Makimura M, Ito Y, Murakoshi Y
Department of Pharmacy, College of Science and Technology, Nihon University, Tokyo, Japan.
Yakubutsu Seishin Kodo. 1988 Jun;8(2):359-66.
Among the tested five species--carp, bullfrog chicken, rat, and mouse--the solubilized fraction derived from the bullfrog brain gave the highest binding activity similar to that of membranes. The difference in their binding activities was demonstrated to depend on the Bmax value, but not on Kd. High-affinity binding of [3H]naloxone and [3H]ethylketocyclazocine (EKC) was proved in supernatant of detergent-treated membranes. The displacement curves of various [3H]ligands binding to the membrane and solubilized fraction by a series of agonists suggested that kappa-receptors are rich in the bullfrog brain. Guanyl-5'yl-imidodiphosphate (GppNHp) and N-ethylmaleimide (NEM) reduced the proportion of opioid receptors with a high affinity for mu-agonist, because the high-affinity states of opioid receptors were converted to the low-affinity states by GppNHp and NEM. The degree in shift of these displacement curves of [3H]naloxone binding by above agonist in bullfrog brain membranes, was slight when compared with that of the rat brain membranes. GppNHp slightly affected the displacement curves of [3H]naloxone binding caused by levorphanol or delta-receptor peptide, but the displacement curve for bremazocine was not affected by GppNHp, suggesting that participation of GTP binding protein is minor in kappa-receptor of the bullfrog.
在测试的五个物种——鲤鱼、牛蛙、鸡、大鼠和小鼠中，来自牛蛙大脑的可溶性组分具有与膜相似的最高结合活性。结果表明，它们结合活性的差异取决于最大结合容量（Bmax）值，而非解离常数（Kd）。在去污剂处理过的膜的上清液中证实了[3H]纳洛酮和[3H]乙基酮环唑辛（EKC）的高亲和力结合。一系列激动剂对各种[3H]配体与膜及可溶性组分结合的置换曲线表明，牛蛙大脑中富含κ受体。鸟苷-5'-亚氨二磷酸（GppNHp）和N-乙基马来酰亚胺（NEM）降低了对μ激动剂具有高亲和力的阿片受体比例，因为GppNHp和NEM将阿片受体的高亲和力状态转变为了低亲和力状态。与大鼠脑膜相比，上述激动剂对牛蛙脑膜中[3H]纳洛酮结合置换曲线的位移程度较小。GppNHp对左啡诺或δ受体肽引起的[3H]纳洛酮结合置换曲线影响轻微，但布马佐辛的置换曲线不受GppNHp影响，这表明GTP结合蛋白在牛蛙κ受体中的参与程度较小。
