Institute of Spine, Longhua Hospital, ShangHai University of Traditional Chinese Medicine, Shanghai, People's Republic of China.
Spine (Phila Pa 1976). 2011 Mar 15;36(6):E380-7. doi: 10.1097/BRS.0b013e3181dbc101.
Both forelimbs of rats were amputated and these rats were kept in the custom-made cages to keep prolonged and repeated upright posture. Changes of bone were observed in the lumbar vertebrae at three different time points after the surgery. OBJECTIVE.: To investigate the effect of prolonged and repeated upright posture on bone formation of rat lumbar vertebrae.
Previous studies show long-term and repeated load-induced bone formation, but there are no clear evidences to indicate whether or not long-term and repeated assumption of the upright posture could result in bone formation at rat lumbar vertebrae.
The forelimbs of 30 rats were amputated when they were 1 month old. These rats were kept in the custom-made cages and were forced to stand upright on their hindlimbs and tails to obtain water and food. Normal rats of the same ages kept in regular cages were used as control. The rats were sacrificed at 5, 7, and 9 months after the surgery and lumbar vertebrae samples were harvested for micro-computed tomographic (CT), histological, and immunohistochemical studies. Total RNA isolated from these samples were used for real-time polymerase chain reaction of type I collagen (Col1α2), type X collagen (Col10α1), transforming growth factor-β1 (TGF-β1) and its related nuclear transcript factor runt-related transcription factor 2 (Runx2), as well as the biomarker of angiogenesis and vascular invasion, which is also a prerequisite for endochondral bone formation: vascular endothelial growth factor (VEGF).
Micro-CT and histological studies showed increased trabecular bone density and increased osteoblast quantities of lumbar vertebrae after surgery. Immunostaining revealed increased protein expression of type I collagen, type X collagen, TGF-β, and VEGF. Real-time polymerase chain reaction showed upregulated expression of Col1α2, Col10α1, VEGF, TGF-β1, and Runx2 mRNA.
Upright posture induces bone acquisition in the rats' lumbar spine, primarily through the mode of the endochondral ossification, which is associated with increased loading, activated VEGF, and TGF-β1 signaling.
大鼠的前肢被截肢，然后将这些大鼠放在特制的笼子里，以保持长时间、重复的直立姿势。手术后三个不同时间点观察腰椎骨的变化。目的：探讨长时间、重复的直立姿势对大鼠腰椎骨形成的影响。
先前的研究表明，长期重复的负荷会导致骨形成，但目前尚无明确证据表明长期、重复的直立姿势是否会导致大鼠腰椎骨形成。
当 1 月龄大鼠的前肢被截肢时，它们被放在特制的笼子里，被迫用后肢和尾巴直立以获取水和食物。同龄的正常大鼠放在常规笼子里作为对照。手术后 5、7 和 9 个月时，处死大鼠并采集腰椎标本进行 micro-CT（微计算机断层扫描）、组织学和免疫组织化学研究。从这些样本中提取总 RNA，用于实时聚合酶链反应检测 I 型胶原（Col1α2）、X 型胶原（Col10α1）、转化生长因子-β1（TGF-β1）及其相关核转录因子 runt 相关转录因子 2（Runx2），以及血管生成和血管侵袭的生物标志物，这也是软骨内骨形成的前提：血管内皮生长因子（VEGF）。
微 CT 和组织学研究表明，手术后腰椎的小梁骨密度增加，成骨细胞数量增加。免疫染色显示 I 型胶原、X 型胶原、TGF-β 和 VEGF 的蛋白表达增加。实时聚合酶链反应显示 Col1α2、Col10α1、VEGF、TGF-β1 和 Runx2 mRNA 的表达上调。
直立姿势会导致大鼠腰椎骨获得骨量，主要通过软骨内骨化的方式，这与增加的负荷、激活的 VEGF 和 TGF-β1 信号有关。
