MRS assessment of glutamate clearance in a novel masticatory muscle pain model.
The injection of 1.0 M glutamate into the masseter (jaw-closer) muscle results in a short period of muscle pain (5-10 min) and a prolonged period of mechanical sensitization (> 30 min). It is unclear, however, whether there is a temporal relationship between intramuscular glutamate concentration and either muscle pain or mechanical sensitization. In the present study, (1)H MRS and electrophysiological recording of masticatory muscle nerve fibers were performed in order to monitor glutamate clearance and nerve fiber activity, respectively, after injection of glutamate into rat masticatory muscles. Glutamate signal amplitude was found to decay rapidly (half-life t 1/2 = 108 +/- 42 s), and became indistinguishable from the baseline 10 min after the injection. Glutamate-evoked nerve fiber activity was also found to decay rapidly (t 1/2 = 76 +/- 28 s). These results suggest that glutamate clearance correlates well with the time course of glutamate-evoked muscle pain fiber discharge.
Gambarota
G
G
Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands. g.gambarota@rad.umcn.nl
Philippens
M
M
Cairns
B E
BE
Dong
X D
XD
Renema
W K J
WK
Heerschap
A
A
D000818:Animals; D004195:Disease Models, Animal; D018698:Glutamic Acid / Q000008:administration & dosage / Q000493:pharmacokinetics*; D007273:Injections, Intramuscular; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008410:Masticatory Muscles / Q000187:drug effects / Q000294:innervation / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D051381:Rats; D017207:Rats, Sprague-Dawley; D013706:Temporomandibular Joint Dysfunction Syndrome / Q000139:chemically induced / Q000378:metabolism*; D017833:Visceral Afferents / Q000187:drug effects / Q000378:metabolism
D018698:Glutamic Acid