J Korean Acad Rehabil Med.  2009 Aug;33(4):477-482.

The Long-Lasting Pattern of the Neuropathic Radicular Pain in An Autologous Nucleus Pulposus Model of Rat

Affiliations
  • 1Department of Rehabilitation Medicine, College of Medicine, Yeungnam University, Korea. spineahn@yumail.ac.kr
  • 2Institute of Medical Science, Yeungnam University, Korea.

Abstract


OBJECTIVE
To observe the long-lasting changes of pain progression with time course in an autologous nucleus pulposus model of rat. METHOD: The subjects were 25 Sprague-Dawley (Sprague- Dawley, 250 gm) male rats. They were randomly assigned into either the sham or experimental group. In the experimental group (n=15), autologous nucleus pulposus was harvested from the coccygeal intervertebral disc of the rat and this was grafted on the left L5 dorsal root ganglion. In the sham group (n=10), the left L4 and L5 nerve roots were exposed by laminectomy, but the nucleus pulposus was not grafted. All the rats were evaluated for mechanical allodynia and thermal hyperalgesia at 2 days before surgery, and on days 1, 5, 10, 20, 30, 40 and 50 after surgery. The morphological changes of the spinal nerves were assessed by toluidine blue staining on days 5 after surgery.
RESULTS
In the ipsilateral hindpaw of the experimental group, there was a dramatic drop of the mechanical withdrawal threshold and the thermal withdrawal latency on day 1 after surgery, which was maintained at day 50 after surgery. In morphological study, pathological findings such as swelling of the myelin sheath, demyelination, swelling and degeneration of the axoplasm were observed in the spinal nerve at day 5 after surgery.
CONCLUSION
The long-lasting pattern of neuropathic radicular pain shown in a rat model of lumbar disc herniations is helpful to understand the natural history of neuropathic radicular pain due to ruptured nucleus pulposus.

Keyword

Autologous nucleus pulposus model; Mechanical allodynia; Thermal hyperalgesia; Neuropathic radicular pain

MeSH Terms

Animals
Demyelinating Diseases
Ganglia, Spinal
Humans
Hyperalgesia
Intervertebral Disc
Laminectomy
Male
Myelin Sheath
Natural History
Rats
Salicylamides
Spinal Nerves
Tolonium Chloride
Transplants
Salicylamides
Tolonium Chloride
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