Ovarian hormone suppression and regulation of adipogenesis in women

描述（由申请人提供）：雌二醇（E2）缺乏会导致女性体重增加，特别是腹部脂肪增加。绝经后向中心性肥胖的转变可能导致代谢综合征和相关慢性疾病的风险增加（即，2型糖尿病、冠状动脉疾病、高血压）。长期目标是了解E2缺乏介导腹部肥胖增加的机制。R21的主要目的（PA 1）是确定绝经前妇女的卵巢激素抑制（已知会导致脂肪增加）是否会引发脂肪生成增加（即，细胞数量增加）。这将通过测量细胞大小分布的变化和氘（2 H）掺入非基质（即，成熟脂肪细胞）级分。次要目的是确定：SA 2）卵巢激素抑制对脂肪形成相关因子mRNA表达的影响（C/EBP 1，PPAR 3）和巨噬细胞浸润的标志物（CD 68，Emr-1）和炎症（IL-6、TNF-1）;和SA 3）使用细胞表面标志物确定新的脂肪细胞是否来自非驻留骨髓祖细胞（BMP）（Notch 4，血小板衍生的生长因子受体（PDGFR）2，整合素15，CD 36），其能够通过流式细胞术检测。为了实现这些目标，将在通过促性腺激素释放激素激动剂治疗并加用安慰剂（GnRHAG+PL）或雌二醇（GnRHAG+E2）进行卵巢激素抑制前和后30天和60天对24名绝经前女性进行研究。假设：H1 a）与GnRHAG+E2相比，GnRHAG+PL 60天将导致小脂肪细胞（<40 5 m）的较大增加。由于GnRHAG+PL期间脂肪量增加，因此小脂肪细胞数量的增加将被解释为脂肪生成增加，而不是脂肪细胞萎缩的证据; H1b）与GnRHAG+E2相比，GnRHAG+PL会增加非基质细胞部分DNA中2 H的掺入。因为非基质部分含有成熟的脂肪细胞，2 H富集的DNA的增加应该反映脂肪形成; H2）卵巢激素抑制将增加与脂肪形成、巨噬细胞浸润和炎症相关的因子的mRNA表达（C/EBP 1、PPAR 3、CD 68、Emr-1、IL-6、TNF-1）与基线相比（GnRHAG+PL治疗前与治疗后）以及与E2反加治疗相比（GnRHAG+PL vs GnRHAG+E2）;和H3）与基线相比，卵巢激素抑制将增加BMP衍生的脂肪细胞（GnRHAG+PL前后）和与E2加回相比（GnRHAG+PL vs GnRHAG+E2）。据我们所知，这将是E2作为人类脂肪形成调节剂的第一个体内研究。因为人们认为脂肪细胞被编程以获得一定体积的脂肪，所以脂肪细胞数量的增加将导致脂肪质量的增加，这将非常难以逆转。因此，确定有效防止卵巢激素戒断期间脂肪生成增加的策略将具有很高的临床意义。 公共卫生相关性：妇女在绝经前基本上可以预防腹部肥胖。绝经期雌激素的丧失会引发腹部脂肪堆积的增加，这可能导致代谢综合征、2型糖尿病、冠状动脉疾病和高血压的风险增加。这项研究将验证一个新的假设，即雌激素缺乏通过触发脂肪细胞数量的增加而导致腹部脂肪增加。

DESCRIPTION (provided by applicant): Estradiol (E2) deficiency triggers weight gain, and specifically abdominal fat gain, in women. The shift toward central adiposity after menopause likely contributes to increased risk for the metabolic syndrome and associated chronic diseases (i.e., type 2 diabetes, coronary artery disease, hypertension). The long-term aim is to understand the mechanisms by which E2 deficiency mediates increases in abdominal adiposity. The primary aim (PA1) of the R21 is to determine whether ovarian hormone suppression in premenopausal women, which is known to cause fat gain, triggers an increase in adipogenesis (i.e., increase in cell number) in abdominal adipose tissue. This will be assessed by measuring the changes in cell size distribution and the incorporation of deuterium (2H) into DNA of cells in the non-stromal (i.e., mature adipocyte) fraction. Secondary aims are to determine: SA2) effects of ovarian hormone suppression on mRNA expression of factors involved in adipogenesis (C/EBP1, PPAR3) and markers of macrophage infiltration (CD68, Emr-1) and inflammation (IL-6, TNF-1); and SA3) whether new adipocytes arise from non-resident bone marrow progenitor (BMP) cells using cell surface markers (Notch 4, Platelet-derived Growth Factor Receptor (PDGFR) 2, Integrin 15, CD36) that enable detection by flow cytometry. To achieve these aims, 24 premenopausal women will be studied before and after 30 and 60 days of ovarian hormone suppression via gonadotropin releasing hormone agonist therapy with add-back of placebo (GnRHAG+PL) or estradiol (GnRHAG+E2). Hypotheses are: H1a) GnRHAG+PL for 60 days will result in a larger increase in small adipocytes (<40 5m) when compared with GnRHAG+E2. Because fat mass increases during GnRHAG+PL, an increase in the number of small adipocytes will be interpreted as an increase in adipogenesis and not as evidence of adipocyte atrophy; H1b) The incorporation of 2H in the non-stromal cell fraction DNA will be increased in response to GnRHAG+PL, as compared with GnRHAG+E2. Because the non-stromal fraction contains mature adipocytes, an increase in 2H- enriched DNA should reflect adipogenesis; H2) Ovarian hormone suppression will increase mRNA expression of factors associated with adipogenesis, macrophage infiltration, and inflammation (C/EBP1, PPAR3, CD68, Emr-1, IL-6, TNF-1) when compared with baseline (before vs after GnRHAG+PL) and when compared with E2 add-back (GnRHAG+PL vs GnRHAG+E2); and H3) Ovarian hormone suppression will increase BMP-derived adipocytes when compared with baseline (before vs after GnRHAG+PL) and when compared with E2 add-back (GnRHAG+PL vs GnRHAG+E2). To the best of our knowledge, this will be the first in vivo study of the role of E2 as a regulator of adipogenesis in humans. Because it is believed that adipocytes are programmed to achieve a certain volume of fat, an increase in adipocyte number would lead to a gain in fat mass that would be very difficult to reverse. Thus, identifying strategies that effectively prevent an increase in adipogenesis during ovarian hormone withdrawal would be of high clinical importance. PUBLIC HEALTH RELEVANCE: Women are largely protected against abdominal adiposity prior to the menopause. The loss of estrogen at the time of the menopause triggers an increase in abdominal fat accumulation, which likely contributes to increased risk for the metabolic syndrome, type 2 diabetes mellitus, coronary artery disease, and hypertension. The proposed studies will test the novel hypothesis that estrogen deficiency results in abdominal fat gain by triggering an increase in the number of fat cells.