Reduction of human monocytic cell neurotoxicity and cytokine secretion by ligands of the cannabinoid-type CB2 receptor

Dynamic endocannabinoid-mediated neuromodulation of retinal circadian circuitry

Circadian rhythms are biological rhythms that originate from the "master circadian clock," called the suprachiasmatic nucleus (SCN). SCN orchestrates the circadian rhythms using light as a chief zeitgeber, enabling humans to synchronize their daily physio-behavioral activities with the Earth's light-dark cycle. However, chronic/ irregular photic disturbances from the retina via the retinohypothalamic tract (RHT) can disrupt the amplitude and the expression of clock genes, such as the period circadian clock 2, causing circadian rhythm disruption (CRd) and associated neuropathologies. The present review discusses neuromodulation across the RHT originating from retinal photic inputs and modulation offered by endocannabinoids as a function of mitigation of the CRd and associated neuro-dysfunction. Literature indicates that cannabinoid agonists alleviate the SCN's ability to get entrained to light by modulating the activity of its chief neurotransmitter, i.e., γ-aminobutyric acid, thus preventing light-induced disruption of activity rhythms in laboratory animals. In the retina, endocannabinoid signaling modulates the overall gain of the retinal ganglion cells by regulating the membrane currents (Ca2+, K+, and Cl- channels) and glutamatergic neurotransmission of photoreceptors and bipolar cells. Additionally, endocannabinoids signalling also regulate the high-voltage-activated Ca2+ channels to mitigate the retinal ganglion cells and intrinsically photosensitive retinal ganglion cells-mediated glutamate release in the SCN, thus regulating the RHT-mediated light stimulation of SCN neurons to prevent excitotoxicity. As per the literature, cannabinoid receptors 1 and 2 are becoming newer targets in drug discovery paradigms, and the involvement of endocannabinoids in light-induced CRd through the RHT may possibly mitigate severe neuropathologies.

Isobolographic Analysis of the Cytoprotective Effect of Dapsone and Cannabidiol Alone or Combination upon Oxygen-Glucose Deprivation/Reoxygenation Model in SH-SY5Y Cells

Oxidative stress and apoptosis cell death are critical secondary damage mechanisms that lead to losing neighboring healthy tissue after cerebral ischemia. This study aims to characterize the type of interaction between dapsone (DDS) and cannabidiol (CBD) and its cytoprotective effect in an in vitro model of oxygen and glucose deprivation for 6 h followed by 24 h of reoxygenation (OGD/R), using the SH-SY5Y cell line. For the combined concentrations, an isobolographic study was designed to determine the optimal concentration-response combinations. Cell viability was evaluated by measuring the lactate dehydrogenase (LDH) release and 3-[4, 5-dimethyl-2-thiazolyl]-2, 5-diphenyl-2H-tetrazolium bromide (MTT) assays. Also, the reactive oxygen species (ROS) and reduced glutathione (GSH) levels were analyzed as oxidative stress markers. Finally, caspase-3 activity was evaluated as a marker cell death by apoptosis. The results showed a decrease in cell viability, an increase in oxidant stress, and the activity of caspase-3 by the effect of OGD/R. Meanwhile, both DDS and CBD demonstrated antioxidant, antiapoptotic, and cytoprotective effects in a concentration-response manner. The isobolographic study indicated that the concentration of 2.5 µM of DDS plus 0.05 µM of CBD presented a synergistic effect so that in treatment, cell death due to OGD/R decreased. The findings indicate that DDS-CBD combined treatment may be a helpful therapy in cerebral ischemia with reperfusion.

The effect of cannabinoid type 2 receptor agonist on morphine tolerance

Pain highly impacts the quality of life of patients. Morphine is used for pain treatment; however, its side effects, especially morphine tolerance, limit its use in the clinic. The problem of morphine tolerance has plagued health workers and patients for years. Unfortunately, the exact mechanism of morphine tolerance has not been fully clarified. The mechanisms of morphine tolerance that are currently being studied may include μ-opioid receptor (MOR) desensitization and internalization, mitogen-activated protein kinase (MAPK) pathway activation and crosstalk, the effects of microglia and the increase in inflammatory factors. Morphine tolerance can be alleviated by improving the pathophysiological changes that lead to morphine tolerance. Previous studies have shown that a cannabinoid type 2 (CB2) receptor agonist could attenuate morphine tolerance in a variety of animal models. Many studies have shown an interaction between the cannabinoid system and the opioid system. The CB2 receptor may modulate the effect of morphine through a pathway that is common to the MOR, since both receptors are G protein-coupled receptors (GPCRs). This study introduces the potential mechanism of morphine tolerance and the effect of CB2 receptor agonists on reducing morphine tolerance, which can provide new ideas for researchers studying morphine and provide beneficial effects for patients suffering from morphine tolerance.

