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[Different views on the association between cannabinoids and cancer].

Cannabinoids are the major active components of the most widely used illegal drug - marihuana. They have a long history of the medicinal use. However, they are still a controversial topic in oncological praxis. Cannabinoids play a role in different organs of human body and they are an integral part of the newly described endocannabinoid system, which regulates several body functions. The important function of endocannabinoids which is related to cancer, is the regulation of cell cycle and cell survival pathways. Presented review gives three different views on the association between cannabinoids and cancer. First, the treatment of adverse symptoms of oncological therapy - nausea and vomiting inhibition, appetite stimulation, pain relieving, mood modulation and muscle stiffness relieving. Second, in the late 1990s, three possible mechanisms of antitumour action were identified - apoptosis induction, direct cell cycle arrest and angiogenesis and metastasis inhibition. The phase I/II of clinical trials are carrying out in Spain. They study effects of local administration of tetrahydrokanabinol on the growth of glioblastoma multiforme. Third, the results of the newest study focused on the association between cannabinoids use and cancer risk showed no significant association between increased cancer incidence and cannabinoids use and it does not depend on the amount of used cannabis. It is important to establish the association between marihuana use and cancer risk regarding the consideration of advantages and risks of medicinal cannabinoids use and the impact on public health.

Animals↗

The enzymatic inactivation of the fatty acid amide class of signaling lipids.

The fatty acid amide (FAA) class of signaling lipids modulates a number of neurobehavioral processes in mammals, including pain, sleep, feeding, and locomotor activity. Representative FAAs include the endogenous cannabinoid anandamide and the sleep-inducing lipid oleamide. Despite activating several neuroreceptor systems in vitro, most FAAs produce only weak and transient behavioral effects in vivo, presumably due to their expeditious catabolism. This review focuses on one enzyme, fatty acid amide hydrolase (FAAH) that appears to play a major role in regulating the amplitude and duration of FAA signals in vivo. In particular, we will highlight a series of recent papers that have investigated the physiological functions of the mouse and human FAAH enzymes. Collectively, these studies promote FAAH as a central component of FAA signaling pathways, especially those mediated by the endocannabinoid anandamide, and suggest that this enzyme may represent an attractive pharmaceutical target for the treatment of pain and related neurophysiological disorders.

Amides↗

Gas chromatography-mass spectrometry analysis of endogenous cannabinoids in healthy and tumoral human brain and human cells in culture.

Endocannabinoids are lipid mediators thought to modulate central and peripheral neural functions. We report here gas chromatography-electron impact mass spectrometry analysis of human brain, showing that lipid extracts contain anandamide and 2-arachidonoylglycerol (2-AG), the most active endocannabinoids known to date. Human brain also contained the endocannabinoid-like compounds N-oleoylethanolamine, N-palmitoylethanolamine and N-stearoylethanolamine. Anandamide and 2-AG (0.16 +/- 0.05 and 0.10 +/- 0.05 nmol/mg protein, respectively) represented 7.7% and 4.8% of total endocannabinoid-like compounds, respectively. N-Palmitoyethanolamine was the most abundant (50%), followed by N-oleoyl (23.6%) and N-stearoyl (13.9%) ethanolamines. A similar composition in endocannabinoid-like compounds was found in human neuroblastoma CHP100 and lymphoma U937 cells, and also in rat brain. Remarkably, human meningioma specimens showed an approximately six-fold smaller content of all N-acylethanolamines, but not of 2-AG, and a similar decrease was observed in a human glioblastoma. These ex vivo results fully support the purported roles of endocannabinoids in the nervous system.

Amides↗

A critical review of the role of endothelial factors in the pathogenesis of hypertension.

