Cardiovascular actions of cannabinoids and their generation during shock

Marijuana is a widely abused recreational drug well known for its psychoactive properties. Cannabinoids, the active ingredients of marijuana, elicit their neurobehavioral effects by interacting with the CB₁ cannabinoid receptor subtype, expressed primarily in the brain but also present in some peripheral tissues. A second receptor subtype, the CB₂ receptor, is expressed on cells of the immune system and is thought to be responsible for the immunosuppressant effects of cannabinoids. Recently, endogenous lipidlike substances have been identified, including arachidonyl ethanolamide (anandamide) and 2-arachidonyl glyceride, that bind to cannabinoid receptors and mimic many of the neurobehavioral effects of plant-derived cannabinoids. Both plant-derived cannabinoids and the endogenous ligands have been shown to elicit hypotension and bradycardia via activation of peripherally located CB₁ receptors. Possible underlying mechanisms include presynaptic CB₁ receptor mediated inhibition of norepinephrine release from peripheral sympathetic nerve terminals, and/or direct vasodilation via activation of vascular cannabinoid receptors. The latter may also be the target of endocannabinoids of vascular endothelial origin. Recent studies indicate that a peripheral endogenous cannabinoid system in circulating macrophages and platelets is activated in hemorrhagic and septic shock and may contribute to the hypotension associated with these conditions via activation of vascular cannabinoid receptors. The potential role of this mechanism in human shock conditions is under investigation. Received: 20 May 1998 / Accepted: 24 August 1998     

Systemic or intrahippocampal cannabinoid administration impairs spatial memory in rats

The purpose of the present study was to investigate the disruptive effects of cannabinoids on working memory as assessed in the eight-arm radial-maze. Systemic administration of ⁹-THC, WIN-55,212-2, and CP-55,940 increased the number of errors committed in the radial-maze. CP-55,940 was the most potent cannabinoid in impairing memory (ED₅₀=0.13 mg/kg). ⁹-THC and WIN-55,212-2 disrupted mazechoice accuracy at equipotent doses (ED₅₀ values =2.1 and 2.2 mg/kg, respectively). In addition, systemic administration of each of these agents retarded completion time. Whereas the doses of ⁹-THC and CP-55,940 required to retard maze performance were higher than those needed to increase error numbers, WIN-55,212-2 was equipotent in both of these measures. On the other hand, neither anandamide, the putative endogenous cannabinoid ligand, nor cannabidiol, an inactive naturally occurring cannabinoid, had any apparent effects on memory. A second aim of this study was to elucidate the neuroanatomical substrates mediating the disruptive effects of cannabinoids on memory. Intrahippocampal injections of CP-55,940 impaired maze performance in a dose-dependent manner (ED₅₀=8 µg/rat), but did not retard the amount of time required to complete the maze. The effects of intrahippocampal CP-55,940 were apparently specific to cognition because no other cannabinoid pharmacological effects (e.g., antinociception, hypothermia, and catalepsy) were detected. This dissociation between choice accuracy in the radial-maze and other cannabinoid pharmacological effects suggests that the working memory deficits produced by cannabinoids may be mediated by cannabinoid receptors in the hippocampus.     

Masturbation to Orgasm Stimulates the Release of the Endocannabinoid 2-Arachidonoylglycerol in Humans

