Strain G, Zumoff B, Rosner W, Pi-Sunyer X
Division of Endocrinology and Metabolism, Mount Sinai Medical Center, New York, New York 10029.
J Clin Endocrinol Metab. 1994 Oct;79(4):1173-6. doi: 10.1210/jcem.79.4.7962291.
It is known that there is an inverse relationship between the serum levels of insulin and sex hormone-binding globulin (SHBG) in women, but the relationship in men has not been reported. It is not known whether changes in the one cause changes in the other, or whether they change in opposite directions in response to some third factor. Because obesity raises insulin levels and lowers SHBG levels in both sexes, we proposed to study the cause-effect question by determining whether the relationship between changes in SHBG and insulin levels during active weight loss. We studied 70 healthy weight-stable men with body mass index (BMI) from 20.7-94 (normal, 22.5 +/- 2.5) and restudied 17 of them during diet-induced weight loss. Fasting serum insulin levels in the weight-stable men showed a positive linear correlation with BMI, increasing 1 microU/mL per unit increase in BMI (P < 0.0001). SHBG levels in the weight-stable men showed a negative linear correlation with BMI, decreasing 0.2 nmol/L per unit increase in BMI (P < 0.0002). In the weight-stable men, there was an inverse hyperbolic correlation between SHBG and insulin levels; SHBG (nmol/L) = 13.1 + [30.1 divided by insulin (microU/mL)] (P < 0.002). During weight loss, insulin levels decreased at an average rate of 6.1 microU/mL per unit decrease in BMI, a much higher slope than the positive slope vs. BMI in weight stable men. During weight loss, SHBG levels increased at an average slope of 0.43 nmol/L per unit decrease in BMI, much higher than the negative slope of 0.2 nmol/L per unit increase in BMI in weight-stable men. Values for the SHBG vs. insulin coordinates in the weight-losing subjects did not differ significantly from those expected from the SHBG vs. insulin equation in weight-stable subjects. The stability of the SHBG-insulin relationship during weight loss despite the profoundly altered relationship of each separate component to BMI strongly suggests a close metabolic link between SHBG and insulin. As SHBG is not known to alter the production or metabolism of insulin, whereas insulin has been shown in vitro to decrease the synthesis of SHBG, it seems a reasonable conclusion that the predictable inverse relationship between serum insulin and SHBG indicates that insulin controls SHBG synthesis in vivo.
已知女性血清胰岛素水平与性激素结合球蛋白（SHBG）之间存在负相关关系，但男性中的这种关系尚未见报道。尚不清楚一方的变化是否会引起另一方的变化，或者它们是否会因某个第三因素而呈相反方向变化。由于肥胖会使男女的胰岛素水平升高且SHBG水平降低，我们建议通过确定在积极减肥期间SHBG变化与胰岛素水平之间的关系来研究因果问题。我们研究了70名体重稳定的健康男性，其体重指数（BMI）为20.7至94（正常范围为22.5±2.5），并在其中17名男性因节食导致体重减轻期间再次进行了研究。体重稳定的男性空腹血清胰岛素水平与BMI呈正线性相关，BMI每增加一个单位，胰岛素水平增加1微单位/毫升（P<0.0001）。体重稳定的男性SHBG水平与BMI呈负线性相关，BMI每增加一个单位，SHBG水平降低0.2纳摩尔/升（P<0.0002）。在体重稳定的男性中，SHBG与胰岛素水平之间存在反双曲线相关性；SHBG（纳摩尔/升）=13.1 + [30.1除以胰岛素（微单位/毫升）]（P<0.002）。在减肥期间，BMI每降低一个单位，胰岛素水平平均降低6.1微单位/毫升，这一斜率远高于体重稳定男性中与BMI的正斜率。在减肥期间，BMI每降低一个单位，SHBG水平平均升高0.43纳摩尔/升，远高于体重稳定男性中BMI每增加一个单位时0.2纳摩尔/升的负斜率。减肥受试者中SHBG与胰岛素坐标的值与体重稳定受试者中根据SHBG与胰岛素方程预期的值无显著差异。尽管减肥期间每个单独成分与BMI的关系发生了深刻变化，但SHBG与胰岛素关系的稳定性强烈表明SHBG与胰岛素之间存在密切的代谢联系。由于尚不清楚SHBG是否会改变胰岛素的产生或代谢，而体外实验已表明胰岛素可降低SHBG的合成，因此血清胰岛素与SHBG之间可预测的负相关关系似乎表明胰岛素在体内控制SHBG的合成，这似乎是一个合理的结论。
