Effect of prednisolone on rabbit articular chondrocytes treated with sodium nitroprusside

Kang, Jin Seok

Abstract

This study was carried out to investigate the protective effect of prednisolone in rabbit primary cultured articular chondrocytes treated with sodium nitroprusside (SNP), a nitric oxide donor. After a cell phenotype was determined, the MTT assay and Western blot analysis of type II collagen, cylooxygenase-2 (COX-2) and phosphorylated extracellular regulated kinase (pERK) were performed in the control, SNP (298 µg/ml) alone or SNP plus prednisolone (0.05-50 µg/ml)-treated rabbit articular chondrocytes. Immunofluorescence staining of type II collagen was also performed. Cell morphology indicated that SNP treatment induced cytotoxicity, and that the SNP-induced cytotoxicity was inhibited by prednisolone treatment. MTT assay showed that the SNP treatment resulted in a significant decrease in the level of cell viability compared with that of control (p < 0.01), and that the prednisolone treatment resulted in a decrease in the SNP-induced cytotoxicity. SNP treatment resulted in a decrease in the level of type II collagen, compared with the control chondrocytes. The prednisolone treatment recovered the down-regulated expression of type II collagen induced by SNP, showing a significant level in 5 µg/ml of the prednisolone treatment group compared to the SNP treatment group (p < 0.05). A significant increase in COX-2 was significantly induced by the SNP treatment compared to control chondrocytes (p < 0.01). The COX-2 expression was decreased by the prednisolone treatment, showing a significant level in 50 µg/ml of the prednisolone treatment group compared to the SNP treatment group (p < 0.05). These phenomena was confirmed by immunofluorescence staining. Furthermore, the SNP treatment significantly induced a decrease of pERK expression compared to the control chondrocytes (p < 0.01). The prednisolone treatment recovered its expression, showing a significant level in 0.5 µg/ml of the prednisolone treatment group compared to the SNP treatment group (p < 0.05). Taken the above results together, prednisolone is considered to inhibit SNP-induced cell death and dedifferentiation, and modulated expression of COX-2 and pERK in rabbit articular chondrocytes.