Robberecht P, De Neef P, Woussen-Colle M C, Vertongen P, De Witte O, Brotchi J
Department of Biochemistry and Nutrition, Faculty of Medicine, Université Libre de Bruxelles, Belgium.
Regul Pept. 1994 Jun 16;52(1):53-60. doi: 10.1016/0167-0115(94)90021-3.
Eleven surgical samples of gliomas (1 of grade II, 3 of grade III and 7 of grade IV) were analyzed. Calcitonin gene-related peptide (CGRP) receptors were identified by 125I-alpha h-CGRP binding in 9 cases and the presence of a CGRP-stimulated adenylate cyclase in all the 11 cases. Tracer binding was inhibited by unlabelled alpha h-CGRP (Kd of 0.3 nM), by (8-37) alpha h-CGRP (Kd of 30 nM), by (12-37) alpha h-CGRP (Kd of 3.000 nM) but not by human calcitonin. The mean density of CGRP receptors (120 fmol/mg membrane protein) was comparable to that of beta-adrenergic receptors. CGRP stimulated 1.4 to 4.7-fold (mean 2.7) the adenylate cyclase activity with a K(act) of 2.0 nM. The CGRP fragments had no intrinsic activity but inhibited the CGRP effect. The (8-37)CGRP fragment had a Ki of 30 nM. Thus, at variance with previous reports on rat and human brain membranes, that showed the presence of CGRP receptors not coupled to adenylate cyclase, we observed in human gliomas the presence of CGRP receptors that, when occupied, stimulated efficiently the adenylate cyclase activity.
分析了11例胶质瘤手术样本（二级1例，三级3例，四级7例）。通过125I-α人降钙素基因相关肽（CGRP）结合在9例中鉴定出CGRP受体，并且在所有11例中均存在CGRP刺激的腺苷酸环化酶。未标记的α人降钙素基因相关肽（解离常数为0.3 nM）、（8-37）α人降钙素基因相关肽（解离常数为30 nM）、（12-37）α人降钙素基因相关肽（解离常数为3000 nM）可抑制示踪剂结合，但人降钙素无此作用。CGRP受体的平均密度（120 fmol/mg膜蛋白）与β-肾上腺素能受体相当。CGRP使腺苷酸环化酶活性提高了1.4至4.7倍（平均2.7倍），激活常数为2.0 nM。CGRP片段无内在活性，但可抑制CGRP的作用。（8-37）CGRP片段的抑制常数为30 nM。因此，与之前关于大鼠和人脑膜的报道不同，之前的报道显示存在不与腺苷酸环化酶偶联的CGRP受体，而我们在人类胶质瘤中观察到存在CGRP受体，当这些受体被占据时，可有效刺激腺苷酸环化酶活性。
