Systemic and Intrathecal Effects of a Novel Series of Phospholipase A<sub>2</sub> Inhibitors on Hyperalgesia and Spinal Prostaglandin E<sub>2</sub> Release
作者:Tony L. Yaksh、George Kokotos、Camilla I. Svensson、Daren Stephens、Christoforos G. Kokotos、Bethany Fitzsimmons、Dimitra Hadjipavlou-Litina、Xiao-Ying Hua、Edward A. Dennis
DOI:10.1124/jpet.105.091686
日期:2006.1
Phospholipase A2 (PLA2) forms are expressed in spinal cord, and inhibiting spinal PLA2 induces a potent antihyperalgesia. Here, we examined the antihyperalgesic effects after systemic and i.t. delivery of four compounds constructed with a common motif consisting of a 2-oxoamide with a hydrocarbon tail and a four-carbon tether. These molecules were characterized for their ability to block group IVA calcium-dependent PLA2 (cPLA2) and group VIA calcium-independent PLA2 (iPLA2) in inhibition assays using human recombinant enzyme. The rank ordering of potency in blocking group IVA cPLA2 was AX048 (ethyl 4-[(2-oxohexadecanoyl)amino]butanoate), AX006 (4-[(2-oxohexadecanoyl)amino]butanoic acid), and AX057 ( tert -butyl 4-[(2-oxohexadecanoyl)amino]butanoate) > AX010 (methyl 4-[(2-oxohexadecanoyl)amino]butanoate) and for inhibiting group VIA iPLA2 was AX048, AX057 > AX006, and AX010. No agent altered recombinant cyclooxygenase activity. In vivo, i.t. (30 μg) and systemic (0.2-3 mg/kg i.p.) AX048 blocked carrageenan hyperalgesia and after systemic delivery in a model of spinally mediated hyperalgesia induced by i.t. substance P (SP). The other agents were without activity. In rats prepared with lumbar i.t. loop dialysis catheters, SP evoked spinal prostaglandin E2 (PGE2) release. AX048 alone inhibited PGE2 release. Intrathecal SR141617, a cannabinoid CB1 inhibitor at doses that blocked the effects of i.t. anandamide had no effect upon i.t. AX048. These results suggest that AX048 is the first systemically bioavailable compound with a significant affinity for group IVA cPLA2, which produces a potent antihyperalgesia. The other agents, although demonstrating enzymatic activity in cell-free assays, appear unable to gain access to the intracellular PLA2 toward which their action is targeted.
磷脂酶 A2(PLA2)在脊髓中表达,抑制脊髓 PLA2 可诱导有效的抗痛觉。在这里,我们研究了四种化合物在全身给药和静脉注射后的镇痛效果,这四种化合物具有一个共同的基团,由一个带有碳氢化合物尾部和一个四碳系链的 2- 氧代酰胺组成。在使用人类重组酶进行的抑制试验中,这些分子阻断第 IVA 组钙依赖性 PLA2(cPLA2)和第 VIA 组钙非依赖性 PLA2(iPLA2)的能力得到了表征。对 IVA 组 cPLA2 的阻断效力排名依次为 AX048(4-[(2-oxohexadecanoyl)氨基]丁酸乙酯)、AX006(4-[(2-oxohexadecanoyl)氨基]丁酸)和 AX057(叔丁酸)、和 AX057(4-[(2-氧代十六碳酰基)氨基]丁酸叔丁酯)>AX010(4-[(2-氧代十六碳酰基)氨基]丁酸甲酯),而抑制 VIA 组 iPLA2 的药物是 AX048、AX057>AX006 和 AX010。没有一种制剂能改变重组环氧化酶的活性。在体内,AX048 经静脉注射(30 微克)和全身注射(0.2-3 毫克/千克,静脉注射)可阻断角叉菜胶引起的痛觉减退,在经静脉注射 P 物质(SP)诱导的脊髓介导的痛觉减退模型中,AX048 经全身注射后也可阻断痛觉减退。其他药物没有活性。在使用腰部 i.t. 循环透析导管的大鼠身上,SP 会诱发脊髓前列腺素 E2(PGE2)的释放。单用 AX048 可抑制 PGE2 的释放。鞘内 SR141617 是一种大麻素 CB1 抑制剂,其剂量可阻断 i.t. 苯甲酰胺的作用,但对 i.t. AX048 没有影响。这些结果表明,AX048 是第一种对 IVA 组 cPLA2 有显著亲和力的全身生物可用化合物,它能产生强效的抗过痛作用。其他药物虽然在无细胞试验中显示出酶活性,但似乎无法进入其作用所针对的细胞内 PLA2。