内源性大麻素对心血管系统的作用

在心肌组织、血管平滑肌细胞、内皮细胞和血管壁周围的神经纤维末梢以及血液中某些细胞存在内源性大麻素和相应的大麻素（CB）受体。在不同的动物模型和器官,内源性大麻素发挥调节血压和扩张血管等效应。内源性大麻素还在减少休克和心肌梗死所致循环和心脏损伤方面发挥重要作用,在心肌预适应中亦发挥关键作用。目前对内源性大麻素在心血管系统中作用的研究还处于起步阶段,本文对内源性大麻素系统在心血管系统中的来源和分布,对血管和心脏的作用及其机制方面的研究进展作简要介绍。     

Fibronectin modulates the endocannabinoid system through the cAMP/PKA pathway during human sperm capacitation

Fibronectin (Fn) enhances human sperm capacitation via the cAMP/PKA pathway, and the endocannabinoid system participates in this process. Moreover, Fn has been linked to endocannabinoid system components in different cellular models, even though no evidence of such interactions in human sperm is available. Normal semen samples were evaluated over a 4‐year period. Our findings suggest that (a) the capacitating effects of Fn were reversed by preincubating the sperm with a cannabinoid receptor 1 (CB1) or transient receptor potential cation channel subfamily V member 1 (TRPV1) antagonist ( p < 0.001 and p < 0.05, respectively); (b) cooperation between CB1 and TRPV1 may exist ( p < 0.01); (c) the activity of specific fatty acid amide hydroxylase (FAAH) decreased after 1 min ( p < 0.01) and increased after 60 min ( p < 0.01) of capacitation in the presence of Fn; (d) the effects of Fn on FAAH activity were prevented by preincubating spermatozoa with a protein kinase A (PKA) inhibitor ( p < 0.01); (e) Fn modulated both the cyclic adenosine monophosphate concentration and PKA activity ( p < 0.05) during early capacitation; and (f) FAAH was a PKA substrate modulated by phosphorylation. These findings indicate that Fn stimulates human sperm capacitation via the cAMP/PKA pathway through modulation of the endocannabinoid system. Understanding the functional competence of human spermatozoa is essential for facilitating clinical advances in infertility treatment and for developing novel contraceptive strategies.     

Dynamic changes to the endocannabinoid system in models of chronic pain

The analgesic effects of cannabinoid ligands, mediated by CB1 receptors are well established. However, the side-effect profile of CB1 receptor ligands has necessitated the search for alternative cannabinoid-based approaches to analgesia. Herein, we review the current literature describing the impact of chronic pain states on the key components of the endocannabinoid receptor system, in terms of regionally restricted changes in receptor expression and levels of key metabolic enzymes that influence the local levels of the endocannabinoids. The evidence that spinal CB2 receptors have a novel role in the modulation of nociceptive processing in models of neuropathic pain, as well as in models of cancer pain and arthritis is discussed. Recent advances in our understanding of the spinal location of the key enzymes that regulate the levels of the endocannabinoid 2-AG are discussed alongside the outcomes of recent studies of the effects of inhibiting the catabolism of 2-AG in models of pain. The complexities of the enzymes capable of metabolizing both anandamide (AEA) and 2-AG have become increasingly apparent. More recently, it has come to light that some of the metabolites of AEA and 2-AG generated by cyclooxygenase-2, lipoxygenases and cytochrome P450 are biologically active and can either exacerbate or inhibit nociceptive signalling.     

