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Increased sensitivity to thermal pain following a single opiate dose is influenced by the COMT val(158)met polymorphism.

ABSTRACT: Increased pain sensitivity after opioid administration (opioid-induced hyperalgesia) and/or repeated painful stimuli is an individually varying and clinically important phenomenon. The functional polymorphism (val(158)met) of the Catechol-O-methyltransferase (COMT) gene regulates the metabolism of dopamine/noradrenaline. Individuals homozygous for the met(158) allele have been reported to have increased pain sensitivity and there are findings of lower micro-opioid system activation during sustained pain. We hypothesized that met/met individuals would exhibit higher pain sensitization and opioid-induced hyperalgesia in response to repeated pain stimuli and an intravenous injection of an opioid drug. Participants were 43 healthy subjects who went through an experiment where five blocks of pain were induced to the hand using a heat probe. After each stimulus subjects rated the pain on a visual analogue scale (VAS) from 0 mm (no pain) to 100 mm (worst possible pain). Before the second stimulus there was an intravenous injection of a rapid and potent opioid drug. At baseline there was no difference in pain ratings between the COMTval(158)met genotypes, F(2, 39)<1. However, a repeated measures ANOVA for all five stimuli revealed a main effect for COMTval(158)met genotype, F(2, 36) = 4.17, p = 0.024. Met/met individuals reported significantly more pain compared to val/val, p = 0.010. A pairwise comparison of baseline and the opioid intervention demonstrated that analgesia was induced in all groups (p = 0.042) without a separating effect for genotype (n.s). We suggest that the initial response of the descending pain system is not influenced by the COMTval(158)met polymorphism but when the system is challenged the difference is revealed. An important clinical implication of this may be that the COMTval(158)met related differences may be more expressed in individuals where the inhibitory system is already challenged and sensitive, e.g. chronic pain patients. This has to be proven in future studies where the impact of the COMTval(158)met polymorphism on opioid treatment in patients is addressed.

SUBMITTER: Jensen KB

PROVIDER: S-EPMC2695541 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Increased sensitivity to thermal pain following a single opiate dose is influenced by the COMT val(158)met polymorphism.

Jensen Karin B KB Lonsdorf Tina B TB Schalling Martin M Kosek Eva E Ingvar Martin M

PloS one 20090623 6

Increased pain sensitivity after opioid administration (opioid-induced hyperalgesia) and/or repeated painful stimuli is an individually varying and clinically important phenomenon. The functional polymorphism (val(158)met) of the Catechol-O-methyltransferase (COMT) gene regulates the metabolism of dopamine/noradrenaline. Individuals homozygous for the met(158) allele have been reported to have increased pain sensitivity and there are findings of lower micro-opioid system activation during sustai ...[more]

PMID: 19547755

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Project description:Schizophrenia and bipolar disorder may share aspects of genetic etiology. Evidence supports the Val 108/158 Met polymorphism of the Catechol-o-Methyltransferase (COMT) gene as potentially contributing to the etiology of both disorders. To determine whether the COMT gene is associated with personality traits related to genetic risk for either schizophrenia or bipolar disorder, we examined dimensions of personality psychopathology in biological relatives of individuals with the disorders. Specifically, we contrasted personality characteristics of first-degree relatives of people with schizophrenia, first-degree relatives of people with bipolar-I disorder, and nonpsychiatric control participants using scores from the Dimensional Assessment of Personality Pathology-Brief Questionnaire (DAPP-BQ). We also characterized the COMT Val 108/158 Met polymorphism of subjects. Compared to controls, relatives of schizophrenia patients scored lower on stimulus seeking and higher on restrictive expression and social avoidance. Compared to relatives of bipolar patients, relatives of schizophrenia patients had lower scores on narcissism, rejectionality (i.e., rejection of ideas of others), stimulus seeking, passive-aggressive oppositionality, and self-harm. The subset of relatives of schizophrenia patients who were COMT val homozygotes exhibited lower scores on narcissism, rejectionality, and stimulus seeking than met homozygote relatives of schizophrenia patients and control participants. Although relatives of bipolar patients showed scale elevations consistent with emotional dysregulation, the scores failed to be associated with the Val 108/158 Met polymorphism. Abnormally low narcissism and rejectionality in val homozygote relatives of schizophrenia patients suggests that the val allele of the COMT polymorphism may be associated with an underdeveloped self-concept phenomenologically similar to made volition and passivity experiences comprising first-rank symptoms of schizophrenia.

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Increased sensitivity to thermal pain following a single opiate dose is influenced by the COMT val(158)met polymorphism.

Publications

Increased sensitivity to thermal pain following a single opiate dose is influenced by the COMT val(158)met polymorphism.

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