title: Behavioral evidence for the differential regulation of p-p38 MAPK and p-NF-κB in rats with trigeminal neuropathic pain.
abstract: BACKGROUND
  We investigated the differential regulation of p-p38 MAPK or p-NF-κB in male Sprague-Dawley rats with inferior alveolar nerve injury resulting from mal-positioned dental implants. For this purpose, we characterized the temporal expression of p-p38 MAPK or p-NF-κB in the medullary dorsal horn and examined changes in nociceptive behavior after a blockade of p-p38 MAPK or p-NF-κB pathways in rats with trigeminal neuropathic pain.
  
  
  RESULTS
  Under anesthesia, the left lower second molar was extracted and replaced with a mini dental implant to intentionally injure the inferior alveolar nerve. Western and immunofluorescence analysis revealed that p-p38 MAPK is upregulated in microglia following nerve injury and that this expression peaked on postoperative day (POD) 3 through 7. However, the activation of p-NF-κB in astrocyte peaked on POD 7 through 21. The intracisternal administration of SB203580 (1 or 10 μg), a p38 MAPK inhibitor, on POD 3 but not on POD 21 markedly inhibits mechanical allodynia and the p-p38 MAPK expression. However, the intracisternal administration of SN50 (0.2 or 2 ng), an NF-κB inhibitor, on POD 21 but not on POD 3 attenuates mechanical allodynia and p-NF-κB expression. Dexamethasone (25 mg/kg) decreases not only the activation of p38 MAPK but also that of NF-κB on POD 7.
  
  
  CONCLUSIONS
  These results suggest that early expression of p-p38 MAPK in the microglia and late induction of p-NF-κB in astrocyte play an important role in trigeminal neuropathic pain and that a blockade of p-p38 MAPK at an early stage and p-NF-κB at a late stage might be a potential therapeutic strategy for treatment of trigeminal neuropathic pain.
authors.affiliation: Department of Oral Physiology, School of Dentistry, Kyungpook National University, Daegu, Korea.
authors.forename: Min K
authors.initials: MK
authors.lastname: Lee
authors.forename: Seung R
authors.initials: SR
authors.lastname: Han
authors.forename: Min K
authors.initials: MK
authors.lastname: Park
authors.forename: Min J
authors.initials: MJ
authors.lastname: Kim
authors.forename: Yong C
authors.initials: YC
authors.lastname: Bae
authors.forename: Sung K
authors.initials: SK
authors.lastname: Kim
authors.forename: Jae S
authors.initials: JS
authors.lastname: Park
authors.forename: Dong K
authors.initials: DK
authors.lastname: Ahn
mesh_terms: D000700:Analgesics / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003907:Dexamethasone / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D007093:Imidazoles / Q000494:pharmacology; D008297:Male; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009437:Neuralgia / Q000201:enzymology* / Q000473:pathology*; D010455:Peptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013997:Time Factors; D014276:Trigeminal Nerve / Q000187:drug effects / Q000201:enzymology* / Q000473:pathology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D000700:Analgesics; D007093:Imidazoles; D016328:NF-kappa B; D010455:Peptides; D011725:Pyridines; C118258:SN50 peptide; D003907:Dexamethasone; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580