The endothelium produces a variety of substances that play important roles in regulation of the circulation and vascular wall homeostasis. The control of blood vessel wall homeostasis is achieved via production of vasorelaxants and vasoconstrictors. Among the vasorelaxants are nitric oxide (NO), prostacyclin, various endothelium-derived hyperpolarizing factors (EDHFs, such as cytochrome P-450 monooxygenase metabolites of arachidonic acid like epoxyeicosatrienoic acids, and endocannabinoids), and C-type natriuretic peptide. Among the vasoconstrictors we find endothelin-1 (ET-1) and endothelium-derived contracting factors (EDCF) that are cyclooxygenase products such as endoperoxides and thromboxanes. The endothelium, via these and other agents, also exerts a critical influence on the blood stream, particularly formed elements such as leucocytes and platelets, and on substances involved in blood coagulation. All these effects contribute to modulating the growth of the vascular wall in hypertension, and participate in the development of atherothrombotic complications associated with hypertension. Inhibition of NO production may induce elevation of blood pressure in experimental animals. However, even today, we do not have incontrovertible evidence of participation of NO, EDHFs or EDCFs, or other endothelial products, in the pathogenesis of hypertension, although there is evidence of abnormal endothelium-dependent relaxation in hypertension in many but not all hypertensives. It is unclear, however, to what extent this may precede hypertension or be a consequence of elevated blood pressure, possibly contributing to its complications. Also, it is often difficult to dissociate abnormal endothelium-dependent relaxation from confounding factors such as the presence of associated conditions like dyslipidaemia, diabetes, smoking, obesity, hyperhomocysteinaemia, and others, that are accompanied themselves by abnormal endothelium-dependent relaxation. There is some evidence for a role of ET-1 in blood pressure elevation in some experimental forms of hypertension, particularly severe, sodium-sensitive hypertension, in which it may play a role in accentuating rather than initiating blood pressure elevation. Endothelin-1 may play a similar role in human hypertension.

8,11,14-Eicosatrienoic Acid↗

Selective inhibitors of fatty acid amide hydrolase relative to neuropathy target esterase and acetylcholinesterase: toxicological implications.

Fatty acid amide hydrolase (FAAH) plays an important role in nerve function by regulating the action of endocannabinoids (e.g., anandamide) and hydrolyzing a sleep-inducing factor (oleamide). Several organophosphorus pesticides and related compounds are shown in this study to be more potent in vivo inhibitors of mouse brain FAAH than neuropathy target esterase (NTE), raising the question of the potential toxicological relevance of FAAH inhibition. These FAAH-selective compounds include tribufos and (R)-octylbenzodioxaphosphorin oxide with delayed neurotoxic effects in mice and hens plus several organophosphorus pesticides (e.g., fenthion) implicated as delayed neurotoxicants in humans. The search for a highly potent and selective inhibitor for FAAH relative to NTE for use as a toxicological probe culminated in the discovery that octylsulfonyl fluoride inhibits FAAH by 50% at 2 nM in vitro and 0.2 mg/kg in vivo and NTE is at least 100-fold less sensitive in each case. More generally, the studies revealed 12 selective in vitro inhibitors for FAAH (mostly octylsulfonyl and octylphosphonyl derivatives) and 9 for NTE (mostly benzodioxaphosphorin oxides and organophosphorus fluoridates). The overall in vivo findings with 16 compounds indicate the expected association of AChE inhibition with acute or cholinergic syndrome and >70% brain NTE inhibition with delayed neurotoxic action. Surprisingly, 75-99% brain FAAH inhibition does not lead to any overt neurotoxicity or change in behavior (other than potentiation of exogenous anandamide action). Thus, FAAH inhibition in mouse brain does not appear to be a primary target for organophosphorus pesticide-induced neurotoxic action (cholinergic or intermediate syndrome or delayed neurotoxicity).

Acetylcholinesterase↗

Effects of cannabinoids on hypothalamic and reproductive function.

Marijuana and cannabinoids have been shown to exert profound effects on hypothalamic regulatory functions and reproduction in both experimental animals and humans. Here we review the role of (endo)cannabinoids in the regulation of appetite and food intake. There is converging evidence that the hypothalamic endocannabinoid system changes after leptin treatment. Cannabinoid administration decreases heat production by altering hypothalamic neurotransmitter production. Experimental and human data have also shown that the endocannabinoid system is involved in the regulation of reproductive function at both central and peripheral levels. We discuss also the role of fatty acid amide hydrolase (FAAH) in gestation, and in particular the regulation of the activity of FAAH by progesterone and leptin. We show that endocannabinoids inhibit the release of leukaemia inhibitory factor (LIF) from peripheral T lymphocytes. Taken together, endocannabinoids not only help to maintain neuroendocrine homeostasis, but also take part in immunological changes occurring during early pregnancy.