Modulation of neuropathic-pain-related behaviour by the spinal endocannabinoid/endovanilloid system

Neuropathic pain refers to chronic pain that results from injury to the nervous system. The mechanisms involved in neuropathic pain are complex and involve both peripheral and central phenomena. Although numerous pharmacological agents are available for the treatment of neuropathic pain, definitive drug therapy has remained elusive. Recent drug discovery efforts have identified an original neurobiological approach to the pathophysiology of neuropathic pain. The development of innovative pharmacological strategies has led to the identification of new promising pharmacological targets, including glutamate antagonists, microglia inhibitors and, interestingly, endogenous ligands of cannabinoids and the transient receptor potential vanilloid type 1 (TRPV1). Endocannabinoids (ECs), endovanilloids and the enzymes that regulate their metabolism represent promising pharmacological targets for the development of a successful pain treatment. This review is an update of the relationship between cannabinoid receptors (CB1) and TRPV1 channels and their possible implications for neuropathic pain. The data are focused on endogenous spinal mechanisms of pain control by anandamide, and the current and emerging pharmacotherapeutic approaches that benefit from the pharmacological modulation of spinal EC and/or endovanilloid systems under chronic pain conditions will be discussed.     

Occurrence and possible biological role of the endocannabinoid system in the sea squirt Ciona intestinalis

A cannabinoid receptor orthologue (CiCBR) has been described in the sea squirt Ciona intestinalis. Here we report that CiCBR mRNA expression is highest in cerebral ganglion, branchial pharynx, heart and testis of C. intestinalis, and that this organism also contains cannabinoid receptor ligands and some of the enzymes for ligand biosynthesis and inactivation. Using liquid chromatography-mass spectrometry, the endocannabinoid anandamide was found in all tissues analysed (0.063-5.423 pmol/mg of lipid extract), with the highest concentrations being found in brain and heart. The endocannabinoid 2-arachidonoylglycerol (2-AG) was fivefold more abundant than anandamide, and was most abundant in stomach and intestine and least abundant in heart and ovaries (2.677-50.607 pmol/mg of lipid extract). Using phylogenomic analysis, we identified orthologues of several endocannabinoid synthesizing and degrading enzymes. In particular, we identified and partly sequenced a fatty acid amide hydrolase (FAAH) orthologue, showing 44% identity with human FAAH and containing nearly all the amino acids necessary for a functional FAAH enzyme. Ciona intestinalis also contained specific binding sites for cannabinoid receptor ligands, and an amidase enzyme with pH-dependency and subcellular/tissue distribution similar to mammalian FAAHs. Finally, a typical C. intestinalis behavioural response, siphon reopening after closure induced by mechanical stimulation, was inhibited by the cannabinoid receptor agonist HU-210, and this effect was significantly attenuated by mammalian cannabinoid receptor antagonists.     

Gender-dependent cellular and biochemical effects of maternal deprivation on the hippocampus of neonatal rats: a possible role for the endocannabinoid system

Adult animals submitted to a single prolonged episode of maternal deprivation (MD) [24 h, postnatal days (PND) 9-10] show behavioral alterations that resemble specific symptoms of schizophrenia. These behavioral impairments may be related to neuronal loss in the hippocampus triggered by elevated glucocorticoids. Furthermore, our previous data suggested functional relationships between MD stress and the endocannabinoid system. In this study, we addressed the effects of MD on hippocampal glial cells and the possible relationship with changes in plasma corticosterone (CORT) levels. In addition, we investigated the putative involvement of the endocannabinoid system by evaluating (a) the effects of MD on hippocampal levels of endocannabinoids (b) The modulation of MD effects by two inhibitors of endocannabinoids inactivation, the fatty acid amide hydrolase inhibitor N-arachidonoyl-serotonin (AA-5-HT), and the endocannabinoid reuptake inhibitor, OMDM-2. Drug treatments were administered once daily from PND 7 to PND 12 at a dose of 5 mg/kg, and the animals were sacrificed at PND 13. MD induced increased CORT levels in both genders. MD males also showed an increased number of astrocytes in CA1 and CA3 areas and a significant increase in hippocampal 2-arachidonoylglycerol. The cannabinoid compounds reversed the endocrine and cellular effects of maternal deprivation. We provide direct evidence for gender-dependent cellular and biochemical effects of MD on developmental hippocampus, including changes in the endocannabinoid system.     

