Radiculopathic pain commonly results from herniation of the nucleus pulposus (NP) from lumbar intervertebral discs. We presently investigated if application of NP to the L5 dorsal root ganglion (DRG) induces central sensitization of nociceptive spinal dorsal horn neurons as assessed by enhanced C-fiber evoked windup. Single-unit recordings were made from wide dynamic range or nociceptive-specific L5 dorsal horn neurons in isoflurane-anesthetized rats. Windup was elicited by C-fiber strength pulse trains delivered subcutaneously to the receptive field at frequencies of 0.1, 0.3 and 1 Hz before, and at 30-min intervals after application of NP (harvested from a coccygeal intervertebral disc) or saline (control) applied to the ipsilateral L5 DRG. In saline controls, windup was not enhanced at any time post-treatment for any stimulus frequency, although there was a trend toward enhancement at 0.3 Hz. Following NP, the response (summed across all 20 stimuli) to 0.1 Hz was enhanced 3 hr post-NP, mainly in the after-discharge (AD) period (latency >400 msec). Total responses to 0.3 & 1.0 Hz were also enhanced at 60 min post-NP in both the C-fiber (100-400 msec latency) and AD periods, while the absolute windup (C-fiber + AD- 20x initial response) increased at 90 min post-treatment. These results are consistent with NP-induced central sensitization. Mechanical responses were not significantly enhanced after saline or NP treatment. We speculate that inflammatory agents released from (or recruited by) NP affect the DRG (and/or are transported to cord) to enhance primary afferent excitation of nociceptive dorsal horn neurons.