Animals↗

Cannabinoids, electrophysiology, and retrograde messengers: challenges for the next 5 years.

Most of the behavioral effects of cannabis and its active ingredients, the cannabinoids (delta9THC being the most abundant of these), appear to be mediated by cannabinoid receptors. Endogenous cannabinoids (endocannabinoids) are lipid mediators that activate these same cannabinoid receptors. Elegant work from several laboratories over the past 5 years has established that endocannabinoids, possibly acting as retrograde messengers, mediate several forms of neuronal plasticity. Endocannabinoid-mediated neuronal plasticity is common, apparently occurring at all neurons that express cannabinoid receptors. Thus, it is likely that delta9THC produces its effects by interacting with endocannabinoid-mediated neuronal plasticity, though whether it does so cooperatively or antagonistically remains an open question. In this review we will briefly discuss the work establishing endocannabinoids as mediators of neuronal plasticity and then present evidence that a major effect of delta9THC may be to antagonize the actions of endocannabinoids.

Animals↗

2-Arachidonoylglycerol (2-AG) membrane transport: history and outlook.

Only a few studies have addressed the transport of 2-arachidonoylglycerol (2-AG), a naturally occurring agonist for cannabinoid receptors. Based upon saturation kinetics, these early reports have proposed that 2-AG enters the cell by a specific 2-AG transporter, via the putative anandamide transporter, or by simple diffusion. In this review, the uptake of 2-AG is discussed in light of the recent advances that have been made for anandamide transport, where the mechanism appears to be rate-limited diffusion through the membrane. Endocannabinoids may be a distinct class of agonists since they are hydrophobic and neutral, exhibiting similar biophysical properties to some anesthetics that freely diffuse through the membrane.

Animals↗

Synergistic efects of opioid and cannabinoid antagonists on food intake.

RATIONALE: Central cannabinoid systems have been implicated in appetite regulation through the hyperphagic effects of exogenous and endogenous cannabinoids. These effects may involve activation of reward systems and be mediated in part by opioidergic processes. OBJECTIVE: Cannabinoid-opioid interactions in feeding were examined by testing the combined effects on food intake of sub-anorectic doses of selective antagonists for CB1 and opioid receptors. METHODS: Male rats (n = 8) received subcutaneous injections of naloxone (0, 0.1, 0.5, 1.0 mg/kg) and SR141716 (0, 0.1, 0.5, 1.0 mg/kg) before l-h, nocturnal food (chow) intake tests. RESULTS: Neither naloxone nor SR141716 reliably affected feeding when administered alone. By contrast, combined administration of the two antagonists significantly suppressed chow intake at each dose combination. Joint administration of the highest doses of each antagonist suppressed intake by 73%, a significantly greater effect than produced by either naloxone (32%) or SR141716 alone (17%). CONCLUSION: The data reveal a synergistic interaction between the effects of naloxone and SR141716 on feeding, provide further evidence of important functional relationships between endogenous cannabinoid and opioid systems, and strengthen the postulated role for endocannabinoids in reward processes contributing to the normal control of appetite.

Animals↗

(R)-methanandamide and Delta 9-THC as discriminative stimuli in rats: tests with the cannabinoid antagonist SR-141716 and the endogenous ligand anandamide.

