Sumner A E, Kushner H, Tulenko T N, Falkner B, Marsh J B
Institute for Women's Health, Allegheny University of the Health Sciences, Philadelphia, PA 19129, USA.
Metabolism. 1997 Apr;46(4):400-5. doi: 10.1016/s0026-0495(97)90055-x.
Insulin is a potent antilipolytic hormone that promotes the deposition of fat and decreases the release of nonesterified fatty acids (NEFA) from adipose tissue. The purpose of this study was to investigate in African-Americans (AAs) sex differences in insulin-mediated suppression of plasma NEFA and fasting triglyceride (TG) levels. Ninety AAs, 44 men and 46 women with a mean age of 34 +/- 8 years were classified by body mass index (BMI) into three groups: non-obese (22 men and 18 women), obese (12 men and 10 women), and severely obese (10 men and 18 women). In each BMI group, women versus men had greater percent body fat (non-obese, 30 +/- 6 v 18 +/- 6, P < .001; obese, 36 +/- 3 v 26 +/- 2, P < .001; and severely obese, 39 +/- 4 v 29 +/- 4, P < .001). An oral glucose tolerance test (OGTT) was performed with fasting TG levels and plasma insulin and NEFA concentrations obtained at 0, 30, 60, and 120 minutes. In women, insulin-mediated NEFA suppression was similar in each of the three BMI groups (non-obese, 85% +/- 14%; obese, 88% +/- 11%; and severely obese, 87% +/- 10%; P = .8). In men, the percent suppression of NEFA declined with increasing obesity (non-obese, 83% +/- 14%; obese, 71% +/- 21%; and severely obese, 68% +/- 16%; P = .04). Changes in NEFA suppression were reflected in the fasting TG levels. TG levels in women were similar in each BMI group (non-obese, 71 +/- 39 mg/dL; obese; 69 +/- 21; severely obese, 79 +/- 30; P = .7). In contrast, fasting TG levels for men were higher in the higher BMI groups. Plasma TG levels in men were 87 +/- 41 mg/dL for obese, 113 +/- 65 for obese, and 169 +/- 81 for severely obese (P = .001). These data demonstrate sex differences in insulin-mediated NEFA metabolism. In AA women, the maintenance of sensitivity to insulin-mediated suppression of NEFA regardless of the degree of obesity may contribute to the normal plasma TG levels. For AA men, the resistance to insulin-mediated suppression of NEFA in the higher BMI categories may allow more NEFA to be released from adipose tissue into the circulation and available to the liver for synthesis into TG-containing lipoproteins.
胰岛素是一种强效的抗脂解激素，可促进脂肪沉积并减少非酯化脂肪酸（NEFA）从脂肪组织的释放。本研究的目的是调查非裔美国人（AA）中胰岛素介导的血浆NEFA抑制和空腹甘油三酯（TG）水平的性别差异。90名AA，44名男性和46名女性，平均年龄34±8岁，根据体重指数（BMI）分为三组：非肥胖（22名男性和18名女性）、肥胖（12名男性和10名女性）和重度肥胖（10名男性和18名女性）。在每个BMI组中，女性的体脂百分比均高于男性（非肥胖组，30±6对18±6，P<.001；肥胖组，36±3对26±2，P<.001；重度肥胖组，39±4对29±4，P<.001）。进行口服葡萄糖耐量试验（OGTT），并在0、30、60和120分钟时测定空腹TG水平以及血浆胰岛素和NEFA浓度。在女性中，三个BMI组中胰岛素介导的NEFA抑制作用相似（非肥胖组，85%±14%；肥胖组，88%±11%；重度肥胖组，87%±10%；P=.8）。在男性中，随着肥胖程度增加，NEFA的抑制百分比下降（非肥胖组，83%±14%；肥胖组，71%±21%；重度肥胖组，68%±16%；P=.04）。NEFA抑制的变化反映在空腹TG水平上。女性各BMI组的TG水平相似（非肥胖组，71±39mg/dL；肥胖组，69±21；重度肥胖组，79±30；P=.7）。相比之下，男性较高BMI组的空腹TG水平更高。男性肥胖组的血浆TG水平为87±41mg/dL，重度肥胖组为113±65，极重度肥胖组为169±81（P=.001）。这些数据表明胰岛素介导的NEFA代谢存在性别差异。在AA女性中，无论肥胖程度如何，对胰岛素介导的NEFA抑制保持敏感性可能有助于维持正常的血浆TG水平。对于AA男性，较高BMI类别中对胰岛素介导的NEFA抑制的抵抗可能使更多的NEFA从脂肪组织释放到循环中，并可被肝脏用于合成含TG的脂蛋白。
