Regulation of Agouti-Related Protein and Pro-Opiomelanocortin Gene Expression in the Avian Arcuate Nucleus.
Regulation of Agouti-Related Protein and Pro-Opiomelanocortin Gene Expression in the Avian Arcuate Nucleus.
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DOI：
10.3389/fendo.2017.00075
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发表时间：
2017
影响因子：
5.2
通讯作者：
Dunn IC
中科院分区：
文献类型：
--
作者：
Boswell T;Dunn IC
弓状核在神经解剖学和神经肽表达方面在脊椎动物分类中通常是保守的。在几种鸟类的弓状核中已经证实了刺鼠相关蛋白(AGRP)、神经肽Y(NPY)、阿片黑素皮质素原(POMC)以及可卡因和苯丙胺调节的转录本(CART)的基因表达，并证明了AGRP和NPY的共同定位。这些基因编码的蛋白质在中央给药后对鸟类摄食量的影响与在其他脊椎动物中看到的类似，AGRP和NPY是厌食症，CART和α黑素细胞刺激素是厌食症。我们重点研究了弓状核AGRP和POMC在几种鸟类模型中的表达与能量平衡、孵化、应激和生长调节的关系。剥夺能量和限制能量后，AgRP和POMC mRNA分别上调和下调。这表明，AGRP和POMC神经元活动的协调变化有助于推动动态平衡反应，以取代鸟类中耗尽的能量储存，就像其他脊椎动物一样。虽然AGRP和POMC的表达通常分别与食物摄入量呈正相关和负相关，但我们在这里综述了一些禽类模型中AGRP基因表达与食物摄入量无关的情况，并可能独立于食欲的变化对生长产生影响。这表明中枢黑素皮质素系统可能在鸟类中发挥更多的多效性功能。虽然AGRP和POMC神经元的神经解剖排列及其活动对营养状态的敏感性与其他脊椎动物一般是保守的，但对作用于鸟类弓状核的关键营养反馈信号缺乏详细的了解，鸟类和哺乳动物之间似乎存在显著差异。特别是，最近发现的鸟类瘦素基因在组织表达模式上显示出不同鸟类之间的差异，并且它们的表达与营养状态的联系似乎不那么密切。目前尚不确定在瘦素和Ghrelin的重要性明显低于哺乳动物的情况下，鸟类中枢黑素皮质素系统的调节是如何实现的。
The arcuate nucleus is generally conserved across vertebrate taxa in its neuroanatomy and neuropeptide expression. Gene expression of agouti-related protein (AGRP), neuropeptide Y (NPY), pro-opiomelanocortin (POMC), and cocaine- and amphetamine-regulated transcript (CART) has been established in the arcuate nucleus of several bird species and co-localization demonstrated for AGRP and NPY. The proteins encoded by these genes exert comparable effects on food intake in birds after central administration to those seen in other vertebrates, with AGRP and NPY being orexigenic and CART and α-melanocyte-stimulating hormone anorexigenic. We have focused on the measurement of arcuate nucleus AGRP and POMC expression in several avian models in relation to the regulation of energy balance, incubation, stress, and growth. AGRP mRNA and POMC mRNA are, respectively, up- and downregulated after energy deprivation and restriction. This suggests that coordinated changes in the activity of AGRP and POMC neurons help to drive the homeostatic response to replace depleted energy stores in birds as in other vertebrates. While AGRP and POMC expression are generally positively and negatively correlated with food intake, respectively, we review here situations in some avian models in which AGRP gene expression is dissociated from the level of food intake and may have an influence on growth independent of changes in appetite. This suggests the possibility that the central melanocortin system exerts more pleiotropic functions in birds. While the neuroanatomical arrangement of AGRP and POMC neurons and the sensitivity of their activity to nutritional state appear generally conserved with other vertebrates, detailed knowledge is lacking of the key nutritional feedback signals acting on the avian arcuate nucleus and there appear to be significant differences between birds and mammals. In particular, recently identified avian leptin genes show differences between bird species in their tissue expression patterns and appear less closely linked in their expression to nutritional state. It is presently uncertain how the regulation of the central melanocortin system in birds is brought about in the situation of the apparently reduced importance of leptin and ghrelin compared to mammals.