Ho J T, Keogh J B, Bornstein S R, Ehrhart-Bornstein M, Lewis J G, Clifton P M, Torpy D J
Royal Adelaide Hospital, Adelaide, South Australia, Australia.
Horm Metab Res. 2007 Sep;39(9):694-9. doi: 10.1055/s-2007-985354.
Body fat mass and nutrition influence secretion of the adrenocortical hormones--aldosterone and cortisol--via several mechanisms. However, there are no data on adrenocortical function following widely prescribed mild diet-induced weight loss (10%) in obese subjects. In the present study, 25 healthy obese volunteers (BMI 32.9+/-4.3 kg/m (2)) followed a 30% calorie restricted diet over 12 weeks. Hypothalamic-pituitary-adrenal (HPA) axis function was assessed by 24-hour urine free cortisol/cortisone and a 1 mcg ACTH stimulation test with measurement of total and free cortisol and corticosteroid-binding globulin (CBG). The renin-angiotensin-aldosterone system (RAAS) was assessed by measurement of plasma aldosterone and renin under salt depleted (30 mmol/d) and loading (250 mmol/d) conditions. Volunteers' weight fell by 8.5+/-0.8 kg (8.9+/-0.7%) and seated systolic blood pressure fell by 8.7+/-2.7 mmHg and diastolic blood pressure by 7.0+/-1.4 mmHg (p<0.01). Plasma aldosterone and renin levels fell significantly with weight loss (aldosterone: 853+/-156-635+/-73 pmol/l; renin: 35.4+/-7-24+/-3 mU/l, both p<0.05). The volunteers were relatively salt insensitive (mean arterial pressure change with salt intake: 4 mmHg) and this was not affected by weight loss. Moderate weight loss had no effect on 24-hour urine free cortisol/cortisone, or on basal, or ACTH-stimulated free and total cortisol, or CBG. Hence this conventional weight loss program reduces blood pressure and activity of the RAAS via an effect on renin release. Despite various described influences of fat mass and energy restriction on HPA axis function, there were no changes in basal and stimulated HPA axis function with moderate weight loss. There may be a threshold effect of weight loss/energy restriction required to alter HPA axis function, or moderate weight loss may lead to a counterbalanced effect of stimulatory and inhibitory influences on HPA axis function.
体脂量和营养状况通过多种机制影响肾上腺皮质激素——醛固酮和皮质醇的分泌。然而，目前尚无关于肥胖受试者在广泛采用的轻度饮食诱导体重减轻（10%）后肾上腺皮质功能的数据。在本研究中，25名健康肥胖志愿者（BMI 32.9±4.3 kg/m²）在12周内遵循了30%热量限制饮食。通过24小时尿游离皮质醇/可的松以及1微克促肾上腺皮质激素（ACTH）刺激试验（测量总皮质醇和游离皮质醇以及皮质类固醇结合球蛋白（CBG））来评估下丘脑-垂体-肾上腺（HPA）轴功能。通过在低钠（30 mmol/d）和高钠（250 mmol/d）条件下测量血浆醛固酮和肾素来评估肾素-血管紧张素-醛固酮系统（RAAS）。志愿者体重下降了8.5±0.8 kg（8.9±0.7%），坐位收缩压下降了8.7±2.7 mmHg，舒张压下降了7.0±1.4 mmHg（p<0.01）。随着体重减轻，血浆醛固酮和肾素水平显著下降（醛固酮：853±156 - 635±73 pmol/l；肾素：35.4±7 - 24±3 mU/l，均p<0.05）。志愿者对盐相对不敏感（盐摄入引起的平均动脉压变化：4 mmHg），且这不受体重减轻的影响。适度体重减轻对24小时尿游离皮质醇/可的松、基础或ACTH刺激的游离及总皮质醇或CBG均无影响。因此，这种传统的减肥方案通过对肾素释放的影响降低血压和RAAS的活性。尽管有多种关于脂肪量和能量限制对HPA轴功能影响的描述，但适度体重减轻并未改变基础和刺激状态下的HPA轴功能。体重减轻/能量限制可能存在改变HPA轴功能所需的阈值效应，或者适度体重减轻可能导致对HPA轴功能的刺激和抑制影响达到平衡。
