Scheett Timothy P, Nemet Dan, Stoppani James, Maresh Carl M, Newcomb Robert, Cooper Dan M
Center for the Study of Health Effects of Exercise in Children, University of California, Irvine, College of Medicine, Orange, California, USA.
Pediatr Res. 2002 Oct;52(4):491-7. doi: 10.1203/00006450-200210000-00006.
Recent studies demonstrate an unexpected reduction in circulating levels of IGF-I after 5 wk of endurance-type exercise training in adolescent boys and girls and prepubertal girls. We hypothesized that the reduction in IGF-I would be accompanied by a training-associated stimulation of proinflammatory cytokines IL-1beta, IL-6, or tumor necrosis factor-alpha (TNF-alpha), each of which can inhibit the GH-->IGF-I axis. Healthy boys (age range 9-11 y old, mean Tanner 1.7) volunteered for the study and were randomized to control (n = 14) and training groups (n = 12) for 5 wk. After the intervention, significant increase in fitness was observed in the training group but not control group. Although IGF-I was correlated at baseline to peak oxygen consumption in all subjects, there was a significant decrease in IGF-I and IGF binding protein-3 in the training subjects (-12.8 +/- 7.3% and -17.5 +/- 7%, respectively, p < 0.05). In contrast, IGF binding protein-2, known to inhibit anabolic effects of IGF-I, increased in the training subjects (27.8 +/- 11%, p < 0.02) as did IL-1beta and TNF-alpha (51.5 +/- 30.22%, p < 0.02, and 44.5 +/- 23.2%, p < 0.02, respectively). Finally, we also found that GHBP was inversely correlated with fitness, suggesting altered GH function in more-sedentary boys. Thus, these data support the hypothesis that a sustained increase in physical activity can stimulate proinflammatory cytokines, which may contribute to suppression of the GH-->IGF-I axis. Physical activity can influence growth and development through its influence on anabolic and catabolic mediators.
最近的研究表明，在青春期男孩、女孩以及青春期前女孩进行为期5周的耐力型运动训练后，循环中的胰岛素样生长因子-I（IGF-I）水平出现了意外下降。我们推测，IGF-I的下降会伴随着与训练相关的促炎细胞因子白细胞介素-1β（IL-1β）、白细胞介素-6或肿瘤坏死因子-α（TNF-α）的刺激，其中每种细胞因子都可抑制生长激素（GH）向IGF-I轴的转化。健康男孩（年龄范围9 - 11岁，平均坦纳发育分级1.7级）自愿参与该研究，并被随机分为对照组（n = 14）和训练组（n = 12），为期5周。干预后，训练组的体能显著增加，而对照组未出现此情况。尽管在所有受试者中，IGF-I在基线时与峰值耗氧量相关，但训练组受试者的IGF-I和IGF结合蛋白-3显著下降（分别下降了-12.8±7.3%和-17.5±7%，p < 0.05）。相反，已知可抑制IGF-I合成代谢作用的IGF结合蛋白-2在训练组受试者中增加（27.8±11%，p < 0.02），IL-1β和TNF-α也增加（分别为51.5±30.22%，p < 0.02，以及44.5±23.2%，p < 0.02）。最后，我们还发现生长激素结合蛋白（GHBP）与体能呈负相关，这表明久坐不动的男孩生长激素功能发生了改变。因此，这些数据支持了以下假设：体力活动的持续增加可刺激促炎细胞因子，这可能有助于抑制GH向IGF-I轴的转化。体力活动可通过影响合成代谢和分解代谢介质来影响生长发育。