The endocannabinoid system in the brain of Carassius auratus and its possible role in the control of food intake

Cannabinoid receptors and the endocannabinoids anandamide and 2-arachidonoylglycerol have been suggested to regulate food intake in several animal phyla. Orthologs of the mammalian cannabinoid CB(1) and CB(2) receptors have been identified in fish. We investigated the presence of this endocannabinoid system in the brain of the goldfish Carassius auratus and its role in food consumption. CB(1)-like immunoreactivity was distributed throughout the goldfish brain. The prosencephalon showed strong CB(1)-like immunoreactivity in the telencephalon and the inferior lobes of the posterior hypothalamus. Endocannabinoids were detected in all brain regions of C. auratus and an anandamide-hydrolysing enzymatic activity with features similar to those of mammalian fatty acid amide hydrolase was found. Food deprivation for 24 h was accompanied by a significant increase of anandamide, but not 2-arachidonoylglycerol, levels only in the telencephalon. Anandamide caused a dose-dependent effect on food intake within 2 h of intraperitoneal administration to satiated fish and significantly enhanced or reduced food intake at low (1 pg/g body weight) or intermediate (10 pg/g) doses, respectively, the highest dose tested (100 pg/g) being inactive. We suggest that endocannabinoids might variously contribute to adaptive responses to food shortage in fish.     

Pharmacological modulation of the endocannabinoid system in a viral model of multiple sclerosis

Theiler's virus infection of the central nervous system (CNS) induces an immune-mediated demyelinating disease in susceptible mouse strains and serves as a relevant infection model for human multiple sclerosis (MS). Cannabinoids have been shown to exert beneficial effects on animal models of MS and evidence suggests that the endocannabinoid system plays a role in the tonic control of spasticity. In this study we show that OMDM1 [(R)-N-oleoyl-(1'-hydroxybenzyl)-2'-ethanolamine] and OMDM2 [(S)-N-oleoyl-(1'-hydroxybenzyl)-2'-ethanolamine], two selective inhibitors of the putative endocannabinoid transporter and hence of endocannabinoid inactivation, provide an effective therapy for Theiler murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD). Treatment of TMEV-infected mice with OMDM1 and OMDM2 enhanced anandamide levels in the spinal cord and ameliorated motor symptoms. This was associated with a down-regulation of inflammatory responses in the spinal cord. In addition we show that OMDM1 and OMDM2 down-regulate macrophage function by (i) decreasing the surface expression of major histocompatibility complex (MHC) class II molecules, (ii) inhibiting nitric oxide synthase-2 (NOS-2) expression and (iii) reducing the production of the pro-inflammatory cytokines interleukin-1beta (IL-1beta) and interleukin-12 (IL-12p40). Taken together, these results point to the manipulation of the endocannabinoid system as a possible strategy to develop future MS therapeutic drugs.     

Opposing retrograde and astrocyte-dependent endocannabinoid signaling mechanisms regulate lateral habenula synaptic transmission

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Alterations of the endocannabinoid system and its therapeutic potential in autism spectrum disorder

Autism spectrum disorder (ASD) is a group of developmental disabilities, the aetiology of which remains elusive. The endocannabinoid (eCB) system modulates neurotransmission and neuronal plasticity. Evidence points to the involvement of this neuromodulatory system in the pathophysiology of ASD. We investigated whether there is a disruption to the eCB system in ASD and whether pharmacological modulation of the eCB system might offer therapeutic potential. We examined three major components of the eCB system—endogenous cannabinoids, their receptors and associated enzymes—in ASD children as well as in the valproic acid (VPA) induced animal model in autism. Furthermore, we specifically increased 2-arachidonoylglycerol (2-AG) levels by administering JZL184, a selective inhibitor of monoacylglycerol lipase which is the hydrolytic enzyme for 2-AG, to examine ASD-like behaviours in VPA-induced rats. Results showed that autistic children and VPA-induced rats exhibited reduced eCB content, increased degradation of enzymes and upregulation of CBRs. We found that repetitive and stereotypical behaviours, hyperactivity, sociability, social preference and cognitive functioning improved after acute and chronic JZL184 treatment. The major efficacy of JZL184 was observed after administration of a dosage regimen of 3 mg kg⁻¹, which affected both the eCB system and ASD-like behaviours. In conclusion, a reduced eCB signalling was observed in autistic children and in the ASD animal model, and boosting 2-AG could ameliorate ASD-like phenotypes in animals. Collectively, the results suggested a novel approach to ASD treatment.     

