Iwamoto J, Yeh J K, Aloia J F
Department of Medicine, Winthrop-University Hospital, Mineola, NY 11501, USA.
Bone. 1999 Mar;24(3):163-9. doi: 10.1016/s8756-3282(98)00189-6.
The aim of the present study was to examine cancellous bone changes induced by exercise on three different skeletal sites, the lumbar vertebra, the proximal, and the distal tibia, in the young growing rat. Forty 4-week-old female Sprague-Dawley rats were randomized into 4 groups of 10 animals each; 8 weeks exercise (8EX), 8 weeks sedentary control (8CON), 12 weeks exercise (12EX), and 12 weeks sedentary control (12CON). The exercise regimen consisted of treadmill running at 24 m/min 1 hr per day 5 days a week. After each period of exercise, the proximal and distal tibial metaphyses (PTM and DTM, respectively) and the fifth lumbar (L5) vertebral body were processed for histomorphometry of the cancellous bone (secondary spongiosa) and cortical periosteum. Eight and twelve weeks of exercise significantly increased the mineral apposition rate and bone formation rate in the PTM and DTM, and 12 weeks of exercise significantly increased the labeled perimeter in the DTM, compared with the age-matched controls. Eight and twelve weeks of exercise significantly increased cancellous bone volume in the PTM (mean +/- standard deviation, 8EX; 19.1 +/- 2.9% vs 8CON; 14.3 +/- 3.1%, P < 0.05 and 12EX; 18.8 +/- 3.5% vs 12CON; 15.2 +/- 3.3%, P < 0.05), and 12 weeks exercise significantly increased cancellous bone volume in the DTM, compared with age-matched control (12EX; 32.5 +/- 7.7%, 12CON; 22.2 +/- 4.8%, P < 0.05). The increase in cancellous bone volume by 12 weeks exercise was higher in the DTM than that in the PTM (43.4% and 24.0%, respectively). On the other hand, the exercise did not significantly affect cancellous bone volume and bone formation in the L5 vertebral body, although the cortical periosteal bone formation rate and the L5 vertebral bone mass were increased. These findings suggest that cancellous bone adaptation to treadmill exercise is site specific, and the effect may be influenced by factors such as mechanical loading and metaphyseal bone architecture in the young growing rat.
本研究的目的是检测在幼年生长大鼠中，运动对三个不同骨骼部位（腰椎、胫骨近端和胫骨远端）的松质骨变化的影响。40只4周龄雌性Sprague-Dawley大鼠被随机分为4组，每组10只动物；8周运动组（8EX）、8周久坐对照组（8CON）、12周运动组（12EX）和12周久坐对照组（12CON）。运动方案包括每周5天、每天1小时在跑步机上以24米/分钟的速度跑步。在每个运动阶段后，对胫骨近端和远端干骺端（分别为PTM和DTM）以及第五腰椎（L5）椎体进行松质骨（次级骨小梁）和皮质骨骨膜的组织形态计量学分析。与年龄匹配的对照组相比，8周和12周的运动显著提高了PTM和DTM中的矿物质沉积率和骨形成率，12周的运动显著增加了DTM中的标记周长。8周和12周的运动显著增加了PTM中的松质骨体积（平均值±标准差，8EX；19.1±2.9% vs 8CON；14.3±3.1%，P<0.05；12EX；18.8±3.5% vs 12CON；15.2±3.3%，P<0.05），与年龄匹配的对照组相比，12周的运动显著增加了DTM中的松质骨体积（12EX；32.5±7.7%，12CON；22.2±4.8%，P<0.05）。12周运动后DTM中松质骨体积的增加高于PTM（分别为43.4%和24.0%）。另一方面，尽管皮质骨骨膜骨形成率和L5椎体骨量增加，但运动对L5椎体的松质骨体积和骨形成没有显著影响。这些发现表明，幼年生长大鼠的松质骨对跑步机运动的适应性具有部位特异性，其影响可能受机械负荷和干骺端骨结构等因素的影响。
