Endocannabinoid brain mechanisms and addiction

内源性大麻素脑机制和成瘾

• 批准号: 8336465
• 负责人: Eliot Gardner
• 金额: $ 52.02万
• 依托单位: NATIONAL INSTITUTE ON DRUG ABUSE
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8336465
• 关键词: AM 251; AM630; Addictive Behavior; Agonist; Animal Model; Attenuated; Behavior; Behavioral; Biochemical; Biological Assay; Brain; CNR1 gene; CNR2 gene; Cannabinoids; Chemicals; Cocaine; Cues; Dependence; Dopamine; Dose; Drug Addiction; Electrical Stimulation of the Brain; Endocannabinoids; Enzymes; Exposure to; Genes; Goals; High Pressure Liquid Chromatography; Immune system; Immunoblotting; Incentives; Intravenous; Knowledge; Laboratory Animals; Laboratory Rat; Link; Locomotion; Measures; Mediating; Microdialysis; Microinjections; Motivation; Mus; Neuraxis; Neurotransmitters; Nucleus Accumbens; Pharmaceutical Preparations; Polymerase Chain Reaction; Proteins; Psychological reinforcement; RNA; Receptor Gene; Relapse; Research; Research Personnel; Research Project Grants; Reverse Transcription; Rewards; Role; Sampling; Self Administration; Self-Administered; Stress; Synapses; System; TRPV1 gene; Techniques; Tetrahydrocannabinol; Time; Western Blotting; Wild Type Mouse; Work; addiction; cannabinoid receptor; capsazepine; craving; dopamine system; extracellular; in vivo; neurochemistry; overexpression; pre-clinical; preference; receptor; relating to nervous system; research study

During the period 01 Oct 10 to 30 Sept 11, very significant progress was made on this research project. The existence of cannabinoid CB2 receptors in the brain has been heretofore controversial. Most evidence has heretofore suggested that only CB1 cannabinoid receptors are found in brain and central nervous system while cannabinoid CB2 receptors are restricted to the body's periphery - primarily in the immune system. However, this view has been challenged by recent claims that CB2 receptors are present in the central nervous system and by recent claims that CB2 receptors modulate synaptic activity. Therefore, we used highly selective CB2 agonists and antagonists, combined with the use of CB1 and CB2 receptor gene-deleted mice, to study CB2 involvement in cocaine's behavioral and neurochemical effects. We found that the CB2 receptor-selective agonist JWH133 attenuates intravenous cocaine self-administration in wild-type and CB1 gene-deleted mice, but not in CB2 gene-deleted mice. This effect was abolished by the CB2 receptor-selective antagonist AM630. To confirm our findings, we also used the CB2-selective agonist GW405833 and found a similar inhibition of intravenous cocaine self-administration in wild-type mice. Under progressive-ratio reinforcement conditions, we found that JWH133 inhibits incentive motivation to self-administer cocaine, as evidenced by strong reductions in the progressive-ratio break-point. Similar effects were found when JWH133 was administered intra-nasally (for direct passage into the brain via the cribiform plate) or administered by direct intracerebral microinjections of JWH133 into the nucleus accumbens. Again, the effect was seen in wild-type but not in CB2 receptor gene-deleted mice. JWH133 by itself was found to have no reinforcing or aversive effects, as assessed by intravenous self-administration and by conditioned place preference/aversion experiments. Further, JWH133 inhibited cocaine-enhanced locomotion in wild-type and CB1 gene-deleted mice, but not in CB2 gene-deleted mice. JWH133 by itself had an inhibitory effect on locmotion, both with systemic administration and with intracerebral microinjection into the nucleus accumbens in wild-type and CB1 gene-deleted mice, but not in CB2 gene-deleted mice. The CB2 selective antagonist AM630 had a stimulatory effect on locomotion, both with systemic administration and with intracerebral microinjection into the nucleus accumbens in wild-type and CB1 gene-deleted mice, but not in CB2 gene-deleted mice. JWH133 by itself inhibited extracellular nucleus accumbens dopamine as measured by real-time in vivo brain microdialysis. JWH133 also inbited basal and cocaine-enhanced extracellular nucleus accumbens dopamine as measured by real-time in vivo brain microdialysis. This effect was blocked by the CB2-selective antagonist AM630. By itself, AM630 - microinjected intracerebrally into the nucleus accumbens - aumented basal extracellular nucleus accumbens dopamine. We conclude that CB2 cannabinoid receptors exist in the brain, that CB2 receptors functionally modulate the meso-accumbens dopamine system, and that CB2 receptors functionally modulate dopamine-mediated behaviors. In addition, we used the electrical brain-stimulation reward preclinical animal model to study the rewarding and/or aversive effects of several cannabinoids and the receptor mechanisms underlying these actions in laboratory rats. We found that the mixed CB1/CB2 cannabinoid agonists delta-9-tetrahydrocannabinol (THC) and WIN55212-2 produce biphasic effects on brain reward - low doses enhancing brain reward mechanism and high doses inhibiting them. On the other hand, the selective CB1 cannabinoid receptor agonist ACEA produces only brain-reward enhancement, while the selective CB2 receptor agonist produces only brain-reward inhibition. Further, the selective cannabinoid CB1 receptor antagonist AM251 selectively blocks the enhanced brain reward produced by low dose THC or WIN55212-2, while the selective cannabinoid CB2 receptor antagonist AM630 selectively blocks the brain reward inhibition produced by high dose THC or WIN55212-2. The TRPV1 antagonist capsazepine (posited by some researchers to act via a non-CB1, non-CB2 cannabinoid receptor) fails to alter THC- or WIN55212-2-induced changes in brain reward. In addition, the CB1 receptor selective antagonist AM251, but not the CB2 receptor selective antagonist AM630, blocks ACEA-enhanced brain reward. The CB2 receptor selective antagonist AM630, but not the CB1 receptor selective antagonist AM251, blocks JWH133-induced inhibition of brain reward. Intranasal JWH133 inhibits brain reward, an effect that is blocked by intranasal co-administration of the CB2 receptor selective antagonist AM630. We conclude that cannabinoid agonists produce biphasic effects on brain reward, with low doses enhancing and high doses inhibiting brain reward mechanisms. We further conclude that cannabinoid-induced reward enhancement is mediated by activation of brain CB1 receptors, while cannabinoid-induced inhibition of brain reward mechanisms is mediated by activation of CB2 receptors in the brain. These research findings suggest that brain CB1 and CB2 receptor-linked neural systems may functionally antagonize each other in a reciprocal mutually antatagonistic manner. Such mechanistic knowledge can aid in the search for new and effective pharmacotherapeutic compounds for the treatment of drug addiction and dependence.