The vanilloid receptor (VR1)-mediated effects of anandamide are potently enhanced by the cAMP-dependent protein kinase

The endogenous cannabinoid receptor ligand, anandamide (AEA), is a full agonist of the vanilloid receptor type 1 (VR1) for capsaicin. Here, we demonstrate that the potency and efficacy of AEA at VR1 receptors can be significantly increased by the concomitant activation of protein kinase A (PKA). In human embryonic kidney (HEK) cells over-expressing human VR1, AEA induces a rise in cytosolic Ca(2+) concentration that is mediated by this receptor. The EC(50) for this effect was decreased five-fold in the presence of forskolin (FRSK, 1-5 microM) or the cAMP analogue, 8-Br-cAMP (10-100 microM). The effects of 8-Br-cAMP and FRSK were blocked by a selective PKA inhibitor. The FRSK (10 nM) also potently enhanced the sensory neurone- and VR1-mediated constriction by AEA of isolated guinea-pig bronchi, and this effect was abolished by a PKA inhibitor. In rat dorsal root ganglia slices, AEA-induced release of substance P, an effect mediated by VR1 activation, was enhanced three-fold by FRSK (10 nM). Thus, the ability of AEA to stimulate sensory VR1, with subsequent neuropeptide release, appears to be regulated by the state of activation of PKA. This observation supports the hypothesis that endogenous AEA might stimulate VR1 under certain pathophysiological conditions.     

Epidermal growth factor receptor expression in human gliomas

Summary The expression of epidermal growth factor receptor (EGFR) was determined in cryosections of 42 human gliomas using biotinylated epidermal growth factor (B-EGF) and two monoclonal antibodies (mAb) against EGFR. All gliomas were found to express EGFR when examined with B-EGF, whereas 33 expressed EGFR when examined with the two mAbs. The highly malignant gliomas (glioblastomas and anaplastic astrocytomas) had a more heterogeneous staining pattern and a larger proportion of tumour cells staining strongly with B-EGF than did the low-grade gliomas (astrocytomas, oligodendrogliomas, mixed gliomas, and ependymomas). This indicates that high-grade gliomas contain more tumour cells rich in EGFR than do the low-grade gliomas. Reactive astrocytes, ependymal cells, and many types of nerve cells (cerebral cortical pyramidal cells, pyramidal and granular hippocampal cells, Purkinje cells, cerebellar granular cells and neurons in the molecular layer of the cerebellum) expressed EGFR, whereas small neurons and normal glial cells were not found to express EGFR.     

The endocannabinoid system in normal and pathological brain ageing

The role of endocannabinoids as inhibitory retrograde transmitters is now widely known and intensively studied. However, endocannabinoids also influence neuronal activity by exerting neuroprotective effects and regulating glial responses. This review centres around this less-studied area, focusing on the cellular and molecular mechanisms underlying the protective effect of the cannabinoid system in brain ageing. The progression of ageing is largely determined by the balance between detrimental, pro-ageing, largely stochastic processes, and the activity of the homeostatic defence system. Experimental evidence suggests that the cannabinoid system is part of the latter system. Cannabinoids as regulators of mitochondrial activity, as anti-oxidants and as modulators of clearance processes protect neurons on the molecular level. On the cellular level, the cannabinoid system regulates the expression of brain-derived neurotrophic factor and neurogenesis. Neuroinflammatory processes contributing to the progression of normal brain ageing and to the pathogenesis of neurodegenerative diseases are suppressed by cannabinoids, suggesting that they may also influence the ageing process on the system level. In good agreement with the hypothesized beneficial role of cannabinoid system activity against brain ageing, it was shown that animals lacking CB1 receptors show early onset of learning deficits associated with age-related histological and molecular changes. In preclinical models of neurodegenerative disorders, cannabinoids show beneficial effects, but the clinical evidence regarding their efficacy as therapeutic tools is either inconclusive or still missing.     

