The upstream Variable Number Tandem Repeat polymorphism of the monoamine oxidase type A gene influences trigeminal pain-related evoked responses.
Monoamines have an important role in neural plasticity, a key factor in cortical pain processing that promotes changes in neuronal network connectivity. Monoamine oxidase type A (MAOA) is an enzyme that, due to its modulating role in monoaminergic activity, could play a role in cortical pain processing. The X-linked MAOA gene is characterized by an allelic variant of length, the MAOA upstream Variable Number Tandem Repeat (MAOA-uVNTR) region polymorphism. Two allelic variants of this gene are known, the high-activity MAOA (HAM) and low-activity MAOA (LAM). We investigated the role of MAOA-uVNTR in cortical pain processing in a group of healthy individuals measured by the trigeminal electric pain-related evoked potential (tPREP) elicited by repeated painful stimulation. A group of healthy volunteers was genotyped to detect MAOA-uVNTR polymorphism. Electrical tPREPs were recorded by stimulating the right supraorbital nerve with a concentric electrode. The N2 and P2 component amplitude and latency as well as the N2-P2 inter-peak amplitude were measured. The recording was divided into three blocks, each containing 10 consecutive stimuli and the N2-P2 amplitude was compared between blocks. Of the 67 volunteers, 37 were HAM and 30 were LAM. HAM subjects differed from LAM subjects in terms of amplitude of the grand-averaged and first-block N2-P2 responses (HAM>LAM). The N2-P2 amplitude decreased between the first and third block in HAM subjects but not LAM subjects. The MAOA-uVNTR polymorphism seemed to influence the brain response in a repeated tPREP paradigm and suggested a role of the MAOA as a modulator of neural plasticity related to cortical pain processing.
Don Carlo Gnocchi Onlus Foundation, Via Maresciallo Caviglia, 30-00135, Rome, Italy.
Cherubino
C
Di Lorenzo
Andrea
A
Daverio
Patrizio
P
Pasqualetti
Gianluca
G
Coppola
Ioannis
I
Giannoudas
Ylenia
Y
Barone
Gaetano S
GS
Grieco
Cinzia
C
Niolu
Esterina
E
Pascale
Filippo M
FM
Santorelli
Ferdinando
F
Nicoletti
Francesco
F
Pierelli
Alberto
A
Siracusano
Stefano
S
Seri
Giorgio
G
Di Lorenzo
D000328:Adult; D016022:Case-Control Studies; D005073:Evoked Potentials, Somatosensory / Q000235:genetics*; D005260:Female; D006579:Heterozygote; D006801:Humans; D008297:Male; D018598:Minisatellite Repeats; D008995:Monoamine Oxidase / Q000235:genetics*; D010146:Pain / Q000235:genetics*; D011110:Polymorphism, Genetic; D014276:Trigeminal Nerve / Q000502:physiology*
D008995:Monoamine Oxidase; C579458:monoamine oxidase A, human
habituation; human; monoamine; neural plasticity; pain-related evoked potential; sensitization