Isolation and structure of a brain constituent that binds to the cannabinoid receptor

Cannabinoid Cancer Biology and Prevention

Plant-based, synthetic, and endogenous cannabinoids have been shown to control a diverse array of biological processes, including regulation of cell fate across cancers. Their promise as broad-based antitumor agents in preclinical models has led to the initiation of pilot clinical trials. Session 5 of the National Cancer Institute's Cannabis, Cannabinoids and Cancer Research Symposium provides an overview of this research topic. Overall, the presentations highlight cannabinoid signal transduction and specific molecular mechanisms underlying cannabinoid antitumor activity. They also demonstrate the broad-based antitumor activity of the plant-based, synthetic, and endogenous cannabinoid compounds. Importantly, evidence is presented demonstrating when cannabinoids may be contraindicated as a treatment for cancer, as in the case of human papilloma virus-meditated oropharynx cancer or potentially other p38 MAPK pathway-driven cancers. Finally, it is discussed that a key to advancing cannabinoids into the clinic is to conduct well-designed, large-scale clinical trials to determine whether cannabinoids are effective antitumor agents in cancer patients.

Palmitoylethanolamide: A Potential Alternative to Cannabidiol

The endocannabinoid system (ECS) is a widespread cell signaling network that maintains homeostasis in response to endogenous and exogenous stressors. This has made the ECS an attractive therapeutic target for various disease states. The ECS is a well-known target of exogenous phytocannabinoids derived from cannabis plants, the most well characterized being Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD). However, the therapeutic efficacy of cannabis products comes with a risk of toxicity and high abuse potential due to the psychoactivity of THC. CBD, on the other hand, is reported to have beneficial medicinal properties including analgesic, neuroprotective, anxiolytic, anticonvulsant, and antipsychotic activities, while apparently lacking the toxicity of THC. Nevertheless, not only is the currently available scientific data concerning CBD's efficacy insufficient, there is also ambiguity surrounding its regulatory status and safety in humans that brings inherent risks to manufacturers. There is a demand for alternative compounds combining similar effects with a robust safety profile and regulatory approval. Palmitoylethanolamide (PEA) is an endocannabinoid-like lipid mediator, primarily known for its anti-inflammatory, analgesic and neuroprotective properties. It appears to have a multi-modal mechanism of action, by primarily activating the nuclear receptor PPAR-α while also potentially working through the ECS, thus targeting similar pathways as CBD. With proven efficacy in several therapeutic areas, its safety and tolerability profile and the development of formulations that maximize its bioavailability, PEA is a promising alternative to CBD.

Translation of animal endocannabinoid models of PTSD mechanisms to humans: Where to next?

The endocannabinoid system is known to be involved in mechanisms relevant to PTSD aetiology and maintenance, though this understanding is mostly based on animal models of the disorder. Here we review how human paradigms can successfully translate animal findings to human subjects, with the view that substantially increased insight into the effect of endocannabinoid signalling on stress responding, emotional and intrusive memories, and fear extinction can be gained using modern paradigms and methods for assessing the state of the endocannabinoid system in PTSD.

Packing polymorphism, odd-even alternation and thermotropic phase transitions in N-,O-diacylethanolamines with varying N-acyl chains. A combined experimental and computational study

N-,O-Diacylethanolamines (DAEs) are derived by simple esterification of bioactive N-acylethanolamines, which are present in plant and animal tissues. In this study, two homologous series of DAEs, namely N-acyl (n = 8-15), O-palmitoylethanolamines (Nn-O16s) and N-acyl (n = 8-14), O-pentadecanoylethanolamines (Nn-O15s) were synthesized and characterized with respect to thermotropic phase transitions, crystal structures and intermolecular interactions. In addition, computational studies were performed to get a molecular level insight into the role of different factors in selective polymorphism in Nn-O16s and Nn-O15s. Differential scanning calorimetric studies revealed that dry Nn-O16s exhibit odd-even alternation in their calorimetric properties, which is absent in Nn-O15s. The 3-dimensional structures of three Nn-O16s (n = 12-14) and two Nn-O15s (n = 12, 14) have been determined by single-crystal X-ray diffraction. Analysis of the molecular packing in these crystals showed the presence of two packing polymorphs (α and β) in the crystal lattice of Nn-O16s, whereas only the β polymorph was observed in the Nn-O15s. Further, intermolecular hydrogen bonding interactions (N-H⋯O and C-H⋯O) and dispersion interactions among acyl chains have been found to stabilize the molecular packing observed in the crystal lattice. Molecular dynamics simulations show that the β polymorph is slightly energetically preferred over the α polymorph in all the systems due to favorable packing of terminal methyl groups at the interlayers. These findings are relevant for understanding the interactions of the DAEs with membrane lipids and proteins.

Cannabidiol Does Not Cause Significant Changes to Working Memory Performance in the N-Back Task

Cannabis use can be traced back to several centuries before the Common Era, when it was used for industrial, medicinal and recreational purposes. More recently, over 100 different cannabinoid compounds have been identified, one of which is cannabidiol (CBD), a compound widely used for anti-inflammatory and anxiolytic treatment. The literature surrounding the cognitive effects of CBD is limited, with most studies focusing on the effects of other cannabinoids on cognition. To expand this literature, this study investigated whether CBD causes significant differences to working memory (WM) functioning, as measured by the N-back task. It was hypothesised that CBD does not cause statistically significant differences to WM. In all, 54 participants, 33 females and 21 males, were recruited, with a mean age of 32.63 years. Of these 54 participants, 26 reported using CBD and no other cannabinoids, while 28 reported not using any cannabinoid. The participants were instructed to answer a short online survey to gather basic demographic data and to complete an online N-back task to measure WM. For the computerised N-back task, the participants completed a practice and three test blocks, where they were instructed to respond to whether a series of letter stimuli were presented one trial back (1-back), two trials back (2-back) or three trials back (3-back). Multivariate analysis of covariance yielded no statistically significant difference on either response time or response accuracy data between groups after controlling for how long the participants use CBD and for what reason they use CBD. These results support our hypothesis that CBD does not cause significant changes to WM functioning. Further research is greatly needed to investigate the long-term effects of CBD use on WM and on general cognitive functioning.

The Endocannabinoid System as a Pharmacological Target for New Cancer Therapies

Simple Summary

Cannabinoids have been shown to suppress tumour cell proliferation, tumour invasion, metastasis, angiogenesis, chemoresistance and epithelial-mesenchymal transition and to induce tumour cell apoptosis, autophagy and immune response. This review focuses on the current status of investigations on the impact of inhibitors of endocannabinoid-degrading enzymes on tumour growth and spread in preclinical oncology research.

Abstract

Despite the long history of cannabinoid use for medicinal and ritual purposes, an endogenous system of cannabinoid-controlled receptors, as well as their ligands and the enzymes that synthesise and degrade them, was only discovered in the 1990s. Since then, the endocannabinoid system has attracted widespread scientific interest regarding new pharmacological targets in cancer treatment among other reasons. Meanwhile, extensive preclinical studies have shown that cannabinoids have an inhibitory effect on tumour cell proliferation, tumour invasion, metastasis, angiogenesis, chemoresistance and epithelial-mesenchymal transition (EMT) and induce tumour cell apoptosis and autophagy as well as immune response. Appropriate cannabinoid compounds could moreover be useful for cancer patients as potential combination partners with other chemotherapeutic agents to increase their efficacy while reducing unwanted side effects. In addition to the direct activation of cannabinoid receptors through the exogenous application of corresponding agonists, another strategy is to activate these receptors by increasing the endocannabinoid levels at the corresponding pathological hotspots. Indeed, a number of studies accordingly showed an inhibitory effect of blockers of the endocannabinoid-degrading enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) on tumour development and spread. This review summarises the relevant preclinical studies with FAAH and MAGL inhibitors compared to studies with cannabinoids and provides an overview of the regulation of the endocannabinoid system in cancer.

