| 1. |
- Murata, Y., et al.
(författare)
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Changes in pain behavior and histologic changes caused by application of tumor necrosis factor-alpha to the dorsal root ganglion in rats
- 2006
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Ingår i: Spine. - 1528-1159. ; 31:5, s. 530-5
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: Histologic changes in the dorsal root ganglion (DRG) and the nociceptive stimulation thresholds were studied in rats. OBJECTIVE: To examine the effects of tumor necrosis factor-alpha (TNF) with special reference to pain behavior and histology of the DRG. SUMMARY OF BACKGROUND DATA: Recently, it was reported that local application of nucleus pulposus induces a characteristic tissue reaction at the surface of the DRG. However, to our knowledge, there have been no previous reports about the relationship between the histologic changes and pain behavior caused by cytokines. METHODS: Recombinant TNF was applied to the L4 DRG. Mechanical and thermal nociceptive thresholds were tested. The L4 DRG was sectioned and observed by light microscopy. RESULTS: After the application of 5 ng/microL TNF, significant differences were observed in mechanical and thermal stimulation thresholds. At the site of application of TNF, a characteristic a semilunar-shaped enlargement was observed. The average width of the part was significantly larger in the 5 ng/microL TNF application, as compared to the 0.5-ng/microL TNF application. CONCLUSIONS: The higher concentration of TNF used induced allodynia and hyperalgesia responses. Because the region showing the histologic changes was significantly larger after application of the higher concentration of TNF, the reaction of the DRG may be related to pain.
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| 2. |
- Murata, Y., et al.
(författare)
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Distribution and appearance of tumor necrosis factor-alpha in the dorsal root ganglion exposed to experimental disc herniation in rats
- 2004
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Ingår i: Spine. - 1528-1159. ; 29:20, s. 2235-41
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: Distribution and appearance of tumor necrosis factor-alpha (TNF-alpha) in the dorsal root ganglion (DRG) exposed to experimental disc herniation were investigated using an immunohistochemical method in rats. OBJECTIVES: To study the distribution and appearance of TNF-alpha in the DRG following experimental disc herniation in rats. SUMMARY OF BACKGROUND DATA: Nucleus pulposus in the epidural space induces spinal nerve root injury not only by mechanical but also chemical mechanisms. Cytokines may play a key role in the chemical damage. There is, however, no report on the distribution and appearance of TNF-alpha in the DRG exposed to nucleus pulposus. METHODS: Nucleus pulposus from the discs was smeared on the glass slides and processed for immunohistochemistry by the avidin-biotinylated peroxidase complex technique using rabbit antisera to TNF-alpha in rats. A herniation of the nucleus pulposus was made by incision of the L4-L5 disc in rats. The L4 and L5 DRGs were resected 1, 3, 7, 14, and 21 days after surgery. The specimens were processed for immunohistochemistry using rabbit antisera to TNF-alpha. The TNF-alpha-positive cells were observed and counted using light microscopy. Distribution of the TNF-alpha products was compared on each day after surgery. RESULTS: A positive staining was seen in the cell bodies and in the matrix between the cells in the smeared nucleus pulposus. In the L4 DRG sections, the number of positive cells was significantly higher in the disc incision group than in the sham group at 1, 3, 7, and 14 days after surgery (P < 0.05). The positive cells showed a decrease in number day by day after surgery. On the contrary, in the L5 DRG, only a few positive cells were observed in the disc incision group after surgery. There was no statistically significant difference between disc incision and the sham groups at each day after surgery for the L5 DRGs. CONCLUSIONS: The immunoreactivity of TNF-alpha in the DRG directly exposed to nucleus pulposus increases during 2 weeks. A collapse of the positive cells was seen in the DRG directly exposed to the nucleus pulposus.
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| 3. |
- Murata, Y., et al.
(författare)
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Incision of the intervertebral disc induces disintegration and increases permeability of the dorsal root ganglion capsule
- 2005
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Ingår i: Spine. - 1528-1159. ; 30:15, s. 1712-6
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: The origin and the barrier properties of the characteristic reaction at the surface of the dorsal root ganglion (DRG) exposed to the nucleus pulposus was studied using Alcian-Blue staining, van Gieson staining, and the application of Evans Blue Albumin (EBA) complex in rats. OBJECTIVE: To study the origin and the barrier properties of the capsule, including the characteristic reaction, at the surface of the DRG exposed to the nucleus pulposus. SUMMARY OF BACKGROUND DATA: Local application of nucleus pulposus may induce a characteristic reaction at the surface of the DRG. This reaction histologically resembles an acute inflammatory reaction. However, it is not evident if this is a swelling of the DRG capsule, if it is located between the capsule and neurons of the DRG, or if it is only an attached nucleus pulposus. METHODS: Nucleus pulposus from the discs was obtained. The nucleus pulposus was smeared on glass slides. Alcian-Blue with hematoxylin and eosin staining was performed for each smear. Herniation of the nucleus pulposus was made in the L4-L5 disc in rats. The L4 DRGs were resected 3, 24, and 72 hours after surgery, and sectioned. The sections were processed for Alcian-Blue staining, van Gieson staining, and EBA complex infiltration. The sections were observed using light or fluorescent microscopy. RESULTS: Smear of nucleus pulposus was stained bright blue indicating mucins. A characteristic reaction, "inflammatory crescent," was confirmed at the surface of the DRG exposed to the nucleus pulposus. No mucins were observed in the crescent using Alcian-Blue. The results of van Gieson staining showed that the reaction started both inside and outside the elastic fiber layer, the DRG capsule, within 3 hours. The EBA complex was capable of infiltrating into the DRG capsule 24 hours after disc incision. CONCLUSIONS: The disintegrated capsule showed an increased permeability even for a large molecule as albumin, which indicates a possible entrance route for various substances induced by locally applied nucleus pulposus.
