Saegusa H, Kurihara T, Zong S, Minowa O, Kazuno A, Han W, Matsuda Y, Yamanaka H, Osanai M, Noda T, Tanabe T
Department of Pharmacology and Neurobiology, Graduate School of Medicine, Tokyo Medical and Dental University, and CREST, Japan.
Proc Natl Acad Sci U S A. 2000 May 23;97(11):6132-7. doi: 10.1073/pnas.100124197.
alpha(1) subunit of the voltage-dependent Ca(2+) channel is essential for channel function and determines the functional specificity of various channel types. alpha(1E) subunit was originally identified as a neuron-specific one, but the physiological function of the Ca(2+) channel containing this subunit (alpha(1E) Ca(2+) channel) was not clear compared with other types of Ca(2+) channels because of the limited availability of specific blockers. To clarify the physiological roles of the alpha(1E) Ca(2+) channel, we have generated alpha(1E) mutant (alpha(1E)-/-) mice by gene targeting. The lacZ gene was inserted in-frame and used as a marker for alpha(1E) subunit expression. alpha(1E)-/- mice showed reduced spontaneous locomotor activities and signs of timidness, but other general behaviors were apparently normal. As involvement of alpha(1E) in pain transmission was suggested by localization analyses with 5-bromo-4-chloro-3-indolyl beta-d-galactopyranoside staining, we conducted several pain-related behavioral tests using the mutant mice. Although alpha(1E)+/- and alpha(1E)-/- mice exhibited normal pain behaviors against acute mechanical, thermal, and chemical stimuli, they both showed reduced responses to somatic inflammatory pain. alpha(1E)+/- mice showed reduced response to visceral inflammatory pain, whereas alpha(1E)-/- mice showed apparently normal response compared with that of wild-type mice. Furthermore, alpha(1E)-/- mice that had been presensitized with a visceral noxious conditioning stimulus showed increased responses to a somatic inflammatory pain, in marked contrast with the wild-type mice in which long-lasting effects of descending antinociceptive pathway were predominant. These results suggest that the alpha(1E) Ca(2 +) channel controls pain behaviors by both spinal and supraspinal mechanisms.
电压依赖性钙通道的α(1)亚基对通道功能至关重要，并决定了各种通道类型的功能特异性。α(1E)亚基最初被鉴定为神经元特异性亚基，但由于缺乏特异性阻滞剂，与其他类型的钙通道相比，含有该亚基的钙通道（α(1E)钙通道）的生理功能尚不清楚。为了阐明α(1E)钙通道的生理作用，我们通过基因打靶技术构建了α(1E)突变体（α(1E)-/-）小鼠。将lacZ基因读框插入并用作α(1E)亚基表达的标记。α(1E)-/-小鼠的自发运动活性降低并表现出胆小的迹象，但其他一般行为明显正常。由于用5-溴-4-氯-3-吲哚基-β-D-吡喃半乳糖苷染色的定位分析提示α(1E)参与疼痛传递，我们使用突变小鼠进行了多项与疼痛相关的行为测试。尽管α(1E)+/-和α(1E)-/-小鼠对急性机械、热和化学刺激表现出正常的疼痛行为，但它们对躯体炎性疼痛的反应均降低。α(1E)+/-小鼠对内脏炎性疼痛的反应降低，而α(1E)-/-小鼠与野生型小鼠相比表现出明显正常的反应。此外，用内脏伤害性条件刺激预先致敏的α(1E)-/-小鼠对躯体炎性疼痛的反应增强，这与以下行抗伤害感受通路的持久作用为主的野生型小鼠形成鲜明对比。这些结果表明，α(1E)钙通道通过脊髓和脊髓上机制控制疼痛行为。
