Skeletal unloading induces a full-thickness patellar cartilage defect with increase of urinary collagen II CTx degradation marker in growing rats.

Mechanical stress plays an important role in tissue morphogenesis and extracellular matrix metabolism. However, little is known about the effects of reduced loading without restriction of joint motion on the patella. We investigated the effects of long-term skeletal unloading on patellar cartilage and subchondral bone and systemic collagen II metabolism.

Effects of reloading after simulated microgravity on proteoglycan metabolism in the nucleus pulposus and anulus fibrosus of the lumbar intervertebral disc: an experimental study using a rat tail suspension model.

Study Design: An experiment to measure proteoglycan (PG) content and PG-related gene mRNA expressions in the lumbar intervertebral disc (IVD) of rats tail-suspended (TS) for up to 6 weeks with subsequent reloading.

Objective: To assess the effects of reloading after simulated microgravity on PG metabolism in nucleus pulposus (NP) and anulus fibrosus (AF).

Summary Of Background Data: Although the PG content of rat lumbar IVD is reportedly decreased by low compressive force (due to so-called microgravity) during spaceflight, it is unknown whether it recovers completely on reloading and whether these effects differ between NP and AF.