Distribution, Neuronal Colocalization, and 17β-E2 Modulation of Small Conductance Calcium-Activated K+ Channel (SK3) mRNA in the Guinea Pig Brain.
Distribution, Neuronal Colocalization, and 17β-E2 Modulation of Small Conductance Calcium-Activated K+ Channel (SK3) mRNA in the Guinea Pig Brain.
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DOI：
10.1210/endo.143.3.8708
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发表时间：
2002-03
期刊：
影响因子：
4.8
通讯作者：
M. Bosch;M. Kelly;O. Rønnekleiv
中科院分区：
文献类型：
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作者：
M. Bosch;M. Kelly;O. Rønnekleiv
分子克隆显示存在三种不同的小电导（SK 1 -3）Ca（2+）激活的K（+）通道。由于SK通道的基础后超极化（AHP），这是雕塑阶段性放电在下丘脑神经元的关键，我们调查了这些渠道在雌性豚鼠的分布。用PCR方法克隆了SK 1和SK 3的cDNA片段，核糖核酸酶保护试验和原位杂交分析表明，SK 3通道是豚鼠下丘脑中主要表达的通道亚型。结合原位杂交和荧光免疫细胞化学显示，SK 3 mRNA表达的GnRH，多巴胺，加压素神经元，所有这些神经元表现出AHP电流。此外，在其他脑区，包括隔，床核，杏仁核，丘脑，中脑和海马发现SK 3 mRNA。采用定量核糖核酸酶保护试验，SK 3 mRNA表达的顺序为隔区>或=中脑>头侧丘脑>或=头侧基底下丘脑>或=尾侧丘脑>或=视前区>>尾侧基底下丘脑>或=海马。此外，17 β-E2治疗，减少血浆LH在负反馈阶段，显着增加SK 3 mRNA水平在吻基底下丘脑（P < 0.05; n = 6）。因此，这些研究结果表明，雌激素增加SK 3通道的mRNA表达，这可能是雌激素调节下丘脑神经元兴奋性的负反馈机制。
Molecular cloning has revealed the existence of three distinct small conductance (SK1-3) Ca(2+)-activated K(+) channels. Because SK channels underlie the afterhyperpolarization (AHP) that is critical for sculpturing phasic firing in hypothalamic neurons, we investigated the distribution of these channels in the female guinea pig. Both SK1 and SK3 cDNA fragments were cloned using PCR, and ribonuclease protection assay as well as in situ hybridization analysis illustrated that the SK3 channel was the predominant subtype expressed in the guinea pig hypothalamus. Combined in situ hybridization and fluorescence immunocytochemistry revealed that SK3 mRNA was expressed in GnRH, dopamine, and vasopressin neurons, and all of these neurons exhibited an AHP current. Moreover, SK3 mRNA was found in other brain areas, including the septum, bed nucleus, amygdala, thalamus, midbrain, and hippocampus. Using quantitative ribonuclease protection assay, the rank order of SK3 mRNA expression was septum >or= midbrain > rostral thalamus >or= rostral basal hypothalamus >or= caudal thalamus >or= preoptic area >> caudal basal hypothalamus >or= hippocampus. Moreover, 17beta-E2 treatment, which reduces plasma LH during the negative feedback phase, significantly increased SK3 mRNA levels in the rostral basal hypothalamus (P < 0.05; n = 6). Therefore, these findings suggest that estrogen increases the mRNA expression of SK3 channels, which may represent a mechanism by which estrogen regulates hypothalamic neuronal excitability during negative feedback.