Document Detail

Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors.
MedLine Citation:
PMID:  17404235     Owner:  NLM     Status:  MEDLINE    
The protozoan parasite Toxoplasma gondii blocks the innate aversion of rats for cat urine, instead producing an attraction to the pheromone; this may increase the likelihood of a cat predating a rat. This is thought to reflect adaptive, behavioral manipulation by Toxoplasma in that the parasite, although capable of infecting rats, reproduces sexually only in the gut of the cat. The "behavioral manipulation" hypothesis postulates that a parasite will specifically manipulate host behaviors essential for enhancing its own transmission. However, the neural circuits implicated in innate fear, anxiety, and learned fear all overlap considerably, raising the possibility that Toxoplasma may disrupt all of these nonspecifically. We investigated these conflicting predictions. In mice and rats, latent Toxoplasma infection converted the aversion to feline odors into attraction. Such loss of fear is remarkably specific, because infection did not diminish learned fear, anxiety-like behavior, olfaction, or nonaversive learning. These effects are associated with a tendency for parasite cysts to be more abundant in amygdalar structures than those found in other regions of the brain. By closely examining other types of behavioral patterns that were predicted to be altered we show that the behavioral effect of chronic Toxoplasma infection is highly specific. Overall, this study provides a strong argument in support of the behavioral manipulation hypothesis. Proximate mechanisms of such behavioral manipulations remain unknown, although a subtle tropism on part of the parasite remains a potent possibility.
Ajai Vyas; Seon-Kyeong Kim; Nicholas Giacomini; John C Boothroyd; Robert M Sapolsky
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2007-04-02
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  104     ISSN:  0027-8424     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2007 Apr 
Date Detail:
Created Date:  2007-04-11     Completed Date:  2007-10-17     Revised Date:  2014-09-21    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  6442-7     Citation Subset:  IM    
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MeSH Terms
Amygdala / parasitology*
Analysis of Variance
Behavior, Animal / physiology*
Fear / physiology*
Host-Parasite Interactions
Mice, Inbred BALB C*
Pheromones / chemistry
Rats, Long-Evans*
Toxoplasmosis, Animal / physiopathology*
Grant Support
Reg. No./Substance:

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