Cannabinoids and epilepsy — Introduction.

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“Over the past five years, the lay press and families of children with catastrophic epilepsies popularized the use of cannabis and cannabinoids to treat seizures. Many state legislatures have responded to the pressure from lay groups and have legalized medical cannabis, which is now available to a majority of people in the United States. Patients throughout the world are also obtaining and using cannabinoids to treat their epilepsy. There is an enormous dissociation between the widespread use of cannabis-based therapies to treat diverse epilepsies and our understanding about the efficacy and safety of different cannabinoids in treating different epilepsy syndromes.”

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Pregnenolone blocks cannabinoid-induced acute psychotic-like states in mice.

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“Cannabis-induced acute psychotic-like states (CIAPS) represent a growing health issue, but their underlying neurobiological mechanisms are poorly understood.

The use of antipsychotics and benzodiazepines against CIAPS is limited by side effects and/or by their ability to tackle only certain aspects of psychosis. Thus, safer wide-spectrum treatments are currently needed.

Although the blockade of cannabinoid type-1 receptor (CB1) had been suggested as a therapeutical means against CIAPS, the use of orthosteric CB1 receptor full antagonists is strongly limited by undesired side effects and low efficacy.

The neurosteroid pregnenolone has been recently shown to act as a potent endogenous allosteric signal-specific inhibitor of CB1 receptors. Thus, we tested in mice the potential therapeutic use of pregnenolone against acute psychotic-like effects of Δ9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis.

We found that pregnenolone blocks a wide spectrum of THC-induced endophenotypes typically associated with psychotic-like states, including impairments in cognitive functions, somatosensory gating and social interaction. Overall, this work reveals that signal-specific inhibitors mimicking pregnenolone effects can be considered as promising new therapeutic tools to treat CIAPS.”

“Pregnenolone can protect the brain from cannabis intoxication. The administration of the main active principle of Cannabis sativa (marijuana), Δ(9)-tetrahydrocannabinol (THC), substantially increases the synthesis of pregnenolone in the brain via activation of the type-1 cannabinoid (CB1) receptor. Pregnenolone then, acting as a signaling-specific inhibitor of the CB1 receptor, reduces several effects of THC. This negative feedback mediated by pregnenolone reveals a previously unknown paracrine/autocrine loop protecting the brain from CB1 receptor overactivation that could open an unforeseen approach for the treatment of cannabis intoxication and addiction.”

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Effects of tetrahydrocannabinol on glucose uptake in the rat brain.

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“Δ9-Tetrahydrocannabinol (THC) is the psychoactive component of the plant Cannabis sativa and acts as a partial agonist at cannabinoid type 1 and type 2 receptors in the brain.

The goal of this study was to assess the effect of THC on the cerebral glucose uptake in the rat brain.

Low blood THC levels of <1 ng/ml corresponded to an increased glucose uptake while blood THC levels > 10 ng/ml coincided with a decreased glucose uptake. The effective concentration in this region was estimated 2.4 ng/ml.

This glucose PET study showed that stimulation of CB1 receptors by THC affects the glucose uptake in the rat brain, whereby the effect of THC is regionally different and dependent on dose – an effect that may be of relevance in behavioural studies.”

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Extinction of avoidance behavior by safety learning depends on endocannabinoid signaling in the hippocampus.

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“The development of exaggerated avoidance behavior is largely responsible for the decreased quality of life in patients suffering from anxiety disorders. Studies using animal models have contributed to the understanding of the neural mechanisms underlying the acquisition of avoidance responses. However, much less is known about its extinction.

Here we provide evidence in mice that learning about the safety of an environment (i.e., safety learning) rather than repeated execution of the avoided response in absence of negative consequences (i.e., response extinction) allowed the animals to overcome their avoidance behavior in a step-down avoidance task.

This process was context-dependent and could be blocked by pharmacological (3 mg/kg, s.c.; SR141716) or genetic (lack of cannabinoid CB1 receptors in neurons expressing dopamine D1 receptors) inactivation of CB1 receptors. In turn, the endocannabinoid reuptake inhibitor AM404 (3 mg/kg, i.p.) facilitated safety learning in a CB1-dependent manner and attenuated the relapse of avoidance behavior 28 days after conditioning.

Safety learning crucially depended on endocannabinoid signaling at level of the hippocampus, since intrahippocampal SR141716 treatment impaired, whereas AM404 facilitated safety learning.

