Toxoplasma gondii infection and testosterone congruently increase tolerance of male rats for risk of reward forfeiture

Tan, Donna; Vyas, Ajai

doi:10.1016/j.yhbeh.2016.01.003

Cited by 26 publications

(16 citation statements)

References 51 publications

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“…In our earlier work, we identified higher reactive aggression scores in T. gondii positive women and higher impulsivity scores in younger men (Cook et al, 2015), which were further expanded by our current finding. These are consistent with previously reported gender differences in linking T. gondii seropositivity and measures of personality (Flegr et al, 1996; Flegr et al, 2000; Lindova et al, 2006; Flegr, 2007; Flegr et al, 2008; Lindova et al, 2010; Fond et al, 2013; Tan et al, 2015; Tan and Vyas, 2016).…”

Section: Discussionsupporting

confidence: 92%

Moderation of the relationship between Toxoplasma gondii seropositivity and trait impulsivity in younger men by the phenylalanine-tyrosine ratio

Peng

Brenner

Mathai

et al. 2018

Psychiatry Research

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Previously, we reported that Toxoplasma gondii (T. gondii)-seropositivity is associated with higher impulsive sensation seeking in younger men. As dopaminergic and serotonergic signaling regulate impulsivity, and as T. gondii directly and indirectly affects dopaminergic signaling and induces activation of the kynurenine pathway leading to the diversion of tryptophan from serotonin production, we investigated if dopamine and serotonin precursors or the tryptophan metabolite kynurenine interact with the T. gondii-impulsivity association. In 950 psychiatrically healthy participants, trait impulsivity scores were related to T. gondii IgG seropositivity. Interactions were also identified between categorized levels of phenylalanine (Phe), tyrosine (Tyr), Phe:Tyr ratio, kynurenine (Kyn), tryptophan (Trp) and Kyn:Trp ratio, and age and gender. Only younger T. gondii-positive men with a high Phe:Tyr ratio, were found to have significantly higher impulsivity scores. There were no significant associations in other demographic groups, including women and older men. No significant effects or interactions were identified for Phe, Tyr, Kyn, Trp, or Kyn:Trp ratio. Phe:Tyr ratio, therefore, may play a moderating role in the association between T. gondii seropositivity and impulsivity in younger men. These results could potentially lead to individualized approaches to reduce impulsivity, based on combined demographic, biochemical and serological factors.

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Section: Discussionsupporting

confidence: 92%

Moderation of the relationship between Toxoplasma gondii seropositivity and trait impulsivity in younger men by the phenylalanine-tyrosine ratio

Peng

Brenner

Mathai

et al. 2018

Psychiatry Research

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“…Gonadectomy has been shown to influence some aspects in decision-making in males (Tan and Vyas, 2016;Wallin-Miller et al, 2017) and females (Uban et al, 2012). However, in the present study, gonadectomy did not exert changes in risky choices in either males or females.…”

Section: Discussioncontrasting

confidence: 82%

“…This discrepancy can be due the different types of costs that were associated with larger rewards across different tasks (Tan and Vyas, 2016;Uban et al, 2012), or the rewards used (Wallin-Miller et al, 2017), as in the later study risky choices were elicited by ethanol, and this stimulus could have a stronger impact on motivation and on the mesolimbic reward pathway. The idea that sex-hormone regulation of decision making can differ depending on the type of cost associated with larger/preferred rewards is further bolstered by the findings of studies examining how stress affects these processes.…”