Nanoscale Sub-Compartmentalization of the Dendritic Spine Compartment

Compartmentalization of the membrane is essential for cells to perform highly specific tasks and spatially constrained biochemical functions in topographically defined areas. These membrane lateral heterogeneities range from nanoscopic dimensions, often involving only a few molecular constituents, to micron-sized mesoscopic domains resulting from the coalescence of nanodomains. Short-lived domains lasting for a few milliseconds coexist with more stable platforms lasting from minutes to days. This panoply of lateral domains subserves the great variety of demands of cell physiology, particularly high for those implicated in signaling. The dendritic spine, a subcellular structure of neurons at the receiving (postsynaptic) end of central nervous system excitatory synapses, exploits this compartmentalization principle. In its most frequent adult morphology, the mushroom-shaped spine harbors neurotransmitter receptors, enzymes, and scaffolding proteins tightly packed in a volume of a few femtoliters. In addition to constituting a mesoscopic lateral heterogeneity of the dendritic arborization, the dendritic spine postsynaptic membrane is further compartmentalized into spatially delimited nanodomains that execute separate functions in the synapse. This review discusses the functional relevance of compartmentalization and nanodomain organization in synaptic transmission and plasticity and exemplifies the importance of this parcelization in various neurotransmitter signaling systems operating at dendritic spines, using two fast ligand-gated ionotropic receptors, the nicotinic acetylcholine receptor and the glutamatergic receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as paradigmatic examples.

Decreasing sperm quality in mice subjected to chronic cannabidiol exposure: New insights of cannabidiol-mediated male reproductive toxicity

Cannabidiol (CBD) is a natural cannabinoid present in the Cannabis sativa plant, widely prescribed as an anticonvulsant drug, especially for pediatric use. However, its effects on male reproduction are still little investigated. Therefore, the present study assessed the effects of CBD on the spermatogenesis and sperm quality. For this, twenty-one-day-old Swiss mice received CBD for 34 consecutive days by gavage at doses of either 15 or 30 mg/kg. Chronic exposure to CBD decreased the frequency of stages VII-VIII and XII of spermatogenesis and an increase in the frequency of stage IX were noted. Furthermore, the seminiferous epithelium height reduced at stage IX and increased at stage XII in both CBD-treated groups. There was a significant rise of sperm DNA damage, while no genotoxic effects were observed in leukocytes. The activities of superoxide dismutase and catalase decreased, while malondialdehyde levels increased in the sperm of mice treated with a higher dose of CBD. Mice exposed to 30 mg/kg of CBD showed a reduction in the mobile spermatozoa percentage and in curvilinear velocity, while straight line and average path velocity decreased in both treated groups. The number of acrosome-intact spermatozoa declined in the CBD 30 group, and the number of abnormal acrosomes raised in both CBD groups. On the other hand, the weight of reproductive organs, sperm count, and hormone levels were not affected by CBD treatment. These findings show that dysregulation of the endocannabinoid system by CBD can reduce sperm quality. The mechanisms responsible may be associated with disorders during spermatogenesis, especially during the final stages of nuclear remodelling and assembly of acrosome. However, changes in mitochondrial function, as well as the reduction on the antioxidant enzyme activities during epididymal transit, at least partly, may also be involved.

Neuroprotective activity of new Δ3-N-acylethanolamines in a focal ischemia stroke model

N-acylethanolamines (NAE, also called ethanolamides) are significant lipid signaling molecules with anti-inflammatory, pain-relieving, cell-protective, and anticancer properties. Here, we present the use of a hitherto unreported group of Δ3-NAE and also some Δ4- and Δ5-NAE, in in vitro and in vivo assays to gain a better understanding of their structure-bioactivity relationships. We have developed an efficient synthetic method to rapidly produce novel unlabeled and ¹³ C-labeled Δ3-NAE (NAE-18:5n-3, NAE-18:4n-6) and Δ4-NAE (NAE-22:5n-6). The new NAE with shorter carbon backbone structures confers greater neuroprotection than their longer carbon backbone counterparts, including anandamide (Δ5-NAE-20:4n-6) in a focal ischemia mouse model of stroke. This study highlights structure-dependent protective effects of new NAE following focal ischemia, in which some of the new NAE, administered intranasally, lead to significantly reduced infarct volume and improved recovery of limb use. The relative affinity of the new NAE toward cannabinoid receptors was assessed against anandamide, NAE-22:6n-3 and NAE-20:5n-3, which are known cannabinoid receptor ligands with high-binding constants. Among the newly synthesized NAE, Δ4-NAE-22:5n-6 shows the greatest relative affinity to cannabinoid receptors hCB₁ and hCB₂ , and inhibition of cyclic adenosine monophosphate activity through hCB₂ compared to anandamide.

Potential therapeutic targets for the treatment of opioid abuse and pain

Although μ-opioid peptide (MOP) receptor agonists are effective analgesics available in clinical settings, their serious adverse effects put limits on their use. The marked increase in abuse and misuse of prescription opioids for pain relief and opioid overdose mortality in the past decade has seriously impacted society. Therefore, safe analgesics that produce potent analgesic effects without causing MOP receptor-related adverse effects are needed. This review highlights the potential therapeutic targets for the treatment of opioid abuse and pain based on available evidence generated through preclinical studies and clinical trials. To ameliorate the abuse-related effects of opioids, orexin-1 receptor antagonists and mixed nociceptin/MOP partial agonists have shown promising results in translational aspects of animal models. There are several promising non-opioid targets for selectively inhibiting pain-related responses, including nerve growth factor inhibitors, voltage-gated sodium channel inhibitors, and cannabinoid- and nociceptin-related ligands. We have also discussed several emerging and novel targets. The current medications for opioid abuse are opioid receptor-based ligands. Although neurobiological studies in rodents have discovered several non-opioid targets, there is a translational gap between rodents and primates. Given that the neuroanatomical aspects underlying opioid abuse and pain are different between rodents and primates, it is pivotal to investigate the functional profiles of these non-opioid compounds compared to those of clinically used drugs in non-human primate models before initiating clinical trials. More pharmacological studies of the functional efficacy, selectivity, and tolerability of these newly discovered compounds in non-human primates will accelerate the development of effective medications for opioid abuse and pain.

On the Biomedical Properties of Endocannabinoid Degradation and Reuptake Inhibitors: Pre-clinical and Clinical Evidence

The endocannabinoid system (ECS) is composed of endogenous cannabinoids; components involved in their synthesis, transport, and degradation; and an expansive variety of cannabinoid receptors. Hypofunction or deregulation of the ECS is related to pathological conditions. Consequently, endogenous enhancement of endocannabinoid levels and/or regulation of their metabolism represent promising therapeutic approaches. Several major strategies have been suggested for the modulation of the ECS: (1) blocking endocannabinoids degradation, (2) inhibition of endocannabinoid cellular uptake, and (3) pharmacological modulation of cannabinoid receptors as potential therapeutic targets. Here, we focused in this review on degradation/reuptake inhibitors over cannabinoid receptor modulators in order to provide an updated synopsis of contemporary evidence advancing mechanisms of endocannabinoids as pharmacological tools with therapeutic properties for the treatment of several disorders. For this purpose, we revisited the available literature and reported the latest advances regarding the biomedical properties of fatty acid amide hydrolase and monoacylglycerol lipase inhibitors in pre-clinical and clinical studies. We also highlighted anandamide and 2-arachidonoylglycerol reuptake inhibitors with promising results in pre-clinical studies using in vitro and animal models as an outlook for future research in clinical trials.

Spinal Cord Stimulation and Treatment of Peripheral or Central Neuropathic Pain: Mechanisms and Clinical Application

Spinal cord stimulation (SCS) as an evidence-based interventional treatment has been used and approved for clinical use in a variety of pathological states including peripheral neuropathic pain; however, until now, it has not been used for the treatment of spinal cord injury- (SCI-) induced central neuropathic pain. This paper reviews the underlying mechanisms of SCS-induced analgesia and its clinical application in the management of peripheral and central neuropathic pain. Evidence from recent research publications indicates that nociceptive processing at peripheral and central sensory systems is thought to be modulated by SCS through (i) inhibition of the ascending nociceptive transmission by the release of analgesic neurotransmitters such as GABA and endocannabinoids at the spinal dorsal horn; (ii) facilitation of the descending inhibition by release of noradrenalin, dopamine, and serotonin acting on their receptors in the spinal cord; and (iii) activation of a variety of supraspinal brain areas related to pain perception and emotion. These insights into the mechanisms have resulted in the clinically approved use of SCS in peripheral neuropathic pain states like Complex Regional Pain Syndrome (CRPS) and Failed Back Surgery Syndrome (FBSS). However, the mechanisms underlying SCS-induced pain relief in central neuropathic pain are only partly understood, and more research is needed before this therapy can be implemented in SCI patients with central neuropathic pain.

