Fig. 4

The effect of interleukin-1beta (IL-1β) on mRNA levels of receptor activator of nuclear factor kappa B (RANK)/RANK ligand (RANKL)/osteoprotegerin (OPG) by rat anulus fibrosus (AF), nucleus pulposus (NP) and cartilaginous endplate (CEP) cells. The mRNA expression levels of RANK (a, d, g), RANKL (b, e, h), and OPG (c, f, i) by AF (a-c), NP (d-f) and CEP (g-i) cells were quantified by real-time polymerase chain reaction. Stimulation of rat NP cells with IL-1β at 10 ng/mL significantly increased mRNA expression of RANK, RANKL and OPG compared with the control group. Stimulation of rat AF and CEP cells with IL-1β at 10 ng/mL significantly increased mRNA expression of RANKL compared with the control group. No significant changes in mRNA expression levels of RANK and OPG in AF and CEP cells were detected from treatment with IL-1β: *p < 0.05, **p < 0.01 vs. control. FBS fetal bovine serum