l-Glutamate is one of the most abundant amino acids in the body and is a constituent of proteins and a substrate in metabolism. It is well known that glutamate serves as a primary excitatory neurotransmitter and a critical neuromodulator in the brain. Recent studies have shown that in addition to its pivotal role in neural functions, glutamate plays many important roles in a variety of cellular functions, including those as intracellular and extracellular signals. In pancreatic islets, glutamate is now known to be required for the normal regulation of insulin secretion, such as incretin-induced insulin secretion. In this review, we primarily discuss the physiological and pathophysiological roles of glutamate as intracellular and extracellular signals in the functions of pancreatic islets.

中文翻译：

---

谷氨酸作为胰岛功能中的细胞内和细胞外信号。

谷氨酸是人体中最丰富的氨基酸之一，是蛋白质的组成部分和代谢的底物。众所周知，谷氨酸是大脑中主要的兴奋性神经递质和关键的神经调节剂。最近的研究表明，谷氨酸除了在神经功能中起关键作用外，还在多种细胞功能中起着重要作用，包括细胞内和细胞外信号。在胰岛中，现已知道谷氨酸是正常调节胰岛素分泌（例如肠降血糖素诱导的胰岛素分泌）所必需的。在这篇综述中，我们主要讨论谷氨酸作为胰岛功能中细胞内和细胞外信号的生理和病理生理作用。