The role of dopamine in Toxoplasma-induced behavioural alterations in mice: an ethological and ethopharmacological study
Toxoplasma gondii, a cosmopolitan protozoan parasite, is known to induce behavioural alterations in rodents and may exert an effect on human personality and behaviour. The mechanism of parasite-induced alterations in host behaviour has not been described, but it was hypothesized that development of Toxoplasma tissue cysts in the brain could affect the dopaminergic neuromodulatory system. In this study, we tested the effect of latent Toxoplasma infection on mouse behaviour associated with activity of the dopaminergic system, i.e. locomotion in a novel environment and exploration test. Additionally, we examined the behavioural response of Toxoplasma-infected mice to a selective dopamine uptake inhibitor, GBR 12909. In both genders, Toxoplasma infection decreased locomotion in the open field. Infected females displayed an increased level of exploration in the holeboard test. GBR 12909 induced suppression in holeboard-exploration in the infected males, but had an opposite effect on the controls. These results suggest an association between Toxoplasma gondii infection and changes in the dopaminergic neuromodulatory system.(Received March 27 2006)
(Revised June 1 2006)
(Accepted June 2 2006)
(Published Online August 2 2006)
Key Words: parasite; dopamine; exploration; holeboard; GBR 12909.
c1 Department of Parasitology, Faculty of Science, Charles University, Vinicná 7, Prague 128 44, Czech Republic. Tel: +420 221951821. Fax: +420 224919704. E-mail: [email protected]