Corp E S, McQuade J, Moran T H, Smith G P
Department of Psychiatry, Cornell University Medical College, White Plains, NY 10605.
Brain Res. 1993 Sep 24;623(1):161-6. doi: 10.1016/0006-8993(93)90024-h.
We employed quantitative receptor autoradiography to analyze pharmacological properties of 125I-Bolton Hunter cholecystokinin (CCK-8)-labeled binding sites in sections of rat cervical vagus nerve that had been ligated 24 h prior to extraction. Binding densities were detected in segments of nerve proximal and distal to the ligature. Analysis was confined to proximal segments. Saturation and competitive binding studies were carried out using sulphated CCK-8 and two selective CCK receptor antagonists: MK-329, to define type-A (CCKA) binding sites; and, L-365,260, to define type-B (CCKB) binding sites. Sulphated CCK-8 was the most potent inhibitor of vagal 125I-CCK binding (IC50 = 2 nM). Nonlinear curve fitting analysis of the CCK binding data favored the presence of a single class of vagal CCK receptors (KDi = 1 nM). However, both MK-329 (IC50 = 18 nM) and L-365,260 (IC50 = 45 nM) competed for vagal 125I-CCK binding indicating the presence of CCKA and CCKB binding sites. Co-analysis of the antagonist binding data suggested that CCKA and CCKB receptors were transported in equal concentrations within the vagus. MK-329 bound with high affinity to CCKA sites (Ki = 3 nM) and low-affinity to CCKB sites (Ki = 462 nM) while L-365,260 bound with high affinity to CCKB sites (Ki = 10 nM) and low-affinity to CCKA sites (Ki = 775 nM). These same ligands were used to characterize the specificity of 125I-CCK binding in the medial and lateral divisions of the nucleus of the solitary tract (NTS), two regions innervated by primary vagal afferents carrying CCK receptors.(ABSTRACT TRUNCATED AT 250 WORDS)
我们采用定量受体放射自显影术，分析在提取前24小时已结扎的大鼠颈迷走神经切片中，125I-博尔顿·亨特胆囊收缩素（CCK-8）标记的结合位点的药理学特性。在结扎部位近端和远端的神经段检测结合密度。分析仅限于近端段。使用硫酸化CCK-8和两种选择性CCK受体拮抗剂进行饱和及竞争性结合研究：MK-329，用于定义A型（CCKA）结合位点；以及L-365,260，用于定义B型（CCKB）结合位点。硫酸化CCK-8是迷走神经125I-CCK结合的最有效抑制剂（IC50 = 2 nM）。CCK结合数据的非线性曲线拟合分析表明存在单一类别的迷走神经CCK受体（KDi = 1 nM）。然而，MK-329（IC50 = 18 nM）和L-365,260（IC50 = 45 nM）均竞争迷走神经125I-CCK结合，表明存在CCKA和CCKB结合位点。拮抗剂结合数据的联合分析表明，CCKA和CCKB受体在迷走神经中以相等浓度转运。MK-329与CCKA位点高亲和力结合（Ki = 3 nM），与CCKB位点低亲和力结合（Ki = 462 nM），而L-365,260与CCKB位点高亲和力结合（Ki = 10 nM），与CCKA位点低亲和力结合（Ki = 775 nM）。这些相同的配体用于表征孤束核（NTS）内侧和外侧区域中125I-CCK结合的特异性，这两个区域由携带CCK受体的初级迷走神经传入纤维支配。（摘要截断于250字）
