title: Masseteric nerve injury increases expression of brain-derived neurotrophic factor in microglia within the rat mesencephalic trigeminal tract nucleus.
abstract: The distribution of brain-derived neurotrophic factor was examined in the rat mesencephalic trigeminal tract nucleus after transection and crush of the masseteric nerve. In the intact mesencephalic trigeminal tract nucleus, brain-derived neurotrophic factor was detected in small cells with fine processes. These cells and processes were occasionally located adjacent to tyrosine kinase B receptor-immunoreactive sensory neurons. The transection and crush of the masseteric nerve increased expression of brain-derived neurotrophic factor in the nucleus. The number and size of brain-derived neurotrophic factor-immunoreactive cells and processes were dramatically elevated by the nerve injury. As a result, the density of brain-derived neurotrophic factor-immunoreactive profiles in the mesencephalic trigeminal tract nucleus at 7 days after the injury was significantly higher compared with the intact nucleus. Double immunofluorescence method also revealed that brain-derived neurotrophic factor-immunoreactive cells were mostly immunoreactive for OX-42 but not glial fibrillary acidic protein. In addition, the retrograde tracing method demonstrated that brain-derived neurotrophic factor-immunoreactive cells and processes surrounded retrogradely labeled neurons which showed tyrosine kinase B receptor-immunoreactivity. These findings indicate that the nerve injury increases expression of brain-derived neurotrophic factor in microglia within the mesencephalic trigeminal tract nucleus. The glial neurotrophic factor may be associated with axonal regeneration of the injured primary proprioceptor in the trigeminal nervous system.
authors.affiliation: Division of Oral and Craniofacial Anatomy, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Sendai, 980-8575, Japan. hiroichi@anat.dent.tohoku.ac.jp
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ichikawa
authors.forename: Tadasu
authors.initials: T
authors.lastname: Sato
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Kano
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Suzuki
authors.forename: Saburo
authors.initials: S
authors.lastname: Matsuo
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Kanetaka
authors.forename: Yoshinaka
authors.initials: Y
authors.lastname: Shimizu
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D039481:CD11b Antigen / Q000378:metabolism; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D008297:Male; D008406:Masseter Muscle / Q000294:innervation* / Q000378:metabolism / Q000473:pathology*; D008636:Mesencephalon / Q000378:metabolism / Q000473:pathology*; D017628:Microglia / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020813:Receptor, trkB / Q000378:metabolism; D013194:Staining and Labeling; D014278:Trigeminal Nuclei / Q000378:metabolism* / Q000473:pathology
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D039481:CD11b Antigen; D005904:Glial Fibrillary Acidic Protein; D020813:Receptor, trkB