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Muscle pain sensitivity after glutamate injection is not modified by systemic administration of monosodium glutamate

Overview of attention for article published in The Journal of Headache and Pain, July 2015
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Title
Muscle pain sensitivity after glutamate injection is not modified by systemic administration of monosodium glutamate
Published in
The Journal of Headache and Pain, July 2015
DOI 10.1186/s10194-015-0546-0
Pubmed ID
Authors

Akiko Shimada, Eduardo Castrillon, Lene Baad-Hansen, Bijar Ghafouri, Björn Gerdle, Malin Ernberg, Brian Cairns, Peter Svensson

Abstract

Monosodium glutamate (MSG) is often thought to be associated with headache and craniofacial pains like temporomandibular disorders. This randomized, double-blinded, placebo-controlled study was performed to investigate how ingestion of MSG affects muscle pain sensitivity before and after experimentally induced muscle pain. Sixteen healthy adult subjects participated in 2 sessions with at least 1-week interval between sessions. In each session, two injections of glutamate (Glu, 0.5 M, 0.2 ml) and two injections of saline (0.9 %, 0.2 ml) into the masseter and temporalis muscles, respectively, were undertaken, with a 15 min interval between each injection. Injections of saline were made contralateral to Glu injections and done in a randomized order. Participants drank 400 mL of soda mixed with either MSG (150 mg/kg) or NaCl (24 mg/kg, placebo) 30 min before the intramuscular injections. Pressure pain thresholds (PPT), autonomic parameters and pain intensity were assessed prior to (baseline) and 30 min after ingestion of soda, as well as 5 min and 10 min after the intramuscular injections and at the end of the session. Whole saliva samples were collected prior to and 30, 45, 60, and 75 min after the ingestion of soda. MSG administration resulted in a significantly higher Glu level in saliva than administration of NaCl and was associated with a significant increase in systolic blood pressure. Injections of Glu were significantly more painful than injections of NaCl. However, ingestion of MSG did not change the intensity of Glu-evoked pain. Glu injections also significantly increased systolic and diastolic blood pressure, but without an additional effect of MSG ingestion. Glu injections into the masseter muscle significantly reduced the PPT. However, pre-injection MSG ingestion did not significantly alter this effect. Interestingly, PPT was significantly increased in the trapezius after MSG ingestion and intramuscular injection of Glu in the jaw muscles. The main finding in this study was that systemic intake of a substantial amount of MSG does not influence either pain intensity or pressure pain sensitivity in the masseter and temporalis muscles into which Glu injections were made.

Mendeley readers

Mendeley readers

The data shown below were compiled from readership statistics for 65 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Australia 1 2%
Unknown 64 98%

Demographic breakdown

Readers by professional status Count As %
Researcher 8 12%
Student > Master 8 12%
Student > Doctoral Student 7 11%
Student > Bachelor 6 9%
Other 4 6%
Other 12 18%
Unknown 20 31%
Readers by discipline Count As %
Medicine and Dentistry 21 32%
Nursing and Health Professions 7 11%
Engineering 4 6%
Unspecified 2 3%
Pharmacology, Toxicology and Pharmaceutical Science 1 2%
Other 4 6%
Unknown 26 40%