Intensity-dependent effect of treadmill running on lubricin metabolism of rat articular cartilageReport as inadecuate

Intensity-dependent effect of treadmill running on lubricin metabolism of rat articular cartilage - Download this document for free, or read online. Document in PDF available to download.

Arthritis Research and Therapy

, 14:R256

First Online: 24 November 2012Received: 15 June 2012Revised: 31 October 2012Accepted: 22 November 2012


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.

AbbreviationsACLanterior cruciate ligament

ANOVAanalysis of variance

AOIareas of interest

CPMcontinuous passive motion

ECMextracellular matrix

HIRhigh intensity running

IgGimmunoglobulin G

IODintegrated optical density

LIRlow intensity running

MIRmoderate intensity running


PBSphosphate-buffered saline

RT-PCRreal-time polymerase chain reaction

PRG4proteoglycan 4

SZPsuperficial zone protein

TGFtransforming growth factor.

Electronic supplementary materialThe online version of this article doi:10.1186-ar4101 contains supplementary material, which is available to authorized users.

Download fulltext PDF

Author: Guo-Xin Ni - Lei Lei - Yue-Zhu Zhou


Related documents