Leptin excites proopiomelanocortin neurons via activation of TRPC channels.
Leptin excites proopiomelanocortin neurons via activation of TRPC channels.
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DOI：
10.1523/jneurosci.4816-09.2010
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发表时间：
2010-01-27
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影响因子：
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通讯作者：
Kelly MJ
中科院分区：
文献类型：
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作者：
Qiu J;Fang Y;Rønnekleiv OK;Kelly MJ
瘦素可以通过激活下丘脑前阿黑皮素（POMC）神经元发挥其有效的食欲抑制作用。它通过激活一种尚未鉴定的非选择性阳离子电流使POMC神经元去极化。因此，我们试图通过转基因小鼠EGFP-POMC神经元的全细胞记录来鉴定瘦素激活的电导。TRPC通道阻断剂SKF 96365、FFA和2-APB均能有效抑制leptin诱导的电流。此外，镧（La 3+）和细胞内Ca 2+加强瘦素的作用。此外，DAG可渗透类似物OAG未能激活任何TRPC电流。使用基于Cs+-酒石酸盐的内部溶液，瘦素激活的电流在-20 mV附近逆转。当Cs+置换Na+和K+后，电流反转移到0 mV附近，I/V曲线在-40 mV以上出现负斜率电导。scRT-PCR结果显示，POMC神经元中TRPC 1和TRPC 4 -7 mRNA均有表达，其中TRPC 5表达最多。瘦素诱导的电流被Jak 2抑制剂AG 490、PI 3激酶抑制剂渥曼青霉素和磷脂酶C抑制剂U 73122和ET-18-OCH 3阻断。值得注意的是，我们在大多数POMC神经元中鉴定了PLCγ1转录本。因此，瘦素通过Jak 2-PI 3激酶-PLC γ通路激活TRPC通道，TRPC 1、4和5是介导瘦素去极化作用的关键通道。
Leptin can exert its potent appetite-suppressing effects via activation of hypothalamic proopiomelanocortin (POMC) neurons. It depolarizes POMC neurons via activation of a yet unidentified non-selective cation current. Therefore, we sought to identify the conductance activated by leptin using whole cell recording in EGFP-POMC neurons from transgenic mice. The TRPC channel blockers SKF96365, FFA and 2-APB potently inhibited the leptin-induced current. Also, lanthanum (La3+) and intracellular Ca2+ potentiated the effects of leptin. Moreover, the DAG permeable analog OAG failed to activate any TRPC current. Using a Cs+-gluconate-based internal solution, leptin-activated current reversed near -20 mV. After replacement of external Na+ and K+ with Cs+, the reversal shifted to near 0 mV, and the I/V curve exhibited a negative slope conductance at voltages more negative than –40 mV. Based on scRT-PCR, TRPC1 and TRPC4-7 mRNA were expressed in POMC neurons with TRPC5 being the most prevalent. The leptin-induced current was blocked by Jak2 inhibitor AG490, the PI3 Kinase inhibitor wortmannin and the phospholipase C inhibitors, U73122 and ET-18-OCH3. Notably, we identified PLCγ1 transcripts in the majority of POMC neurons. Therefore, leptin through a Jak2-PI3 kinase-PLCγ pathway activates TRPC channels, and TRPC1, 4 and 5 appear to be the key channels mediating the depolarizing effects of leptin in POMC neurons.