Collagen gene expression is suppressed in organ culture model of disc degeneration. Expression of important disc matrix collagens decreases with tumor necrosis factor-alpha, interleukin-1beta, and limited nutrition. Expression of type 1 collagen (COL1) and type 2 collagen (COL 2) is significantly suppressed in (A) nucleus pulposus (NP) and (B) annulus fibrosus (AF) tissues of treated discs at 3 and 10 days. Note a significant decrease in type 6 collagen (COL 6) after the treatment in (C) NP and (D) AF. Type 9 collagen (COL 9) expression is decreased only in AF after 10 days of treatment (C,D). Results are shown as the mean ± standard error for three independent experiments (n = 6 discs/group per experiment). *P <0.05. Ctr., control group; Exp, experimental group.