Antidepressant-like effects of cannabidiol in mice: possible involvement of 5-HT1A receptors

 “Extracts of the Cannabis sativa plant elicit in humans a complex subjective experience that includes euphoria, heightened sensitivity to external stimuli and relaxation. This plant contains more than 400 different compounds, of which 66 are termed cannabinoids. Δ9-tetrahydrocannabinol (Δ9-THC), one of the major constituents of C. sativa extracts is thought to account for most of the effects of cannabis through the activation of cannabinoid CB1 receptors in the brain….The major endogenous agonists of the CB1 receptor are anandamide and 2-arachidonoyl glycerol, referred to as endocannabinoids…”

“It has recently been suggested that the endocannabinoid system may be involved in the pathophysiology of depression. This is supported by several pieces of evidence showing that endocannabinoids and CB1 receptors are widely distributed in brain areas that are often related to affective disorders and that their expression is regulated by antidepressant drugs. Moreover, administration of inhibitors of anandamide uptake or metabolism, as well as CB1 receptor agonists induces antidepressant-like effects in different animal models. In accordance with these preclinical results, many patients report benefits from cannabis use in depressive syndromes…”

“Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa that induces anxiolytic- and antipsychotic-like effects in animal models. Effects of CBD may be mediated by the activation of 5-HT1A receptors. As 5-HT1A receptor activation may induce antidepressant-like effects, the aim of this work was to test the hypothesis that CBD would have antidepressant-like activity in mice as assessed by the forced swimming test. We also investigated if these responses depended on the activation of 5-HT1A receptors and on hippocampal expression of brain-derived neurotrophic factor (BDNF).”

“Conclusion and implications:

CBD induces antidepressant-like effects comparable to those of imipramine. These effects of CBD were probably mediated by activation of 5-HT1A receptors.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2823358/

Abnormal mGlu 5 Receptor/Endocannabinoid Coupling in Mice Lacking FMRP and BC1 RNA

“Transcriptional silencing of the gene encoding the fragile X mental retardation protein (FMRP) causes fragile X syndrome (FXS)…

Our data indicate for the first time that mGlu5R-driven endocannabinoid signaling in the striatum is under the control of both FMRP and BC1 RNA. The abnormal mGlu5R/2-AG coupling found in FMRP-KO mice emphasizes the involvement of mGlu5Rs in the synaptic defects of FXSand identifies the modulation of the endocannabinoid system as a novel target for the treatment of this severe neuropsychiatric disorder.

In conclusion, this is the first study addressing endocannabinoid system in a model of FXS. Our results show that dysfunctional mGlu5R signaling leads to abnormal 2-AG metabolism and physiological activity, and indicate that inhibition of 2-AG synthesis or activity at CB1Rs might be a useful treatment option in FXS patients. In this respect, recent investigations suggest that this modulation could be achieved not only by direct pharmacological blockade of CB1Rs, but also indirectly, for example through the inhibition of anandamide degradation or the stimulation of transient receptor potential vanilloid 1 (TRPV1) channels. These two components of the endocannabinoid system, in fact, have been shown to selectively interact with mGlu5R/2-AG coupling in striatal neurons, and might interfere with the synaptic alterations seen after FMRP ablation with less side effects than those of widespread pharmacological inhibition of CB1Rs, which control not only GABA but also glutamate synapses.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3055456/

[Cannabinoids in the control of pain].

Abstract

“Hemp (Cannabis sativa L.) has been used since remotes ages as a herbal remedy. Only recently the medical community highlighted the pharmacological scientific bases of its effects. The most important active principle, Delta-9-tetrahydrocannabinol, was identified in the second half of the last century, and subsequently two receptors were identified and cloned: CB1 that is primarily present in the central nervous system, and CB2 that is present on the cells of the immune system. Endogenous ligands, called endocannabinoids, were characterized. The anandamide was the first one to be discovered. The effectiveness of the cannabinoids in the treatment of nausea and vomit due to anti-neoplastic chemotherapy and in the wasting-syndrome during AIDS is recognized. Moreover, the cannabinoids are analgesic, and their activity is comparable to the weak opioids. Furthermore, parallels exist between opioid and cannabinoid receptors, and evidence is accumulating that the two systems sometimes may operate synergistically. The interest of the pharmaceutical companies led to the production of various drugs, whether synthetic or natural derived. The good ratio between the polyunsatured fatty acids omega-3 and omega-6 of the oil of Cannabis seeds led to reduction of the phlogosis and an improvement of the pain symptoms in patients with chronic musculo-skeletal inflammation.”

http://www.ncbi.nlm.nih.gov/pubmed/19388223

Attenuation of Experimental Autoimmune Hepatitis by Exogenous and Endogenous Cannabinoids: Involvement of Regulatory T Cells

“The endocannabinoid system plays a protective role in various inflammatory diseases, and it is considered an attractive therapeutic target.”

