الفهرس 
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Abstract
ENGLISH SUMMARY
T. gondii is one of the neurotropic intracellular protozoan parasites that infect brain; it affects a large number of the population in the world. Its intermediate hosts are human and other warm-blooded animals.
Schizophrenia is a neuropsychiatric disorder with worldwide prevalence and the main substances responsible for the development of these symptoms are dopamine, serotonin, GABA and glutamate. The protozoan T. gondii has been repeatedly associated with schizophrenia. T. gondii modulates the secretion of many neurotransmitters including dopamine by synthesizing of tyrosine hydroxylase and DOPA decarboxylase enzyme.
Diagnosis of toxoplasmosis is based mainly on serology like IgG and IgM detection by ELISA technique and western blot method in blood samples as molecular technique is done by taking biological samples from different body sites which can be difficult or may be impossible.
The present study was done to detect T. gondii infection in patients with schizophrenia in comparison with non–schizophrenic individuals as a control group and to detect the serum dopamine level in studied populations.
The study was conducted on 45 schizophrenic patients and 45 healthy non-schizophrenic individuals as controls. A structural questionnaire sheet was used to collect the subjects’ socio-demographic characteristics and their clinical data.
Serum samples were collected from the study groups. Serum samples from the two groups were subjected to detect IgM and IgG anti-T. gondii antibodies by a commercial ELISA Kit and immunoblotting method was carried for the detection of IgG anti-Toxoplasma. Dopamine was detected in human serum of both groups by human dopamine ELISA kit.
By ELISA; anti- T. gondii IgM antibody was negative in all the 90 studied individuals indicating no acute infection. However, anti- T. gondii IgG antibody was positive in 25 schizophrenic patients (55.6%) and 13 normal healthy controls (28.9%) with statistical significance between the two groups (P-value=0.0009).
Serum dopamine level was significantly higher among studied schizophrenic patients (Mean ±SD =47.22) as compared with non- schizophrenic healthy controls (Mean ±SD = 25.79) and serum dopamine level was significantly higher among studied Population with positive IgG antibodies (Mean ±SD =49.75) as compared with those cases with negative IgG antibodies (Mean ±SD =26.83) (p-value <0.001).
No statistically significant difference between both groups regarding cat exposure as a risk factor for Toxoplasmosis of schizophrenia.
So infection with T. gondii considered higher risk for schizophrenic disease and T. gondii infection is a cause of increasing of serum dopamine level.
Higher IgG seropositive cases than IgM indicated the chronic infection of schizophrenic patients with toxoplasmosis so the current study could show the higher number of positive anti-T. gondii IgG (55.6%) in schizophrenic cases compared to 28.9% in healthy control. These results confirmed the previous reports which indicated that Toxoplasma infection is a risk factor for the genesis and symptomatology of schizophrenia.
Also, our results showed an increase of dopamine levels in seropositive compared to seronegative schizophrenic cases. Such changes in the dopamine levels could be responsible for behavioral changes. It was proposed that the presence of the parasite cysts in the brain is the reason for increased dopamine levels.
The data of western blotting showed a specific recognition of two proteins at 50 and 60 kDa by schizophrenic patients. However, the reaction was more common and stronger in patients who showed +ve IgG in ELISA. This showed that the chronic infection-induced schizophrenia was related to IgG specific reactions to 50 and 60 kDa in tachyzoites.
So infection with T. gondii considered higher risk for schizophrenic disease and T. gondii infection is a cause of increasing of serum dopamine level so the importance of serological diagnosis of T. gondii infection in healthy individuals and schizophrenic patients is to avoid development and progression of the disease.