A Study Of Microtubule, Tubulin And Tau Protein In Platelets Of Patients With Alzheimer's Disease

Objectives: To search for an extraneuronal biomarker which is helpful in diagnosing Alzheimer's Disease.Methods: According to the clinical diagnostic standards, 15 subjects were selected, including 5 patients with Alzheimer's disease, 5 patients with vascular dementia and 5 normal controls to study the changes of microtubules of their platelets. Qualitative and quantitative analyses of β -tubulin and tau protein were done by using immunoelectron microscopy and stereology techniques.Results: (1) There were no significant differences in morphology of platelet microtubules among Alzheimer's disease, vascular dementia and normal control. Microtubules were visible in platelets of the three groups. The quantity of platelet microtubules in patients with Alzheimer's disease patients is significantly fewer than those of vascular dementia patients and normal controls. The quantity of platelet microtubules in patients with vascular dementia is obviously more than that in normal controls. (2) The double immuno-labeling display that the granules of colloidal gold labeled by β -tubulin and tau protein antibodies are mainly distributed in cytoplasm of platelet. The number of 15nm and 5nm colloidal gold in Alzheimer's disease patients is significantly more than those in vascular dementia patients and normal controls. And among the three groups the number of the two kind colloidal gold particles is least in vasculardementia patients.Conclusions: In platelets of Alzheimer's disease patients the microtubulesdeployed and the number of microtubule decreased. The level of free β-tubulin and tau protein increased in platelets. These changes ofmicrotubule in platelet may reflect those in brain tissues and would bevaluable as an extraneuronal biomarker in diagnosing Alzheimer'sdisease.