In Brief:
SPARC (secreted protein, acidic, rich in cysteine)-null mice show behavioral signs of axial low back pain, radiating leg pain and reduced physical function. Sensory innervation in or near the intervertebral discs, pain-related neuropeptide expression in dorsal root ganglia neurons, and astrocyte and microglia expression in the spinal cord were increased with age and in SPARC-null mice.