Boonstra R, Tinnikov A A
Division of Life Sciences, University of Toronto, Scarborough, Ontario, Canada.
J Endocrinol. 1998 Jan;156(1):205-12. doi: 10.1677/joe.0.1560205.
Free fatty acids (FFAs) are rapidly mobilized by ACTH and have been shown to be potent endogenous modulators of steroid-protein interactions. We increased FFA in lagomorphs by ACTH and then separated the transient increase in glucocorticoid binding capacity of plasma into that accounted for by changes in binding to albumin and to corticosteroid-binding globulin (CBG). Sequential injections of dexamethasone and ACTH into both snowshoe hares and laboratory rabbits resulted in the rapid mobilization of FFA only after the ACTH injection. The maximum corticosteroid binding capacity increase paralleled that of the FFA increase in both species. In rabbits, CBG levels remained constant over the duration of the experiment. Corticosterone binding by rabbit albumin increased in a dose-dependent fashion in response to increases in FFA (oleic and linoleic acid) concentrations. Finally, by stimulating FFA release in snowshoe hares with ACTH and separating the increase in corticosteroid binding capacity through selective denaturing of CBG by heat, we determined that the increase in plasma binding capacity was a response to changes in binding by albumin, not CBG. Thus FFA released in response to stressors in lagomorphs may effect short-term increases in steroid binding.
游离脂肪酸（FFAs）可被促肾上腺皮质激素（ACTH）迅速动员，并且已被证明是类固醇 - 蛋白质相互作用的强效内源性调节剂。我们通过ACTH增加兔形目动物体内的FFA，然后将血浆糖皮质激素结合能力的短暂增加分离为与白蛋白结合和与皮质类固醇结合球蛋白（CBG）结合变化所导致的增加。对雪兔和实验兔依次注射地塞米松和ACTH后，仅在注射ACTH后才导致FFA迅速动员。两种动物中皮质类固醇结合能力的最大增加与FFA的增加平行。在兔子中，整个实验过程中CBG水平保持恒定。兔白蛋白与皮质酮的结合随着FFA（油酸和亚油酸）浓度的增加呈剂量依赖性增加。最后，通过用ACTH刺激雪兔释放FFA，并通过热选择性变性CBG来分离皮质类固醇结合能力的增加，我们确定血浆结合能力的增加是对白蛋白结合变化的反应，而非CBG。因此，兔形目动物对应激源释放的FFA可能会导致类固醇结合的短期增加。
