Bennet Hedvig, Mollet Inês G, Balhuizen Alexander, Medina Anya, Nagorny Cecilia, Bagge Annika, Fadista Joao, Ottosson-Laakso Emilia, Vikman Petter, Dekker-Nitert Marloes, Eliasson Lena, Wierup Nils, Artner Isabella, Fex Malin
Lund University Diabetes Centre, Department of Clinical Sciences, Unit of Diabetes and Celiac disease, Clinical Research Centre, Jan Waldenströms gata 35, Clinical Research Centre House 91:10, Skåne University Hospital Malmö, SE-20502, Malmö, Sweden.
Lund University Diabetes Centre, Islet Cell Exocytosis, Malmö, Sweden.
Diabetologia. 2016 Apr;59(4):744-54. doi: 10.1007/s00125-015-3847-6. Epub 2016 Jan 6.
AIMS/HYPOTHESIS: The Gq-coupled 5-hydroxytryptamine 2B (5-HT2B) receptor is known to regulate the proliferation of islet beta cells during pregnancy. However, the role of serotonin in the control of insulin release is still controversial. The aim of the present study was to explore the role of the 5-HT2B receptor in the regulation of insulin secretion in mouse and human islets, as well as in clonal INS-1(832/13) cells.
Expression of HTR2B mRNA and 5-HT2B protein was examined with quantitative real-time PCR, RNA sequencing and immunohistochemistry. α-Methyl serotonin maleate salt (AMS), a serotonin receptor agonist, was employed for robust 5-HT2B receptor activation. Htr2b was silenced with small interfering RNA in INS-1(832/13) cells. Insulin secretion, Ca(2+) response and oxygen consumption rate were determined.
Immunohistochemistry revealed that 5-HT2B is expressed in human and mouse islet beta cells. Activation of 5-HT2B receptors by AMS enhanced glucose-stimulated insulin secretion (GSIS) in human and mouse islets as well as in INS-1(832/13) cells. Silencing Htr2b in INS-1(832/13) cells led to a 30% reduction in GSIS. 5-HT2B receptor activation produced robust, regular and sustained Ca(2+) oscillations in mouse islets with an increase in both peak distance (period) and time in the active phase as compared with control. Enhanced insulin secretion and Ca(2+) changes induced by AMS coincided with an increase in oxygen consumption in INS-1(832/13) cells.
CONCLUSIONS/INTERPRETATION: Activation of 5-HT2B receptors stimulates GSIS in beta cells by triggering downstream changes in cellular Ca(2+) flux that enhance mitochondrial metabolism. Our findings suggest that serotonin and the 5-HT2B receptor stimulate insulin release.
目的/假设：已知Gq偶联的5-羟色胺2B（5-HT2B）受体在孕期调节胰岛β细胞增殖。然而，血清素在胰岛素释放控制中的作用仍存在争议。本研究旨在探讨5-HT2B受体在调节小鼠和人类胰岛以及克隆的INS-1(832/13)细胞胰岛素分泌中的作用。
采用定量实时PCR、RNA测序和免疫组织化学检测HTR2B mRNA和5-HT2B蛋白的表达。使用血清素受体激动剂马来酸α-甲基血清素盐（AMS）来强力激活5-HT2B受体。在INS-1(832/13)细胞中用小干扰RNA使Htr2b沉默。测定胰岛素分泌、Ca(2+)反应和氧消耗率。
免疫组织化学显示5-HT2B在人类和小鼠胰岛β细胞中表达。AMS激活5-HT2B受体可增强人类和小鼠胰岛以及INS-1(832/13)细胞中的葡萄糖刺激的胰岛素分泌（GSIS）。在INS-1(832/13)细胞中使Htr2b沉默导致GSIS降低30%。与对照相比，5-HT2B受体激活在小鼠胰岛中产生强烈、规律且持续的Ca(2+)振荡，峰间距（周期）和活跃期时间均增加。AMS诱导的胰岛素分泌增强和Ca(2+)变化与INS-1(832/13)细胞中氧消耗增加一致。
结论/解读：5-HT2B受体激活通过触发细胞Ca(2+)通量的下游变化来刺激β细胞中的GSIS，从而增强线粒体代谢。我们的研究结果表明血清素和5-HT2B受体刺激胰岛素释放。
