[Mechanism of radiculopathy induced by experimentally herniated nucleus pulposus in rats].

OBJECTIVE: To determine the effects of the autologous nucleus pulposus on the pain-related behaviors of hind paws in rats. METHODS: The nucleus pulposus harvested from autologous coccygeal vertebra was applied beside the unilateral L4 and L5 nerve roots without compression. The mechanical withdrawal threshold of both paws were measured in different times after surgery. And hematoxylin and eosin (HE) staining was applied to observe the changes of nucleus pulposus and nerve roots. RESULTS: Mechanical sensitivity of the operated side in paws obviously increased after application of autologous nucleus pulposus beside the lumbar nerve roots without compression. And HE staining showed obviously inflammatory changes in the nucleus pulposus and vacuolation in the nerve roots. CONCLUSIONS: Inflammation resulted from nucleus pulposus may contribute to the development of mechanical hyperalgesia. The results suggest that in addition to mechanical compression, inflammation may be an important factor in the pathogenesis of sciatica.