PMID- 18162423
OWN - NLM
STAT- MEDLINE
DCOM- 20080926
LR  - 20181113
IS  - 1532-2149 (Electronic)
IS  - 1090-3801 (Print)
IS  - 1090-3801 (Linking)
VI  - 12
IP  - 5
DP  - 2008 Jul
TI  - Interactions between glutamate and capsaicin in inducing muscle pain and 
      sensitization in humans.
PG  - 661-70
AB  - The aim of the study was to investigate the interaction between glutamate and 
      capsaicin in inducing muscle pain and sensitization in humans. Fifteen male 
      volunteers participated. Glutamate or capsaicin or isotonic saline, in a 
      paired-sequence order, was injected randomly into the right or left masseter 
      muscle. Two injections were given in a double-blinded design 25 min apart in 1 
      session/week over 4 weeks: saline (A1) followed by glutamate (A2), capsaicin (B1) 
      followed by glutamate (B2), saline (C1) followed by capsaicin (C2), and glutamate 
      (D1) followed by capsaicin (D2). The subjects drew the area of perceived pain and 
      scored pain intensity on a 0-10 visual analogue scale (VAS). Pressure pain 
      threshold (PPT) at the injection site, at a site 2-cm away, and on the 
      contralateral side, as well as pressure pain tolerance (PPTol) at the injection 
      site and contralateral site, were also measured before and after injection and 
      subsequently at 5-min intervals. Paired t-test analyses showed that the pain 
      drawing area was significantly smaller in the B2 compared to the A2 condition 
      (P=0.028), and significantly larger in the D2 compared to the C2 condition 
      (P=0.027). It also revealed significantly lower VAS peak pain intensity (P=0.008) 
      and smaller VAS area under the curve (P=0.003) for the B2 compared to the A2 
      condition, and significantly higher VAS peak pain (P=0.015) and larger VAS area 
      under the curve (P=0.037) for the D2 compared to the C2 condition. There was a 
      significant PPT and PPTol decrease at the injection site after glutamate or 
      capsaicin injection (ANOVA: P<0.028). The percentage decrease in PPT or PPTol (at 
      the injection site) was not significantly different for the B2 compared to the A2 
      condition (Paired t-test: P>0.682) or for the D2 compared to the C2 condition 
      (P>0.133). Significant PPT changes were also observed at the site 2 cm away, but 
      not on the contralateral side. In conclusion, these findings indicate that 
      intramuscular administrations of glutamate and capsaicin interact and influence 
      pain and sensitization of muscle nociceptors: glutamate causes a sensitization to 
      subsequent administration of capsaicin, whereas capsaicin is associated with a 
      desensitization to subsequent injection of glutamate. These findings support 
      previous animal data.
FAU - Arendt-Nielsen, L
AU  - Arendt-Nielsen L
AD  - Center for Sensory-Motor Interaction, Orofacial Pain Laboratory, Aalborg 
      University, DK-9220 Aalborg, Denmark.
FAU - Svensson, P
AU  - Svensson P
FAU - Sessle, B J
AU  - Sessle BJ
FAU - Cairns, B E
AU  - Cairns BE
FAU - Wang, K
AU  - Wang K
LA  - eng
GR  - M01 RR001032-328849/RR/NCRR NIH HHS/United States
GR  - R01 DE015420/DE/NIDCR NIH HHS/United States
GR  - R01 DE015420-01/DE/NIDCR NIH HHS/United States
GR  - 1 R01DE015420-01/DE/NIDCR NIH HHS/United States
PT  - Comparative Study
PT  - Journal Article
PT  - Randomized Controlled Trial
PT  - Research Support, N.I.H., Extramural
DEP - 20071226
PL  - England
TA  - Eur J Pain
JT  - European journal of pain (London, England)
JID - 9801774
RN  - 0 (Neurotoxins)
RN  - 3KX376GY7L (Glutamic Acid)
RN  - S07O44R1ZM (Capsaicin)
SB  - IM
MH  - Adult
MH  - Capsaicin/administration & dosage/pharmacology/*toxicity
MH  - Double-Blind Method
MH  - Drug Interactions
MH  - Facial Pain/*chemically induced/physiopathology
MH  - Female
MH  - Glutamic Acid/administration & dosage/pharmacology/*toxicity
MH  - Humans
MH  - Injections, Intramuscular
MH  - Male
MH  - Masseter Muscle/innervation
MH  - Neurotoxins/administration & dosage/pharmacology/*toxicity
MH  - Pain Measurement
MH  - Pain Threshold/*drug effects
MH  - Pressure/adverse effects
PMC - PMC2491497
MID - NIHMS53075
EDAT- 2007/12/29 09:00
MHDA- 2008/09/27 09:00
PMCR- 2009/07/01
CRDT- 2007/12/29 09:00
PHST- 2007/06/07 00:00 [received]
PHST- 2007/10/12 00:00 [revised]
PHST- 2007/10/24 00:00 [accepted]
PHST- 2007/12/29 09:00 [pubmed]
PHST- 2008/09/27 09:00 [medline]
PHST- 2007/12/29 09:00 [entrez]
PHST- 2009/07/01 00:00 [pmc-release]
AID - S1090-3801(07)00675-1 [pii]
AID - 10.1016/j.ejpain.2007.10.013 [doi]
PST - ppublish
SO  - Eur J Pain. 2008 Jul;12(5):661-70. doi: 10.1016/j.ejpain.2007.10.013. Epub 2007 
      Dec 26.