大鼠衰老过程中脊髓外周型苯二氮卓受体的变化

Ageing-induced changes of peripheral benzodiazepine receptors in rat spinal cord synaptosoms

0.3760/cma.j.issn.0254-9026.2013.05.031 摘要： 目的 探讨大鼠衰老过程中脊髓突触体外周型苯二氮卓受体（PBRs）的变化以及与血小板膜PBRs的相关性. 方法 实验动物SD大鼠（雌雄各半）分为3月龄青年组和24月龄老龄组.动物断头处死后,迅速取脊髓.采用梯度离心技术制备脊髓突触体,低渗溶血法制备外周血血小板膜.应用放射配基[3H]PK11195结合实验测定PBRs结合活力. 结果 各组动物雄性、雌性间比较,脊髓突触体、外周血血小板膜PBRs结合活性差异均无显著意义（P＞0.05）.3月龄和24月龄脊髓突触体[3H]PK11195结合活性分别为（213.94±10.65）和（50.65±2.74） fmol/mg pro.（t=51.418,P＜0.001）,外周血血小板膜[3H]PK11195结合活性分别为（104.97±2.24）和（56.20±5.36） fmol/mg pro.（t=29.041,P＜0.001）.与青年组比较,老龄组大脊髓突触体及血小板膜[3H]PK11195结合活性分别下降了76.33％、46.46％.血小板膜[^3H]PK11195结合活性与脊髓突触体[3H]PK11195结合活性间具有显著相关性（r=0.985,P＜0.001）. 结论 脊髓突触体PBRs水平呈增龄下降改变,血小板膜[3H]PK11195结合活性能够反映脊髓组织该指标的变化.

Objective To investigate the changes of peripheral benzodiazepine receptors （PBRs）in rat spinal cord synaptosomes during ageing and to explore the correlation between PBRs in spinal cord synaptosomes and PBRs on platelet membranes.Methods A total of 24 Sprague-Dawley rats were divided into 3-month group and 24-month group （n=6 males and 6 females for each）.All animals were sacrificed by decapitation and the spinal cords were immediately removed.Synaptosomal fractions from spinal cords were isolated by gradient centrifugation.The platelet membranes were prepared from venous blood by the method of hypotonic haemolysis.The specific binding of the radioactive PBRs antagonist [3H]PK11195 to membranes was determined.Results No significant differences in [3H] PK11195 binding activity in spinal cords and platelet membranes were observed between male and female rats in the same group （all P〉0.05）.[3H] PK11195 binding activity in spinal cords and platelet membranes were higher in 3-month group than in 24 month group [（213.94±10.65） fmol/mg pro.vs.（50.65± 2.74） fmol/mg pro.,（104.97± 2.24） fmol/mg pro.vs.（56.20±5.36） fmol/mg pro.,respectively,t=51.418,29.041,both P〈 0.001].There was a positive correlation between [3H]PK11195 binding activity in platelet membranes and in spinal cord synaptosomes （r=0.985,P〈0.001）.Conclusions The level of PBRs is gradually decreased in rat spinal cord synaptosomes with ageing.[3H] PK11195 binding activity of platelet membranes can reflect the changes of PBRs in spinal cords.