Landt M, Gingerich R L, Havel P J, Mueller W M, Schoner B, Hale J E, Heiman M L
Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110, USA.
Clin Chem. 1998 Mar;44(3):565-70.
Adipose tissue secretes leptin, which interacts with receptors in the hypothalamus. In rodent models of obesity, leptin increases metabolism and decreases food intake, which helps to maintain normal body composition. Accurate and precise methods to quantitate circulating leptin concentrations are needed for physiological studies. We developed an RIA to measure leptin in rat plasma, serum, or adipocyte culture fluids. The working range of the assay, defined by the detection limit and the highest calibrator, was 0.5-50 micrograms/L. Recovery of 1.6-11.6 micrograms/L leptin added to serum was 92-103%. The rat leptin RIA correlated well with a previously developed mouse RIA when rat plasma was assayed with both methods (r = 0.94), but the mouse leptin assay underestimated rat leptin in plasma. Within- and between-run CVs were 2.4% to 5.7%. Plasma leptin concentrations correlated directly with percentage of body fat, and correlation improved when the results were separated by gender (r = 0.796, P < 0.001 for males; r = 0.710, P < 0.001 for females). Leptin concentrations were generally higher in male rats than in females; plasma leptin increased 0.60 microgram/L for each percentage of increase in body fat for males but only 0.22 microgram/L for females. We conclude that rat serum/plasma leptin concentrations are accurately and precisely measured with this new RIA.
脂肪组织分泌瘦素，瘦素与下丘脑的受体相互作用。在肥胖的啮齿动物模型中，瘦素可提高新陈代谢并减少食物摄入量，有助于维持正常的身体组成。生理学研究需要准确、精确的方法来定量循环中的瘦素浓度。我们开发了一种放射免疫分析法（RIA）来测量大鼠血浆、血清或脂肪细胞培养液中的瘦素。该分析方法的工作范围由检测限和最高校准品定义，为0.5 - 50微克/升。添加到血清中的1.6 - 11.6微克/升瘦素的回收率为92 - 103%。当用两种方法检测大鼠血浆时，大鼠瘦素RIA与先前开发的小鼠RIA相关性良好（r = 0.94），但小鼠瘦素分析低估了血浆中的大鼠瘦素。批内和批间变异系数为2.4%至5.7%。血浆瘦素浓度与体脂百分比直接相关，按性别分开结果时相关性有所改善（男性r = 0.796，P < 0.001；女性r = 0.710，P < 0.001）。雄性大鼠的瘦素浓度通常高于雌性大鼠；雄性大鼠体脂每增加一个百分点，血浆瘦素增加0.60微克/升，而雌性大鼠仅增加0.22微克/升。我们得出结论，使用这种新的RIA可以准确、精确地测量大鼠血清/血浆中的瘦素浓度。
