Wang X J, Fan S G, Ren M F, Han J S
Department of Physiology, Beijing Medical University, China.
Life Sci. 1989;45(2):117-23. doi: 10.1016/0024-3205(89)90285-3.
Radio receptor assay (RRA) was adopted to analyse the influence of CCK-8 on 3H-etorphine binding to opiate receptors in rat brain synaptosomal membranes (P2). In the competition experiment CCK-8 (1pM to 1 microM) suppressed the binding of 3H-etorphine. This effect was completely reversed by proglumide at 1 microM. Rosenthal analysis for saturation revealed two populations of 3H-etorphine binding sites. CCK-8 (1pM to 1 microM) inhibited 3H-etorphine binding to the high affinity sites by an increase in Kd (up to +235%) and decrease in Bmax (up to -80%) without significant changes in the Kd and Bmax of the low affinity sites. This effect of CCK-8 (10nM) was also completely reversed by proglumide at 1 microM. Unsulfated CCK-8 (100pM to 1 microM) produced only a slight increase in Kd of the high affinity sites (+64%) without affecting Bmax. The results suggest that CCK-8 might be capable of suppressing the high affinity opioid binding sites via the activation of CCK receptor.
采用放射受体分析法（RRA）分析胆囊收缩素-8（CCK-8）对3H-埃托啡与大鼠脑突触体膜（P2）中阿片受体结合的影响。在竞争实验中，CCK-8（1皮摩尔至1微摩尔）抑制了3H-埃托啡的结合。1微摩尔的丙谷胺可完全逆转这种效应。饱和的罗森塔尔分析显示存在两类3H-埃托啡结合位点。CCK-8（1皮摩尔至1微摩尔）通过增加解离常数（Kd）（高达+235%）和降低最大结合容量（Bmax）（高达-80%）来抑制3H-埃托啡与高亲和力位点的结合，而低亲和力位点的Kd和Bmax无显著变化。1微摩尔的丙谷胺也可完全逆转CCK-8（10纳摩尔）的这种效应。未硫酸化的CCK-8（100皮摩尔至1微摩尔）仅使高亲和力位点的Kd略有增加（+64%），而不影响Bmax。结果表明，CCK-8可能通过激活CCK受体来抑制高亲和力阿片类结合位点。
