Wang Yun, Szabo Tamas, Welter Jacqueline D, Toth Attila, Tran Richard, Lee Jiyoun, Kang Sang Uk, Suh Young-Ger, Blumberg Peter M, Lee Jeewoo
National Cancer Institute, Bethesda, Maryland 20892, USA.
Mol Pharmacol. 2002 Oct;62(4):947-56. doi: 10.1124/mol.62.4.947.
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 [(3)H]resiniferatoxin binding to rVR1 with an affinity of 53.5 +/- 6.5 nM and antagonized capsaicin-induced calcium uptake with an EC(50) 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.
香草酸受体VR1作为辣椒素、质子和热的感觉转导器以及治疗靶点，已引起了人们极大的兴趣。在此，我们对两种新型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]进行了特性描述，与辣椒平相比，它们对中国仓鼠卵巢（CHO）细胞中表达的大鼠VR1具有增强的活性。JYL1421是这两种新型拮抗剂中活性更强的一种，它抑制[(3)H]树脂毒素与rVR1的结合，亲和力为53.5±6.5 nM，拮抗辣椒素诱导的钙摄取，EC(50)为9.2±1.6 nM，其效力分别比辣椒平高25倍和60倍。JYL1421和KJM429都能拮抗RTX以及辣椒素，其作用机制为竞争性。rVR1对热或pH诱导的钙摄取对JYL1421和KJM429的反应不同。JYL1421能拮抗pH 6.0和5.5时的反应，而KJM429在pH 6.0时起拮抗作用，但在较低pH（<5.5）时是激动剂。对于热，JYL1421完全拮抗，KJM429部分拮抗。辣椒平对pH和热均仅表现出微弱的拮抗作用。因此，rVR1对不同激活剂的反应可能受到不同配体的不同影响。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，证实这种拮抗作用不限于异源表达系统。最后，与辣椒平不同，JYL1421和KJM429对缺乏rVR1的CHO细胞中ATP诱导的钙摄取几乎没有影响。我们得出结论，JYL1421是rVR1的竞争性拮抗剂，相对于辣椒平，它能更有效地阻断对所有三种激动剂（辣椒素、热和质子）的反应。
