作者:Yun Wang、Tamas Szabo、Jacqueline D. Welter、Attila Toth、Richard Tran、Jiyoun Lee、Sang Uk Kang、Young-Ger Suh、Peter M. Blumberg、Jeewoo Lee
DOI:10.1124/mol.62.4.947
日期:2002.10.1
The vanilloid receptor VR1 has attracted great interest as a sensory transducer for capsaicin, protons, and heat, and as a therapeutic target. Here we characterize two novel VR1 antagonists, KJM429 [ N -(4- tert -butylbenzyl)- N ′-[4-(methylsulfonylamino)benzyl]thiourea] and JYL1421 [ N -(4- tert -butylbenzyl)- N ′-[3-fluoro-4-(methylsulfonylamino)benzyl]thiourea], with enhanced activity compared with capsazepine on rat VR1 expressed in Chinese hamster ovary (CHO) cells. JYL1421, the more potent of the two novel antagonists, inhibited [3H]resiniferatoxin binding to rVR1 with an affinity of 53.5 ± 6.5 nM and antagonized capsaicin-induced calcium uptake with an EC50 of 9.2 ± 1.6 nM, reflecting 25- and 60-fold greater potencies than capsazepine. Both JYL1421 and KJM429 antagonized RTX as well as capsaicin and their mechanism was competitive. The responses to JYL1421 and KJM429 differed for calcium uptake by rVR1 induced by heat or pH. JYL1421 antagonized the response to both pH 6.0 and 5.5, whereas KJM429 antagonized at pH 6.0 but was an agonist at lower pH (<5.5). For heat, JYL1421 fully antagonized and KJM429 partially antagonized. Capsazepine showed only weak antagonism for both pH and heat. Responses of rVR1 to different activators could thus be differentially affected by different ligands. In cultured dorsal root ganglion neurons, JYL1421 and KJM429 likewise behaved as antagonists for capsaicin, confirming that the antagonism is not limited to heterologous expression systems. Finally, JYL1421 and KJM429 had little or no effect on ATP-induced calcium uptake in CHO cells lacking rVR1, unlike capsazepine. We conclude that JYL1421 is a competitive antagonist of rVR1, blocking response to all three of the agonists (capsaicin, heat, and protons) with enhanced potency relative to capsazepine.
香草素受体VR1因其作为辣椒素、质子和热的传感转换器以及作为治疗靶点而引起了极大的兴趣。在这里,我们描述了两种新的VR1拮抗剂,KJM429[N-(4-叔丁基苄基)-N′-[4-(甲磺酰氨基)苄基]硫脲]和JYL1421[N-(4-叔丁基苄基)-N′-[3-氟-4-(甲磺酰氨基)苄基]硫脲],它们在大鼠VR1在中国仓鼠卵巢(CHO)细胞中表达时,活性比capsazepine更强。在这两种新型拮抗剂中,JYL1421的活性更强,它抑制[3H]树脂毒素与rVR1的结合,亲和力为53.5±6.5 nM,并拮抗辣椒素诱导的钙吸收,EC50为9.2±1.6 nM,反映出比capsazepine强25倍和60倍的效力。JYL1421和KJM429均能拮抗RTX和辣椒素,其机制为竞争性。JYL1421和KJM429在钙吸收上的反应不同,前者对热或pH诱导的rVR1反应产生拮抗或激动作用。JYL1421拮抗pH 6.0和5.5的反应,而KJM429在pH 6.0时拮抗,但在更低的pH(<5.5)时为激动剂。对于热刺激,JYL1421完全拮抗,而KJM429部分拮抗。Capsazepine对pH和热的拮抗作用很弱。因此,rVR1对不同激动剂的反应可以被不同的配体不同程度地影响。在培养的背根神经节神经元中,JYL1421和KJM429同样表现为辣椒素的拮抗剂,证实了这种拮抗作用不仅限于异源表达系统。最后,与capsazepine不同,JYL1421和KJM429对缺乏rVR1的CHO细胞中的ATP诱导的钙吸收几乎没有影响。我们得出结论,JYL1421是rVR1的竞争性拮抗剂,相对于capsazepine,它阻止了对所有三种激动剂(辣椒素、热和质子)的反应,并增强了效力。