This study tests the hypothesis 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 the Tehran strain of T. gondii . We injected amyloid-beta 1-42 peptide (Aβ, 1 and 2 μl) 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 the Morris water maze test. The mRNA levels of TNF-α, IL-1β, IFN-γ, 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 + Aβ (1 μl) group, T. gondii infection could potentiate AD in infected mice receiving subdoses of Aβ (1 μl) and caused considerable impairment in learning and memory functions similar to AD group. Comparison of the results demonstrated that mRNA levels of IL-1β, TNF-α, IFN-γ, and iNOS significantly (P < 0.001) increased in T. gondii + Aβ (1 μl) 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 induces pathological progression of AD in the mice brain, whereas the presence of neuroanatomical Toxoplasma tissue cysts in the brain could also affect the behavioral functions in T. gondii -infected mice.

Previous studies have been shown that exercise can improve short-term spatial learning, memory and synaptic plasticity impairments in sleep deprived female rats. The aim of the present study was to investigate the effects of treadmill exercise on sleep deprivation (SD) induced impairment in hippocampal dependent long-term memory in female rats. Intact and ovariectomized female rats were used in the current study. Exercise protocol was 4 weeks treadmill running. Twenty four hour SD was induced by using multiple platform apparatus after learning phase. Spatial learning and long-term memory was examined by using the Morris Water Maze (MWM) test. Our results indicated that sleep deprivation impaired long term memory in the intact and ovariectomized female rats, regardless of reproductive status (p<0.05) and treadmill exercise compensated this impairment (p<0.05). In conclusion the results of the current study confirmed the negative effect of SD on cognitive functions and regular exercise seems to protect rats from these factors, however more investigations need to be done.

Recent epidemiological and experimental studies also showed that latent toxoplasmosis can lead to a number of neurological and behavioral disorders such as learning and memory impairments. Recent studies showed that the essential oil and methanolic extract of the Zataria multiflora revealed a significant anticholinesterase activity on in vitro ().Here, we evaluated the effect of Z. multiflora essential oil to ameliorate learning and memory impairments induced by T. gondii infection in BALB/c mice. The animal model of Toxoplasma infection was established by the intraperitoneal inoculation of 20-25 tissue cysts from Tehran strain of T. gondii. Morris water maze (MWM) task was used to assay spatial learning and short term spatial memory in all groups. The findings revealed that in this study demonstrated that latent toxoplasmosis impaired spatial leaning and short term spatial memory of the infected BALB/c mice, while ZME, due having AChE inhibitor activity, improved impairments induced by Toxoplasma infection. The obtained findings demonstrated ZME as an AChE inhibitor to improves learning and memory disorders in mice with latent toxoplasmosis probably via restoring ACh levels in brain. However, additional studies are needed to clarify these mechanisms and also other possible ones.