11β-hydroxysteroid dehydrogenase type-II activity is affected by grapefruit juice and intense muscular work

ABSTRACT Objective The enzymatic activity of 11β-hydroxysteroid dehydrogenase-2 (11β-HSD2) is key to protecting mineral corticoid receptors from cortisol and has been implicated in blood pressure regulation. Grapefruit juice (GFJ) and acidity are thought to inhibit this enzyme in vitro. This study examines the effect of GFJ and intense exercise on 11β-HSD2 enzyme activity in vivo. Subjects and methods Eighteen subjects ingested GFJ or apple juice (CON) on separate days prior to reporting to the laboratory in a randomized order. Saliva (Sal) samples were obtained at baseline, 15 and 45 minutes post-treadmill stress test; Sal cortisone (E) and cortisol (F) levels were determined, and the Sal cortisone:cortisol (E:F) ratio was used as an index of 11β-HSD2 enzyme activity at rest and after intense muscular work. Results GFJ treatment decreased baseline 11β-HSD2 enzyme activity (44%) and Sal-E (28%) compared to CON (both, p < 0.05). Sal-E (r = 0.61, p < 0.05) and Sal-F (r = 0.66, p < 0.05) were correlated with diastolic blood pressure (DBP) in GFJ-treated individuals. Treadmill stress significantly increased Sal-E and Sal-F but did not alter 11β-HSD2 enzyme activity regardless of treatment. When treatments were examined separately, CON 11β-HSD2 enzyme activity decreased by 36% (p < 0.05) from baseline to 15 post-treadmill exercise. Conclusion Our findings suggest that GFJ and intense muscular work decrease 11β-HSD-2 activity independently, and no additive effect was noted. The association between DBP and the levels of Sal-F and Sal-E during the GFJ trial should be interpreted cautiously and warrants further investigation.

摘要
目的：11β-羟类固醇脱氢酶2（11β-hydroxysteroid dehydrogenase-2, 11β-HSD2）的酶活性是保护盐皮质激素受体免受皮质醇侵扰的关键环节，且与血压调控密切相关。既往研究认为西柚汁（Grapefruit juice, GFJ）及其酸性环境可在体外抑制该酶活性。本研究旨在探讨西柚汁与高强度运动对体内11β-HSD2酶活性的影响。
对象与方法：18名受试者采用随机顺序，于不同日期分别摄入西柚汁或苹果汁（对照组, CON），随后前往实验室开展检测。分别于基线状态、跑步机应激试验后15分钟及45分钟采集唾液（Saliva, Sal）样本；检测唾液中皮质酮（E）与皮质醇（F）水平，并以唾液皮质酮/皮质醇（E:F）比值作为静息状态及高强度肌肉活动后11β-HSD2酶活性的评价指标。
结果：与对照组相比，西柚汁干预组的基线11β-HSD2酶活性降低44%，唾液皮质酮水平降低28%（两组比较均p<0.05）。在西柚汁干预的受试者中，唾液皮质酮（r=0.61, p<0.05）与唾液皮质醇（r=0.66, p<0.05）均与舒张压（diastolic blood pressure, DBP）呈显著正相关。跑步机应激试验可显著升高唾液皮质酮与皮质醇水平，但无论接受何种干预，均未改变11β-HSD2酶活性。单独分析各组干预效果时，对照组受试者的11β-HSD2酶活性自基线至跑步机运动后15分钟下降36%（p<0.05）。
结论：本研究结果表明，西柚汁与高强度肌肉活动可分别降低11β-HSD2酶活性，未观察到叠加效应。西柚汁干预组中舒张压与唾液皮质醇、皮质酮水平的相关性需谨慎解读，且有待进一步研究验证。