Other than AM404, treatment with diazepam (1 mg/kg, i.p.) impaired safety learning. Drug effects on behavior were directly mirrored by drug effects on evoked activity propagation through the hippocampal trisynaptic circuit in brain slices: As revealed by voltage-sensitive dye imaging, diazepam impaired whereas AM404 facilitated activity propagation to CA1 in a CB1-dependent manner. In line with this, systemic AM404 enhanced safety learning-induced expression of Egr1 at level of CA1.

Together, our data render it likely that AM404 promotes safety learning by enhancing information flow through the trisynaptic circuit to CA1.”

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Involvement of Cannabinoid Signaling in Vincristine-Induced Gastrointestinal Dysmotility in the Rat.

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“In different models of paralytic ileus, cannabinoid receptors are overexpressed and endogenous cannabinoids are massively released, contributing to gastrointestinal dysmotility. The antitumoral drug vincristine depresses gastrointestinal motility and a similar mechanism could participate in this effect. Therefore, our aim was to determine, using CB1 and CB2 antagonists, whether an increased endocannabinoid tone is involved in vincristine-induced gastrointestinal ileus.

Key results: Vincristine induced damage to the mucosa of ileum and colon and reduced gastrointestinal motor function at 0.5 mg/kg. The effect on motor function was particularly evident when the study started 24 h after administration. AM251, but not AM630, significantly prevented vincristine effect, particularly in the small intestine, when administered thrice. AM251 alone did not significantly alter gastrointestinal motility.

Conclusions: The fact that AM251, but not AM630, is capable of reducing the effect of vincristine suggests that, like in other experimental models of paralytic ileus, an increased cannabinoid tone develops and is at least partially responsible for the alterations induced by the antitumoral drug on gastrointestinal motor function. Thus, CB1 antagonists might be useful to prevent/treat ileus induced by vincristine.”

“Paralytic ileus: Obstruction of the intestine due to paralysis of the intestinal muscles.”

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Gut-brain axis: Role of lipids in the regulation of inflammation, pain and CNS diseases.

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“The human gut is a composite anaerobic environment with a large, diverse and dynamic enteric microbiota, represented by more than 100 trillion microorganisms, including at least 1000 distinct species. The discovery that a different microbial composition can influence behavior and cognition, and in turn the nervous system can indirectly influence enteric microbiota composition, has significantly contributed to establish the well-accepted concept of gut-brain axis.

This hypothesis is supported by several evidence showing mutual mechanisms, which involve the vague nerve, the immune system, the hypothalamic-pituitary-adrenal (HPA) axis modulation and the bacteria-derived metabolites. Many studies have focused on delineating a role for this axis in health and disease, ranging from stress-related disorders such as depression, anxiety and irritable bowel syndrome (IBS) to neurodevelopmental disorders, such as autism, and to neurodegenerative diseases, such as Parkinson Disease, Alzheimer Disease etc.

Based on this background, and considering the relevance of alteration of the symbiotic state between host and microbiota, this review focuses on the role and the involvement of bioactive lipids, such as the N-acylethanolamine (NAE) family whose main members are N-arachidonoylethanolamine (AEA), palmitoylethanolamide (PEA) and oleoilethanolamide (OEA), and short chain fatty acids (SCFAs), such as butyrate, belonging to a large group of bioactive lipids able to modulate peripheral and central pathologic processes.

It is well established their effective role in inflammation, acute and chronic pain, obesity and central nervous system diseases. It has been shown a possible correlation between these lipids and gut microbiota through different mechanisms.

Indeed, systemic administration of specific bacteria can reduce abdominal pain through the involvement of cannabinoid receptor 1 in rat; on the other hand, PEA reduces inflammation markers in a murine model of inflammatory bowel disease (IBD), and butyrate, producted by gut microbiota, is effective in reducing inflammation and pain in irritable bowel syndrome and IBD animal models.

In this review, we underline the relationship among inflammation, pain, microbiota and the different lipids, focusing on a possible involvement of NAEs and SCFAs in the gut-brain axis and their role in central nervous system diseases.”

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Human Cannabinoid Receptor 2 Ligand-interaction Motif: Transmembrane Helix 2 Cysteine, C2.59(89), as Determinant of Classical Cannabinoid Agonist Activity and Binding Pose.

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“Cannabinoid receptor 2 (CB2R)-dependent signaling is implicated in neuronal physiology and immune surveillance by brain microglia. Selective CB2R agonists hold therapeutic promise for inflammatory and other neurological disorders.

Information on human CB2R (hCB2R) ligand-binding and functional domains is needed to inform the rational design and optimization of candidate drug-like hCB2R agonists.

