Leptin and the Nutritional Programming of Obesity and Diabetes

摘要 肥胖症和相关的II型糖尿病的流行日益普遍是一个主要的健康问题，尤其是 在孩子们中间。母体肥胖是促进新陈代谢的发育风险因素 在后代中的扰动。来自我们实验室的最新数据表明，母亲肥胖与 胚胎中的瘦素水平异常高，但这种病理性的高瘦素血症是否有助于 发育中的胚胎的代谢编程错误在很大程度上仍然是未知的。同样，神经生物学 母体糖尿病对血糖稳态有害影响的潜在机制仍不清楚 明白了。自主神经系统在葡萄糖代谢中起着关键的作用，通过它的两个 交感和副交感神经分支。我们最近发现了产前瘦素在胎盘中的一个意外作用。 胆碱能投射到胰岛的发展以及这种发育效应对 成人血糖稳态。这一建议的总体假设是，母亲肥胖容易患上 后代通过扰乱后脑胆碱能胰腺回路的发育而患上糖尿病。我们也 假设胆碱能神经元中的瘦素信号在营养中起重要作用 葡萄糖动态平衡编程错误。我们的多学科方法结合了一套互补的 遗传学、光遗传学、轴突标记、电生理和生理学工具，以解决以下问题 目的：特定目的1.我们将利用病毒轴突标记和免疫组织化学实验来研究 母体肥胖背景下胰腺b细胞的后脑胆碱能神经支配的发育。我们会 也使用光遗传学方法来测试动物的后脑胆碱能胰腺回路是否发生改变 暴露在母亲肥胖的环境中。具体目标2.我们将系统地检测胚胎和 在肥胖的水坝中出生的幼崽。然后我们将进行免疫组织化学标记(pSTAT3和PERK)，切片 电生理记录(测量神经元兴奋性、电流和突触输入)和体外 外植体培养以验证母亲肥胖破坏神经生理、细胞内和 子代后脑胆碱能神经元对瘦素的神经营养反应。我们将特别注意 关注支配胰腺的后脑胆碱能神经元的反应。具体目标3.最后，我们将 将携带胆碱能神经元特异性瘦素受体基因缺失的DAMs暴露于高水平 高脂高糖饮食对胆碱能瘦素受体信号转导的影响 母体肥胖对胰岛副交感神经投射发育的不利影响 和血糖调节。这些目标的完成将促进我们对母亲肥胖如何 子代维持葡萄糖稳态所需的神经系统基本组件中的程序 并可能识别新的生物标记物和治疗靶点。

SUMMARY The growing prevalence of obesity and associated type II diabetes is a major health concern, particularly among children. Maternal obesity represents a developmental risk factor that contributes to metabolic perturbations in the offspring. Recent data from our lab indicate that maternal obesity is associated with abnormally high levels of leptin in the embryo, but whether this pathological hyperleptinemia contributes to the metabolic malprogramming of the developing embryos remains largely unknown. Similarly, the neurobiological mechanisms underlying the detrimental effects of maternal diabetes on glucose homeostasis remain poorly understood. The autonomic nervous system plays a critical role in glucose metabolism through both its sympathetic and parasympathetic branches. We recently found an unanticipated role for prenatal leptin in the development of cholinergic projections to pancreatic islets and that this developmental effect has an impact on adult glucose homeostasis. The overall hypothesis of this proposal is that maternal obesity predisposes the offspring to diabetes by disrupting the development of hindbrain cholinergicèpancreas circuits. We also hypothesize that leptin signaling in cholinergic neurons plays an important role in the nutritional malprogramming of glucose homeostasis. Our multidisciplinary approach incorporates a complementary set of genetic, optogenetic, axonal labeling, electrophysiological, and physiological tools to address the following aims: Specific Aim 1. We will use viral axonal labeling and immunohistochemical experiments to study the development of hindbrain cholinergic innervation of pancreatic b cells in a context of maternal obesity. We will also use optogenetic approaches to test if hindbrain cholinergicèpancreas circuits are altered in animals exposed to maternal obesity. Specific Aim 2. We will systematically examine leptin levels in embryos and pups born to obese dams. We will then perform immunohistochemical labeling (pSTAT3 and pERK), slice electrophysiological recordings (measuring neuronal excitability, currents and synaptic inputs), and in vitro explant cultures to test the hypothesis that maternal obesity disrupts the neurophysiological, intracellular, and neurotrophic response of hindbrain cholinergic neurons to leptin in the offspring. Particular attention will be paid to the response of hindbrain cholinergic neurons innervating the pancreas. Specific Aim 3. Finally, we will expose dams carrying mice with genetic deletion of leptin receptor specifically in cholinergic neurons to a high fat/high sucrose diet to explore the importance of cholinergic leptin receptor signaling in mediating the detrimental effects of maternal obesity on the development of parasympathetic projections to pancreatic islets and glucose regulation. Completion of these aims will advance our understanding of how maternal obesity programs in the offspring essential components of neural systems required to maintain glucose homeostasis and may identify novel biomarkers and therapeutic targets.