School of Pharmacy, Pharmacology Unit, University of Camerino, Camerino, Italy.
Center for Social and Affective Neuroscience, Institute for Clinical and Experimental Medicine, Linkoping University, Linkoping, Sweden.
Br J Pharmacol. 2022 Jun;179(11):2647-2658. doi: 10.1111/bph.15762. Epub 2022 Feb 10.
BACKGROUND AND PURPOSE: The nociceptin/orphanin FQ (N/OFQ)-nociceptin opioid-like peptide (NOP) receptor system is widely distributed in the brain and pharmacological activation of this system revealed therapeutic potential in animal models of substance use disorder. Studies also showed that genetic deletion or pharmacological blockade of NOP receptors confer resistance to the development of alcohol abuse. Here, we have used a genetic and pharmacological approach to evaluate the therapeutic potential of NOP antagonism in smoking cessation. EXPERIMENTAL APPROACH: Constitutive NOP receptor knockout rats (NOP ) and their wild-type counterparts (NOP ) were tested over a range of behaviours to characterize their motivation for nicotine. We next explored the effects of systemic administration of the NOP receptor antagonist LY2817412 (1.0 & 3.0 mg·kg ) on nicotine self-administration. NOP receptor blockade was further evaluated at the brain circuitry level, by microinjecting LY2817412 (3.0 & 6.0 μg·μl ) into the ventral tegmental area (VTA), nucleus accumbens (NAc) and central amygdala (CeA). KEY RESULTS: Genetic NOP receptor deletion resulted in decreased nicotine intake, decreased motivation to self-administer and attenuation of cue-induced nicotine reinstatement. LY2817412 reduced nicotine intake in NOP but not in NOP rats, confirming that its effect is mediated by inhibition of NOP transmission. Finally, injection of LY2817412 into the VTA but not into the NAc or CeA decreased nicotine self-administration. CONCLUSIONS AND IMPLICATIONS: These findings indicate that inhibition of NOP transmission attenuates the motivation for nicotine through mechanisms involving the VTA and suggest that NOP receptor antagonism may represent a potential treatment for smoking cessation.
背景与目的:孤啡肽/N 端前体(N/OFQ)-孤啡肽受体样肽(NOP)受体系统广泛分布于脑内,该系统的药理学激活在物质使用障碍的动物模型中显示出治疗潜力。研究还表明,NOP 受体的基因缺失或药理学阻断可赋予对酒精滥用发展的抗性。在这里,我们使用遗传和药理学方法来评估 NOP 拮抗作用在戒烟中的治疗潜力。
实验方法:组成型 NOP 受体敲除大鼠(NOP -/-)及其野生型对照(NOP +/+)用于一系列行为测试,以表征其对尼古丁的动机。我们接下来研究了全身给予 NOP 受体拮抗剂 LY2817412(1.0 和 3.0mg·kg -1 )对尼古丁自我给药的影响。通过将 LY2817412(3.0 和 6.0μg·μl -1 )微注射到腹侧被盖区(VTA)、伏隔核(NAc)和中央杏仁核(CeA),进一步评估了 NOP 受体阻断在脑回路水平上的作用。
主要结果:NOP 受体基因缺失导致尼古丁摄入减少、自我给药动机降低以及线索诱导的尼古丁复吸减弱。LY2817412 减少了 NOP -/-但不减少 NOP +/+大鼠的尼古丁摄入,证实其作用是通过抑制 NOP 传递介导的。最后,LY2817412 注射到 VTA 而不是 NAc 或 CeA 可减少尼古丁自我给药。
结论与意义:这些发现表明,抑制 NOP 传递通过涉及 VTA 的机制减弱了对尼古丁的动机,并表明 NOP 受体拮抗作用可能代表戒烟的潜在治疗方法。
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