The val158met polymorphism of human catechol-O-methyltransferase (COMT) affects anterior cingulate cortex activation in response to painful laser stimulation.
BACKGROUND
Pain is a complex experience with sensory, emotional and cognitive aspects. Genetic and environmental factors contribute to pain-related phenotypes such as chronic pain states. Genetic variations in the gene coding for catechol-O-methyltransferase (COMT) have been suggested to affect clinical and experimental pain-related phenotypes including regional mu-opioid system responses to painful stimulation as measured by ligand-PET (positron emission tomography). The functional val158met single nucleotide polymorphism has been most widely studied. However, apart from its impact on pain-induced opioid release the effect of this genetic variation on cerebral pain processing has not been studied with activation measures such as functional magnetic resonance imaging (fMRI), PET or electroencephalography. In the present fMRI study we therefore sought to investigate the impact of the COMT val158met polymorphism on the blood oxygen level-dependent (BOLD) response to painful laser stimulation.


RESULTS
57 subjects were studied. We found that subjects homozygous for the met158 allele exhibit a higher BOLD response in the anterior cingulate cortex (ACC), foremost in the mid-cingulate cortex, than carriers of the val158 allele.


CONCLUSIONS
This result is in line with previous studies that reported higher pain sensitivity in homozygous met carriers. It adds to the current literature in suggesting that this behavioral phenotype may be mediated by, or is at least associated with, increased ACC activity. More generally, apart from one report that focused on pain-induced opioid release, this is the first functional neuroimaging study showing an effect of the COMT val158met polymorphism on cerebral pain processing.
Department of Psychiatry, Johannes Gutenberg-University, Untere Zahlbacher Str. 8, 55131, Germany. mobascher_a@psychiatrie.klinik.uni-mainz.de
Arian
A
Mobascher
Juergen
J
Brinkmeyer
Holger
H
Thiele
Mohammad R
MR
Toliat
Michael
M
Steffens
Tracy
T
Warbrick
Francesco
F
Musso
Hans-Joerg
HJ
Wittsack
Andreas
A
Saleh
Alfons
A
Schnitzler
Georg
G
Winterer
D000328:Adult; D002394:Catechol O-Methyltransferase / Q000235:genetics*; D002540:Cerebral Cortex / Q000378:metabolism*; D005260:Female; D005838:Genotype; D006179:Gyrus Cinguli / Q000378:metabolism; D006801:Humans; D007834:Lasers / Q000009:adverse effects*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000235:genetics*; D011110:Polymorphism, Genetic / Q000235:genetics*; D049268:Positron-Emission Tomography; D055815:Young Adult
D002394:Catechol O-Methyltransferase