Change in Ratio of Platelet Beta-Amyloid Precursor Protein (APP) Forms in Schizophrenia Compared with Control Group

Background: p-amyloid precursor protein (APP) and its proteolytic fragments have important physiological functions in nervous system. Literature data suggests that APP metabolism may be impaired in schizophrenia. Aim of study: to compare concentration of platelet APP forms in patients with schizophrenia and in control group.

Material and methods: 14 patients (19-35 years old) with acute paranoid schizophrenia (ICD-10 F20.0) and 14 normal controls (20-36 years old) were included to analyse concentration of platelet APP forms by ECL-immunoblotting. Blood was collected before starting antipsychotic therapy. Net intensity was measured for zones corresponding to 130 kDa (zone 1), 110 kDa (zone 2) and 100 kDa (zone 3), and {zone 1/(zone 2 + zone 3)} ratio was calculated.

Results: intensity of zone 1 was significantly reduced in patients compared with controls (р = 0,0001), its proportion comprised 9,7% of all detected APP forms (vs 29,2% in controls). {zone 1/(zone 2 + zone 3)} ratio was also reduced in patients compared with controls (р = 0,00003). Significant negative correlations of zone 1, zone 2, and {zone 1/(zone 2 + zone 3)} with age were present in patients: R = -0,68, р = 0,007, R = -0,77, р = 0,001, R = -0,55, р = 0,04, respectively, but these links were absent in control group. Negative correlation between {zone 1/(zone 2 + zone 3)} and PANSSpsy score was found in patients: R = -0,57, р = 0,035.

Conclusion: concentration of distinct APP forms in platelets of patients with schizophrenia and their ratio are altered. Considering the regulatory activity of APP fragments in nervous system and revealed changes in APP metabolism, further research is needed on APP role in schizophrenia.

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