Scheffel U, Taylor G F, Kepler J A, Carroll F I, Kuhar M J
Johns Hopkins University School of Medicine, Department of Radiology, Division of Nuclear Medicine, Baltimore, MD, 21205, USA.
Neuroreport. 1995 Dec 15;6(18):2483-8. doi: 10.1097/00001756-199512150-00011.
In vitro binding studies have shown that epibatidine and its norchloro analogues have high affinities for the cholinergic nicotinic receptor. In this study, the in vivo binding characteristics of 3Hnorchloroepibatidine (NCEPB) and 3HNCEPB in mice were examined. After injection of 3HNCEPB, radioactivity levels in all brain regions examined increased and then decreased, with different regions accumulating different levels of radioactivity. The regional distribution of radioactivity at later times paralleled the distribution of nicotinic receptor binding in vitro. The ratio of radioactivity in the superior colliculus to that in the cerebellum, a reflection or estimate of total: non-specific binding, was strikingly high at 8 h (about 35). Drugs known to bind to nicotinic receptors reduced 3HNCEPB binding, while atropine and spiperone, muscarinic and dopaminergic drugs respectively, did not. 3HNCEPB had a similar regional distribution to 3HNCEPB. Pretreatment with increasing doses of non-radioactive (-)NCEPB resulted in saturation of in vivo binding of 3HNCEPB. These data indicate that 3H and (-)NCEPB are useful in vivo binding ligands for the cholinergic nicotinic receptor.
体外结合研究表明，埃博霉素及其去氯类似物对胆碱能烟碱受体具有高亲和力。在本研究中，检测了3H去氯埃博霉素（NCEPB）和3HNCEPB在小鼠体内的结合特性。注射3HNCEPB后，所有检测脑区的放射性水平先升高后降低，不同脑区积累的放射性水平不同。后期放射性的区域分布与体外烟碱受体结合的分布平行。上丘与小脑放射性之比反映或估计了总非特异性结合，在8小时时显著较高（约为35）。已知与烟碱受体结合的药物可降低3HNCEPB结合，而阿托品和舒必利（分别为毒蕈碱能和多巴胺能药物）则无此作用。3HNCEPB与3HNCEPB具有相似的区域分布。用递增剂量的非放射性(-)NCEPB预处理导致3HNCEPB体内结合饱和。这些数据表明，3H和(-)NCEPB是胆碱能烟碱受体有用的体内结合配体。
