Adeno-associated virus-mediated knockdown of melanocortin-4 receptor in the paraventricular nucleus of the hypothalamus promotes high-fat diet-induced hyperphagia and obesity
Adeno-associated virus-mediated knockdown of melanocortin-4 receptor in the paraventricular nucleus of the hypothalamus promotes high-fat diet-induced hyperphagia and obesity
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DOI：
10.1677/joe-08-0009
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发表时间：
2008-06-01
影响因子：
4
通讯作者：
Lu, Xin-Yun
中科院分区：
文献类型：
--
作者：
Garza, Jacob C.;Kim, Chung Sub;Lu, Xin-Yun
药理学和遗传学研究表明，下丘脑室旁核(PVN)中的黑素皮质素-4受体(MC4R)信号调节食欲和能量平衡。然而，在发育正常的动物中，MC4R信号在PVN神经元中的具体作用仍有待进一步阐明。在本研究中，我们使用RNA干扰来确定下丘脑室旁核中MC4R基因敲除是否调节成年大鼠的摄食量和体重。构建靶向MC4R的短发夹状RNA(AAV-shRNA-MC4R)的腺相关病毒载体(AAV-shRNA-MC4R)，在PVN中诱导MC4R基因敲除。通过原位杂交，我们检测到在下丘脑室旁核的整个吻尾部都有高水平的DICER表达，这是shRNA介导的基因沉默所必需的一个关键酶。成年大鼠双侧室旁核注射AAV-shRNA-MC4R载体后，MC4R基因表达显著降低。MC4R基因敲除的动物在高脂肪饮食下表现出食物摄入量的增加和体重的过度增加。我们的结果提供了证据，AAV介导的PVN神经元上MC4R的沉默促进了成年动物对饮食挑战的过度吞噬和肥胖。
Pharmacological and genetic studies have suggested that melanocortin-4 receptor (MC4R) signaling in the paraventricular nucleus of hypothalamus (PVN) regulates appetite and energy balance. However, the specific role of MC4R signaling in PVN neurons in these processes remains to be further elucidated in normally developed animals. In the present study, we employed RNA interference to determine whether MC4R knockdown in the PVN modulates food intake and body weight in adult rats. Adeno-associated viral (AAV) vectors encoding short hairpin RNAs targeting MC4R (AAV-shRNA-MC4R) were generated to induce MC4R knockdown in the PVN. By in situ hybridization, we detected a high-level expression of Dicer, a key enzyme required for shRNA-mediated gene silencing, along the entire rostrocaudal extent of the PVN. Bilateral injection of AAV-shRNA-MC4R vectors into the PVN of the adult rat resulted in significant and specific reduction of MC4R mRNA expression. Animals with MC4R knockdown exhibited an increase in food intake and excessive body weight gain when exposed to a high-fat diet. Our results provide evidence that AAV-mediated silencing of MC4R on PVN neurons promotes hyperphagia and obesity in response to the dietary challenge in the adult animal.