“The aim of the present study was to determine the immunomodulatory effect of THC in the murine model of ConA-induced hepatitis. We demonstrate that a single injection of THC significantly ameliorates ConA-induced T-cell-mediated liver injury by up-regulating Forkhead helix transcription factor p3 (Foxp3)+ regulatory T cells and down-regulating inflammatory cytokines. Using select cannabinoid receptor agonists and antagonists, we demonstrate that THC mediates immune modulation in this model by signaling through both CB1 and CB2 receptors. We also demonstrate that anandamide, an endocannabinoid can effectively attenuate the disease.”

“There is growing interest in recent years to target cannabinoid receptors for treating liver diseases. In the current study, CB1 or CB2 activation alone had no anti-inflammatory effect on hepatitis. However, cannabinoids that bind to both CB1 and CB2 receptors (THC, CP55,940, WIN55212, and anandamide) effectively attenuated hepatitis. That CB1/CB2 mixed agonists could suppress the disease but not the coadministered CB1 and CB2 agonists indicates that both the cannabinoid receptors need to be activated simultaneously to produce the observed effect and that the different pharmacokinetics of the two coadministered agonists may not allow this to happen. Signaling through both the receptors is important because blocking either CB1 or CB2 could reverse the effect of THC.”

“Taken together, our data suggest that exogenous cannabinoids such as THC upon binding to CB1 and CB2 receptors on immune cells, induce apoptosis in effector T cells, up-regulate Treg function, and suppress inflammatory cytokines there by preventing ConA-induced activated T-cell-mediated liver injury. The observation that the anandamide treatment ameliorates ConA-induced hepatitis, together with FAAH deficiency or inhibition leading to increased resistance to the disease, strongly suggests that the endocannabinoid system serves to attenuate the inflammatory response in ConA-induced acute hepatitis. These findings raise the promising potential of developing novel pharmacological treatments for T-cell-mediated liver diseases.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2828293/

New insights into endocannabinoid degradation and its therapeutic potential.

Abstract

“Endocannabinoids are amides, esters and ethers of long chain polyunsaturated fatty acids, which act as new lipidic mediators. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the main endogenous agonists of cannabinoid receptors, able to mimic several pharmacological effects of (-)-Delta9-tetrahydrocannabinol (THC), the active principle of Cannabis sativa preparations like hashish and marijuana. The activity of AEA and 2-AG at their receptors is limited by cellular uptake through an anandamide membrane transporter (AMT), followed by intracellular degradation. A fatty acid amide hydrolase (FAAH) is the main AEA hydrolase, whereas a monoacylglycerol lipase (MAGL) is critical in degrading 2-AG. Here, we will review growing evidence that demonstrates that these hydrolases are pivotal regulators of the endogenous levels of AEA and 2-AG in vivo, overall suggesting that specific inhibitors of AMT, FAAH or MAGL may serve as attractive therapeutic targets for the treatment of human disorders. Recently, the N-acylphosphatidylethanolamine-specific phospholipase D (NAPE-PLD), which synthesizes AEA from N-arachidonoylphosphatidylethanolamine (NArPE), and the diacylglycerol lipase (DAGL), which generates 2-AG from diacylglycerol (DAG) substrates, have been characterized. The role of these synthetic routes in maintaining the endocannabinoid tone in vivo will be discussed. Finally, the effects of inhibitors of endocannabinoid degradation in animal models of human disease will be reviewed, with an emphasis on their ongoing applications in anxiety, cancer and neurodegenerative disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/16515464

A metabolically stable analogue of anandamide, Met-F-AEA, inhibits human thyroid carcinoma cell lines by activation of apoptosis.

Abstract

  “The active components of Cannabis sativa and their derivatives produce a wide spectrum of effects, some of which may have clinical application. The discovery of specific cannabinoid receptors and a family of endogenous ligands of those receptors has attracted much attention to cannabinoids as agents capable of controlling the decision of cells to survive or die. We analysed the effects exerted by 2-methyl-2′-F-anandamide (Met-F-AEA), a metabolically stable analogue of anandamide, and observed a growth inhibition in cell lines derived from thyroid carcinomas. Growth inhibition was associated with a high level of CB1 receptor expression, suggesting that the cytotoxic effect is due to interaction with the CB1 receptor. This phenomenon was associated with activation of the protein, p53, an increased apoptotic rate, and expression of p21(CIP1/WAF1). This study provides new insights into the mechanism of Met-F-AEA action, and could have significance in providing a basis for the management of thyroid carcinoma.”

http://www.ncbi.nlm.nih.gov/pubmed/19189054

Inhibition of cancer cell invasion by cannabinoids via increased expression of tissue inhibitor of matrix metalloproteinases-1.

JNCI: Journal of the National Cancer Institute

“Cannabinoids, in addition to having palliative benefits in cancer therapy, have been associated with anticarcinogenic effects. Although the antiproliferative activities of cannabinoids have been intensively investigated, little is known about their effects on tumor invasion.”