Implications of dysregulated endogenous cannabinoid family members in the pathophysiology of endometriosis

OBJECTIVE

To determine the involvement of the endocannabinoid (EC) family member in the pathophysiology of endometriosis (EMS).

DESIGN

Mass spectrometry analysis of plasma and tissue samples from patients with EMS, controls, and a mouse model of EMS and messenger RNA and immunohistochemistry analysis of the samples from patients with EMS and controls.

SETTING

Academic teaching hospital and university.

PATIENT(S)

Patients with EMS and healthy fertile control subjects.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Endocannabinoid analysis in patient plasma, EMS lesions, and healthy endometrial samples.

RESULT(S)

Circulating ECs were detected in the plasma samples, whereas no significant changes were observed in patients with EMS compared with healthy fertile controls. However, the palmitoylethanolamide levels were significantly higher in the EMS lesions than in the endometrium from patients with EMS. Similarly, genes involved in the EC signaling pathways were differentially expressed in the EMS lesions. Analysis of cannabinoid 1 and 2 receptors in the EMS lesions revealed a significantly lower cannabinoid 2 receptor expression, whereas no significant changes were observed in cannabinoid 1 receptor expression compared with those in the endometrium from both patients with EMS and healthy fertile controls. The palmitoylethanolamide levels were significantly elevated in plasma from EMS mice compared with that from sham controls and in EMS lesions compared with uterine samples.

CONCLUSION(S)

Together, we provide evidence toward dysregulation of members of the ECs in both patients with EMS and the mouse model of EMS. These findings will advance the knowledge of the role of ECs in EMS and their potential implications as therapeutic targets.

Amygdalar endocannabinoids are affected by predator odor stress in a sex-specific manner and modulate acoustic startle reactivity in female rats

Understanding sex differences in behavioral and molecular effects of stress has important implications for understanding the vulnerability to chronic psychiatric disorders associated with stress response circuitry. The amygdala is critical for emotional learning and generating behavioral responses to stressful stimuli, and preclinical studies indicate that amygdalar endocannabinoid (eCB) signaling regulates emotional states. This study measured eCB contents in the basolateral (BLA) and central (CeA) amygdala of male and female rats exposed to predator odor stress (bobcat urine) and tested for contextual avoidance 24 h later. Stressed females had lower levels of 2-arachidonoyl glycerol (2-AG) in the BLA and higher levels of anandamide (AEA) in the CeA, while exposure to bobcat urine did not affect amygdalar eCB contents in males. We previously reported that female rats exposed to bobcat urine exhibit blunted acoustic startle reactivity (ASR) 48 h after predator odor stress. Therefore, we tested the hypothesis that intra-BLA injection of a diacylglycerol lipase (DAGL) inhibitor (which would be expected to reduce 2-AG levels in BLA) and intra-CeA injection of a fatty acid amide hydrolase (FAAH) inhibitor (which would be expected to increase AEA levels in CeA) would mimic previously observed predator odor stress-induced reductions in ASR. Contrary to our hypothesis, microinjections of either the DAGL inhibitor DO34 into the BLA or the FAAH inhibitor URB597 into the CeA significantly increased ASR in females compared to vehicle-treated rats. These findings describe sex-specific effects of predator odor stress on amygdalar eCBs, and new roles for amygdalar eCBs in regulating behavior in females.

Hippocampal Cb2 receptors: an untold story

The field of cannabinoid research has been receiving ever-growing interest. Ongoing debates worldwide about the legislation of medical cannabis further motivates research into cannabinoid function within the central nervous system (CNS). To date, two well-characterized cannabinoid receptors exist. While most research has investigated Cb₁ receptors (Cb₁Rs), Cb₂ receptors (Cb₂Rs) in the brain have started to attract considerable interest in recent years. With indisputable evidence showing the wide-distribution of Cb₂Rs in the brain of different species, they are no longer considered just peripheral receptors. However, in contrast to Cb₁Rs, the functionality of central Cb₂Rs remains largely unexplored. Here we review recent studies on hippocampal Cb₂Rs. While conflicting results about their function have been reported, we have made significant progress in understanding the involvement of Cb₂Rs in modulating cellular properties and network excitability. Moreover, Cb₂Rs have been shown to be expressed in different subregions of the hippocampus, challenging our prior understanding of the endocannabinoid system. Although more insight into their functional roles is necessary, we propose that targeting hippocampal Cb₂Rs may offer novel therapies for diseases related to memory and adult neurogenesis deficits.

Plasmatic endocannabinoids are decreased in subjects with ultra-high risk of psychosis

The onset of frank psychosis is usually preceded by a prodromal phase characterized by attenuated psychotic symptoms. Currently, research on schizophrenia prodromal phase (ultra-high risk for psychosis [UHR]) has focused on the risk of developing psychosis, on the transition to full blown psychosis and on its prediction. Neurobiological differences between UHR individuals who fully recover (remitters) versus those who show persistent/progressive prodromal symptoms (nonremitters) have been little explored. The endocannabinoid system constitutes a neuromodulatory system that plays a major role in brain development, synaptic plasticity, emotional behaviours and cognition. It comprises two cannabinoid receptors (CB1/CB2), two endocannabinoid ligands, arachidonylethanolamide (AEA) and 2-arachidonoylglycerol (2AG) along with their inactivation enzymes. Despite much evidence that the endocannabinoid system is imbalanced during psychosis, very little is known about it in UHR. Therefore, we aimed to quantify the plasma endocannabinoid levels in UHR and healthy controls (HC) and verify if these metabolites could differentiate between remitters and nonremitters. Circulating concentrations of AEA (p = .003) and 2AG (p < .001) were lower in UHR when compared with HC, with no difference between remitters and nonremitters. Regarding clinical evolution, it was observed that out of 91 UHRs initially considered, 16 had psychiatric complaints (3 years of follow-up). Considering those subjects, there were weak correlations between clinical parameters and plasma concentrations of endocannabinoids. Our results suggest that the endocannabinoids are imbalanced before frank psychosis and that changes can be seen in plasma of UHR individuals. These molecules proved to be potential biomarkers to identify individuals in the prodromal phase of psychosis.

The Inhibition of the Degrading Enzyme Fatty Acid Amide Hydrolase Alters the Activity of the Cone System in the Vervet Monkey Retina

Recent studies using full-field electroretinography (ffERG) that triggers a non-specific mass response generated by several retinal sources have attributed an important role for cannabinoid receptors in mediating vision in primates. Specific cone-mediated responses evoked through the photopic flicker ERG appear to be a better way to validate the assumption that endogenous cannabinoids modulate the cone pathway, since FAAH is mainly expressed in the vervet monkey cone photoreceptors. The aim of this study is two-fold: (1) to use the photopic flicker ERG to target the cone pathway specifically, and (2) use URB597 as a selective inhibitor of the endocannabinoid degrading enzyme Fatty Acid Amide Hydrolase (FAAH) to enhance the levels of fatty acid amides, particularly anandamide. We recorded ERGs under four different flicker frequencies (15, 20, 25, and 30 Hz) in light-adapted conditions after intravitreal injections of URB597. Our results show that intravitreal injections of URB597, compared to the vehicle DMSO, increased significantly ffERG amplitudes at 30 Hz, a frequency that solely recruits cone activity. However, at 15 Hz, a frequency that activates both rods and cones, no significant difference was found in the ERG response amplitude. Additionally, we found no differences in implicit times after URB597 injections compared to DMSO vehicle. These results support the role of molecules degraded by FAAH in cone-mediated vision in non-human primates.

