Toxoplasma infection and response to novelty in mice

Abstract

Three groups of mice were infected with Toxoplasma and used for behavioral testing using a Y-maze. One group was infected when adult and two groups congenitally, one of these born to dams infected during gestation, the other to dams chronically infected prior to mating. In an initial habituation period each mouse was exposed to a black arm and stem of the maze, entrance to a white arm being blocked by a transparent door. In a subsequent free-choice trial both arms were black and the mouse was free to explore all parts of the maze. During both periods infected mice were more active than controls. Infected mice engaged in less grooming behavior indicative of less approach-avoidance conflict than controls prior to entry into a choice arm at the beginning of the free-choice trial. Infected mice spent more time in the familiar than in the novel (previously blocked) arm during the free-choice trial; conversely, uninfected mice spent more time in the novel than in the familiar arm. It is suggested that the reported behavioural changes would lead to dissemination of the infection in the environment by ultimately making infected mouse intermediate hosts more susceptible to predation by domestic cats, the definitive hosts of Toxoplasma.

Toxoplasma Gondii and Cognitive Deficits in Schizophrenia: An Animal Model Perspective

“…The outcome was interpreted as T. gondii-induced neophobia. 16 The increased neophobia in infected mice appears different from the behavioral responses seen in rats, although the rat studies used a different paradigm. 17 Adult infected male mice demonstrated deficits in spatial recognition memory measured as lack of preference for either arm of Y maze.…”

“…15 In a different study, mice were exposed to T. gondii at 1 of 3 time points: (1) 8 weeks of age, (2) congenitally by infecting pregnant dams, or (3) congenitally through mating of chronically infected females. 16 It was found that male and female strain A albino mice, exposed at all 3 time points to the Beverley Type II strain of parasite, preferred the familiar arm over the novel one, while controls expectedly preferred the novel arm. Intriguingly, the groups exposed congenitally to the parasite spent more time in the familiar arm compared with the adult acquired infection group.…”

Dopamine Stimulates Propagation ofToxoplasma gondiiTachyzoites in Human Fibroblast and Primary Neonatal Rat Astrocyte Cell Cultures

“…Because of their location in the brain, there has been increasing interest in the association of chronic T. gondii infection and alterations in intermediate host behavior. Hutchinson et al (1980) and Hay et al (1984) determined that mice chronically infected with T. gondii demonstrated increased open field activity, decreased coordination, and diminished capacity to learn a maze. Goodwin et al (2012) recently reported that minimal behavioral changes, consisting of altered short-term memory, were observed in mice congenitally infected with T. gondii.…”

Congenital Infection of Mice with Toxoplasma gondii Induces Minimal Change in Behavior and No Change in Neurotransmitter Concentrations

“…Chronic postnatal T. gondii infections have been correlated with human behavioral changes (see Webster and McConkey, 2010). Rodents infected postnatally with T. gondii and tested after the infection has become chronic exhibit increased open field activity, decreased exploration, and loss of neophobia (Hutchinson et al, 1980;Hay et al, 1984;Webster et al, 1994;Vyas et al, 2007). People with mental health disorders associated with cognitive dysfunction have been shown to have a decreased intelligence quotient, decreased rate of learning, and difficultly interacting with society, and they may have memory impairment.…”