The postmortal accumulation of brain N-arachidonylethanolamine (anandamide) is dependent upon fatty acid amide hydrolase activity

N-arachidonylethanolamine (AEA) accumulates during brain injury and postmortem. Because fatty acid amide hydrolase (FAAH) regulates brain AEA content, the purpose of this study was to determine its role in the postmortal accumulation of AEA using FAAH null mice. As expected, AEA content in immediately frozen brain tissue was significantly greater in FAAH-deficient (FAAH-/-) than in wild-type mice. However, AEA content was significantly lower in brains from FAAH-/- mice at 5 and 24 h postmortem. Similarly, wild-type mice treated in vivo with a FAAH inhibitor (URB532) had significantly lower brain AEA content 24 h postmortem compared with controls. These data indicate that FAAH contributes significantly to the postmortal accumulation of AEA. In contrast, the accumulations of two other N-acylethanolamines, N-oleoylethanolamine (OEA) and N-palmitoylethanolamine (PEA), were not reduced at 24 h postmortem in either the FAAH-/- mice or mice treated with URB532. FAAH-/- mice accumulated significantly less ethanolamine at 24 h postmortem compared with wild-type mice, suggesting that FAAH activity plays a role in the accumulation of ethanolamine postmortem. These data demonstrate that FAAH activity differentially affects AEA and OEA/PEA contents postmortem and suggest that AEA formation specifically occurs via an ethanolamine-dependent route postmortem.     

Cannabinoid receptors in invertebrates

Two cannabinoid receptors, CB1 and CB2, are expressed in mammals, birds, reptiles, and fish. The presence of cannabinoid receptors in invertebrates has been controversial, due to conflicting evidence. We conducted a systematic review of the literature, using expanded search parameters. Evidence presented in the literature varied in validity, ranging from crude in vivo behavioural assays to robust in silico ortholog discovery. No research existed for several clades of invertebrates; we therefore tested for cannabinoid receptors in seven representative species, using tritiated ligand binding assays with [3H]CP55,940 displaced by the CB1-selective antagonist SR141716A. Specific binding of [3H]CP55,940 was found in neural membranes of Ciona intestinalis (Deuterstoma, a positive control), Lumbricusterrestris (Lophotrochozoa), and three ecdysozoans: Peripatoides novae-zealandiae (Onychophora), Jasus edwardi (Crustacea) and Panagrellus redivivus (Nematoda); the potency of displacement by SR141716A was comparable to measurements on rat cerebellum. No specific binding was observed in Actinothoe albocincta (Cnidaria) or Tethya aurantium (Porifera). The phylogenetic distribution of cannabinoid receptors may address taxonomic questions; previous studies suggested that the loss of CB1 was a synapomorphy shared by ecdysozoans. Our discovery of cannabinoid receptors in some nematodes, onychophorans, and crustaceans does not contradict the Ecdysozoa hypothesis, but gives it no support. We hypothesize that cannabinoid receptors evolved in the last common ancestor of bilaterians, with secondary loss occurring in insects and other clades. Conflicting data regarding Cnidarians precludes hypotheses regarding the last common ancestor of eumetazoans. No cannabinoid receptors are expressed in sponges, which probably diverged before the origin of the eumetazoan ancestor.     

