Assessing the response of pancreatic islet cells to glucose stimulation is important for understanding β-cell function. Zebrafish are a promising model for studies of metabolism in general, including stimulus-secretion coupling in the pancreas. We used transgenic zebrafish embryos expressing a genetically-encoded Ca²⁺ sensor in pancreatic β-cells to monitor a key step in glucose induced insulin secretion; the elevations of intracellular [Ca²⁺]_i. In vivo and ex vivo analyses of [Ca²⁺]_i demonstrate that β-cell responsiveness to glucose is well established in late embryogenesis and that embryonic β-cells also respond to free fatty acid and amino acid challenges. In vivo imaging of whole embryos further shows that indirect glucose administration, for example by yolk injection, results in a slow and asynchronous induction of β-cell [Ca²⁺]_i responses, while intravenous glucose injections cause immediate and islet-wide synchronized [Ca²⁺]_i fluctuations. Finally, we demonstrate that embryos with disrupted mutation of the Ca_V1.2 channel gene cacna1c are hyperglycemic and that this phenotype is associated with glucose-independent [Ca²⁺]_i fluctuation in β-cells. The data reveal a novel central role of cacna1c in β-cell specific stimulus-secretion coupling in zebrafish and demonstrate that the novel approach we propose – to monitor the [Ca²⁺]_i dynamics in embryonic β-cells in vivo – will help to expand the understanding of β-cell physiological functions in healthy and diseased states.

评估胰岛细胞对葡萄糖刺激的反应对于理解 β 细胞功能很重要。斑马鱼是一般代谢研究的有前途的模型，包括胰腺中的刺激 - 分泌耦合。我们使用转基因斑马鱼胚胎在胰腺 β 细胞中表达基因编码的 Ca ²⁺传感器来监测葡萄糖诱导的胰岛素分泌的关键步骤；细胞内[Ca ²⁺ ] _i的升高。[Ca ²⁺ ] _{i 的}体内和体外分析证明 β 细胞对葡萄糖的反应在胚胎发生后期已经很好地建立，并且胚胎 β 细胞也对游离脂肪酸和氨基酸挑战作出反应。整个胚胎的体内成像进一步表明，间接葡萄糖给药，例如通过蛋黄注射，导致 β 细胞 [Ca ²⁺ ] _i反应的缓慢和异步诱导，而静脉注射葡萄糖会导致立即和胰岛范围内的同步。 Ca ²⁺ ] _i波动。最后，我们证明了Ca _V 1.2通道基因cacna1c突变中断的胚胎是高血糖症，并且这种表型与β 细胞中不依赖葡萄糖的 [Ca ²⁺ ] _i波动有关。数据揭示了cacna1c在斑马鱼 β 细胞特异性刺激 - 分泌偶联中的新核心作用，并证明我们提出的新方法——监测体内胚胎 β 细胞中的 [Ca ²⁺ ] _i动力学——将有助于扩展对健康和患病状态下 β 细胞生理功能的理解。