These data constitute initial evidence that TMH2 cysteine C2.59(89) is a component of the hCB2R binding pocket for classical cannabinoids.

The results further demonstrate how interactions between classical cannabinoids and specific amino acids within the hCB2R* ligand-binding domain act as determinants of agonist pharmacological properties and the architecture of the agonist-hCB2R* conformational ensemble, allowing the receptor to adopt distinct activity states, such that interaction of classical cannabinoids with TMH6 cysteine C6.47(257) favors a binding pose more advantageous for agonist potency than does their interaction with TMH2 cysteine C2.59(89).”

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The Inhibitory Effect of S-777469, a Cannabinoid Type 2 Receptor Agonist, on Skin Inflammation in Mice.

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“We investigated the effects of S-777469 (1-[[6-Ethyl-1-[4-fluorobenzyl]-5-methyl-2-oxo-1, 2-dihydropyridine-3-carbonyl]amino]-cyclohexanecarboxylic acid), a novel cannabinoid type 2 receptor (CB2) agonist, on 1-fluoro-2,4-dinitrobenzene (DNFB)-induced ear inflammation and mite antigen-induced dermatitis in mice. The oral administration of S-777469 significantly suppressed DNFB-induced ear swelling in a dose-dependent manner. In addition, S-777469 significantly alleviated mite antigen-induced atopic dermatitis-like skin lesions in NC/Nga mice. A histological analysis revealed that S-777469 significantly reduced the epidermal thickness and the number of mast cells infiltrating skin lesions. We demonstrated that S-777469 inhibited mite antigen-induced eosinophil accumulation in skin lesions and an endogenous CB2 ligand, 2-arachidonoylglycerol (2-AG)-induced eosinophil migration in vitro. Moreover, we confirmed that 2-AG levels significantly increased in skin lesions of mite antigen-induced dermatitis model. Together, these results suggest that S-777469 inhibits skin inflammation in mice by blocking the activities of 2-AG.”

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MicroRNA-139 modulates Alzheimer’s-associated pathogenesis in SAMP8 mice by targeting cannabinoid receptor type 2.

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“Alzheimer’s disease (AD) is a neurodegenerative disorder, and is the most common type of dementia in the elderly population. Growing evidence indicates that microRNAs (miRNAs) play a crucial role in neuroinflammation associated with AD progression. In this study, we analyzed the expression of microRNA-139 (miR-139) as well as the learning and memory function in AD. We observed that the miR-139 expression was significantly higher in the hippocampus of aged senescence accelerated mouse prone 8 (SAMP8) mice (2.92 ± 0.13) than in the control mice (1.49 ± 0.08). Likewise, the overexpression of miR-139 by means of hippocampal injection impaired the hippocampus-dependent learning and memory formation. In contrast, the downregulation of miR-139 in mice improved learning and memory function in the mice. The level of cannabinoid receptor type 2 (CB2), a potential target gene of miR-139, was inversely correlated with the miR-139 expression in primary hippocampal cells. Furthermore, we demonstrated that miR-139 inversely modulated the responses to proinflammatory stimuli. Together, our findings demonstrate that miR-139 exerts a pathogenic effect in AD by modulating CB2-meditated neuroinflammatory processes.”

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Acetylcholinesterase inhibitors in Alzheimer’s disease

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“Alzheimer’s Disease (AD) is the most common single cause of dementia in our ageing society. On full assessment and diagnosis of AD, initiation of an AChe inhibitor is recommended as early as possible, it is important that AChe inhibitor therapy is considered for patients with mild to moderate AD.”

“Characterization of Lignanamides from Hemp (Cannabis sativa L.) Seed and Their Antioxidant and Acetylcholinesterase Inhibitory Activities. Hempseed is known for its content in fatty acids, proteins and fiber, which contribute to its nutritional value. Lignanamides 2, 7, 9-14 showed good antioxidant activity among which 7, 10 and 13 also inhibited acetylcholinesterase in vitro. The new identified compounds in this study added to the diversity of hempseed composition and the bioassays implied that hempseed, with lignanamides as nutrients, may be a good source of bioactive and protective compounds.”

“The Effects of Hempseed Meal Intake and Linoleic Acid on Drosophila Models of Neurodegenerative Diseases and Hypercholesterolemia. Our results indicate that hempseed meal (HSM) and linoleic acid are potential candidates for the treatment of Alzheimer’s disease (AD) and cardiovascular disease. These results show that HSM may prove of great utility as a health food, with potential for the prevention of AD and cardiovascular disease.”

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