BackgroundEndocannabinoids are critical for rewarding behaviors such as eating, physical exercise, and social interaction. The role of endocannabinoids in mammalian sexual behavior has been suggested because of the influence of cannabinoid receptor agonists and antagonists on rodent sexual activity. However, the involvement of endocannabinoids in human sexual behavior has not been studied.AimTo investigate plasma endocannabinoid levels before and after masturbation in healthy male and female volunteers.OutcomesPlasma levels of the endocannabinoids 2-arachidonoylglycerol (2-AG), anandamide, the endocannabinoid-like lipids oleoyl ethanolamide and palmitoyl ethanolamide, arachidonic acid, and cortisol before and after masturbation to orgasm.MethodsIn study 1, endocannabinoid and cortisol levels were measured before and after masturbation to orgasm. In study 2, masturbation to orgasm was compared with a control condition using a single-blinded, randomized, 2-session crossover design.ResultsIn study 1, masturbation to orgasm significantly increased plasma levels of the endocannabinoid 2-AG, whereas anandamide, oleoyl ethanolamide, palmitoyl ethanolamide, arachidonic acid, and cortisol levels were not altered. In study 2, only masturbation to orgasm, not the control condition, led to a significant increase in 2-AG levels. Interestingly, we also found a significant increase of oleoyl ethanolamide after masturbation to orgasm in study 2.Clinical TranslationEndocannabinoids might play an important role in the sexual response cycle, leading to possible implications for the understanding and treatment of sexual dysfunctions.Strengths and LimitationsWe found an increase of 2-AG through masturbation to orgasm in 2 studies including a single-blinded randomized design. The exact role of endocannabinoid release as part of the sexual response cycle and the biological significance of the finding should be studied further. Cannabis and other drug use and the attainment of orgasm were self-reported in the present study.ConclusionOur data indicate that the endocannabinoid 2-AG is involved in the human sexual response cycle and we hypothesize that 2-AG release plays a role in the rewarding consequences of sexual arousal and orgasm.Fuss J, Bindila L, Wiedemann K, et al. Masturbation to Orgasm Stimulates the Release of the Endocannabinoid 2-Arachidonoylglycerol in Humans. J Sex Med 2017;14:1372–1379.     

Effects of TRPV1 activation on synaptic excitation in the dentate gyrus of a mouse model of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is a condition characterized by an imbalance between excitation and inhibition in the temporal lobe. Hallmarks of this change are axon sprouting and accompanying synaptic reorganization in the temporal lobe. Synthetic and endogenous cannabinoids have variable therapeutic potential in treating intractable temporal lobe epilepsy, in part because cannabinoid ligands can bind multiple receptor types. This study utilized in vitro electrophysiological methods to examine the effect of transient receptor potential vanilloid type 1 (TRPV1) activation in dentate gyrus granule cells in a murine model of TLE. Capsaicin, a selective TRPV1 agonist had no measurable effect on overall synaptic input to granule cells in control animals, but significantly enhanced spontaneous and miniature EPSC frequency in mice with TLE. Exogenous application of anandamide, an endogenous cannabinoid that acts at both TRPV1 and cannabinoid type 1 receptors (CB1R), also enhanced glutamate release in the presence of a CB1R antagonist. Anandamide reduced the EPSC frequency when TRPV1 were blocked with capsazepine. Western blot analysis of TRPV1 receptor indicated protein expression was significantly greater in the dentate gyrus of mice with TLE compared with control mice. This study indicates that a prominent cannabinoid agonist can increase excitatory circuit activity in the synaptically reorganized dentate gyrus of mice with TLE by activating TRPV1 receptors, and suggests caution in designing anticonvulsant therapy based on modulating the endocannabinoid system.     

Cannabinoid and vanilloid effects of R(+)-methanandamide in the hemisected meningeal preparation

The endogenous cannabinoid R(+)-methanandamide (mAEA) exerts differential anti- and pronociceptive effects by activating both cannabinoid (CB1) and vanilloid (TRPV1) receptors of nociceptive primary afferents. The significance of these effects in meningeal nociception was evaluated by modulation of calcitonin gene-related peptide (CGRP) release from meningeal afferents measured in an in vitro preparation of the hemisected rat skull. Temperature steps to 39 degrees C and 45 degrees C caused heat-dependent increases in CGRP release. One micromolar mAEA inhibited CGRP release at 32 degrees C but facilitated it at 45 degrees C. This effect was abolished in the presence of the TRPV1 receptor antagonist capsazepine. Lower doses of mAEA had no effect on basal or heat-evoked release. In the presence of the CB1 receptor antagonist SR141716 (0.2 microm) heat-stimulated increase in CGRP release was facilitated. CGRP release in the presence of SR141716 (0.2 microm) was further increased by adding mAEA at a concentration which had no effect on its own. These results confirm an opposing functional role for anandamide at CB1 and TRPV1 receptors on meningeal afferents.     

