| Title: | Behavioral changes induced by Toxoplasma infection of rodents are highly specific to aversion of cat odors |
| Author(s): | Vyas A; Kim SK; Giacomini N; Boothroyd JC; Sapolsky RM; |
| Address: | "Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA. ajaivyas@stanford.edu" |
| ISSN/ISBN: | 0027-8424 (Print) 1091-6490 (Electronic) 0027-8424 (Linking) |
| Abstract: | "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" |
| Keywords: | "Amygdala/*parasitology Analysis of Variance Animals Behavior, Animal/*physiology Cats Fear/*physiology Female Host-Parasite Interactions Male Mice *Mice, Inbred BALB C *Odorants Pheromones/chemistry Rats *Rats, Long-Evans Toxoplasmosis, Animal/*physiopath;" |
| Notes: | "MedlineVyas, Ajai Kim, Seon-Kyeong Giacomini, Nicholas Boothroyd, John C Sapolsky, Robert M eng R01 AI041014/AI/NIAID NIH HHS/ R21 MH070903/MH/NIMH NIH HHS/ AI41014/AI/NIAID NIH HHS/ MH70903/MH/NIMH NIH HHS/ Comparative Study Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't 2007/04/04 Proc Natl Acad Sci U S A. 2007 Apr 10; 104(15):6442-7. doi: 10.1073/pnas.0608310104. Epub 2007 Apr 2" |