Section: Discussionmentioning

confidence: 86%

Risk-based Decision Making in Rats: Modulation by Sex and Amphetamine

Islas-Preciado¹,

Wainwright

Sniegocki³

et al. 2020

Preprint

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Highlights• Male rats made more risky choices in the probability discounting task than females.• Gonadectomy (GDX) did not influence risk-based decision making in both sexes.• A high dose of testosterone reduced risky choices in GDX male rats.• A high dose of amphetamine enhanced risky choices in intact male and female rats.• 17β-estradiol did not affect risk-based decision making in male or female rats.3 AbstractDecision-making is a complex process essential to daily adaptation in many species. Risk is an inherent aspect of decision-making and it is influenced by gonadal hormones. Testosterone and 17β-estradiol may modulate decision making and impact the mesocorticolimbic dopamine pathway. Here, we explored sex differences, the effect of gonadal hormones and the dopamine agonist amphetamine on risk-based decision making. Intact or gonadectomised (GDX) male and female rats underwent to a probabilistic discounting task. High and low doses of testosterone propionate (1.0 or 0.2 mg) and 17β-estradiol benzoate (0.3 µg) were administered to assess acute effects on risk-based decision making. After 3-days of washout period, intact and GDX rats received high or low (0.5 or 0.125 mg/kg) doses of amphetamine and re-tested in the probabilistic discounting task. Results showed that males made more risk-based choices during the probability discounting task than female rats, but GDX did not influence risky choices. The high dose, but not the low dose, of testosterone reduced risky decision making in GDX male rats.However, 17β-estradiol had no significant effect on risk-based decision making regardless GDX status in either sex. Lastly, the high dose of amphetamine enhanced risky decision making in both intact males and females, with no effect in GDX rats. These findings demonstrated sex differences in risk-based decision making, with males making more risky choices. GDX status influenced the effects of amphetamine, suggesting different dopaminergic regulation in riskbased choices among males and females.

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“…But while several recent studies have shown toxoplasmosis-associated changes in executive functions such as inhibition, task switching, and working memory 7 , 9 , 26 , virtually nothing is known about whether or how latent toxoplasmosis alters the effects of rewards on behavior in otherwise healthy individuals, even though rewards have been shown to modulate the before-mentioned cognitive processes 27 – 29 . In rodents, T. gondii infection has been associated with a greater tolerance of reward forfeiture 30 , more risk-taking/less risk aversion 30 , 31 , and an increased delay aversion for rewards 32 . In humans, latent toxoplasmosis has so far only been associated with increased sensation seeking 33 and addiction 34 but it has not been investigated at all whether or how T. gondii alters the behavioral modulation by reward.…”

Section: Introductionmentioning

confidence: 99%

Humans with latent toxoplasmosis display altered reward modulation of cognitive control

Stock

Dajkic

Köhling

et al. 2017

Sci Rep

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Latent infection with Toxoplasma gondii has repeatedly been shown to be associated with behavioral changes that are commonly attributed to a presumed increase in dopaminergic signaling. Yet, virtually nothing is known about its effects on dopamine-driven reward processing. We therefore assessed behavior and event-related potentials in individuals with vs. without latent toxoplasmosis performing a rewarded control task. The data show that otherwise healthy young adults with latent toxoplasmosis show a greatly diminished response to monetary rewards as compared to their non-infected counterparts. While this selective effect eliminated a toxoplasmosis-induced speed advantage previously observed for non-rewarded behavior, Toxo-positive subjects could still be demonstrated to be superior to Toxo-negative subjects with respect to response accuracy. Event-related potential (ERP) and source localization analyses revealed that this advantage during rewarded behavior was based on increased allocation of processing resources reflected by larger visual late positive component (LPC) amplitudes and associated activity changes in the right temporo-parietal junction (BA40) and left auditory cortex (BA41). Taken together, individuals with latent toxoplasmosis show superior behavioral performance in challenging cognitive control situations but may at the same time have a reduced sensitivity towards motivational effects of rewards, which might be explained by the presumed increase in dopamine.

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Toxoplasma gondii infection and testosterone congruently increase tolerance of male rats for risk of reward forfeiture

Cited by 26 publications

References 51 publications

Moderation of the relationship between Toxoplasma gondii seropositivity and trait impulsivity in younger men by the phenylalanine-tyrosine ratio

Moderation of the relationship between Toxoplasma gondii seropositivity and trait impulsivity in younger men by the phenylalanine-tyrosine ratio

Risk-based Decision Making in Rats: Modulation by Sex and Amphetamine

Humans with latent toxoplasmosis display altered reward modulation of cognitive control

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