Héron C, Costentin J, Bonnet J J
EP 076 du C.N.R.S., U.F.R. de Médecine & Pharmacie de Rouen, Saint Etienne du Rouvray, France.
Eur J Pharmacol. 1994 Nov 3;264(3):391-8. doi: 10.1016/0014-2999(94)00502-8.
We have studied the ability of various uptake blockers to protect the dopamine neuronal carrier labeled with [3H]GBR 12783 (1-[2-(diphenylmethoxy)ethyl]-4-(3-phenyl-2-(propenyl)-piperazine) against N-ethylmaleimide-induced alkylation, using membrane preparations obtained from rat striatum. Pure uptake inhibitors such as mazindol, pyrovalerone, nomifensine and methylphenidate, and substrates (dopamine, d-amphetamine, m-tyramine) protected the [3H]GBR 12783 binding site in a concentration-dependent manner. Preincubation of the membranes with these agents prior to N-ethylmaleimide treatment did not modify the protecting ability of substrates, whereas it significantly improved that of pure uptake inhibitors including cocaine. When the preincubation was omitted, the concentration dependence of the protection observed with pure uptake inhibitors decreased and a maximal 40% protection was observed for 10 microM to 1 mM cocaine concentrations. Effective protecting concentrations of blockers are correlated with their Ki determined in standard binding studies. These results reveal that all pure uptake inhibitors bind slowly to the dopamine neuronal carrier whereas substrates interact with it rapidly.
我们利用从大鼠纹状体获得的膜制剂，研究了各种摄取阻滞剂保护用[3H]GBR 12783（1-[2-(二苯基甲氧基)乙基]-4-(3-苯基-2-(丙烯基)-哌嗪)标记的多巴胺神经元载体免受N-乙基马来酰亚胺诱导的烷基化的能力。纯摄取抑制剂如马吲哚、吡咯戊酮、诺米芬辛和哌醋甲酯以及底物（多巴胺、d-苯丙胺、间酪氨酸）以浓度依赖性方式保护[3H]GBR 12783结合位点。在N-乙基马来酰亚胺处理之前用这些试剂对膜进行预孵育，不会改变底物的保护能力，而它显著提高了包括可卡因在内的纯摄取抑制剂的保护能力。当省略预孵育时，纯摄取抑制剂观察到的保护的浓度依赖性降低，并且在10 microM至1 mM可卡因浓度下观察到最大40%的保护。阻滞剂的有效保护浓度与其在标准结合研究中测定的Ki相关。这些结果表明，所有纯摄取抑制剂与多巴胺神经元载体的结合缓慢，而底物与它快速相互作用。