The endocannabinoid system modulates the ovarian physiology and its activation can improve in vitro oocyte maturation

The cannabinoid (CB) system has been involved in many aspects of reproduction and it is known that the systemic chronic use of exogenous CBs are deleterious to reproductive processes. Even so, it is not known what happens in relation to the physiology of the ovary when CB receptors are absent. The present study investigated the effect of the lack of CB1 and CB2 receptors in mice ovarian morphology, folliculogenesis, oocyte retrieval, and oocyte maturation and evaluated the use of Δ9-tetrahydrocannabinol (THC) on oocyte in vitro maturation (IVM) by comparing classical IVM and two-step IVM by analyzing the meiotic competence of the oocytes and their evolution toward embryos. Thus, when CB1 and CB2 receptors were missed, the ovary area and volume was significantly less and the action of the equine chorionic gonadotropin (eCG) hormone was diminished. In addition, the mutant genotypes had fewer ovarian follicles and they were less competent after eCG administration compared with wild-type mice, and this lack of CB receptors showed a mismatch of oocyte maturation. However, the in vitro use of THC showed improvements in oocytes IVM after a Pre-IVM step for 48 hr, as those oocytes reached a significantly higher polar body rate, a larger diameter and the best result on blastocysts rate was achieved when THC was used during the IVM step.     

Identification and characterization of a novel synthetic cannabinoid CP 55,940 binder in rat brain cytosol

We have detected the presence of a specific [³H] CP 55,940 binder in the cytosol of rat cerebral cortex. Competition studies showed that only cold CP 55,940 and to a lesser extent D⁹THC was able to compete with [³H] CP 55,940; little competition was observed with either D⁸;THC or anandamide. Scatchard analysis of the data indicate the presence of two distinct binding components having affinity constants (Kd) of 0.97 ± 0.03 nM, 5.83 ± 0.08 nM, and B_max of 3.31 ± 0.06 pmol/mg protein, 22.2 ± 1.2 pmol/mg protein respectively. The cytosolic CP 55,940 binder was heat stable up to 30øC. Besides the brain cytosol, lesser amounts of binding were also detected in the spleen, and testis. Liver, kidney and muscle cytosol preparations were found to be devoid of this binder. Unlike the previously characterized brain membrane cannabinoid receptor, this binder was found to be salt, sulfhydryl blocking reagents and nucleotide resistant. Interestingly, dithiothreitol (DTT), a protein-disulfide group reducing agent, inhibited the binding of [³H] CP-55,940 to the receptor and approximately 80% binding inhibition was obtained at a 5 mM concentration. Western blot analysis using anti-receptor antibody reveal the presence of a 95-110, 50 and 38 kDa band in the brain, spleen and testis cytosolic preparations. In conclusion, we have identified the presence of a novel CP 55,940 binder in rat cerebral cortex cytosol possessing biochemical properties distinct from those previously observed using rat cerebral cortex membrane cannabinoid receptor.     

The FGF receptor uses the endocannabinoid signaling system to couple to an axonal growth response

A key role for DAG lipase activity in the control of axonal growth and guidance in vitro and in vivo has been established. For example, DAG lipase activity is required for FGF-stimulated calcium influx into neuronal growth cones, and this response is both necessary and sufficient for an axonal growth response. The mechanism that couples the hydrolysis of DAG to the calcium response is not known. The initial hydrolysis of DAG at the sn-1 position (by DAG lipase) will generate 2-arachidonylglycerol, and this molecule is well established as an endogenous cannabinoid receptor agonist in the brain. In the present paper, we show that in rat cerebellar granule neurons, CB1 cannabinoid receptor antagonists inhibit axonal growth responses stimulated by N-cadherin and FGF2. Furthermore, three CB1 receptor agonists mimic the N-cadherin/FGF2 response at a step downstream from FGF receptor activation, but upstream from calcium influx into cells. In contrast, we could find no evidence for the CB1 receptor coupling the TrkB neurotrophin receptor to an axonal growth response in the same neurons. The observation that the CB1 receptor can couple the activated FGF receptor to an axonal growth response raises novel therapeutic opportunities.     

A single-cell transcriptome atlas of glial diversity in the human hippocampus across the postnatal lifespan

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