In Brief:
Quantitative real-time polymerase chain reaction was performed to measure the messenger ribonucleic acid levels of anabolic cytokines bone morphogenetic protein (BMP)-2, BMP-7, transforming growth factor-β, and insulin-like growth factor-I from anulus fibrosus and nucleus pulposus tissue from young and old rabbits. The disc tissue from the old rabbits as compared to the young rabbits showed, in general, significantly higher levels of endogenous BMP-2, BMP-7, and transforming growth factor-β.