Caloric restriction (CR) is well described and has received extensive attention for its multiple benefits, including longevity and stress resistance. However, some studies have shown that CR negatively influences bone, although a mechanism hasn't been provided. Adiponectin, an adipocyte-derived hormone, can affect bone metabolism by various pathways. To explore the role of adiponectin in short-term CR on bone, we tested the effect of short-term CR on limb bones (tibia and femur) and lumbar vertebral bodies of young C57BL/6 wild-type (WT) and adiponectin-deficient (Apn-/- ) mice. Two dietary regimes, ad libitum (AL) and CR (70% of the AL diet), were used. Dietary restriction led to increased serum adiponectin in WT mice, while bone mineral density, bone microarchitecture, and biomechanical outcomes of limb bone and vertebrae were decreased. In contrast, bone length, microarchitecture, and biomechanical outcomes were not impaired after CR in Apn-/- mice. Furthermore, CR increased adiponectin expression both in white adipose tissue and bone marrow adipose tissue in young WT mice. Histology analysis showed that expansion of bone marrow adipose tissue after CR in Apn-/- mice was impaired compared with WT mice. These results suggest that increased adiponectin induced by short-term CR may negatively influence bones.

中文翻译：

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短期热量限制通过增加脂联素诱导中轴骨和四肢骨的骨质流失

热量限制 (CR) 得到了很好的描述，并因其多种益处而受到广泛关注，包括长寿和抗压性。然而，一些研究表明 CR 会对骨骼产生负面影响，尽管尚未提供机制。脂联素是一种脂肪细胞衍生的激素，可以通过多种途径影响骨代谢。为了探索脂联素在短期 CR 对骨骼的作用，我们测试了短期 CR 对年轻 C57BL/6 野生型 (WT) 和脂联素缺乏的四肢骨（胫骨和股骨）和腰椎体的影响(Apn-/-) 小鼠。使用了两种饮食方案，随意（AL）和 CR（AL 饮食的 70%）。饮食限制导致 WT 小鼠血清脂联素增加，而四肢骨和椎骨的骨矿物质密度、骨微结构和生物力学结果降低。相比之下，Apn-/- 小鼠的骨长度、微结构和生物力学结果在 CR 后没有受到损害。此外，CR 增加了年轻 WT 小鼠白色脂肪组织和骨髓脂肪组织中脂联素的表达。组织学分析表明，与 WT 小鼠相比，Apn-/- 小鼠 CR 后骨髓脂肪组织的扩张受损。这些结果表明，短期 CR 引起的脂联素增加可能会对骨骼产生负面影响。