促肾上腺皮质激素释放激素对下丘脑神经元钙信号的调节作用

Regulation of calcium signaling in rat hypothalamic neurons by exogeneous corticotropin-releasing hormone

目的 研究促肾上腺皮质激素释放激素 (CRH)对下丘脑神经元内游离钙离子浓度([Ca2 +]i)的调节作用。 方法 取孕 17d胎鼠下丘脑分散培养下丘脑神经元 ,采用PTI荧光成像系统测量 [Ca2 +]i变化 ;测量和分析外源性CRH对培养下丘脑神经元内钙信号变化的影响 ,分别与用Ryanodine系统特异性拮抗剂钌红和神经细胞膜L -型钙通道拮抗剂尼莫地平处理下丘脑神经元后 [Ca2 +]i的变化作比较。 结果 正常对照组下丘脑神经元 [Ca2 +]i含量较低 ,外源性CRH刺激后 ,[Ca2 +]i立即升高 ;预先应用L -型钙通道拮抗剂尼莫地平处理后再用CRH刺激的神经元[Ca2 +]i含量的增加明显被抑制 ;Ryanodine受体特异性拮抗剂钌红也可明显抑制 [Ca2 +]i含量的增加。 结论 在急性应激反应中 ,CRH可直接作用于下丘脑神经元 ,开放膜L -型钙离子通道并促使钙离子内流 ,从而进一步激活内贮钙释放 ,使其 [Ca2 +]i明显增加。在调节下丘脑神经元激活过程中 。

Objective To study regulation of intracellular free Ca 2+ concentration ([Ca 2+ ]i) in rat hypothalamic neurons by exogeneous corticotropin releasing hormone (CRH). Methods Hypothalamic neurons from a 17 day old rat embryo were cultured separately. By using photon technology international (PTI), [Ca 2+ ]i was assayed and the regulative effect of exogenous CRH on the changes of calcium signaling in rat hypothalamic neurons measured and analyzed. Then, the changes of [Ca 2+ ]i were observed and compared after the neurons were processed respectively by specific antagonist ruthenium red of ryanodine system and antagonist nimodipine of L calcium passage of neuron membrane. Results The basal [Ca 2+ ]i of separate cultures of rat hypothalamic neurons on coverslip was low and markedly increased under stimulation by CRH. But intracellular [Ca 2+ ]i level was significantly attenuated by stimulation of CRH following management with nimodipine. The increase of [Ca 2+ ]i was significantly suppressed by ruthenium red. Conclusions CRH has a direct effect on hypothalamic neurons, induces Ca 2+ influx via high voltage activated Ca 2+ channels, triggers Ca 2+ release from internal stores and as a result increases the [Ca 2+ ]i level. Meanwhile, CRH plays an important role in regulating the activation of hypothalamic neurons.