RATIONALE AND OBJECTIVES: (R)-methanandamide (AM-356), a metabolically more stable chiral analog of the endocannabinoid ligand anandamide, was used as a representative of fatty acid ethanolamide CB1 receptor ligands to characterize the discriminative stimulus functions of anandamides. METHODS: Rats discriminated between 10 mg/kg (R)-methanandamide and vehicle administered IP 15 min prior to session onset. Another group of rats was initially trained to discriminate between 3 mg/kg Delta9-THC and vehicle given IP 30 min prior to session onset; for anandamide testing, the animals were retrained with 1.8 and 5.6 mg/kg Delta9-THC. A two lever operant methodology (FR10) was used. RESULTS: Delta9-THC was more potent than (R)-methanandamide at both 15 and 30 min post-injection, irrespective of the training drug used. Additional tests with 10 and 18 mg/kg (R)-methanandamide suggested that the effects were declining by 1 h. The cannabinoid antagonist SR 141716 (0.3 and 1 mg/kg) produced rightward shifts in the Delta9-THC dose-response curve for Delta9-THC-appropriate responding and for (R)-methanandamide-appropriate responding (surmountable antagonism). SR-141716 (0.3 and 1 mg/kg) antagonized the ability of (R)-methanandamide to occasion either Delta9-THC-appropriate responding or (R)-methanandamide-appropriate responding. This antagonism was surmountable only at a dose of 0.3 mg/kg SR-1421716 in the (R)-methanandamide-trained rats. SR-141716 did not antagonize the rate-decreasing effects of (R)-methanandamide in either the Delta9-THC or the (R)-methanandamide trained rats. Response suppression precluded testing doses higher than 30 mg/kg (R)-methanandamide. Tests with SR-141716 (1 and 10 mg/kg) alone resulted in <3% Delta9-THC-appropriate responding. With 10 mg/kg SR-141716, response rate was significantly lower as compared to the rate observed during a vehicle test. Tests with anandamide (10 and 18 mg/kg) resulted in 41% and 85% (R)-methanandamide-appropriate responding at a 3-min pre-treatment time, but in a maximum of 15% (R)-methanandamide-appropriate responding at a longer (15 min) pre-treatment time. In the Delta9-THC (1.8 and 5.6 mg/kg) trained rats, anandamide never produced more than about 20% Delta9-THC-appropriate responding. CONCLUSION: The results add to a growing body of evidence indicating that there are both similarities and dissimilarities between classical cannabinoids such as THC and endogenous fatty acid ethanolamides.

Adjuvants, Immunologic↗

Quantitative profiling of endocannabinoids and related compounds in rat brain using liquid chromatography-tandem electrospray ionization mass spectrometry.

A sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) method is described for the simultaneous identification and quantification of eight endocannabinoid (EC) or related "entourage" compounds in rat brain tissue. Analytes were extracted and purified from rat brain tissue using an ethyl acetate/hexane solvent extraction, followed by a solid phase extraction (SPE) protocol. Chromatographic separation was achieved using a gradient elution, with a mobile phase of acetonitrile, formic acid, and ammonium acetate, at pH 3.6. A Thermo Hypersil C8 HyPurity Advance column (100x2.1 mm i.d., 3 microm) was used with a flow rate of 0.3 ml/min). Anandamide (AEA), 2-arachidonyl glycerol (2-AG), 2-arachidonylglyceryl ether (noladin ether), O-arachidonyl ethanolamide (virodhamine), 2-linoleoyl glycerol (2-LG), arachidonyl glycine, oleoyl ethanolamide (OEA), and palmitoyl ethanolamide (PEA) were quantified by positive ion tandem electrospray ionization mass spectrometry. Internal standards were deuterated AEA, deuterated 2-AG, and heptadecanoyl ethanolamide (HEA). Linearity was proven over the range of 25 fmol to 250 pmol, with a limit of detection of 25 fmol on column for all analytes except 2-AG, noladin ether, and 2-LG (250 fmol). This corresponded to a limit of quantification in biological tissue of 10 pmol/g for all analytes except 2-AG (100 pmol/g). Intra- and interday precision in biological tissue was routinely approximately 20% or lower, and accuracy was between 65% and 155%. This method was used to quantitatively profile regional differences in nine discrete rat brain regions for AEA, 2-AG, 2-LG, OEA, PEA, noladin ether, virodhamine, and arachidonyl glycine.

Animals↗

Central glucocorticoid receptors modulate the expression of spinal cannabinoid receptors induced by chronic morphine exposure.

Central cannabinoid receptors (CBRs) have been implicated in the opioid analgesic effects. However, it remains unclear as to whether the expression of central CBRs would be altered after repeated morphine exposure. Here, we show that chronic intrathecal treatment with morphine (10 microg, twice daily for 6 days) induced a time-dependent upregulation of both CB-1 and CB-2 receptors within the spinal cord dorsal horn. This morphine-induced CB-1 and CB-2 upregulation was dose-dependently attenuated by the intrathecal co-administration of morphine with the glucocorticoid receptor (GR) antagonist RU38486 (0.25, 0.5, or 2 microg). The intrathecal RU38486 treatment regimen also attenuated the development of morphine tolerance. These results indicate that the expression of spinal CBRs was altered following repeated morphine exposure and regulated by the activation of central GRs.

