The MAO-A genotype does not modulate resting brain metabolism in adults

Medical Department, Brookhaven National Laboratory, Upton, New York 11973, United States.
Psychiatry Research (Impact Factor: 2.47). 09/2008; 164(1):73-6. DOI: 10.1016/j.pscychresns.2007.12.010
Source: PubMed


Variation in the monoamine-oxidase-A (MAO-A) gene has been associated with volumetric changes in corticolimbic regions with differences in their response to relevant emotional tasks. Here we show no changes in baseline regional brain metabolism as a function of genotype indicating that, unchallenged, corticolimbic activity is not modulated by the MAO-A genotype.

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Available from: Ian W Craig, Oct 06, 2015
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    • "Structural MRI studies employing voxel-based morphometry (VBM) also produced conflicting findings with respect to the effect of MAOA genotypes on amygdala volume [20] [21] [22]. However, a positron emission tomography (PET) study found no differences in the glucose metabolism between MAOA-L and MAOA-H groups [23]. Currently, the neurobiological mechanisms underlying the effects of the MAOA polymorphism on impulsiveness are still unclear. "
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    ABSTRACT: Objective: To investigate the effects of a functional polymorphism of the monoamine oxidase A (MAOA) gene on spontaneous brain activity in healthy male adolescents. Methods: Thirty-one healthy male adolescents with the low-activity MAOA genotype (MAOA-L) and 25 healthy male adolescents with the high-activity MAOA genotype (MAOA-H) completed the 11-item Barratt Impulsiveness Scale (BIS-11) questionnaire and were subjected to resting-state functional magnetic resonance imaging (rs-fMRI) scans. The amplitude of low-frequency fluctuation (ALFF) of the blood oxygen level-dependent (BOLD) signal was calculated using REST software. ALFF data were related to BIS scores and compared between genotype groups. Results: Compared with the MAOA-H group, the MAOA-L group showed significantly lower ALFFs in the pons. There was a significant correlation between the BIS scores and the ALFF values in the pons for MAOA-L group, but not for the MAOA-H group. Further regression analysis showed a significant genotype by ALFF values interaction effect on BIS scores. Conclusions: Lower spontaneous brain activity in the pons of the MAOA-L male adolescents may provide a neural mechanism by which boys with the MAOA-L genotype confers risk for impulsivity and aggression.
    BioMed Research International 05/2014; DOI:10.1155/2014/243280 · 3.17 Impact Factor
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    • "In summary, these fMRI studies clearly show that specific brain regions, previously implicated in emotion processing, and behaviour were functionally and anatomically affected by genetic variation in the genes for MAOA and 5HTT, indicating a potential effect of variable serotonin levels on these structures. The fact that levels and activity of the MAOA and 5HTT in the adult brain are poorly associated with genotype (19–26) argues for a developmental effect of the functional polymorphisms on these neurocircuits by regulating embryonic/foetal serotonin levels. This interpretation is supported by recent studies showing disturbances to the same corticolimbic structures resulting from absence of the serotonin transporter during development (64,65) and also from the identification of non-serotonergic neurons in various limbic areas, transiently expressing the serotonin transporter (66). "
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    ABSTRACT: Brain monoamines, and serotonin in particular, have repeatedly been shown to be linked to different psychiatric conditions such as depression, anxiety, antisocial behaviour, and dependence. Many studies have implicated genetic variability in the genes encoding monoamine oxidase A (MAOA) and the serotonin transporter (5HTT) in modulating susceptibility to these conditions. Paradoxically, the risk variants of these genes have been shown, in vitro, to increase levels of serotonin, although many of the conditions are associated with decreased levels of serotonin. Furthermore, in adult humans, and monkeys with orthologous genetic polymorphisms, there is no observable correlation between these functional genetic variants and the amount or activity of the corresponding proteins in the brain. These seemingly contradictory data might be explained if the association between serotonin and these behavioural and psychiatric conditions were mainly a consequence of events taking place during foetal and neonatal brain development. In this review we explore, based on recent research, the hypothesis that the dual role of serotonin as a neurotransmitter and a neurotrophic factor has a significant impact on behaviour and risk for neuropsychiatric disorders through altered development of limbic neurocircuitry involved in emotional processing, and development of the serotonergic neurons, during early brain development.
    Upsala journal of medical sciences 02/2010; 115(1):2-10. DOI:10.3109/03009730903573246 · 1.98 Impact Factor
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    ABSTRACT: Depression and Genetic variation in serotonin and monoamine transmission have both been associated with body mass index (BMI), but their interaction effects are not well understood. We examined the interaction between depressive symptoms and functional polymorphisms of serotonin transporter (SLC6A4) and monoamine oxidase A (MAOA) on categories of BMI. Participants were from the National Longitudinal Study of Adolescent Health. Multiple logistic regression was used to investigate interactions between candidate genes and depression on risk of obesity (BMI≥30) or overweight+obese combined (BMI≥25). Males with an MAOA active allele with high depressive symptoms were at decreased risk of obesity (OR 0.22; 95% CI 0.06–0.78) and overweight+obesity (OR 0.48; 95% CI 0.26–0.89). No similar effect was observed among females. These findings highlight that the obesity–depression relationship may vary as a function of gender and genetic polymorphism, and suggest the need for further study.
    Behavior Genetics 05/2009; 39(3):296-305. DOI:10.1007/s10519-009-9266-z · 3.21 Impact Factor
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