Cannabis, a Miracle Drug with Polyvalent Therapeutic Utility: Preclinical and Clinical-Based Evidence

Cannabis sativa L. is an annual herbaceous dioecious plant which was first cultivated by agricultural human societies in Asia. Over the period of time, various parts of the plant like leaf, flower, and seed were used for recreational as well as therapeutic purposes. The main chemical components of Cannabis sativa are termed as cannabinoids, among them the key psychoactive constituent is Δ-9-tetrahydrocannabinol and cannabidiol (CBD) as active nonpsychotic constituent. Upon doing extensive literature review, it was found that cannabis has been widely studied for a number of disorders. Very recently, a pure CBD formulation, named Epidiolex, got a green flag from both United States Food and Drug Administration and Drug Enforcement Administration for 2 rare types of epilepsies. This laid a milestone in medical cannabis research. This review intends to give a basic and extensive assessment, from past till present, of the ethnological, plant, chemical, pharmacological, and legal aspects of C. sativa. Further, this review contemplates the evidence the studies obtained of cannabis components on Alzheimer's, Parkinson's, amyotrophic lateral sclerosis, multiple sclerosis, emesis, epilepsy, chronic pain, and cancer as a cytotoxic agent as well as a palliative therapy. The assessment in this study was done by reviewing in extensive details from studies on historical importance, ethnopharmacological aspects, and legal grounds of C. sativa from extensive literature available on the scientific databases, with a vision for elevating further pharmaceutical research to investigate its total potential as a therapeutic agent.

CB2 Receptor Involvement in the Treatment of Substance Use Disorders

The pharmacological modulation of the cannabinoid receptor 2 (CB2r) has emerged as a promising potential therapeutic option in addiction. The purpose of this review was to determine the functional involvement of CB2r in the effects produced by drugs of abuse at the central nervous system (CNS) level by assessing evidence from preclinical and clinical studies. In rodents, several reports suggest the functional involvement of CB2r in the effects produced by drugs of abuse such as alcohol, cocaine, or nicotine. In addition, the discovery of CB2r in brain areas that are part of the reward system supports the relevance of CB2r in the field of addiction. Interestingly, animal studies support that the CB2r regulates anxiety and depression behavioral traits. Due to its frequent comorbidity with neuropsychiatric disorders, these pharmacological actions may be of great interest in managing SUD. Preliminary clinical trials are focused on exploring the therapeutic potential of modulating CB2r in treating addictive disorders. These promising results support the development of new pharmacological tools regulating the CB2r that may help to increase the therapeutic success in the management of SUD.

Cannabinoids and Neurogenesis: The Promised Solution for Neurodegeneration?

The concept of neurons as irreplaceable cells does not hold true today. Experiments and evidence of neurogenesis, also, in the adult brain give hope that some compounds or drugs can enhance this process, helping to reverse the outcomes of diseases or traumas that once were thought to be everlasting. Cannabinoids, both from natural and artificial origins, already proved to have several beneficial effects (e.g., anti-inflammatory, anti-oxidants and analgesic action), but also capacity to increase neuronal population, by replacing the cells that were lost and/or regenerate a damaged nerve cell. Neurogenesis is a process which is not highly represented in literature as neuroprotection, though it is as important as prevention of nervous system damage, because it can represent a possible solution when neuronal death is already present, such as in neurodegenerative diseases. The aim of this review is to resume the experimental evidence of phyto- and synthetic cannabinoids effects on neurogenesis, both in vitro and in vivo, in order to elucidate if they possess also neurogenetic and neurorepairing properties.

Diabetes and Cannabinoid CB1 receptor deficiency promote similar early onset aging-like changes in the skin

BACKGROUND

The cannabinoid receptor type-1 (CB1R) is a major regulator of metabolism, growth and inflammation. Yet, its potential role in the skin is not well understood. Our aim was to evaluate the role of CB1R in aging-like diabetic skin changes by using a CB1R knockout mouse model.

METHODS

We evaluated several signals of skin aging in wild-type control (WT), WT streptozotocin-induced type 1 diabetic mice (WT DM), CB1R knockout (CB1RKO) and CB1RKO DM mice. We quantified markers of inflammation, angiogenesis, antioxidant enzymes and collagen content. Moreover, we evaluate reactive oxygen species (ROS) levels and macrophage phenotype, M1 and M2.

RESULTS

CB1R expression is decreased in the skin of WT DM mice and collagen levels are decreased in the skin of WT DM, CB1RKO and CB1RKO DM mice. Additionally, the absence of CB1R correlated with higher expression of pro-inflammatory markers, also evident in WT DM or CB1RKO DM mice. Moreover, the M1/M2 macrophage ratio and ROS levels were significantly elevated but in the diabetic WT and the CB1RKO mice, consistent with a significant decrease in the antioxidant capacity of the skin.

CONCLUSIONS

Our results indicate that CB1R deficiency in the skin may lead to accelerated skin aging due to the increased production of ROS, a decrease in the antioxidant defenses and a higher pro-inflammatory environment. A significant decrease in the CB1R expression may be a significant contributing factor to the early aging-like changes in diabetes.

A Role for Peripheral Anandamide and 2-Arachidonoylglycerol in Short-Term Food Intake and Orexigenic Hypothalamic Responses in a Species with Continuous Nutrient Delivery

The endocannabinoid system (ECS) plays a pivotal role in the complex control and regulation of food intake. Pharmacological ECS activation could improve health in energy-deficient stages by increasing food intake, at least in intermittent feeders. However, knowledge of the mechanism regulating appetite in species with continued nutrient delivery is incomplete. The objectives of this pilot study were to investigate the effect of the intraperitoneal (i.p.) administration of the endocannabinoids (ECs) anandamide (AEA) and 2-arachidonoylglycerol (2-AG) on food intake, plasma EC concentrations and hypothalamic orexigenic signaling, and to study how the circulatory EC tone changes in response to short-term food deprivation in dairy cows, a species with continuous nutrient delivery. The administration of EC resulted in higher food intake during the first hour after treatment. Plasma AEA concentrations were significantly increased 2.5 h after AEA injection, whereas plasma 2-AG concentrations remained unchanged 2.5 h after 2-AG injection. The hypothalamic immunoreactivity of cannabinoid receptor 1, agouti-related protein, and orexin-A was not affected by either treatment; however, neuropeptide Y and agouti-related protein mRNA abundances were downregulated in the arcuate nucleus of AEA-treated animals. Short-term food deprivation increased plasma 2-AG, while plasma AEA remained unchanged. In conclusion, i.p.-administered 2-AG and AEA increase food intake in the short term, but only AEA accumulates in the circulation. However, plasma 2-AG concentrations are more responsive to food deprivation than AEA.

Repurposing Peroxisome Proliferator-Activated Receptor Agonists in Neurological and Psychiatric Disorders

Common pathophysiological mechanisms have emerged for different neurological and neuropsychiatric conditions. In particular, mechanisms of oxidative stress, immuno-inflammation, and altered metabolic pathways converge and cause neuronal and non-neuronal maladaptative phenomena, which underlie multifaceted brain disorders. The peroxisome proliferator-activated receptors (PPARs) are nuclear receptors modulating, among others, anti-inflammatory and neuroprotective genes in diverse tissues. Both endogenous and synthetic PPAR agonists are approved treatments for metabolic and systemic disorders, such as diabetes, fatty liver disease, and dyslipidemia(s), showing high tolerability and safety profiles. Considering that some PPAR-acting drugs permeate through the blood-brain barrier, the possibility to extend their scope from the periphery to central nervous system has gained interest in recent years. Here, we review preclinical and clinical evidence that PPARs possibly exert a neuroprotective role, thereby providing a rationale for repurposing PPAR-targeting drugs to counteract several diseases affecting the central nervous system.

Current review of hemp-based medicines in dogs

Medical use of Cannabis (or hemp) began thousands of years ago. In the 20th century, mechanisms of action were demonstrated with the discovery of its active substances, the phytocannabinoids, and its pharmacological targets, the endocannabinoid system. This system is composed of receptors, endogenous substances, and enzymes, and it participates in the modulation of physiological mechanisms in several species, including dogs. Studies indicate that changes in this system may contribute to the genesis of some diseases. Therefore, the use of substances that act on its components may help in the treatment of these diseases. The main phytocannabinoids described are ^Δ9- tetrahydrocannabinol (THC) and cannabidiol (CBD). In humans, the benefits of using CBD in several diseases have been demonstrated. The popularization of this type of treatment has also reached veterinary medicine, which on one hand was related to an increase in adverse event records, but on the other also allowed reports of anecdotal evidences of its effectiveness and safety in animals. Clinical studies published so far indicate that the use of CBD in dogs can be safe at given doses and can contribute to osteoarthritis and idiopathic epilepsy treatments. Clinical and pre-clinical studies and case reports were reviewed in this report to identify the main characteristics of hemp-based therapies in dogs, including its pharmacokinetics, pharmacodynamics, safety, and efficacy in the treatment of diseases.

