Age-related degeneration of lumbar intervertebral discs in rabbits revealed by deuterium oxide-assisted MRI

Abstract

Objectives: Intervertebral disc (IVD) degeneration is associated with a loss of disc water content and change in biochemical composition of the disc. Rabbit is a frequently used model to evaluate the efficacy of therapeutics for disc degeneration. This study addresses whether rabbits undergo age-related disc degeneration, assessed using deuterium oxide-assisted magnetic resonance imaging (MRI) of the lumbar IVDs. Materials and methods: The lumbar spines of adolescent, adult, and aged rabbits (6-36 months) were subjected to T2-weighted/short-tau inversion recovery (STIR) MRI scan along with water-deuterium oxide (H2O:D2O) dilutions. The total and maximum H2O:D2O index (HDi) of the lumbar IVDs were determined and compared between disc levels at different ages. Results: Adolescent rabbit lumbar discs had similar total HDi, suggesting the hydration and biochemical composition was similar among the lumbar levels. With the use of H2O:D2O reference, the discs were shown to undergo continual decrease in signal with aging which non-calibrated measurement method could not reveal. The HDi decrease rate was higher at the caudal than cranial levels. Conclusion: This study provided in vivo evidence of age-related progressive disc degenerative change in rabbit lumbar discs, suggesting aged rabbits can be considered as a natural disc degeneration model in disc regeneration studies. However, it is important to select proper disc levels as intra-subject controls due to different rates of degenerative changes between caudal and cranial levels. © 2008 Osteoarthritis Research Society International.