Effects of isometric contraction on intramuscular level of neuropeptide Y and local pain perception.
OBJECTIVE
The release of neuropeptide Y (NPY) is reported to increase in ischemic conditions and may thus be involved in chronic myalgia. The purpose of this study was to investigate the effect of isometric contraction on intramuscular levels of NPY in relation to local pain development.


METHODS
Intramuscular microdialysis was performed in the masseter and trapezius muscles to determine NPY levels before, during, and after isometric contraction in 16 healthy females. Pain intensity was assessed simultaneously with VAS. Repeated measures ANOVA, t-test, and Pearson correlation analysis were used for statistical analyses.


RESULTS
The level of NPY in the trapezius muscle was increased during and after contraction, while there was no change in the masseter muscle. The level of NPY before contraction was higher in the masseter muscle than in the trapezius muscle, and the levels in the two muscles were correlated before and during contraction. Low-level pain in both muscles after probe insertion increased significantly during contraction, but the pain was not correlated to the NPY level.


CONCLUSIONS
Pain is developed in the trapezius and masseter muscles during repeated isometric contraction. The NPY level is increased in the trapezius muscle but is not associated with the pain development.
Hedenberg-Magnusson
Britt
B
Department of stomatognathic physiology, Eastman Institute, Stockholm, Sweden. britt.hedenberg@ftv.sll.se
Brodda Jansen
Gunilla
G
Ernberg
Malin
M
Kopp
Sigvard
S
D001732:Bite Force; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D008406:Masseter Muscle / Q000378:metabolism / Q000503:physiopathology*; D017551:Microdialysis; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism / Q000503:physiopathology*; D009478:Neuropeptide Y / Q000032:analysis* / Q000097:blood; D010146:Pain / Q000378:metabolism / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology
D009478:Neuropeptide Y