TOXOPLASMA GONDII INFECTION POTENTIATES COGNITIVE IMPAIRMENTS OF ALZHEIMER'S DISEASE IN THE BALB/C MICE.
J Parasitol. 2016 Aug 11. Epub 2016 Aug 11. PMID: 27513205
Here, we hypothesized that in chronic Toxoplasma gondii infection communication among immune cells promotes neuroinflammation through cytokine networks and potentiate cognitive impairments in BALB/c mice with Alzheimer's disease (AD). The animal model of Toxoplasma infection was established by the intraperitoneal inoculation of 20-25 tissue cysts from Tehran strain of T. gondii. We injected amyloid-beta 1-42 peptide (A1-42, 1 and 2ÂµL) into the hippocampus of BALB/c mice to establish an animal model of AD. The behavioral experiments such as spatial learning and memory were performed using Morris water maze test. The mRNA levels of TNF-, IL-1, IFN-, and inducible nitric oxide synthase (iNOS) were examined by real-time PCR. We found that T. gondii infection caused AD-like symptoms and impaired learning and memory functions of the infected BALB/c mice. We also found that in Toxoplasma infection + A1-42 (1 ÂµL) group, T. gondii infection could potentiate AD in infected mice receiving sub-dose of A1-42 (1 ÂµL) and caused considerable impairment in learning and memory functions similar to AD group. Comparison of the results demonstrated that mRNA levels of IL-1, TNF-, IFN-, and also iNOS significantly (P<0.001) increased in T. gondii + A1-42 (1ÂµL) in comparison with the other tested groups. The obtained results showed that chronic T. gondii infection communication among immune cells promotes neuroinflammation through cytokine networks and induce pathological progression of AD in the mice brain, whereas, neuroanatomical Toxoplasma tissue cysts presence in the brain could also affect the behavioral functions in T. gondii infected mice.