The aging mouse partially models the aging human spine: lumbar and coccygeal disc height, composition, mechanical properties, and Wnt signaling in young and old mice.
| Publication Type | Academic Article |
| Authors | Holguin N, Aguilar R, Harland R, Bomar B, Silva M |
| Journal | J Appl Physiol (1985) |
| Volume | 116 |
| Issue | 12 |
| Pagination | 1551-60 |
| Date Published | 05/01/2014 |
| ISSN | 1522-1601 |
| Keywords | Aging, Intervertebral Disc, Lumbar Vertebrae, Wnt Signaling Pathway |
| Abstract | Murine lumbar and coccygeal (tail) regions of spines are commonly used to study cellular signaling of age-related disc diseases, but the tissue-level changes of aging intervertebral discs and vertebrae of each spinal region remain unclear. Furthermore, the impact of aging lumbar and coccygeal discs on Wnt/β-catenin signaling, which is putatively involved in the catabolism of intervertebral discs, is also unclear. We compared disc/vertebrae morphology and mechanics and biochemical composition of intervertebral discs from lumbar and coccygeal regions between young (4-5 mo) and old (20-22 mo) female C57BL/6 mice. Center intervertebral disc height from both regions was greater in old discs than young discs. Compared with young, old lumbar discs had a lower early viscous coefficient (a measure of stiffness) by 40%, while conversely old coccygeal discs were stiffer by 53%. Biochemically, old mice had double the collagen content in lumbar and coccygeal discs of young discs, greater glycosaminoglycan in lumbar discs by 37%, but less glycosaminoglycan in coccygeal discs by 32%. Next, we compared Wnt activity of lumbar and coccygeal discs of 4- to 5-mo and 12- to 14-mo TOPGAL mice. Despite the disc-specific changes, aging decreased Wnt signaling in the nucleus pulposus from both spinal regions by ≥64%. Compared with young, trabecular bone volume/tissue volume and ultimate force were less in old lumbar vertebrae, but greater in old coccygeal vertebrae. Thus intervertebral discs and vertebrae age in a spinal region-dependent manner, but these differential age-related changes may be uncoupled from Wnt signaling. Overall, lumbar and coccygeal regions are not interchangeable in modeling human aging. |
| DOI | 10.1152/japplphysiol.01322.2013 |
| PubMed ID | 24790018 |
| PubMed Central ID | PMC4064379 |