Macallan D R, Lunt G G, Wonnacott S, Swanson K L, Rapoport H, Albuquerque E X
Department of Biochemistry, University of Bath, England.
FEBS Lett. 1988 Jan 4;226(2):357-63. doi: 10.1016/0014-5793(88)81454-6.
Specific high-affinity binding sites for 125I-alpha-bungarotoxin and (-)-[3H]nicotine have been measured in rat brain and locust (Schistocerca gregaria) ganglia. The binding sites for 125I-alpha-bungarotoxin had similar Kd values of 1.5 x 10(-9) and 0.8 x 10(-9) M for rat and locust preparations, respectively; the corresponding values for the (-)-[3H]nicotine-binding site were 9.3 x 10(-9) and 1.7 x 10(-7) M. Methyllycaconitine (MLA) potently inhibited 125I-alpha-bungarotoxin binding in both rat and locust. MLA was a less effective inhibitor of (-)-[3H]nicotine binding whereas (+)-anatoxin-a was a very potent inhibitor at this site in the rat but not in the locust. These data suggest that (+)-anatoxin-a is a useful probe for the high-affinity nicotine-binding receptor in vertebrate brain, whereas MLA is a preferential probe for the subclass of receptor that binds alpha-bungarotoxin.
已在大鼠脑和蝗虫（沙漠蝗）神经节中测定了125I-α-银环蛇毒素和（-）-[3H]尼古丁的特异性高亲和力结合位点。125I-α-银环蛇毒素的结合位点在大鼠和蝗虫制剂中的Kd值分别相似，为1.5×10^(-9)和0.8×10^(-9) M；（-）-[3H]尼古丁结合位点的相应值为9.3×10^(-9)和1.7×10^(-7) M。甲基lycaconitine（MLA）能有效抑制大鼠和蝗虫中125I-α-银环蛇毒素的结合。MLA对（-）-[3H]尼古丁结合的抑制作用较弱，而（+）-anatoxin-a在大鼠的该位点是一种非常有效的抑制剂，但在蝗虫中不是。这些数据表明，（+）-anatoxin-a是脊椎动物脑中高亲和力尼古丁结合受体的有用探针，而MLA是结合α-银环蛇毒素的受体亚类的优先探针。
