title: Involvement of astroglial glutamate-glutamine shuttle in modulation of the jaw-opening reflex following infraorbital nerve injury.
abstract: To evaluate the mechanisms underlying orofacial motor dysfunction associated with trigeminal nerve injury, we studied the astroglial cell activation following chronic constriction injury (CCI) of the infraorbital nerve (ION) immunohistochemically, nocifensive behavior in ION-CCI rats, and the effect of the glutamine synthase (GS) blocker methionine sulfoximine (MSO) on the jaw-opening reflex (JOR), and also studied whether glutamate-glutamine shuttle mechanism is involved in orofacial motor dysfunction. GFAP-immunoreactive (IR) cells were observed in the trigeminal motor nucleus (motV) 3 and 14 days after ION-CCI, and the nocifensive behavior and JOR amplitude were also strongly enhanced at these times. The number of GS- and GFAP-IR cells was also significantly higher in ION-CCI rats on day 7. The amplitude and duration of the JOR were strongly suppressed after MSO microinjection (m.i.) into the motV compared with that before MSO administration in ION-CCI rats. After MSO administration, the JOR amplitude was strongly suppressed, and the duration of the JOR was shortened. Forty minutes after m.i. of glutamine, the JOR amplitude was gradually returned to the control level and the strongest attenuation of the suppressive effect of MSO was observed at 180 min after glutamine m.i. In addition, glutamine also attenuated the MSO effect on the JOR duration, and the JOR duration was extended and returned to the control level thereafter. The present findings suggest that astroglial glutamate-glutamine shuttle in the motV is involved in the modulation of excitability of the trigeminal motoneurons affecting the enhancement of various jaw reflexes associated with trigeminal nerve injury.
authors.affiliation: Division of Oral Physiology, Department of Oral Biological Science, Niigata University Graduate School of Medical and Dental Sciences, 2-5274, Gakkocho-dori, Niigata, 951-8514, Japan.
authors.forename: Rahman Md
authors.initials: RM
authors.lastname: Mostafeezur
authors.forename: Masamichi
authors.initials: M
authors.lastname: Shinoda
authors.forename: Syunpei
authors.initials: S
authors.lastname: Unno
authors.forename: Hossain Md
authors.initials: HM
authors.lastname: Zakir
authors.forename: Hanako
authors.initials: H
authors.lastname: Takatsuji
authors.forename: Kojiro
authors.initials: K
authors.lastname: Takahashi
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Yamada
authors.forename: Kensuke
authors.initials: K
authors.lastname: Yamamura
authors.forename: Koichi
authors.initials: K
authors.lastname: Iwata
authors.forename: Junichi
authors.initials: J
authors.lastname: Kitagawa
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D003251:Constriction, Pathologic; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005974:Glutamate-Ammonia Ligase / Q000037:antagonists & inhibitors / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D007568:Jaw / Q000187:drug effects / Q000503:physiopathology*; D008297:Male; D008340:Mandibular Nerve / Q000187:drug effects / Q000503:physiopathology; D008442:Maxillary Nerve / Q000187:drug effects / Q000293:injuries* / Q000503:physiopathology*; D008717:Methionine Sulfoximine / Q000494:pharmacology; D009069:Movement Disorders / Q000209:etiology / Q000503:physiopathology; D018482:Muscle, Skeletal / Q000187:drug effects / Q000503:physiopathology; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D012879:Skin Physiological Phenomena / Q000187:drug effects; D066266:Trigeminal Motor Nucleus / Q000187:drug effects / Q000503:physiopathology
chemical_list: D004791:Enzyme Inhibitors; D005904:Glial Fibrillary Acidic Protein; D008717:Methionine Sulfoximine; D018698:Glutamic Acid; D005974:Glutamate-Ammonia Ligase
keywords: chronic constriction injury; jaw reflex; methionine sulfoximine; neuropathic pain; trigeminal nerve