Analgesics, Opioid↗

[Maternal cannabis use and intra-uterine growth restriction].

Marijuana is the most commonly used illegal drug, especially among young women in Western societies. The effects of cannabis use during pregnancy have been studied for many years. The vast majority of studies have shown a link between maternal consumption of cannabis and foetal development. Foetal growth restriction seems to be the major complication of cannabis exposure. Nevertheless, all these studies have suffered from several methodological biases. The maternal marijuana use should be first and foremost detected in pregnant women for a specific addiction management and pregnancy follow-up.

Adolescent↗

Natural cannabinoids: templates for drug discovery.

Recent studies have elucidated the biosynthetic pathway of cannabinoids and have highlighted the preference for a C-3 n-pentyl side chain in the most prominently represented cannabinoids from Cannabis sativa and their medicinally important decarboxylation products. The corresponding C-3 n-propyl side chain containing cannabinoids are also found, although in lesser quantities. Structure-activity relationship (SAR) studies performed on Delta(9)-tetrahydrocannabinol (Delta(9)-THC), the key psychoactive ingredient of Cannabis, and its synthetic analogues have identified the C-3 side chain as the key pharmacophore for ligand affinity and selectivity for the known cannabinoid receptors and for pharmacological potency. Interestingly, the terminal n-pentyl saturated hydrocarbon side chain of endocannabinoids also plays a corresponding crucial role in conferring similar properties. This review briefly summarizes the biosynthesis of cannabinoids and endocannabinoids and focuses on their side chain SAR.

Animals↗

The role of the cannabinoid system in nicotine addiction.

Nicotine, the main psychoactive component in tobacco smoke, appears to play a major role in tobacco addiction, producing a high morbidity and mortality in the world. A great amount of research has been developed to elucidate the neural pathways and neurotransmitter systems involved in such a complex addictive behaviour. One possible candidate is the cannabinoid system, which has been reported to participate in the addictive properties of other drugs of abuse. This review is focused on the recent pharmacological and molecular studies assessing cannabinoid-nicotine interactions, with special attention to those studies evaluating the behavioural responses related to the development of nicotine addiction.

Animals↗

Endocannabinoid signaling system and brain reward: emphasis on dopamine.

The brain's reward circuitry consists of an "in series" circuit of dopaminergic (DA) neurons in the ventral tegmental area (VTA), nucleus accumbens (Acb), and that portion of the medial forebrain bundle (MFB) which links the VTA and Acb. Drugs which enhance brain reward (and have derivative addictive potential) have common actions on this core DA reward system and on animal behaviors relating to its function. Such drugs enhance electrical brain-stimulation reward in this reward system; enhance neural firing and DA tone within it; produce conditioned place preference (CPP), a behavioral model of incentive motivation; are self-administered; and trigger reinstatement of drug-seeking behavior in animals extinguished from drug self-administration. Cannabinoids were long considered different from other reward-enhancing drugs in reward efficacy and in underlying neurobiological substrates activated. However, it is now clear that cannabinoids activate these brain reward processes and reward-related behaviors in similar fashion to other reward-enhancing drugs. This brief review discusses the roles that endogenous cannabinoids (especially activation of the CB1 receptor) may play within the core reward system, and concludes that while cannabinoids activate the reward pathways in a manner consistent with other reward-enhancing drugs, the neural mechanisms by which this occurs may differ.

Animals↗

How lipophilic cannabinergic ligands reach their receptor sites.

It is postulated that lipophilic ligands reach their sites of action on membrane-bound functional proteins through fast lateral diffusion across the membrane bilayer. We have shown using NMR experiments that such ligands when incorporated in a membrane system assume a preferred orientation and conformation. While occupying a specific location within the bilayer, these molecules undergo fast lateral diffusion which allows them to engage in productive interactions with their respective protein sites of action. The proposed model is discussed using a group of classical and non-classical cannabinoids as well as the endogenous cannabinoid ligand anandamide.

Animals↗