The effect of chronic experimental toxoplasmosis on some brain neurotransmitters level and behavior changes.

Toxoplasma is capable of causing long-lasting brain cysts in its hosts, which can lead to physiological disturbances in brain neurotransmitters and result in changes in the host's behavior. This study aimed to investigate these changes using an experimental model. Twenty-five female Wistar rats, weighing 220-220 g and six weeks old, were selected for the study. The rats were divided into two control and experimental groups. The experimental group was injected with 5 × 105 tachyzoites of Toxoplasma gondii (virulent RH strain) intra-peritoneally. Four months after the injection, the rats were subjected to behavioral tests, including learning, memory, depression, and locomotor activity tests. The rats were then euthanized, and their brain and serum samples were analyzed for dopamine and serotonin levels. To ensure the presence of cysts in the brain tissue, a PCR test and preparation of pathological slides from the brain tissue were performed. The results showed that the amount of dopamine in the brain of the infected group was significantly higher than that of the control group, while the level of serotonin in brain of the infected group was significantly lower than that of the control group (P < 0.05). However, no significant difference was observed in the amount of these neurotransmitters in the blood of the two groups (P > 0.05). Behavioral changes were evaluated, and it was found that the learning and memory levels of the infected rats were significantly lower than those of the control group (P < 0.05), but no difference was observed in locomotor activity between the two groups (P > 0.05). This experimental infection model indicated that changes in neurotransmitter levels lead to behavior changes. CONCLUSION: The presence of parasite cysts in the brain can affect some of the host's behaviors through changes in neurotransmitter levels. Therefore, there is a possibility that there is a relationship between the presence of Toxoplasma cysts in the brain and neurological disorders. The results of this study suggest that chronic toxoplasmosis may play a role in behavior changes in psychotic diseases.

Moderating effects of crocin on some stress oxidative markers in rat brain following demyelination with ethidium bromide.

BACKGROUND: The purpose of this study was to investigate the effects of Crocin on oxidative markers (GPx, SOD, MDA) in animal model of demyelination with Ethidium bromide (EB). METHODS: Female Wistar rats were assigned in to 4 groups; Sham, with no receiving any agent (Sham), Sham Operated group with injection of EB into the brain received no agent (SO), Sham Treatment group with injection of EB and receiving PBS as vehicle and Treatment group with injection of EB and receiving Crocin (100 mg/kg). Demyelination was induced by single dose injection of 10 µl of EB 0.1% into the Cisterna magna of the brain. Crocin was diluted and applied to each animal for 21 days, once per day gavage. The levels of oxidative markers (GPx, SOD and MDA) were measured by related standard kits. Data were analyzed by paired t-test and ANOVA with post hoc test. RESULTS: The results showed that crocin decreases the levels of GPx and SOD significantly as well as MDA level after 21 days (α ≤ 0.05). In addition, results showed that there were significant differences in the GPx, SOD and MDA levels between all groups at post treatment phase (α ≤ 0.05). CONCLUSION: It can be concluded that crocin can moderate the level of oxidative markers after demyelination of the brain cells in MS cases. Due to this effect, crocin can be considered as an effective anti-oxidant in management of degenerative nervous system diseases.