Functional Selectivity and Antinociceptive Effects of a Novel KOPr Agonist
Functional Selectivity and Antinociceptive Effects of a Novel KOPr Agonist
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DOI：
10.3389/fphar.2020.00188
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发表时间：
2020-03-05
影响因子：
5.6
通讯作者：
Spampinato, Santi
中科院分区：
文献类型：
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作者：
Bedini, Andrea;Mannelli, Lorenzo Di Cesare;Spampinato, Santi
κ阿片受体（KOPr）激动剂因其低滥用潜力而代表替代镇痛剂，尽管相关的不良反应限制了其临床使用。功能选择性KOPr激动剂可以以途径特异性方式激活G蛋白介导的信号传导，产生抗伤害感受，而不是β-arrestin 2依赖性诱导p38 MAPK，这优先导致不良反应。因此，功能选择性KOPr激动剂偏向于G蛋白偶联的细胞内信号传导，而不是β-抑制蛋白-2介导的途径，可以被认为是可能没有经典KOPr激动剂引起的许多典型不良反应的候选治疗剂。尽管如此，阿片受体的功能选择性激动剂的潜在效用仍然存在很大争议;因此，有必要进一步研究，以充分了解是否有可能通过利用KOPr的功能选择性来开发更有效和更安全的镇痛药。在本研究中，我们研究了LOR 17的体外功能选择性和体内抗伤害效应，LOR 17是我们合成的一种新型KOPr选择性肽激动剂。在表达hKOPr的HEK-293细胞、U87-MG胶质母细胞瘤细胞和原代人星形胶质细胞中研究了LOR 17介导的对腺苷酸环化酶抑制、ERK 1/2、p38 MAPK磷酸化和星形胶质细胞增殖的影响;通过cAMP ELISA和β-抑制蛋白2募集试验研究了偏倚激动作用。通过温水尾部戒断试验、腹腔酸诱导的扭体反应和奥沙利铂诱导的神经性冷超敏反应模型评估小鼠的抗伤害感受和抗超敏反应。还测定了LOR 17对自发活动、探索活动和强迫游泳行为的影响。我们发现，LOR 17是一种选择性的，G蛋白偏向KOPr激动剂，抑制腺苷酸环化酶和激活早期ERK 1/2磷酸化。与经典的KOPr激动剂U 50，488相反，LOR 17既不诱导p38 MAPK磷酸化，也不增加星形胶质细胞中KOPr依赖性的p38 MAPK介导的细胞增殖。此外，LOR 17以浓度依赖性方式抵消U 50，488诱导的p38 MAPK磷酸化和星形胶质细胞增殖。U 50，488和LOR 17在急性伤害感受模型中均表现出强效的抗伤害感受作用，而LOR 17比U 50，488更好地对抗奥沙利铂诱导的热超敏反应，并且在单次或重复皮下注射后有效局以完全缓解奥沙利铂诱导的热超敏反应的剂量施用的LOR 17不改变运动协调、运动和探索活动，也不诱导促炎样行为。因此，LOR 17可能成为一种新型KOPr激动剂，在不同的动物模型（包括奥沙利铂诱导的神经病变）中显示对G蛋白信号传导的功能选择性，并引发抗伤害感受/抗超敏反应作用。
Kappa opioid receptor (KOPr) agonists represent alternative analgesics for their low abuse potential, although relevant adverse effects have limited their clinical use. Functionally selective KOPr agonists may activate, in a pathway-specific manner, G protein-mediated signaling, that produces antinociception, over beta-arrestin 2-dependent induction of p38MAPK, which preferentially contributes to adverse effects. Thus, functionally selective KOPr agonists biased toward G protein-coupled intracellular signaling over beta-arrestin-2-mediated pathways may be considered candidate therapeutics possibly devoid of many of the typical adverse effects elicited by classic KOPr agonists. Nonetheless, the potential utility of functionally selective agonists at opioid receptors is still highly debated; therefore, further studies are necessary to fully understand whether it will be possible to develop more effective and safer analgesics by exploiting functional selectivity at KOPr. In the present study we investigated in vitro functional selectivity and in vivo antinociceptive effects of LOR17, a novel KOPr selective peptidic agonist that we synthesized. LOR17-mediated effects on adenylyl cyclase inhibition, ERK1/2, p38MAPK phosphorylation, and astrocyte cell proliferation were studied in HEK-293 cells expressing hKOPr, U87-MG glioblastoma cells, and primary human astrocytes; biased agonism was investigated via cAMP ELISA and beta-arrestin 2 recruitment assays. Antinociception and antihypersensitivity were assessed in mice via warm-water tail-withdrawal test, intraperitoneal acid-induced writhing, and a model of oxaliplatin-induced neuropathic cold hypersensitivity. Effects of LOR17 on locomotor activity, exploratory activity, and forced-swim behavior were also assayed. We found that LOR17 is a selective, G protein biased KOPr agonist that inhibits adenylyl cyclase and activates early-phase ERK1/2 phosphorylation. Conversely to classic KOPr agonists as U50,488, LOR17 neither induces p38MAPK phosphorylation nor increases KOPr-dependent, p38MAPK-mediated cell proliferation in astrocytes. Moreover, LOR17 counteracts, in a concentration-dependent manner, U50,488-induced p38MAPK phosphorylation and astrocyte cell proliferation. Both U50,488 and LOR17 display potent antinociception in models of acute nociception, whereas LOR17 counteracts oxaliplatin-induced thermal hypersensitivity better than U50,488, and it is effective after single or repeated s.c. administration. LOR17 administered at a dose that fully alleviated oxaliplatin-induced thermal hypersensitivity did not alter motor coordination, locomotor and exploratory activities nor induced pro-depressant-like behavior. LOR17, therefore, may emerge as a novel KOPr agonist displaying functional selectivity toward G protein signaling and eliciting antinociceptive/antihypersensitivity effects in different animal models, including oxaliplatin-induced neuropathy.