Pharmacological and Toxicological Effects of Phytocannabinoids and Recreational Synthetic Cannabinoids: Increasing Risk of Public Health

Synthetic Cannabinoids (CBs) are a novel class of psychoactive substances that have rapidly evolved around the world with the addition of diverse structural modifications to existing molecules which produce new structural analogues that can be associated with serious adverse health effects. Synthetic CBs represent the largest class of drugs detected by the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) with a total of 207 substances identified from 2008 to October 2020, and 9 compounds being reported for the first time. Synthetic CBs are sprayed on natural harmless herbs with an aim to mimic the euphoric effect of Cannabis. They are sold under different brand names including Black mamba, spice, K2, Bombay Blue, etc. As these synthetic CBs act as full agonists at the CB receptors, they are much more potent than natural Cannabis and have been increasingly associated with acute to chronic intoxications and death. Due to their potential toxicity and abuse, the US government has listed some synthetic CBs under schedule 1 classification. The present review aims to provide a focused overview of the literature concerning the development of synthetic CBs, their abuse, and potential toxicological effects including renal toxicity, respiratory depression, hyperemesis syndrome, cardiovascular effects, and a range of effects on brain function.

Endocannabinoid-Based Therapies

The endocannabinoids are lipid-derived messengers that play a diversity of regulatory roles in mammalian physiology. Dysfunctions in their activity have been implicated in various disease conditions, attracting attention to the endocannabinoid system as a possible source of therapeutic drugs. This signaling complex has three components: the endogenous ligands, anandamide and 2-arachidonoyl-sn-glycerol (2-AG); a set of enzymes and transporters that generate, eliminate, or modify such ligands; and selective cell surface receptors that mediate their biological actions. We provide an overview of endocannabinoid formation, deactivation, and biotransformation and outline the properties and therapeutic potential of pharmacological agents that interfere with those processes. We describe small-molecule inhibitors that target endocannabinoid-producing enzymes, carrier proteins that transport the endocannabinoids into cells, and intracellular endocannabinoid-metabolizing enzymes. We briefly discuss selected agents that simultaneously interfere with components of the endocannabinoid system and with other functionally related signaling pathways. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Cannabidiol modulation of oxidative stress and signalling

Cannabidiol (CBD), one of the primary non-euphoric components in the Cannabis sativa L. plant, has undergone clinical development over the last number of years as a therapeutic for patients with Lennox-Gastaut syndrome and Dravet syndromes. This phytocannabinoid demonstrates functional and pharmacological diversity, and research data indicate that CBD is a comparable antioxidant to common antioxidants. This review gathers the latest knowledge regarding the impact of CBD on oxidative signalling, with focus on the proclivity of CBD to regulate antioxidants and control the production of reactive oxygen species. CBD is considered an attractive therapeutic agent for neuroimmune disorders, and a body of literature indicates that CBD can regulate redox function at multiple levels, with a range of downstream effects on cells and tissues. However, pro-oxidant capacity of CBD has also been reported, and hence caution must be applied when considering CBD from a therapeutic standpoint. Such pro- and antioxidant functions of CBD may be cell- and model-dependent and may also be influenced by CBD dose, the duration of CBD treatment and the underlying pathology.

CB1 Cannabinoid Receptor Signaling and Biased Signaling

The CB1 cannabinoid receptor is a G-protein coupled receptor highly expressed throughout the central nervous system that is a promising target for the treatment of various disorders, including anxiety, pain, and neurodegeneration. Despite the wide therapeutic potential of CB1, the development of drug candidates is hindered by adverse effects, rapid tolerance development, and abuse potential. Ligands that produce biased signaling—the preferential activation of a signaling transducer in detriment of another—have been proposed as a strategy to dissociate therapeutic and adverse effects for a variety of G-protein coupled receptors. However, biased signaling at the CB1 receptor is poorly understood due to a lack of strongly biased agonists. Here, we review studies that have investigated the biased signaling profile of classical cannabinoid agonists and allosteric ligands, searching for a potential therapeutic advantage of CB1 biased signaling in different pathological states. Agonist and antagonist bound structures of CB1 and proposed mechanisms of action of biased allosteric modulators are used to discuss a putative molecular mechanism for CB1 receptor activation and biased signaling. Current studies suggest that allosteric binding sites on CB1 can be explored to yield biased ligands that favor or hinder conformational changes important for biased signaling.

Successful and Unsuccessful Brain Aging in Pets: Pathophysiological Mechanisms behind Clinical Signs and Potential Benefits from Palmitoylethanolamide Nutritional Intervention

Simple Summary

Cognitive dysfunction syndrome is a common yet underreported neurodegenerative disorder of elderly dogs and cats and a natural model of human Alzheimer’s disease. The increasingly expanding life expectancy means a larger proportion of affected animals in the coming decades. Although far from being curative, available treatments are more effective the sooner they are started. Educating veterinary practitioners and owners in the early recognition of age-related cognitive dysfunction is thus mandatory. By shedding light on the mechanism underlying the disease, novel and more effective approaches might be developed. Emerging evidence shows that successful and unsuccessful brain aging share a common underlying mechanism that is neuroinflammation. This process involves astrocytes, microglia, and mast cells and has a restorative homeostatic intent. However, for reasons not fully elucidated yet, neuroinflammation can also exert detrimental consequences substantially contributing to neurodegeneration. Here we summarize the evidence accumulated so far on the pathogenic role of neuroinflammation in the onset and progression of age-related neurodegenerative disorders, such as Alzheimer’s disease. The potential benefit of palmitoylethanolamide dietary intervention in rebalancing neuroinflammation and exerting neuroprotection is also discussed.

Abstract

Canine and feline cognitive dysfunction syndrome is a common neurodegenerative disorder of old age and a natural model of human Alzheimer’s disease. With the unavoidable expanding life expectancy, an increasing number of small animals will be affected. Although there is no cure, early detection and intervention are vitally important to delay cognitive decline. Knowledge of cellular and molecular mechanisms underlying disease onset and progression is an equally decisive factor for developing effective approaches. Uncontrolled neuroinflammation, orchestrated in the central nervous system mainly by astrocytes, microglia, and resident mast cells, is currently acknowledged as a hallmark of neurodegeneration. This has prompted scientists to find a way to rebalance the altered crosstalk between these cells. In this context, great emphasis has been given to the role played by the expanded endocannabinoid system, i.e., endocannabinoidome, because of its prominent role in physiological and pathological neuroinflammation. Within the endocannabinoidome, great attention has been paid to palmitoylethanolamide due to its safe and pro-homeostatic effects. The availability of new ultramicronized formulations highly improved the oral bioavailability of palmitoylethanolamide, paving the way to its dietary use. Ultramicronized palmitoylethanolamide has been repeatedly tested in animal models of age-related neurodegeneration with promising results. Data accumulated so far suggest that supplementation with ultramicronized palmitoylethanolamide helps to accomplish successful brain aging.

Combining endocannabinoids with retigabine for enhanced M-channel effect and improved KV7 subtype selectivity

Retigabine is unique among anticonvulsant drugs by targeting the neuronal M-channel, which is composed of KV7.2/KV7.3 and contributes to the negative neuronal resting membrane potential. Unfortunately, retigabine causes adverse effects, which limits its clinical use. Adverse effects may be reduced by developing M-channel activators with improved KV7 subtype selectivity. The aim of this study was to evaluate the prospect of endocannabinoids as M-channel activators, either in isolation or combined with retigabine. Human KV7 channels were expressed in Xenopus laevis oocytes. The effect of extracellular application of compounds with different properties was studied using two-electrode voltage clamp electrophysiology. Site-directed mutagenesis was used to construct channels with mutated residues to aid in the mechanistic understanding of these effects. We find that arachidonoyl-L-serine (ARA-S), a weak endocannabinoid, potently activates the human M-channel expressed in Xenopus oocytes. Importantly, we show that ARA-S activates the M-channel via a different mechanism and displays a different KV7 subtype selectivity compared with retigabine. We demonstrate that coapplication of ARA-S and retigabine at low concentrations retains the effect on the M-channel while limiting effects on other KV7 subtypes. Our findings suggest that improved KV7 subtype selectivity of M-channel activators can be achieved through strategically combining compounds with different subtype selectivity.

