Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
Centre for Cell Biology, Development and Disease, Simon Fraser University, Burnaby, Canada.
PLoS One. 2021 Sep 1;16(9):e0256906. doi: 10.1371/journal.pone.0256906. eCollection 2021.
Lactation results in substantial maternal bone loss that is recovered following weaning. However, the mechanisms underlying this recovery, and in particular the role of insulin-like growth factor 1 (IGF-I), is not clear. Furthermore, there is little data regarding whether recovery is affected by advanced maternal age.
Using micro-computed tomography, we studied bone recovery following lactation in mice at 2, 5 and 7 months of age. We also investigated the effects of reduced IGF-I availability using mice lacking PAPP-A2, a protease of insulin-like growth factor binding protein 5 (IGFBP-5).
In 2 month old mice, lactation affected femoral trabecular and cortical bone, but only cortical bone showed recovery 3 weeks after weaning. This recovery was not affected by deletion of the Pappa2 gene. The amount of trabecular bone was reduced in 5 and 7 month old mice, and was not further reduced by lactation. However, the recovery of cortical bone was impaired at 5 and 7 months compared with at 2 months.
Recovery of the maternal skeleton after lactation is impaired in moderately-aged mice compared with younger mice. Our results may be relevant to the long-term effects of breastfeeding on the maternal skeleton in humans, particularly given the increasing median maternal age at childbearing.
哺乳期会导致母体大量的骨质流失，而在断奶后会恢复。然而，这种恢复的机制，特别是胰岛素样生长因子 1（IGF-1）的作用，尚不清楚。此外，关于母体年龄较大是否会影响恢复，数据也很少。
我们使用微计算机断层扫描技术，研究了 2、5 和 7 月龄小鼠在哺乳期后的骨恢复情况。我们还研究了使用缺乏 PAPP-A2 的小鼠（一种胰岛素样生长因子结合蛋白 5（IGFBP-5）的蛋白酶）来减少 IGF-I 的可用性的影响。
在 2 月龄的小鼠中，哺乳期影响了股骨小梁和皮质骨，但只有皮质骨在断奶后 3 周才显示出恢复。这种恢复不受 Pappa2 基因缺失的影响。5 月龄和 7 月龄的小鼠的小梁骨数量减少，哺乳期不会进一步减少。然而，与 2 月龄相比，5 月龄和 7 月龄时皮质骨的恢复受损。
与年轻小鼠相比，中等年龄的哺乳期小鼠的母体骨骼恢复受损。我们的结果可能与母乳喂养对人类母体骨骼的长期影响有关，特别是考虑到生育时的产妇年龄中位数不断增加。
