Intensity-dependent effect of treadmill running on lubricin metabolism of rat articular cartilage

Abstract

IntroductionWe aimed to understand the changes in cartilage lubricin expression and immunolocalisation in responsed to treadmill running with different intensities in a rat model.MethodsA total of 24 male Wistar rats were randomly assigned into groups of control (CON), low-intensity running (LIR), moderate-intensity running (MIR), and high-intensity running (HIR). Rats in LIR, MIR, and HIR groups were trained for 8 weeks on the treadmill with low, moderate, and high intensity, respectively. After sacrifice, femoral condyles were collected to take histological observation for cartilage characteristics, and immunohistochemistry for lubricin. In addition, cartilage samples were obtained to assess PRG4 and TGF-β mRNA expression by quantitative RT-PCR.ResultsHistological examination showed osteoarthritic changes in rats after eight weeks of high intensity running. In comparison to CON group, significantly lower Mankin score was found in LIR and MIR groups, whereas, HIR group had significantly higher Mankin score than either CON, LIR, or MIR group. On the other hand, both LIR and MIR groups have significantly higher lubricin content than CON group, whereas, significantly lower lubricin content was found in HIR group compared with CON, LIR or MIR group. A significant inverse correlation was detected between the lubricin content and Mankin score. In addition, considerably higher mRNA gene expression of PRG4 and TGF-β was found in LIR and MIR groups, compared with those in CON and HIR groups.ConclusionsThere is a marked intensity-specific effect of running on the immunolocalisation and gene expression of lubricin in cartilage, which is inversely correlated with Mankin score. Our findings provide evidences that mechanical factors are key determinants of lubricin metabolism in vivo.

Two compartment pharmacokinetic model describes the intra‐articular delivery and retention of rhprg4 following ACL transection in the Yucatan mini pig

“…The introduction of rhPRG4 into an injured joint may have several positive consequences. Local PRG4 expression is upregulated by physical activity . The combination of compression and shear in vitro has been observed to increase expression of PRG4 by several laboratories .…”

Effect of Running on Inclined Treadmill on the Occurrence of Knee Joint Osteoarthritis in the Male and Female Wistar Rats

“…In this regard, Ni et al, revealed the intensity -dependent impact of treadmill running on the lubricin metabolism of articular cartilage in rats (22). In another study, they showed different cartilage responses by changing the running intensity.…”

Exercise intervention increases expression of bone morphogenetic proteins and prevents the progression of cartilage-subchondral bone lesions in a post-traumatic rat knee model

“…Another important limitation is lack of variety in exercise intensity, although, we chose exercise protocol based on earlier study that showed anti-inflammatory/matrix synthesis effects of treadmill exercise in monoiodoacetateinduced arthritis 15 . As articular cartilage responds to mechanical stimuli with dose-dependent manner 7,12,13,44 , investigating multiple intensity level exercise would be worth doing to elucidate whether these manners are confirmed even in cartilagesubchondral bone unit. Nevertheless, exercise protocol used in this study is consistent with previous studies that assessed chondroprotective effects for adult or instability-induced OA model rat knees (12e18 m/min for 30e60 min/day, 3e7 days/ week) 12,13,15,45 .…”

“…Subjects in human OA clinical trials are likely to be at various stages of the disease when an exercise intervention is initiated 11 . Conversely, exercise is often initiated in pre-clinical animal models shortly after the PTOA process begins 12,13 . Given that there is phasic development of PTOA with early matrix remodeling and transcriptional activity in an experimental PTOA model 14 , the response to intervention for treating PTOA would depend on the timing of the intervention.…”