| Background and Objective: Sensory gating is the normal ability of the human brain to modulate its response to sensory stimuli and to filter out irrelevant stimuli. The sensory gating impairment may lead to sensory overload, attention deficit, cognition fragmentation and information processing disturbance. P50 sensory gating is an electrophysiological index to reflect the brain inhibition recorded by auditory evoked potential. There are two record paradigms: conditioning-testing stimulus paradigm and stimulus train paradigm. There is a large body of evidence to suggest that schizophrenia has P50 sensory gating deficits, but there is little available data to address what illness mechanism and whether antipsychotics effects are associated with P50. Adenosine is a very important depressive neuromodulator in centre neural system, which can modulate with most of neurotransmitters. The strange phenomenon that caffeine can contaminate the sensory gating in the normal subject, which arise the human's great interesting in what role that adenosine play in the causes. The aim of this study is to explore the difference of the two P50 sensory gating (SG P50) between the schizophrenics and normal subjects, to compare the expressive lever of adenosine A2a receptor mRNA which express on human platelet between the schizophrenics and normal subjects, to evaluate influences of antipsychotics on SG P50 and the expressive lever of adenosine A2a receptor, to explore the relationship between adenosine A2a receptor and P50 sensory gating deficits and psychotic symptoms.Methods: (1) Subjects: 34 schizophrenics (Sch group) and 24 normal controls (NC). The schizophrenics meet the diagnostic for schizophrenia (PANSS≥60), according to the China Diagnostic Criteria of Mental Disorders-3rd edition (CCMD-3). Organic disease of brain and mental disorders associated with physical diseases and substances dependence and disease of hematological system have been excluded.(2) Steps: All the subjects were tested about their SG P50 with two different stimulus paradigm when admission and the expression lever of adenosine A2a receptor on the human platelet with real-time PCR. The Positive and Negative Syndrome Scale (PANSS) were used to assess the schizophrenics'symptoms. And the Sch group was tested about SG P50 and expression lever of adenosine A2a receptor on the human platelet again after 6 weeks treatment. (3) Tools: The machine for testing brain evoked potential using to record SG P50 is fully functional, digital, 40 leads, EBNeuro Sirius BB BE and made in Italy. The ABI 7300 PCR machine which is produced by Applied Biology Corporation is used to evaluate the expression lever of adenosine A2a receptor on the human platelet. PANSS of Chinese version is used to evaluate the psychiatric symptoms of patients.(4) Statistical method: The SPSS 13.0 statistical package is adopted to process the data, mainly including t-test, Paired t-test, Mann-Whitney non-parametric test, Wilcoxon paired-test, Pearson and Spearman correlation analysis.Result: (1) There were no significantly different on S1 wave amplitude and S2 latency between Sch group and NC groupe. The S1 latency and S2 wave amplitude of Sch group were higher than those of NC group (P<0.05). The S2/S1 ratio and the value of S1-S2 of Sch group have significantly different between Sch group and NC groupe (P<0.001). In the stimulus train paradigm, there were also significantly different on 5.1Hz and 9.9Hz suppression between Sch group and NC group(P<0.001).(2) By coincidence analysis of the P50 suppression ratios between the two stimulus paradigms, we found no coincidence in Sch group and NC group.(3) There were no significantly different for the index of SG P50 between pre- and after- 6-week antipsychotic treatment ( all P<0.05),however, after-6-week antipsychotic treatment, the stimulus train paradigm have great improved in Sch group.(4) The expression lever of adenosine A2a receptor mRNA which expressed on the human platelet have no significantly different between pre- and after-6-week antipsychotic treatment(5) There were no significantly different on the expression lever of adenosine A2a receptor mRNA in Sch group who not receive antipsychotic treatment and NC group.(6) There were significantly different on the expression lever of adenosine A2a receptor mRNA for the Sch group who receive antipsychotic treatment after-6-weeks and the normal subjects. There was great improvement on the expression lever of adenosine A2a receptor mRNA in Sch group between pre- and after- antipsychotic treatment.(7) By spearman correlation analysis, there were no significant coincidence between the expression lever of adenosine A2a receptor mRNA and two stimulus paradigms of SG P50.(8) Before treatment, none of the coefficients correlation of the total scores, the scores of positive syndrome factor and negative syndrome factor of PANSS scale and the expression lever of adenosine A2a receptor mRNA on the human platelet. There are tendency of correlation between expression lever of adenosine A2a receptor mRNA and equation of positive syndrome factor's score of PANSS after treatment. The coefficients correlation of expression lever of adenosine A2a receptor mRNA and the other factors of PANSS have no statistical significance after treatment.Conclusion: 1. The schizophrenics have two stimulus paradigms of the P50 sensory gating deficiency which reflects brain inhibition deficit.2. There is no coincidence of the two kinds of evoked P50 suppression, which suggest that different central neuron mechanisms exist in schizophrenics.3. The antipsychotics medications did no effect on conditonal-test stimulus paradigms of P50 sensory gating and greatly improve the stimulus train paradigm P50 sensory gating for 6-weeks treatment, which possibly represent different trait of schizophrenia.4. There are great increase in expression lever of adenosine A2a receptor mRNA after 6-weeks antipsychotics treatment, which partly indicate pathological change in centre neural system of the schizophrenia.5. The expression lever of adenosine A2a receptor mRNA was independent of inhibition function of P50 sensory getting in schizophrenia at different stages in pre- and after- treatment, which indicate that the two parts possibly have independent biological mechanism. The antipsychotics medications possibly relate with some clinical symptoms, which partly reflect the adenosine A2a receptor in the centre neural system.In general, the schizophrenics have deficit in SG P50, which reflects the abnormality of central inhibition. The adenosine A2a receptors of human platelet have some relationship with clinical symptoms and partly reflect adenosine A2a receptor in the centre neural system with antipsychotics medications. The adenosine A2a receptor of platelet and P50 sensory gating may have independent biological mechanism. |
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