Ottowitz William E, Dougherty Darin D, Fischman Alan J, Hall Janet E
Reproductive Endocrine Unit, BHX-5, Massachusetts General Hospital, 55 Fruit Street, Boston, Massachusetts 02114, USA.
J Clin Endocrinol Metab. 2008 Aug;93(8):3208-14. doi: 10.1210/jc.2008-0203. Epub 2008 Jun 3.
Precise regulation of the neuroendocrine components of the female reproductive axis involves both negative and positive feedback of estrogen on gonadotropin secretion.
Our objective was to determine the hypothalamic and/or pituitary sites of estrogen negative and positive feedback using neuroimaging techniques.
A graded estrogen infusion protocol was administered at a General Clinical Research Center in an academic medical center.
Healthy postmenopausal women (n = 11) were recruited for study.
Serum samples were measured every 4 h. A structural magnetic resonance imaging was performed at baseline, and [(18)F]2-fluoro-2-deoxy-d-glucose ((18)FDG) positron emission tomography was performed at baseline and 24 and 72 h. FDG positron emission tomography was co-registered with magnetic resonance imaging scans, and region of interest analysis was performed.
Serum LH and estradiol were assessed. Normalized values for glucose uptake were extracted from each region of interest for each subject at each time point.
A decrease in normalized (18)FDG uptake was apparent in the hypothalamus at 24 h (P < 0.02) associated with decreased LH (P < 0.0005). The increase in LH at 72 h (P < 0.0005) was associated with increased pituitary (18)FDG uptake (P < 0.02) but no change in hypothalamic uptake.
Changes in (18)FDG uptake as a measure of metabolic activity can be demonstrated in the hypothalamus and pituitary in association with discrete hormonal events. Results are consistent with mediation of estrogen negative feedback on LH at the hypothalamus, whereas estrogen positive feedback occurs at the pituitary with no evidence of increased hypothalamic activity in women.
女性生殖轴神经内分泌成分的精确调节涉及雌激素对促性腺激素分泌的负反馈和正反馈。
我们的目的是使用神经成像技术确定雌激素负反馈和正反馈的下丘脑和/或垂体部位。
在一所学术医疗中心的综合临床研究中心实施了分级雌激素输注方案。
招募了健康的绝经后女性（n = 11）进行研究。
每4小时测量一次血清样本。在基线时进行结构磁共振成像，并在基线、24小时和72小时进行[(18)F]2-氟-2-脱氧-d-葡萄糖（(18)FDG）正电子发射断层扫描。将FDG正电子发射断层扫描与磁共振成像扫描进行配准，并进行感兴趣区分析。
评估血清促黄体生成素（LH）和雌二醇。在每个时间点从每个受试者的每个感兴趣区提取葡萄糖摄取的标准化值。
24小时时下丘脑的标准化(18)FDG摄取明显降低（P < 0.02），同时LH降低（P < 0.0005）。72小时时LH升高（P < 0.0005）与垂体(18)FDG摄取增加（P < 0.02）相关，但下丘脑摄取无变化。
作为代谢活性指标的(18)FDG摄取变化可在下丘脑和垂体中与离散的激素事件相关联地得到证实。结果与雌激素在下丘脑对LH的负反馈调节一致，而雌激素正反馈发生在垂体，且没有证据表明女性下丘脑活动增加。
