Diabetes, Obesity and Metabolism Institute.
Nash Family Department of Neuroscience and Friedman Brain Institute, and.
JCI Insight. 2020 Nov 5;5(21):133488. doi: 10.1172/jci.insight.133488.
Hypoglycemia is a frequent complication of diabetes, limiting therapy and increasing morbidity and mortality. With recurrent hypoglycemia, the counterregulatory response (CRR) to decreased blood glucose is blunted, resulting in hypoglycemia-associated autonomic failure (HAAF). The mechanisms leading to these blunted effects are only poorly understood. Here, we report, with ISH, IHC, and the tissue-clearing capability of iDISCO+, that growth hormone releasing hormone (GHRH) neurons represent a unique population of arcuate nucleus neurons activated by glucose deprivation in vivo. Repeated glucose deprivation reduces GHRH neuron activation and remodels excitatory and inhibitory inputs to GHRH neurons. We show that low glucose sensing is coupled to GHRH neuron depolarization, decreased ATP production, and mitochondrial fusion. Repeated hypoglycemia attenuates these responses during low glucose. By maintaining mitochondrial length with the small molecule mitochondrial division inhibitor-1, we preserved hypoglycemia sensitivity in vitro and in vivo. Our findings present possible mechanisms for the blunting of the CRR, significantly broaden our understanding of the structure of GHRH neurons, and reveal that mitochondrial dynamics play an important role in HAAF. We conclude that interventions targeting mitochondrial fission in GHRH neurons may offer a new pathway to prevent HAAF in patients with diabetes.
低血糖是糖尿病的常见并发症,限制了治疗方法的选择并增加了发病率和死亡率。随着反复发作的低血糖,对血糖降低的代偿反应(CRR)会减弱,导致与低血糖相关的自主神经衰竭(HAAF)。导致这些减弱效应的机制尚未完全了解。在这里,我们通过 ISH、IHC 和 iDISCO+的组织清除能力报告,生长激素释放激素(GHRH)神经元是在体内葡萄糖剥夺时被激活的独特弓状核神经元群体。反复的葡萄糖剥夺会减少 GHRH 神经元的激活,并重塑对 GHRH 神经元的兴奋性和抑制性输入。我们表明,低血糖检测与 GHRH 神经元去极化、ATP 产生减少和线粒体融合有关。在低血糖期间,反复低血糖会减弱这些反应。通过使用小分子线粒体分裂抑制剂-1 维持线粒体长度,我们在体外和体内保留了低血糖敏感性。我们的研究结果为 CRR 的减弱提供了可能的机制,显著拓宽了我们对 GHRH 神经元结构的理解,并揭示了线粒体动力学在 HAAF 中起着重要作用。我们得出结论,针对 GHRH 神经元中线粒体分裂的干预措施可能为预防糖尿病患者的 HAAF 提供新途径。