Activity of anandamide (AEA) metabolic enzymes in rat placental bed

Endocannabinoids are endogenous lipid mediators, with anandamide (AEA) being the first member identified. It is now widely accepted that AEA influences early pregnancy events and its levels, which primarily depend on its synthesis by an N-acyl-phosphatidylethanolamine-specific phospholipase D (NAPE-PLD) and degradation by a fatty acid amide hydrolase (FAAH), must be tightly regulated. Previous studies demonstrated that AEA levels require in situ regulation of these respective metabolic enzymes, and thus, any disturbance in AEA levels may impact maternal remodeling processes occurring during placental development. In this study, the activities of the AEA-metabolic enzymes that result in the establishment of proper local AEA levels during rat gestation were examined. Here, we demonstrate that during placentation NAPE-PLD and FAAH activities change in a temporal manner. Our findings suggest that NAPE-PLD and FAAH create the appropriate AEA levels required for tissue remodeling in the placental bed, a process essential to pregnancy maintenance.     

月经周期中内源性大麻素与性激素和促性腺激素的相关性研究分析

目的分析月经周期中不同时期正常女性血浆中N-花生四烯酸氨基乙醇(AEA)的水平变化及其与性激素和促性腺激素的相关性。方法选择2015年5~10月因输卵管梗阻或男方因素到本院生殖医学科就诊并欲行IVF助孕、月经周期和排卵正常的育龄妇女为研究对象。根据实验目的分为横断面研究组(79例)和纵向研究组(10例),检测AEA在两组女性月经周期中不同时期的变化,以及AEA与FSH、LH、E2、P之间的相关性。结果横断面研究组中早卵泡期、晚卵泡期、排卵期和黄体期AEA水平分别为(9.71±0.86)ng/ml、(10.61±1.05)ng/ml、(12.24±0.73)ng/ml和(7.46±0.71)ng/ml。排卵期AEA水平最高,黄体期最低(P0.05)。纵向研究组4个时期AEA水平分别(8.76±0.91)ng/ml、(11.61±1.28)ng/ml、(13.85±1.18)ng/ml、(8.50±1.08)ng/ml,排卵期AEA水平最高,黄体期最低(P0.05)。横断面研究组和纵向研究组各个时期的AEA水平比较均无显著性差异(P0.05)。AEA与FSH、LH、E2之间存在显著的正相关(P0.05),与P水平则无显著相关性(P=0.067)。结论正常女性血浆内AEA的浓度随月经周期的变化而变化,且与性激素和促性腺激素呈明显相关。但AEA与FSH、LH、E2、P之间的具体作用机制,有待进一步研究。     

内源性大麻素诱导人肝癌细胞MHCC97H凋亡中Caspase-3的作用

目的 检测内源性大麻素(AEA)是否诱导人肝癌高转移细胞株MHCC97H细胞凋亡、以及Caspase-3在细胞凋亡过程中的作用.方法 分别于AEA(100 μmol/L)作用细胞前后,应用Annexin V Binding方法 、流式细胞仪检测细胞凋亡率;荧光活性检测试剂盒检测细胞Caspase-3活性;半定量逆转录-聚合酶链反应(RT-PCR)方法 ,检测Caspase-3、bcl-2及bax的mRNA表达.结果 AEA作用细胞3、6、12、24 h,细胞凋亡率分别为(14.13±2.17)%、(27.04±3.21)%、(34.98±7.74)%及(81.35±9.71)%,其中24 h的细胞凋亡率与对照组(12.72±0.44)%比较,差异有统计学意义(P<0.01).AEA作用细胞24 h,细胞的Caspase-3活性由142.0±5.8增加至226.0±6.4(P<0.01);Caspase-3 mRNA的表达由0.24±0.13升高至0.54±0.32(P<0.05);如预先加入Caspase-3抑制剂(Z-VAD-FMK)后再加入AEA,则细胞的Caspase-3活性不再升高90.0±4.3.RT-PCR方法 未检测到bcl-2 mRNA及bax mRNA的表达.结论 AEA对人肝癌高转移细胞MHCC97H具有凋亡诱导作用,Caspase-3参与了凋亡的调控.