在10月10日至30日11月11日的期间，该研究项目取得了非常重大的进展。 迄今为止，大脑中大麻素CB2受体的存在引起了争议。迄今为止，大多数证据表明，在大脑和中枢神经系统中只发现CB1大麻素受体，而大麻素CB2受体仅限于人体的周围 - 主要在免疫系统中。但是，最近的说法挑战了这种观点，即中枢神经系统中存在CB2受体，并且最近声称CB2受体调节突触活动。因此，我们使用高度选择性的CB2激动剂和拮抗剂，结合使用CB1和CB2受体基因删除小鼠，研究CB2参与可卡因的行为和神经化学作用。我们发现，CB2受体选择性激动剂JWH133减弱了野生型和CB1基因剥落小鼠中可卡因自我给药，但在CB2基因删除的小鼠中却没有。 CB2受体选择性拮抗剂AM630废除了这种效果。为了确认我们的发现，我们还使用了CB2选择性激动剂GW405833，并发现在野生型小鼠中对可卡因自我给药的抑制类似。在渐进率的增强条件下，我们发现JWH133抑制了自我管理可卡因的激励动机，这证明了渐进式利益突破点的强劲降低。当JWH133被纳入神经内（用于通过婴儿型板直接传递到大脑）或通过直接脑内显微注射jWH133施用JWH133时，也发现了类似的效果。同样，这种作用在野生型中观察到，但在CB2受体基因删除的小鼠中没有看到。通过静脉自我给药和条件的位置偏好/厌恶实验，发现JWH133本身没有增强或厌恶作用。此外，JWH133抑制了野生型和CB1基因删除的小鼠中可卡因增强的运动，但在CB2基因删除的小鼠中却没有。 JWH133本身对LocMotion具有抑制作用，无论是全身给药，并且在野生型和CB1基因删除的小鼠中对伏隔核的脑静脉显微注射，但在CB2基因删除的小鼠中却没有。 CB2选择性拮抗剂AM630对野生型和CB1基因剥落的小鼠的运动和脑内显微注射均具有刺激作用，并且在CB2基因上含量的小鼠中均具有脑脑中的显微注射。 JWH133本身抑制了通过体内脑微透析实时测量的细胞外伏伏胺多巴胺。 JWH133还通过实时的体内脑微透析测量了基底和可卡因增强的细胞外核多巴胺。 CB2选择性拮抗剂AM630阻止了这种效果。本身，AM630-微型注射在伏隔核中 - 尤其是尤其的基础细胞外核伏托胺多巴胺。我们得出的结论是，CB2大麻素受体存在于大脑中，CB2受体在功能上调节了中曲胺多巴胺系统，并且CB2受体在功能上调节了多巴胺介导的行为。此外，我们使用电脑刺激奖励临床前动物模型来研究几种大麻素的奖励和/或厌恶作用以及实验室大鼠中这些作用的受体机制。 我们发现，混合的CB1/CB2大麻素激动剂Delta-9-四氢大麻酚（THC）和WIN555212-2对脑奖励产生双相影响 - 低剂量增强了大脑奖励机制，并抑制了高剂量。 另一方面，选择性CB1大麻素受体激动剂ACEA仅产生脑奖励，而选择性CB2受体激动剂仅产生脑奖励抑制作用。 此外，选择性大麻素CB1受体拮抗剂AM251选择性地阻止了低剂量THC或WIN55212-2产生的增强的大脑奖励，而选择性大麻素CB2受体拮抗剂AM630选择性地阻止了高剂量THC THC或WIN552212-2产生的大脑奖励。 TRPV1拮抗剂辣椒粉（一些研究人员通过非CB1，非CB2大麻素受体起作用）未能改变THC或WIN555212-2诱导的大脑奖励变化。 此外，CB1受体选择性拮抗剂AM251，而不是CB2受体选择性拮抗剂AM630阻塞艾艾艾艾氏型脑奖励。 CB2受体选择性拮抗剂AM630，但没有CB1受体选择性拮抗剂AM251阻止JWH133诱导的脑奖励抑制。 鼻内JWH133抑制了大脑奖励，这种作用被CB2受体选择性拮抗剂AM630的鼻内共同给药所阻断。 我们得出的结论是，大麻素激动剂会对脑奖励产生双相影响，低剂量增强和高剂量抑制大脑奖励机制。 我们进一步得出结论，大麻素诱导的奖励增强是通过脑CB1受体的激活介导的，而大麻素诱导的脑奖励机制的抑制是通过大脑中CB2受体的激活介导的。 这些研究发现表明，脑CB1和CB2受体连接的神经系统可能在功能上以相互互补的方式相互拮抗。这种机械知识可以帮助寻找用于治疗药物成瘾和依赖性的新的有效的药物治疗化合物。