Metabolic Consequences of Gestational Cannabinoid Exposure

Up to 20% of pregnant women ages 18-24 consume cannabis during pregnancy. Moreover, clinical studies indicate that cannabis consumption during pregnancy leads to fetal growth restriction (FGR), which is associated with an increased risk of obesity, type II diabetes (T2D), and cardiovascular disease in the offspring. This is of great concern considering that the concentration of Δ9- tetrahydrocannabinol (Δ9-THC), a major psychoactive component of cannabis, has doubled over the last decade and can readily cross the placenta and enter fetal circulation, with the potential to negatively impact fetal development via the endocannabinoid (eCB) system. Cannabis exposure in utero could also lead to FGR via placental insufficiency. In this review, we aim to examine current pre-clinical and clinical findings on the direct effects of exposure to cannabis and its constituents on fetal development as well as indirect effects, namely placental insufficiency, on postnatal metabolic diseases.

Involvement of acid ceramidase in the degradation of bioactive N-acylethanolamines

Bioactive N-acylethanolamines (NAEs) include palmitoylethanolamide, oleoylethanolamide, and anandamide, which exert anti-inflammatory, anorexic, and cannabimimetic actions, respectively. The degradation of NAEs has been attributed to two hydrolases, fatty acid amide hydrolase and NAE acid amidase (NAAA). Acid ceramidase (AC) is a lysosomal enzyme that hydrolyzes ceramide (N-acylsphingosine), which resembles NAAA in structure and function. In the present study, we examined the role of AC in the degradation of NAEs. First, we demonstrated that purified recombinant human AC can hydrolyze various NAEs with lauroylethanolamide (C12:0-NAE) as the most reactive NAE substrate. We then used HEK293 cells metabolically labeled with [14C]ethanolamine, and revealed that overexpressed AC lowered the levels of 14C-labeled NAE. As analyzed with liquid chromatography-tandem mass spectrometry, AC overexpression decreased the amounts of different NAE species. Furthermore, suppression of endogenous AC in LNCaP prostate cells by siRNA increased the levels of various NAEs. Lastly, tissue homogenates from mice genetically lacking saposin D, a presumable activator protein of AC, showed much lower hydrolyzing activity for NAE as well as ceramide than the homogenates from wild-type mice. These results demonstrate the ability of AC to hydrolyze NAEs and suggest its physiological role as a third NAE hydrolase.

Discovering a New Metabolic Pathway. Early Work with My Friend, Viswanathan Natarajan

This article summarizes our early work with Viswanathan Natarajan in the 1980s at the University of Minnesota's Hormel Institute, when he was at the beginning of his brilliant academic career. At that time most metabolic pathways for the biosynthesis and degradation of phospholipids were well established and known in considerable detail. Hence, it was exciting to discover a novel sequence of biochemical reactions, first in dog heart and later in various other vertebrate cells and tissues that became known as the transacylation-phosphodiesterase pathway of phospholipid metabolism. Because one of the metabolites, N-arachidonoylethanolamine, produced by this reaction sequence, was later found to bind to and activate cannabinoid receptors, investigations of this pathway became part of the rapidly growing field of endocannabinoid research. This is briefly summarized here as well.

Rho-Kinase as a Therapeutic Target for Nonalcoholic Fatty Liver Diseases

Nonalcoholic fatty liver disease (NAFLD) is a major public health problem and the most common form of chronic liver disease, affecting 25% of the global population. Although NAFLD is closely linked with obesity, insulin resistance, and type 2 diabetes mellitus, knowledge on its pathogenesis remains incomplete. Emerging data have underscored the importance of Rho-kinase (Rho-associated coiled-coil-containing kinase [ROCK]) action in the maintenance of normal hepatic lipid homeostasis. In particular, pharmacological blockade of ROCK in hepatocytes or hepatic stellate cells prevents the progression of liver diseases such as NAFLD and fibrosis. Moreover, mice lacking hepatic ROCK1 are protected against obesity-induced fatty liver diseases by suppressing hepatic de novo lipogenesis. Here we review the roles of ROCK as an indispensable regulator of obesity-induced fatty liver disease and highlight the key cellular pathway governing hepatic lipid accumulation, with focus on de novo lipogenesis and its impact on therapeutic potential. Consequently, a comprehensive understanding of the metabolic milieu linking to liver dysfunction triggered by ROCK activation may help identify new targets for treating fatty liver diseases such as NAFLD.

The role of endocannabinoid pathway in the neuropathology of Alzheimer's disease: Can the inhibitors of MAGL and FAAH prove to be potential therapeutic targets against the cognitive impairment associated with Alzheimer's disease?

Alzheimer's disease is a neurodegenerative disease characterized by progressive decline of cognitive function in combination with neuronal death. Current approved treatment target single dysregulated pathway instead of multiple mechanism, resulting in lack of efficacy in slowing down disease progression. The proclivity of endocannabinoid system to exert neuroprotective action and mitigate symptoms of neurodegeneration condition has received substantial interest. Growing evidence suggest the endocannabinoids (eCB) system, viz. anadamide (AEA) and arachidonoyl glycerol (2-AG), as potential therapeutic targets with the ability to modify Alzheimer's pathology by targeting the inflammatory, neurodegenerative and cognitive aspects of the disease. In order to modulate endocannabinoid system, number of agents have been reported amongst which are inhibitors of the monoacylglycerol (MAGL) and fatty acid amide hydrolase (FAAH), the enzymes that hydrolyses 2-AG and AEA respectively. However, little is known regarding the exact mechanistic signalling and their effects on pathophysiology and cognitive decline associated with Alzheimer's disease. Both MAGL and FAAH inhibitors possess fascinating properties that may offer a multi-faceted approach for the treatment of Alzheimer's disease such as potential to protect neurons from deleterious effect of amyloid-β, reducing phosphorylation of tau, reducing amyloid-β induced oxidative stress, stimulating neurotrophin to support brain intrinsic repair mechanism etc. Based on empirical evidence, MAGL and FAAH inhibitors might have potential for therapeutic efficacy against cognitive impairment associated with Alzheimer's disease. The aim of this review is to summarize the experimental studies demonstrating the polyvalent properties of MAGL or FAAH inhibitor compounds for the treatment of Alzheimer's disease, and also effect of these on learning and types of memories, which together encourage to study these compounds over other therapeutics targets. Further research in this direction would enhance the molecular mechanisms and development of applicable interventions for the treatment of Alzheimer's disease, which nevertheless stay as the primary unmet need.

Cannabinoids for SARS-CoV-2 and is there evidence of their therapeutic efficacy?

To combat the coronaviruses and their novel variants, therapeutic drugs and the development of vaccines that are to be effective throughout human life are urgently needed. The endocannabinoid system (ECS) acts as a modulator in the activation of the microcirculation, immune system, and autonomic nervous system, along with controlling pharmacological functions such as emotional responses, homeostasis, motor functions, cognition, and motivation. The ECS contains endogenous cannabinoids, cannabinoid receptor (CBRs), and enzymes that regulate their biosynthesis, transport, and degradation. Moreover, phytocannabinoids and synthetic cannabinoids that mimic the action of endocannabinoids also play an essential role in the modulation of the ECS. Cannabinoids, the main constituents of cannabis (Cannabis sativa L.), are therapeutic compounds that have received international attention in the health field due to their therapeutic properties. Recently, they have been tested for the treatment of COVID-19 due to their antiviral properties. Indeed, cannabinoid-type compounds, and in particular cannabidiol (CBD), isolated from glandular trichomes found in the calyx of cannabis flowers with reported antiviral properties is hypothesized to be a therapeutic option in the ministration of SARS-CoV-2 consorted with COVID-19 disease. The relevant articles were determined from the database search published mainly in Web of Science, Google scholar, PubMed, Crossref, and ClinicalTrials.gov database during the pandemic period. The articles were evaluated for the therapeutic potentials, mechanisms of action of cannabinoids, the roles of the ECS in the immune system, impact of cannabinoids in SARS-CoV-2 septic, especially if they address the application of cannabinoids as drugs for the curability and management of SARS-CoV-2 and its novel variants. Although the evidence needed to be considered using cannabinoids in the control and treatment of viral diseases is currently in its infancy, they already offer an opportunity for clinicians due to their effects in relieving pain, improving appetite, and improving childhood epilepsy, especially in cancer and human immunodeficiency virus (HIV/AIDS) patients. In addition to these, the most recent scientific evidence emphasizes their use in the treatment of the coronavirus infected patients. In brief, all preclinic and clinic studies that have been reported show that, through the cannabinoid system, cannabinoids, particularly CBD, have many mechanisms that are effective in the treatment of patients infected by SARS-CoV-2. Thus, more extensive studies are necessary in this area to fully identify the effects of cannabinoids on SARS-CoV-2.

