Characterization of Estrogen Sensitive Ventromedial Hypothalamic Glucose Sensing

雌激素敏感的腹内侧下丘脑葡萄糖传感的表征

• 批准号: 8205202
• 负责人: Ammy Marie Santiago
• 金额: $ 2.84万
• 依托单位: UNIV OF MED/DENT OF NJ-NJ MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8205202
• 关键词: 5' -AMP-activated protein kinase; Ablation; Action Potentials; Acute; Anterior Pituitary Gland; Attenuated; Bovine Serum Albumin; Cell Nucleus; Cells; Conjugated Estrogens; Data; Disease; Eating; Electrophysiology (science); Epidemic; Estrogen Receptors; Estrogen receptor positive; Estrogens; Exhibits; Female; Fertility; Frequencies; Gluconeogenesis; Glucose; Gonadotropin Hormone Releasing Hormone; Homeostasis; Hormones; Hypoglycemia; Hypothalamic structure; Incidence; Individual; Insulin; Insulin Resistance; Knock-out; Knockout Mice; Lead; Leptin; Location; Medial; Membrane; Menopause; Methodology; Middle Hypothalamus; Mus; Neurons; Neurotransmitters; Nitric Oxide Synthase Type I; Non-Insulin-Dependent Diabetes Mellitus; Nuclear; Nutrient; Nutritional status; Obesity; Patch-Clamp Techniques; Phenotype; Phosphotransferases; Physiological; Play; Postabsorptive Hypoglycemia; Postmenopause; Potassium Channel; Predisposition; Preoptic Areas; Prevalence; Protein Isoforms; Receptor Activation; Receptor Signaling; Regulation; Risk; Role; SF1; Satiation; Signal Pathway; Signal Transduction; Signaling Molecule; Techniques; Testing; Tracer; Western Blotting; Woman; analog; blood glucose regulation; combat; inhibitor/antagonist; male; new therapeutic target; pre-doctoral; receptor expression; reproductive; response; sex; sexual dimorphism

DESCRIPTION (provided by applicant): Glucose sensing neurons (GSN) of the ventromedial hypothalamus (VMH) are believed to play a role in the regulation of energy and glucose homeostasis. However, the underlying mechanisms by which GSNs fulfill this role remain elusive. The current obesity epidemic and the rise in the prevalence of Type II Diabetes Mellitus (TIIDM) underscore the necessity to clarify these mechanisms and potentially illuminate novel therapeutic targets for these diseases. This is especially important for females since there is a greater incidence of obesity and TIIDM in females yet virtually all studies of GSNs have been performed in males. We have previously shown, in male mice, that VMH GSNs are dysfunctional during TIIDM. The strong correlation between estrogen receptor (ER) expression, in both sexes, and the location of VMH GSNs within the ventrolateral VMH suggests that estrogen regulates GSNs. This project hypothesizes that ER activation attenuates VMH GSN sensitivity to decreased glucose. Thus diminished estrogen levels following menopause may enhance responsiveness of GSNs to glucose decreases. This could lead to inappropriate signals of energy deficit and initiation of inappropriate compensatory mechanisms during energy sufficiency. Such a response may explain the increased susceptibility to TIIDM in post-menopausal females. To test this hypothesis, the pre-doctoral fellow will first determine whether glucose-excited or glucose-inhibited neurons are ER positive (either alpha or beta) using immunohistochemical and single-cell PCR methodologies. The neurotransmitter phenotype of these neurons will also be determined in order to better understand their role in energy homeostasis. Secondly, electrophysiological patch-clamp techniques will be used to determine how estrogen and the membrane impermeable BSA-conjugated estrogen regulate the acute activity as well as the glucose sensitivity of GSNs. The fellow will also utilize inhibitors of potential ER signaling molecules and western blot analysis to understand the mechanism of estrogenic regulation of VMH GSNs sensitivity. Using these same techniques, the fellow will investigate the effects of ER1 or ER2 ablation on the glucose sensitivity of VMH GSNs via the use of steroidogenic factor-1 driven ER1- or ER2-knockout mice (VMH exclusive knockout) and selective ER1 or ER2 antagonist application. Finally, using a fluorescent retrograde tracer, the fellow will determine whether estrogen-sensitive GSNs project directly to the anterior pituitary or to the preoptic area where they could potentially relay nutrient status information influencing the reproductive state of the individual. PUBLIC HEALTH RELEVANCE: Females, and especially post-menopausal women, are more prone than males to develop two of the most serious diseases of the modern world: obesity and Type II Diabetes Mellitus (TIIDM). Glucose sensing neurons (GSNs) in the ventromedial hypothalamus, which express the estrogen receptor, may play a key role in regulating glucose and energy homeostasis. This proposal will investigate whether estrogen regulates GSNs and thus, whether diminished estrogen could contribute to the increased susceptibility of post-menopausal women to obesity and TIIDM.

描述（由申请人提供）：下丘脑腹内侧（VMH）的葡萄糖感应神经元（GSN）被认为在调节能量和葡萄糖稳态中起作用。然而，GSNs实现这一作用的潜在机制仍然难以捉摸。当前的肥胖流行和II型糖尿病（TIIDM）患病率的上升强调了阐明这些机制和潜在的阐明这些疾病的新治疗靶点的必要性。这对女性尤其重要，因为女性中肥胖和糖尿病的发病率更高，但几乎所有关于GSNs的研究都是在男性中进行的。我们之前已经在雄性小鼠中表明，在TIIDM期间VMH gsn功能失调。雌激素受体（ER）在两性中的表达与腹内侧壁VMH内GSNs的位置密切相关，表明雌激素调节GSNs。本项目假设内质网激活会减弱VMH GSN对葡萄糖降低的敏感性。因此，绝经后雌激素水平的降低可能会增强GSNs对葡萄糖减少的反应性。这可能导致能量不足的不适当信号，并在能量充足时启动不适当的补偿机制。这种反应可以解释绝经后女性对TIIDM的易感性增加。为了验证这一假设，博士前研究员将首先使用免疫组织化学和单细胞PCR方法确定葡萄糖兴奋或葡萄糖抑制神经元是否为ER阳性（α或β）。这些神经元的神经递质表型也将被确定，以便更好地了解它们在能量稳态中的作用。其次，电生理膜片钳技术将用于确定雌激素和膜不透性bsa偶联雌激素如何调节GSNs的急性活性和葡萄糖敏感性。该研究员还将利用潜在ER信号分子的抑制剂和western blot分析来了解雌激素调节VMH GSNs敏感性的机制。使用相同的技术，研究员将通过使用类固醇生成因子-1驱动的ER1或ER2敲除小鼠（VMH独家敲除）和选择性ER1或ER2拮抗剂，研究ER1或ER2消融对VMH GSNs葡萄糖敏感性的影响。最后，使用荧光逆行示踪剂，研究人员将确定雌激素敏感的GSNs是否直接投射到垂体前叶或视前区，在那里它们可能传递影响个体生殖状态的营养状态信息。