激动多巴胺受体抑制大鼠纹状体脑片Ca2+-钙调蛋白依赖性蛋白激酶Ⅱ活性

摘要

AIM: To investigate the mechanism underlying doparnminergic neurotoxicity in the striamm during anoxia.rnMETHODS: Using rat striatal slices as an in vitro rnmodel, the activity of Ca2 + -calmodulin-dependent protein rnkinase Ⅱ (CCDPK Ⅱ ) was examined by the method of rnsubstrate phosphorylation 32 P-incorporation. RESULTS:rnAnoxia for 30 min greatly reduced CCDPK Ⅱ activity by rnabout 75 %. Reserpinization by repeated reserpine rnadministration ( 1 mg· kg- 1 · d- 1 for 7 d, sc ) preserved rnCCDPK Ⅱ activity against the anoxia-induced decrease rn(about 40 % of control). The activity of CCDPK Ⅱ rnwas reduced significantly by exposure of rat striatal slices rnto micromolar concentrations of dopamine in the presence rnof extracellular Ca2+. Omission of Ca2+ in the rnincubation medium (with addition of 1 mmol/L egtazic rnacid) diminished the dopamine-induced decrease of the rnkinase activity. Application of apomorphine, a nonrnselective dopamine receptor agonist, produced a similar rnconcentration-related decrease of CCDPK Ⅱ activity.rnExposure to SKF38393 (selective D1-like receptor rnagonist) or quinpirole (selective D2-like receptor agonist)rnalso inhibited the kinase activity. The dopamine-induced rndecrease of CCDPK Ⅱ activity was attenuated by rnpreincubation with Sch-23390 (selective D1-like receptor rnantagonist) or domperidone (selective D2-like receptor rnantagonist). CONCLUSION: Dopamine is involved in rnthe anoxia-induced inhibition of CCDPK Ⅱ activity by rnactivation of both D1-like and D2-like receptors and influx rnof Ca2+, which may contribute to dopamine-mediated rnstriatal neuronal damage.%目的：研究缺氧时纹状体多巴胺能神经毒性的机制.rn方法：采用大鼠纹状体脑片体外培养模型，以底物rn磷酸化32P-掺入法测定Ca2+-钙调蛋白依赖性蛋白激rn酶Ⅱ(CCDPKⅡ)的活性.结果：缺氧30 min，纹状rn体脑片CCTPKⅡ活性降低75％，慢性利血平化使rn得缺氧诱导的酶活性降低程度减轻，与对照组相比rn大约降低40％.外源性多巴胺显著降低纹状体脑rn片CCDPKⅡ活性.去除胞外Ca2+后，多巴胺诱导rn的酶活性降低作用被削弱.阿扑吗啡(非特异性多rn巴胺受体激动剂)、SKF38393(特异性D1样受体激rn动剂)和喹吡罗(特异性D2样受体激动剂)均可显著rn降低CCDPKⅡ的活性.Sch-23390(特异性D1样受rn体拮抗剂)和吗丁啉(特异性D2样受体拮抗剂)均可rn拮抗多巴胺所诱导的酶活性的抑制作用.结论：多rn巴胺参与缺氧诱导的纹状体CCDPKⅡ活性抑制，其rn作用机制与D1样和D2样受体的激活以及胞外Ca2+rn的内流有关，从而导致多巴胺介导的纹状体神经损rn伤.