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    Online Resource
    Online Resource
    In psychiatrically healthy individuals, overweight women but not men have lower tryptophan levels
    Walter de Gruyter GmbH ; 2015
    In:  Pteridines Vol. 26, No. 2 ( 2015-6-1), p. 79-84
    Details
    In: Pteridines, Walter de Gruyter GmbH, Vol. 26, No. 2 ( 2015-6-1), p. 79-84
    Abstract: Gender differences in tryptophan (TRP) breakdown in obese individuals have been previously reported. This could be both contributory to, as well as a consequence of, gender differences in mood changes among obese people. To exclude the potential effect of depression on TRP breakdown and its levels in obesity, we replicated analyses in psychiatrically healthy individuals. In 1000 participants, plasma kynurenine (KYN), TRP, and the KYN/TRP ratio were compared between overweight/obese and normal-weight individuals using analysis of covariance, with adjustment for age and gender. Bivariate post hoc tests were also conducted. There were no significant relationships between KYN, TRP, or the KYN/TRP ratio and overall overweight/obese status. However, a significant gender by weight category interaction was identified for TRP only, with overweight/obese women having lower TRP than overweight/obese men (p=0.02). No gender differences in TRP were found in non-obese participants. Our study in psychiatrically healthy individuals suggested that lower TRP levels in obese women were not secondary to depression, strengthening the possibility that TRP levels could mediate depression in vulnerable women. Thus experimental manipulations of TRP levels could be used to advance theoretical knowledge, prevention, and clinical control of depression in obese women.
    Type of Medium: Online Resource
    ISSN: 2195-4720 , 0933-4807
    URL: Article
    DOI: 10.1515/pterid-2015-0002
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2015
    detail.hit.zdb_id: 2279565-0
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  • 2
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    Reciprocal moderation by Toxoplasma gondii seropositivity and blood phenylalanine – tyrosine ratio of their associations with trait aggression
    Walter de Gruyter GmbH ; 2016
    In:  Pteridines Vol. 27, No. 3-4 ( 2016-12-1), p. 77-85
    Details
    In: Pteridines, Walter de Gruyter GmbH, Vol. 27, No. 3-4 ( 2016-12-1), p. 77-85
    Abstract: We previously reported that trait aggression, proposed as an endophenotype for suicidal behavior, is positively associated with Toxoplasma gondii ( T. gondii ) seropositivity in females, but not in males. Additionally, older males seropositive for T. gondii had lower scores on measures of trait aggression, including self-aggression. Trait aggression may be influenced by dopaminergic signaling, which is known to be moderated by gender and age, and potentially enhanced in T. gondii positives through the intrinsic production of dopamine by the microorganism. Therefore, we investigated associations between trait aggression and interactions between T. gondii enzyme-linked immunoabsorbant assay (ELISA) IgG titer-determined seropositivity and high-performance liquid chromatography- (HPLC-) measured blood levels of dopamine precursors phenylalanine (Phe), tyrosine (Tyr), and their ratio in a sample of 1000 psychiatrically healthy participants. Aggressive traits were assessed using the questionnaire for measuring factors of aggression (FAF), the German version of the Buss-Durkee hostility questionnaire. We found that 1) the decrease in trait aggression scores in T. gondii - positive older males was only present in individuals with a low Phe:Tyr ratio, and 2) that there was a positive correlation between Phe:Tyr ratio and total aggression and selected subscales of aggression in T. gondii -positive males, but not in T. gondii -negative males. These findings point toward a gender-specific reciprocal moderation by Phe:Tyr ratio and T. gondii seropositivity of their associations with aggression scores, and lead to experimental interventions geared to manipulating levels of dopamine precursors in selected T. gondii positive individuals with increased propensity for aggression.
    Type of Medium: Online Resource
    ISSN: 2195-4720 , 0933-4807
    URL: Article
    DOI: 10.1515/pterid-2016-0006
    Language: English
    Publisher: Walter de Gruyter GmbH
    Publication Date: 2016
    detail.hit.zdb_id: 2279565-0
    Location Call Number Limitation Availability
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    Online Resource
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