Figure 4.

Leptin synergism does not depend upon chondrocyte differation state. Effect of different inhibitors on nitrite (NO₂^-) accumulation in 15-day differentiated ATDC5 cells stimulated or not with leptin, alone or in combination with IL-1, during (a) 24 and (b) 48 hours. The effect of inhibitors was also evaluated in 21-day differentiated ATDC5 cells, after (c) 24 or (d) 48 hours of stimulation with leptin and IL-1 (alone or in combination). Values are expressed as mean ± standard error of the mean. OB, leptin.