ABSTRACT
AIM:To explore the effect of leptin on the expression of degeneration-related genes in rat nucleus pulposus ( NP) cells and to detect the possible mechanism .METHODS:The normal NP cells isolated from SD rats were analyzed by immunochemistry and immunofluorescence for the collagen II and cytokeratin 19 expression.The NP cells were treated with leptin and/or interleukin-1β( IL-β).The mRNA expression of MMP-1, MMP-3, MMP-9, MMP-13, ADAMTS-4, ADAMTS-5, aggrecan and COL2A1 in the cells was detected by real-time PCR.Alcian blue staining and im-munochemistry were used to examine the expression of proteoglycan and collagen II .Activation of involved pathways was studied by Western blot .The inhibitors of the pathways were used to reveal the effect of these pathways on NP cells .RE-SULTS:The results of real-time PCR revealed that leptin alone up-regulated the mRNA expression of MMP-1, MMP-13, ADAMTS-4, ADAMTS-5 and COL2A1.The synergy of leptin and IL-βwas found in the increased expression of MMP-1, MMP-3 and ADAMTS-5.The NP cells treated with leptin showed less expression of collagen II .Both PI3K/Akt and JAK2/SATA3 pathways were activated by leptin , whereas only inhibitor of JAK 2/SATA3 pathway reversed the expression of MMP-1 and MMP-13.CONCLUSION:Leptin may promote catabolism in rat NP cells via JAK2/SATA3 pathways, which may be the mechanism mediating the association between obesity and intervertebral disc degeneration .
ABSTRACT
AIM:Toexploretheeffectofglucocorticoidonautophagyandsenescenceinthechondrocytes. METHODS:The collagen II in the normal chondrocytes isolated from the SD rats was checked.After stimulation with glu-cocorticoid, LysoTracker Red staining, MDC staining and Western blot were used to detect the level of autophagy in the chondrocytes.The mTOR pathway related molecules were investigated by Western blot.Cell senescence was analyzed by SA-β-gal staining.RESULTS:A dose-dependent increase in the number of autophagic vacuoles was observed in the dexa-methasone-treated chondrocytes, which was demonstrated by the LysoTracker Red and MDC staining.The expression of LC3-II and beclin-1 was increased by dexamethasone, especially in the cells treated with dexamethasone for 4 d.However, P62 expression was decreased.SA-β-gal staining showed that the percentage of cell senescence was increased by dexam-ethasone.Surprisingly, the cell senescence induced by dexamethasone was exacerbated by the autophagic inhibitor 3-MA. CONCLUSION:Autophagy induced by dexamethasone protects chondrocyte from senescence.The mTOR pathway may be involved in the autophagy activation.