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タイトル: Involvement of Host Defense Mechanisms against Toxoplasma gondii Infection in Anhedonic and Despair-Like Behaviors in Mice
著者: Mahmoud, Motamed Elsayed
Fereig, Ragab
Nishikawa, Yoshifumi
キーワード: Toxoplasma gondii
1-methyl tryptophan
minocycline
interferon gamma
sickness behavior
anhedonic behavior
despair-like behavior
発行日: Apr-2017
出版者: American Society for Microbiology
誌名: Infection and Immunity
巻: 85
号: 4
開始ページ: e00007-17
抄録: Toxoplasma gondii is a pathogen relevant to psychiatric disorders. We recently showed that reactivation of chronic T. gondii infection induced depression-like behaviors in mice. Furthermore, it has been hypothesized that depression-like behaviors are mediated via a host defense mechanism against invading pathogens; proximate mechanisms of this behavioral hypothesis remain unclear. In the present study, we investigate the contribution of indoleamine 2,3-dioxygenase (IDO), inflammation, and interferon gamma (IFN-gamma) to anhedonic and despair-related behaviors in T. gondii-infected mice by using sucrose preference and forced-swim tests, respectively. First, we confirmed that BALB/c mice exhibited both sickness and depression-like behaviors during acute infection. Treatment of infected wild-type mice with minocycline (anti-inflammatory drug) abated sickness and anhedonic and despair-like behaviors, whereas in T. gondii-infected mice, treatment normalized kynurenine/tryptophan (Kyn/Trp) ratios in both plasma and brain tissue. Additionally, T. gondii infection failed to induce anhedonic and despair-like behaviors or increase the Kyn/Trp ratio in immunocompromised (IFN-gamma(-/-)) mice, whereas sickness behavior was observed in both immunocompetent and IFN-gamma(-/-) mice following infection. Furthermore, treatment with 1-methyl tryptophan (an IDO inhibitor) did not affect locomotor activity, attenuated clinical scores and anhedonic and despair-like behaviors, and resulted in normal Kyn/Trp ratios in T. gondii-infected wild-type mice. Although low levels of serotonin and dopamine were observed in the brain during acute and chronic infections, anhedonic and despair-like behaviors were not detected in the chronic stage of infection. Collectively, our results demonstrated that immune enhancement in response to infection with T. gondii resulted in IFN-gamma production, IDO activation, and inflammation associated with anhedonic and despair-like behaviors.
URI: http://ir.obihiro.ac.jp/dspace/handle/10322/4507
DOI: info:doi/10.1128/IAI.00007-17
ISSN: 0019-9567
出現コレクション:05001学術雑誌論文

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