Nakai Yoshikatsu, Hosoda Hiroshi, Nin Kazuko, Ooya Chizuru, Hayashi Hiromi, Akamizu Takashi, Kangawa Kenji
College of Medical Technology, Kyoto University, Kyoto University Hospital, 53 Kawaharacho, Shogoin, Sakyo-ku, Kyoto, 606-8507, Japan.
Eur J Endocrinol. 2003 Jul;149(1):R1-3. doi: 10.1530/eje.0.149r001.
Ghrelin is an acylated peptide, whose octanoyl modification is essential for its biological activities. Previous studies demonstrated that fasting plasma ghrelin levels were high in anorectic patients, suggesting ghrelin may play an important role in the pathophysiology of anorexia nervosa. However, antibodies used in previous work to measure ghrelin concentrations in human blood do not distinguish between the active form of ghrelin (active ghrelin) and desacyl ghrelin with no biological activities. Therefore, we studied plasma levels of active ghrelin during oral glucose tolerance test (OGTT) in anorectic patients, using a radioimmunoassay (RIA) specific for active ghrelin.
Active ghrelin response to OGTT was evaluated in five female anorectic patients and seven age-matched control females. All subjects were given a 75 g/225 ml glucose solution orally after overnight fasting. For RIA of active ghrelin, 1 N hydrogen chloride was added to the samples at final concentration of 0.1 N immediately after separation of plasma.
Plasma basal levels of active ghrelin were significantly higher in anorectic patients than in controls (52.1+/-10.5 vs 21.2+/-3.1 fmol/ml, P<0.01). They were significantly decreased during OGTT in anorectic patients and in controls, reaching a nadir of 49.0+/-7.7% and 57.3+/-4.5% of the basal levels, respectively.
These results suggest that hyperghrelinemia in anorectic patients is caused at least partly by increased secretion of active ghrelin and that glucose ingestion suppresses active ghrelin release in these patients.
胃饥饿素是一种酰化肽，其辛酰化修饰对其生物学活性至关重要。先前的研究表明，厌食症患者空腹血浆胃饥饿素水平较高，提示胃饥饿素可能在神经性厌食症的病理生理学中起重要作用。然而，先前用于测量人体血液中胃饥饿素浓度的抗体无法区分具有生物活性的胃饥饿素（活性胃饥饿素）和无生物活性的去酰基胃饥饿素。因此，我们使用针对活性胃饥饿素的放射免疫分析法（RIA），研究了厌食症患者口服葡萄糖耐量试验（OGTT）期间活性胃饥饿素的血浆水平。
评估了5名女性厌食症患者和7名年龄匹配的对照女性对OGTT的活性胃饥饿素反应。所有受试者在过夜禁食后口服75 g/225 ml葡萄糖溶液。对于活性胃饥饿素的RIA，血浆分离后立即向样品中加入终浓度为0.1 N的1 N盐酸。
厌食症患者血浆活性胃饥饿素基础水平显著高于对照组（52.1±10.5对21.2±3.1 fmol/ml，P<0.01）。在厌食症患者和对照组的OGTT期间，它们均显著降低，分别降至基础水平的49.0±7.7%和57.3±4.5%的最低点。
这些结果表明，厌食症患者的高胃饥饿素血症至少部分是由活性胃饥饿素分泌增加引起的，并且葡萄糖摄入可抑制这些患者的活性胃饥饿素释放。