“Increased expression of TIMP-1 mediates an anti-invasive effect of cannabinoids. Cannabinoids may therefore offer a therapeutic option in the treatment of highly invasive cancers.”

“There is considerable evidence to suggest an important role for cannabinoids in conferring anticarcinogenic activities. In this study, we identified TIMP-1 as a mediator of the anti-invasive actions of MA, a hydrolysis-stable analog of the endocannabinoid anandamide, and THC, a plant-derived cannabinoid.”

“In conclusion, our results suggest that there exists a signaling pathway by which the binding of cannabinoids to specific receptors leads via intracellular MAPK activation to induction of TIMP-1 expression and subsequent inhibition of tumor cell invasion. To our knowledge, this is the first report of TIMP-1–dependent anti-invasive effects of cannabinoids.”

http://jnci.oxfordjournals.org/content/100/1/59.long

Antiangiogenic activity of the endocannabinoid anandamide: correlation to its tumor-suppressor efficacy.

  “Endocannabinoids are now emerging as suppressors of key cell-signaling pathways involved in cancer cell growth, invasion, and metastasis. We have previously observed that the metabolically stable anandamide analog, 2-methyl-2′-F-anandamide (Met-F-AEA) can inhibit the growth of thyroid cancer in vivo. Our hypothesis was that the anti-tumor effect observed could be at least in part ascribed to inhibition of neo-angiogenesis… our results suggest that anandamide could be involved in the control of cancer growth targeting both tumor cell proliferation and the angiogenic stimulation of the vasculature.”

http://www.ncbi.nlm.nih.gov/pubmed/17192847

The phylogenetic distribution and evolutionary origins of endocannabinoid signalling.

Abstract

“The endocannabinoid signalling system in mammals comprises several molecular components, including cannabinoid receptors (e.g. CB1, CB2), putative endogenous ligands for these receptors [e.g. anandamide, 2-arachidonoylglycerol (2-AG)] and enzymes involved in the biosynthesis and inactivation of anandamide (e.g. NAPE-PLD, FAAH) and 2-AG (e.g. DAG lipase, MGL). In this review we examine the occurrence of these molecules in non-mammalian organisms (in particular, animals and plants) by surveying published data and by basic local alignment search tool (BLAST) analysis of the GenBank database and of genomic sequence data from several vertebrate and invertebrate species. We conclude that the ability of cells to synthesise molecules that are categorised as “endocannabinoids” in mammals is an evolutionarily ancient phenomenon that may date back to the unicellular common ancestor of animals and plants. However, exploitation of these molecules for intercellular signalling may have occurred independently in different lineages during the evolution of the eukaryotes. The CB1- and CB2-type receptors that mediate effects of endocannabinoids in mammals occur throughout the vertebrates, and an orthologue of vertebrate cannabinoid receptors was recently identified in the deuterostomian invertebrate Ciona intestinalis (CiCBR). However, orthologues of the vertebrate cannabinoid receptors are not found in protostomian invertebrates (e.g. Drosophila, Caenorhabditis elegans). Therefore, it is likely that a CB1/CB2-type cannabinoid receptor originated in a deuterostomian invertebrate. This phylogenetic information provides a basis for exploitation of selected non-mammalian organisms as model systems for research on endocannabinoid signalling”

.http://www.ncbi.nlm.nih.gov/pubmed/16596778

Cannabinoid signalling in the enteric nervous system.

Abstract

“Cannabinoid signalling is an important mechanism of synaptic modulation in the nervous system. Endogenous cannabinoids (anandamide and 2-arachidonyl-glycerol) are synthesized and released via calcium-activated biosynthetic pathways. Exogenous cannabinoids and endocannabinoids act on CB1 and CB2 receptors. CB1 receptors are neuronal receptors which couple via G-proteins to inhibition of adenylate cyclase or to activation or inhibition of ion channels. CB2 receptors are expressed by immune cells and cannabinoids can suppress immune function. In the central nervous system, the endocannabinoids may function as retrograde signals released by the postsynaptic neuron to inhibit neurotransmitter release from presynaptic nerve terminals. Enteric neurons also express CB receptors. Exogenously applied CB receptor agonists inhibit enteric neuronal activity but it is not clear if endocannabinoids released by enteric neurons can produce similar responses in the enteric nervous system (ENS). In this issue of Neurogastroenterology and Motility, Boesmans et al. show that CB1 receptor activation on myenteric neurons maintained in primary culture can suppress neuronal activity, inhibit synaptic transmission and mitochondrial transport along axons. They also provide initial evidence that myenteric neurons (or other cell types present in the cultures) release endocannabinoids and which activate CB1 receptors constitutively. These data provide new information about targets for cannabinoid signalling in the ENS and highlight the potential importance of CB receptors as drug targets. It is necessary that future work extends these interesting findings to intact tissues and ideally to the in vivo setting.”

http://www.ncbi.nlm.nih.gov/pubmed/19689654