The synthetic CB1 cannabinoid receptor selective agonists: Putative medical uses and their legalization

More than 500 molecules have been identified as components of Cannabis sativa (C. sativa), of which the most studied is Δ⁹-tetrahydrocannabinol (Δ⁹-THC). Several studies have suggested that Δ⁹-THC exerts diverse biological effects, ranging from fragmentation of DNA to behavioral disruptions. Currently, it is accepted that most of the pharmacological properties of Δ⁹-THC engage the activation of the cannabinoid receptors, named CB₁ and CB₂. Interestingly, multiple pieces of evidence have suggested that the cannabinoid receptors play an active role in the modulation of several diseases leading to the design of synthetic cannabinoid-like compounds. Advances in the development of synthetic CB₁ cannabinoid receptor selective agonists as therapeutical approaches are, however, limited. This review focuses on available evidence searched in PubMed regarding the synthetic CB₁ cannabinoid receptor selective agonists such as AM-1235, arachidonyl-2' chloroethylamide (ACEA), CP 50,556-1 (Levonantradol), CP-55,940, HU-210, JWH-007, JWH-018, JWH-200 (WIN 55,225), methanandamide, nabilone, O-1812, UR-144, WIN 55,212-2, nabiximols, and dronabinol. Indeed, it would be ambitious to describe all available evidence related to the synthetic CB₁ cannabinoid receptor selective agonists. However, and despite the positive evidence on the positive results of using these compounds in experimental models of health disturbances and preclinical trials, we discuss evidence in regards some concerns due to side effects.

The endocannabinoid system in social anxiety disorder: from pathophysiology to novel therapeutics

Social anxiety disorder (SAD) is a highly prevalent psychiatric disorder that presents with an early age of onset, chronic disease course, and increased risk of psychiatric comorbidity. Current treatment options for SAD are associated with low response rates, suboptimal efficacy, and possible risk of adverse effects. Investigation of new neurobiological mechanisms may aid in the identification of more specific therapeutic targets for the treatment of this disorder. Emerging evidence suggests that the endogenous cannabinoid system, also referred to as the endocannabinoid system (ECS), could play a potential role in the pathophysiology of SAD. This review discusses the known pathophysiological mechanisms of SAD, the potential role of the ECS in this disorder, current drugs targeting the ECS, and the potential of these novel compounds to enhance the therapeutic armamentarium for SAD. Further investigational efforts, specifically in human populations, are warranted to improve our knowledge of the ECS in SAD.

Cannabinoids and Endocannabinoid System Changes in Intestinal Inflammation and Colorectal Cancer

Despite the multiple preventive measures and treatment options, colorectal cancer holds a significant place in the world's disease and mortality rates. The development of novel therapy is in critical need, and based on recent experimental data, cannabinoids could become excellent candidates. This review covered known experimental studies regarding the effects of cannabinoids on intestinal inflammation and colorectal cancer. In our opinion, because colorectal cancer is a heterogeneous disease with different genomic landscapes, the choice of cannabinoids for tumor prevention and treatment depends on the type of the disease, its etiology, driver mutations, and the expression levels of cannabinoid receptors. In this review, we describe the molecular changes of the endocannabinoid system in the pathologies of the large intestine, focusing on inflammation and cancer.

Involvement of the γ Isoform of cPLA2 in the Biosynthesis of Bioactive N-Acylethanolamines

Arachidonylethanolamide (anandamide) acts as an endogenous ligand of cannabinoid receptors, while other N-acylethanolamines (NAEs), such as palmitylethanolamide and oleylethanolamide, show analgesic, anti-inflammatory, and appetite-suppressing effects through other receptors. In mammalian tissues, NAEs, including anandamide, are produced from glycerophospholipid via N-acyl-phosphatidylethanolamine (NAPE). The ɛ isoform of cytosolic phospholipase A₂ (cPLA₂) functions as an N-acyltransferase to form NAPE. Since the cPLA₂ family consists of six isoforms (α, β, γ, δ, ɛ, and ζ), the present study investigated a possible involvement of isoforms other than ɛ in the NAE biosynthesis. Firstly, when the cells overexpressing one of the cPLA₂ isoforms were labeled with [¹⁴C]ethanolamine, the increase in the production of [¹⁴C]NAPE was observed only with the ɛ-expressing cells. Secondly, when the cells co-expressing ɛ and one of the other isoforms were analyzed, the increase in [¹⁴C]N-acyl-lysophosphatidylethanolamine (lysoNAPE) and [¹⁴C]NAE was seen with the combination of ɛ and γ isoforms. Furthermore, the purified cPLA₂γ hydrolyzed not only NAPE to lysoNAPE, but also lysoNAPE to glycerophospho-N-acylethanolamine (GP-NAE). Thus, the produced GP-NAE was further hydrolyzed to NAE by glycerophosphodiesterase 1. These results suggested that cPLA₂γ is involved in the biosynthesis of NAE by its phospholipase A₁/A₂ and lysophospholipase activities.

The CB2 cannabinoid receptor as a therapeutic target in the central nervous system

INTRODUCTION

Targeting CB2 cannabinoid receptor (CB2r) represents a promising approach for the treatment of central nervous system disorders. These receptors were identified in peripheral tissues, but also in neurons in the central nervous system. New findings have highlighted the interest to target these central receptors to obtain therapeutic effects devoid of the classical cannabinoid side-effects.

AREAS COVERED

In this review, we searched PubMed (January 1991-May 2021), ClinicalTrials.gov and Cochrane Library databases for articles, reviews and clinical trials. We first introduce the relevance of CB2r as a key component of the endocannabinoid system. We discuss CB2r interest as a possible novel target in the treatment of pain. This receptor has raised interest as a potential target for neurodegenerative disorders treatment, as we then discussed. Finally, we underline studies revealing a novel potential CB2r interest in mental disorders treatment.

EXPERT OPINION

In spite of the interest of targeting CB2r for pain, clinical trials evaluating CB2r agonist analgesic efficacy have currently failed. The preferential involvement of CB2r in preventing the development of chronic pain could influence the failure of clinical trials designed for the treatment of already established pain syndromes. Specific trials should be designed to target the prevention of chronic pain development.

The Impact of Early Life Exposure to Cannabis: The Role of the Endocannabinoid System

Cannabis use during pregnancy has continued to rise, particularly in developed countries, as a result of the trend towards legalization and lack of consistent, evidence-based knowledge on the matter. While there is conflicting data regarding whether cannabis use during pregnancy leads to adverse outcomes such as stillbirth, preterm birth, low birthweight, or increased admission to neonatal intensive care units, investigations into long-term effects on the offspring’s health are limited. Historically, studies have focused on the neurobehavioral effects of prenatal cannabis exposure on the offspring. The effects of cannabis on other physiological aspects of the developing fetus have received less attention. Importantly, our knowledge about cannabinoid signaling in the placenta is also limited. The endocannabinoid system (ECS) is present at early stages of development and represents a potential target for exogenous cannabinoids in utero. The ECS is expressed in a broad range of tissues and influences a spectrum of cellular functions. The aim of this review is to explore the current evidence surrounding the effects of prenatal exposure to cannabinoids and the role of the ECS in the placenta and the developing fetus.

FMR1 and Autism, an Intriguing Connection Revisited

Autism Spectrum Disorder (ASD) represents a distinct phenotype of behavioral dysfunction that includes deficiencies in communication and stereotypic behaviors. ASD affects about 2% of the US population. It is a highly heritable spectrum of conditions with substantial genetic heterogeneity. To date, mutations in over 100 genes have been reported in association with ASD phenotypes. Fragile X syndrome (FXS) is the most common single-gene disorder associated with ASD. The gene associated with FXS, FMR1 is located on chromosome X. Accordingly, the condition has more severe manifestations in males. FXS results from the loss of function of FMR1 due to the expansion of an unstable CGG repeat located in the 5'' untranslated region of the gene. About 50% of the FXS males and 20% of the FXS females meet the Diagnostic Statistical Manual 5 (DSM-5) criteria for ASD. Among the individuals with ASD, about 3% test positive for FXS. FMRP, the protein product of FMR1, is a major gene regulator in the central nervous system. Multiple pathways regulated by FMRP are found to be dysfunctional in ASD patients who do not have FXS. Thus, FXS presents the opportunity to study cellular phenomena that may have wider applications in the management of ASD and to develop new strategies for ASD therapy.