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| 4. |
- Murata, Y., et al.
(författare)
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Nucleus pulposus-induced apoptosis in dorsal root ganglion following experimental disc herniation in rats
- 2006
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Ingår i: Spine. - 1528-1159. ; 31:4, s. 382-90
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: The mechanisms behind the formation of a characteristic tissue reaction at the surface of the dorsal root ganglion (DRG) exposed to nucleus pulposus was studied with special reference to apoptosis using electron microscopy and immunohistochemistry in rats. OBJECTIVES: To study the mechanism of the characteristic tissue reaction at the surface of the DRG exposed to nucleus pulposus. SUMMARY OF BACKGROUND DATA: Recently, it was observed that local application of nucleus pulposus may induce a characteristic tissue reaction at the surface of the DRG. This change occurred as early as 1 day after the application of nucleus pulposus. METHODS.: Herniation of nucleus pulposus was created in the L4-L5 disc in rats. The L4 DRG were resected 3 and 24 hours after surgery. The sections of the specimens were observed using light and electron microscopy. The sections were processed for immunohistochemistry using antibodies to single-stranded DNA (ssDNA), caspase 3, and tumor necrosis factor alpha (TNF). RESULTS: There were typical changes of the cell nuclei observed by light and electron microscopy, especially those of the small-sized cells, in the DRG 24 hours after application of nucleus pulposus, indicating the presence of apoptosis. The presence of ssDNA, caspase 3, and TNF further enhanced the impression that there was apoptosis in the DRG. Nucleus pulposus induced apoptosis in the DRG at the site of application within as little as 24 hours. CONCLUSIONS: Nucleus pulposus herniated from the disc induced apoptosis in at the surface of the DRG exposed to nucleus pulpous as early as 24 hours after exposure.
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| 5. |
- Murata, Y., et al.
(författare)
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Selective inhibition of tumor necrosis factor-alpha prevents nucleus pulposus-induced histologic changes in the dorsal root ganglion
- 2004
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Ingår i: Spine. - 1528-1159. ; 29:22, s. 2477-84
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Tidskriftsartikel (refereegranskat)abstract
- STUDY DESIGN: The possibility to prevent nucleus pulposus-induced structural changes of the dorsal root ganglion (DRG) by selective tumor necrosis factor-alpha (TNF-alpha) inhibition was assessed in an experimental model in the rat spine. OBJECTIVES: To evaluate the role of TNF-alpha in the mediation of nucleus pulposus-induced structural changes by using selective inhibition and to confirm the effect of TNF-alpha inhibitor at the point of histologic findings. SUMMARY OF BACKGROUND DATA: TNF-alpha is known to be released from the nucleus pulposus, and has been suggested to play a key role in chemical damage of the adjacent nerve tissue. The TNF-alpha inhibitor prevents the reduction of nerve conduction velocity and may limit the nerve fiber injury, intracapillary thrombus formation, and intraneural edema formation caused by nucleus pulposus. However, there is no report on the effect of the inhibitor regarding histologic findings and the appearance of the TNF-alpha in the DRG exposed to nucleus pulposus. METHODS: 1) Rats were treated with an intraperitoneal injection of infliximab. Nucleus pulposus from the disc was obtained 1, 3, 7, 14, and 21 days after the injection. The TNF-alpha-positive cells were observed using immunohistochemistry. 2) Disc herniation of the nucleus pulposus was made on the L4-L5 disc in rats. Two groups were treated with selective TNF-alpha inhibitor 1 day before or 3 hours after surgery. The other group received no TNF-alpha inhibitor. The L4 DRG was resected 1, 3, 7, 14, and 21 days after surgery. The specimens were processed for hematoxylin and eosin staining and immunohistochemistry using rabbit antisera to TNF-alpha. The histologic findings and TNF-alpha-positive cells were observed by light microscopy. RESULTS: 1) While positively stained immunoreactive TNF-alpha appeared between 7 and 21 days, no immunoreactive TNF-alpha was observed 1 and 3 days after injection in the nucleus pulposus. 2) The histologic changes of the DRG caused by nucleus pulposus were smaller in the infliximab treatment group than those in the nontreatment group. The number of immunoreactive TNF-alpha cells was high 1 and 3 days after surgery in the DRGs of disc herniation rats that were treated without an injection of the inhibitor, low on day 7 and 14, and very low on day 21 after surgery. No immunoreactive TNF-alpha was observed in the DRGs of the TNF-alpha inhibitor treatment groups on day 1, 3, and 21 after surgery. Weakly stained cells were sometimes observed in rats at day 7 and 14 after surgery. CONCLUSIONS: Infliximab may prevent the histologic damage induced by nucleus pulposus. When rats were given a single intraperitoneal injection of infliximab at the beginning of disc herniation, the histologic damage seemed to be reduced in comparison with the nontreated rats.
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