Aims

We investigate the effects of RT on the mechanical function, gene, and protein expression of key factors involved in bone remodeling during aging.

Main methods

Male rats of 3 and 21 months of age were randomly allocated into four groups (8 per group): young sedentary (YS), young trained (YT), old sedentary (OS), and old trained (OT). RT was performed three times per week (12 weeks). Bone tenacity and stiffness were measured by biomechanical tests and mRNA levels of COL1A1, MEPE, SOST, OPG, BMP-2, PPAR-y, MMP-2-9-13, and TIMP-1 were evaluated by quantitative PCR. COL1A1 protein and MMP-2 activity were detected by western blotting and zymography assays.

Key findings

Aging increased stiffness, while BMP-2, OPG, COL1A1 and MMP-2 mRNA levels reduced (OS vs YS; p ≤ 0.05). RT increased the tenacity of the femur and reduced PPAR-γ regardless of age (YT vs. YS; OT vs. OS; p ≤ 0.05). RT downregulated SOST mRNA levels only in the OT group (vs. OS group, p ≤ 0.05). RT mitigated the age-associated increase in MMP-9 mRNA levels (p ≤ 0.05). In young animals, upregulation in MEPE, MMP-13, TIMP-1 were observed after RT, as well an increase in COL1A1 protein and MMP-2 activity (p ≤ 0.05).

Significance

RT improved bone tenacity independent of aging, which is relevant for mechanical function, while, at protein levels, RT upregulated MMP-2 activity and collagen 1 only in young rats. This study highlights the importance of exercise on bone health and identifies specific molecular changes in response to RT. Our findings provide insights into the mechanisms involved in age-related changes.

中文翻译：

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响应阻力训练，老年大鼠骨骼的重塑过程。

目的

我们研究了RT对衰老过程中参与骨骼重构的关键因素的机械功能，基因和蛋白质表达的影响。

主要方法

将3和21个月大的雄性大鼠随机分为四组（每组8只）：久坐的年轻人（YS），久坐的年轻人（YT），久坐的老人（OS）和久坐的老人（OT）。每周（12周）进行3次RT。通过生物力学测试测量骨强度和刚度，并通过定量PCR评估COL1A1，MEPE，SOST，OPG，BMP-2，PPAR-y，MMP-2-9-13和TIMP-1的mRNA水平。Western blotting和酶谱测定法检测COL1A1蛋白和MMP-2活性。

主要发现

衰老增加了刚度，而BMP-2，OPG，COL1A1和MMP-2 mRNA水平降低了（OS vs YS； p≤0.05）。无论年龄大小，RT均可增加股骨的韧性，降低PPAR-γ（YT vs. YS； OT vs. OS； p≤0.05）。RT仅在OT组下调SOST mRNA水平（与OS组相比，p≤0.05）。RT减轻了与年龄相关的MMP-9 mRNA水平升高（p≤0.05）。在幼小动物中，RT后观察到MEPE，MMP-13，TIMP-1上调，以及COL1A1蛋白和MMP-2活性增加（p≤0.05）。

意义

RT改善了与衰老无关的骨骼韧性，而衰老与机械功能有关，而在蛋白质水平上，RT仅在年轻大鼠中上调MMP-2活性和胶原1。这项研究强调了锻炼对骨骼健康的重要性，并确定了响应RT的特定分子变化。我们的发现提供了与年龄有关的变化所涉及的机制的见解。