关键词: 衰老, 血小板, 线粒体, 外周型苯二氮卓受体

Abstract: Objective To investigate correlations between peripheral benzodiazepine receptors (PBRs) in mitochondria and synaptosomes in the brain and platelet membrane of rats during aging and to explore the significance of the relationships. Methods Sprague-Dawley rats of both sexes were divided into 3-,12- and 24-month groups. All animals were sacrificed by decapitation an d the brains were immediately removed. Mitochondrial components from dissected cerebral cortex and synaptosomal fractions from dissected hippocampus were isolated by gradient centrifugation. The membrane of platelets from venous blood was prepared by the method of hypotonic haemolysis. The specific binding assay of the rad ioactive PBRs antagonist ［³H］PK11195 to membrane was performed. Results A significant difference about ［³H］PK11195 binding activity of mitochondria was observed among three groups（F＝194.6,P＜0.001), while the same change was noted for synaptosomes（F＝94.2,P＜0.001) and for platelet membrane (F＝162.2,P＜0.001). An age-related decrease was found for the three indexes above. A positive relationship about ［³H］PK11195 binding activity (P＜0.001) was found between platelet membrane and cortex mitochondria (r＝0.894) as well as hippocampus synaptosomes ( r＝0.893).　 Conclusion The levels of PBRs decrease in cortex mitochondria and hippocampus synaptosomes with aging in rats. ［³H］PK11195 binding activity of platelet membrane might reflect the changes of PBRs in the brain tissue.

Key words: aging, platelets, mitochondria, peripheral benzodiazepine receptors