The major endocannabinoid anandamide (AEA) induces apoptosis of human granulosa cells

The endocannabinoid system (ECS) plays a crucial role in human reproduction. Changes in anandamide (AEA) levels affect reproductive events and has already been suggested as biomarker of reproductive potential of male and female gametes. Although cannabinoid-receptor 1 (CB1) was already identified in human granulosa cells (hGCs) the ECS was not characterized on granulosa cells line COV434 nor the effects of AEA on GCs viability and function depicted. Therefore, the aim of this study was to characterize the ECS elements and explore the effects of AEA on both COV434 and hGCs. Our results revealed that hGCs express the full enzymatic machinery responsible for AEA metabolism as well as cannabinoid receptors. In addition, AEA induced a reduction in both COV434 and hGCs viability in a concentration and time-dependent manner. Nevertheless, the effects of AEA in cell viability was independent of either CB1 or CB2 receptors. There was no ROS release in both cell models; however, AEA induced morphological changes, presenting chromatin condensation at 72 h, and variation on mitochondrial membrane potential. Moreover, AEA induced an increase in caspase -3/-7 activities in both cell models, but in hGCs there was also an increase in caspase 8 activity. This study supports the idea that ECS balance is crucial for folliculogenesis and oocyte quality as dysregulated AEA levels may compromise female fertility.

Synthesis and molecular targets of N-13-hydroxy-octadienoyl-ethanolamine, a novel endogenous bioactive 15-lipoxygenase-derived metabolite of N-linoleoyl-ethanolamine found in the skin and saliva

N-Arachidonoyl-ethanolamine (AEA) is an endocannabinoid (eCB) and endogenous lipid mimicking many of the effects of Δ9-tetrahydrocannabinol, notably on brain functions, appetite, pain and inflammation. The eCBs and eCB-like compounds contain fatty acids, the main classes being the monoacylglycerols and the N-acyl-ethanolamines (NAEs). Thus, each long chain fatty acid likely exists under the form of a monoacylglycerol and NAE, as it is the case for arachidonic acid (AA) and linoleic acid (LA). Following their biosynthesis, AA and AEA can be further metabolized into additional eicosanoids, notably by the 15-lipoxygenase pathway. Thus, we postulated that NAEs possessing a 1Z,4Z-pentadiene motif, near their omega end, would be transformed into their 15-lipoxygenase metabolites. As a proof of concept, we investigated N-linoleoyl-ethanolamine (LAE). We successfully synthesized LEA and LEA-d4 as well as their 15-lipoxygenase-derived derivatives, namely 13-hydroxy-9Z,11E-octadecadienoyl-N-ethanolamine (13-HODE-EA) and 13-HODE-EA-d4, using Novozyme 435 immobilized on acrylic resin and soybean lipoxygenase respectively. We also show that both human 15-lipoxygenase-1 and -2 can biosynthesize 13-HODE-EA. Co-incubation of LEA and LA with either human 15-lipoxygenase led to the biosynthesis of 13-HODE-EA and 13-HODE in a ratio equal to or greater than 3:1, indicating that LEA is preferred to LA by these enzymes. Finally, we show that 13-HODE-EA is found in human saliva and skin and is a weak although selective TRPV1 agonist. The full biological importance of 13-HODE-EA remains to be explored.

Exploiting cannabinoid and vanilloid mechanisms for epilepsy treatment

This review focuses on the possible roles of phytocannabinoids, synthetic cannabinoids, endocannabinoids, and "transient receptor potential cation channel, subfamily V, member 1" (TRPV1) channel blockers in epilepsy treatment. The phytocannabinoids are compounds produced by the herb Cannabis sativa, from which Δ⁹-tetrahydrocannabinol (Δ⁹-THC) is the main active compound. The therapeutic applications of Δ⁹-THC are limited, whereas cannabidiol (CBD), another phytocannabinoid, induces antiepileptic effects in experimental animals and in patients with refractory epilepsies. Synthetic CB₁ agonists induce mixed effects, which hamper their therapeutic applications. A more promising strategy focuses on compounds that increase the brain levels of anandamide, an endocannabinoid produced on-demand to counteract hyperexcitability. Thus, anandamide hydrolysis inhibitors might represent a future class of antiepileptic drugs. Finally, compounds that block the TRPV1 ("vanilloid") channel, a possible anandamide target in the brain, have also been investigated. In conclusion, the therapeutic use of phytocannabinoids (CBD) is already in practice, although its mechanisms of action remain unclear. Endocannabinoid and TRPV1 mechanisms warrant further basic studies to support their potential clinical applications. This article is part of the Special Issue "NEWroscience 2018".

Expression of the putative cannabinoid receptor GPR55 is increased in endometrial carcinoma

Although the expression of the putative cannabinoid receptor GPR55 has been shown to be involved in the growth of various tumours and is increased in a number of cancers, its expression has not been examined in patients with endometrial cancer (EC). Quantitative RT-PCR (for mRNA levels) and immunohistochemistry (for protein levels) were used to measure GPR55 expression in patients with Type 1 and Type 2 EC and correlated against cannabinoid receptor (CB1 and CB2) protein levels using non-cancerous endometrium as the control tissue. The data indicated that GPR55 transcript and GPR55 protein levels were significantly (p < 0.002 and p < 0.0001, respectively) higher in EC tissues than in control tissues. The levels of immunoreactive GPR55 protein were correlated with GPR55 transcript levels, but not with the expression of CB1 receptor protein, and were inversely correlated with CB2 protein expression, which was significantly decreased. It can be concluded that GPR55 expression is elevated in women with EC, and thus could provide a potential novel biomarker and therapeutic target for this disease.

Development of [18F]LU14 for PET Imaging of Cannabinoid Receptor Type 2 in the Brain

Cannabinoid receptors type 2 (CB2R) represent an attractive therapeutic target for neurodegenerative diseases and cancer. Aiming at the development of a positron emission tomography (PET) radiotracer to monitor receptor density and/or occupancy during a CB2R-tailored therapy, we herein describe the radiosynthesis of cis-[¹⁸F]1-(4-fluorobutyl-N-((1s,4s)-4-methylcyclohexyl)-2-oxo-1,2-dihydro-1,8-naphthyridine-3-carboxamide ([¹⁸F]LU14) starting from the corresponding mesylate precursor. The first biological evaluation revealed that [¹⁸F]LU14 is a highly affine CB2R radioligand with >80% intact tracer in the brain at 30 min p.i. Its further evaluation by PET in a well-established rat model of CB2R overexpression demonstrated its ability to selectively image the CB2R in the brain and its potential as a tracer to further investigate disease-related changes in CB2R expression.

Palmitoleoylethanolamide Is an Efficient Anti-Obesity Endogenous Compound: Comparison with Oleylethanolamide in Diet-Induced Obesity

Obesity is currently a major epidemic in the developed world. However, we lack a wide range of effective pharmacological treatments and therapies against obesity, and those approved are not devoid of adverse effects. Dietary components such as palmitoleic acid have been proposed to improve metabolic disbalance in obesity, although the mechanisms involved are not well understood. Both palmitoleic acid (POA) and oleic acid (OA) can be transformed in N-acylethanolamines (NAEs), mediating the effects of dietary POA and OA. To test this hypothesis, here, we study the effects on food intake and body weight gain of palmitoleylethanolamide (POEA) and the OA-derived NAE analogue, oleoylethanolamide (OEA), in Sprague-Dawley rats with a hypercaloric cafeteria diet (HFD). Plasma biochemical metabolites, inflammatory mediators, and lipogenesis-associated liver protein expression were also measured. The results indicate that POEA is able to improve health status in diet-induced obesity, decreasing weight, liver steatosis, inflammation, and dyslipemia. The action of POEA was found to be almost identical to that of OEA, which is an activator of the nuclear peroxisome proliferator receptor alpha (PPARα), and it is structurally related to POEA. These results suggest that the dietary administration of either POA or POEA might be considered as nutritional intervention as complementary treatment for complicated obesity in humans.