Rigamonti A E, Haenelt M, Bidlingmaier M, De Col A, Tamini S, Tringali G, De Micheli R, Abbruzzese L, Goncalves da Cruz C R, Bernardo-Filho M, Cella S G, Sartorio A
Department of Clinical Sciences and Community Health, University of Milan, Milan, Italy.
Endocrine Research Laboratories, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany.
BMC Endocr Disord. 2018 Dec 27;18(1):96. doi: 10.1186/s12902-018-0323-6.
Growth hormone (GH) is a heterogeneous protein composed of several molecular isoforms, the most abundant ones being the 22 kDa- and 20 kDa-GH. Exercise-induced secretion of GH isoforms has been extensively investigated in normal-weight individuals due to antidoping purposes, particularly recombinant human GH (rhGH) abuse. On the other hand, the evaluation of exercise-induced responses in GH isoforms has never been performed in obese subjects.
The acute effects of whole body vibration (WBV) or maximal voluntary contraction (MVC) alone and the combination of MVC with WBV (MVC + WBV) on circulating levels of 22 kDa- and 20 kDa-GH were evaluated in 8 obese male adolescents [mean age ± SD: 17.1 ± 3.3 yrs.; weight: 107.4 ± 17.8 kg; body mass index (BMI): 36.5 ± 6.6 kg/m; BMI standard deviation score (SDS): 3.1 ± 0.6].
MVC (alone or combined with WBV) significantly stimulated 22 kDa- and 20 kDa-GH secretion, while WBV alone was ineffective. In particular, 22 kDa- and 20 kDa-GH peaks were significantly higher after MVC + WBV and MVC than WBV. In addition, 22 kDa-GH (but not 20 kDa-GH) peak was significantly higher after MVC + WBV than MVC. Importantly, the ratio of circulating levels of 22 kDa- to 20 kDa-GH was constant throughout the time window of evaluation after exercise and similar among the three different protocols of exercise.
The results of the present study confirm the ability of MVC, alone and in combination with WBV, to stimulate both 22 kDa- and 20 kDa-GH secretion in obese patients, these responses being related to the exercise workload. Since the ratio of 22 kDa- to 20 kDa-GH is constant after exercise and independent from the protocols of exercise as in normal-weight subjects, hyposomatotropism in obesity does not seem to depend on an unbalance of circulating GH isoforms. Since the present study was carried out in a small cohort of obese sedentary adolescents, these preliminary results should be confirmed in further future studies enrolling overweight/obese subjects with a wider age range.
生长激素（GH）是一种由几种分子异构体组成的异质性蛋白质，其中最丰富的是22 kDa和20 kDa的生长激素。由于反兴奋剂目的，尤其是重组人生长激素（rhGH）滥用问题，正常体重个体中运动诱导的生长激素异构体分泌已得到广泛研究。另一方面，肥胖受试者中运动诱导的生长激素异构体反应评估从未进行过。
在8名肥胖男性青少年[平均年龄±标准差：17.1±3.3岁；体重：107.4±17.8 kg；体重指数（BMI）：36.5±6.6 kg/m²；BMI标准差评分（SDS）：3.1±0.6]中，评估全身振动（WBV）或最大自主收缩（MVC）单独以及MVC与WBV联合（MVC + WBV）对22 kDa和20 kDa生长激素循环水平的急性影响。
MVC（单独或与WBV联合）显著刺激22 kDa和20 kDa生长激素的分泌，而单独的WBV无效。特别是，MVC + WBV和MVC后22 kDa和20 kDa生长激素的峰值显著高于WBV。此外，MVC + WBV后22 kDa生长激素（但不是20 kDa生长激素）的峰值显著高于MVC。重要的是，运动后评估的整个时间窗口内，22 kDa与20 kDa生长激素的循环水平之比保持恒定，且在三种不同运动方案中相似。
本研究结果证实，MVC单独以及与WBV联合能够刺激肥胖患者22 kDa和20 kDa生长激素的分泌，这些反应与运动负荷有关。由于运动后22 kDa与20 kDa生长激素的比例恒定，且与正常体重受试者一样与运动方案无关，肥胖中的生长激素缺乏似乎不取决于循环生长激素异构体的失衡。由于本研究是在一小群肥胖久坐的青少年中进行的，这些初步结果应在未来纳入更广泛年龄范围的超重/肥胖受试者的进一步研究中得到证实。