Increasing CB2 Receptor Activity after Early Life Stress Prevents Depressive Behavior in Female Rats

Early adversity, the loss of the inhibitory GABAergic interneuron parvalbumin, and elevated neuroinflammation are associated with depression. Individuals with a maltreatment history initiate medicinal cannabis use earlier in life than non-maltreated individuals, suggesting self-medication. Female rats underwent maternal separation (MS) between 2 and 20 days of age to model early adversity or served as colony controls. The prelimbic cortex and behavior were examined to determine whether MS alters the cannabinoid receptor 2 (CB2), which has anti-inflammatory properties. A reduction in the CB2-associated regulatory enzyme MARCH7 leading to increased NLRP3 was observed with Western immunoblots in MS females. Immunohistochemistry with stereology quantified numbers of parvalbumin-immunoreactive cells and CB2 at 25, 40, and 100 days of age, revealing that the CB2 receptor associated with PV neurons initially increases at P25 and subsequently decreases by P40 in MS animals, with no change in controls. Confocal and triple-label microscopy suggest colocalization of these CB2 receptors to microglia wrapped around the parvalbumin neuron. Depressive-like behavior in MS animals was elevated at P40 and reduced with the CB2 agonist HU-308 or a CB2-overexpressing lentivirus microinjected into the prelimbic cortex. These results suggest that increasing CB2 expression by P40 in the prelimbic cortex prevents depressive behavior in MS female rats.

Research progress on the cannabinoid type-2 receptor and Parkinson's disease

Parkinson's disease (PD) is featured by movement impairments, including tremors, bradykinesia, muscle stiffness, and imbalance. PD is also associated with many non-motor symptoms, such as cognitive impairments, dementia, and mental disorders. Previous studies identify the associations between PD progression and factors such as α-synuclein aggregation, mitochondrial dysfunction, inflammation, and cell death. The cannabinoid type-2 receptor (CB2 receptor) is a transmembrane G-protein-coupled receptor and has been extensively studied as part of the endocannabinoid system. CB2 receptor is recently emerged as a promising target for anti-inflammatory treatment for neurodegenerative diseases. It is reported to modulate mitochondrial function, oxidative stress, iron transport, and neuroinflammation that contribute to neuronal cell death. Additionally, CB2 receptor possesses the potential to provide feedback on electrophysiological processes, offering new possibilities for PD treatment. This review summarized the mechanisms underlying PD pathogenesis. We also discussed the potential regulatory role played by CB2 receptor in PD.

Alzheimer's Disease and Cancer: Common Targets

There is growing epidemiologic evidence of an inverse association between cancer and AD. In addition, both cell survival and death are regulated by the same signaling pathways, and their abnormal regulation may be implicated in the occurrence and development of cancer and AD. Research shows that there may be a common molecular mechanism between cancer and AD. This review will discuss the role of GSK3, DAPK1, PP2A, P53 and CB2R in the pathogenesis of cancer and AD and describe the current research status of drug development based on these targets.

Neuroprotection and Beyond: The Central Role of CB1 and CB2 Receptors in Stroke Recovery

The endocannabinoid system, with its intricate presence in numerous cells, tissues, and organs, offers a compelling avenue for therapeutic interventions. Central to this system are the cannabinoid receptors 1 and 2 (CB1R and CB2R), whose ubiquity can introduce complexities in targeted treatments due to their wide-ranging physiological influence. Injuries to the central nervous system (CNS), including strokes and traumatic brain injuries, induce localized pro-inflammatory immune responses, termed neuroinflammation. Research has shown that compensatory immunodepression usually follows, and these mechanisms might influence immunity, potentially affecting infection risks in patients. As traditional preventive treatments like antibiotics face challenges, the exploration of immunomodulatory therapies offers a promising alternative. This review delves into the potential neuroprotective roles of the cannabinoid receptors: CB1R's involvement in mitigating excitotoxicity and CB2R's dual role in promoting cell survival and anti-inflammatory responses. However, the potential of cannabinoids to reduce neuroinflammation must be weighed against the risk of exacerbating immunodepression. Though the endocannabinoid system promises numerous therapeutic benefits, understanding its multifaceted signaling mechanisms and outcomes remains a challenge.

Beta-Caryophyllene, a Plant-Derived CB2 Receptor Agonist, Protects SH-SY5Y Cells from Cadmium-Induced Toxicity

Cadmium (Cd) is a transition heavy metal that is able to accumulate in the central nervous system and may induce cell death through reactive oxygen species (ROS)-mediated mechanisms and inactivating the antioxidant processes, becoming an important risk factor for neurodegenerative diseases. The antioxidant effects of cannabinoid receptor modulation have been extensively described, and, in particular, β-Caryophyllene (BCP), a plant-derived cannabinoid 2 receptor (CB2R) agonist, not only showed significant antioxidant properties but also anti-inflammatory, analgesic, and neuroprotective effects. Therefore, the aim of the present study was to evaluate BCP effects in a model of Cd-induced toxicity in the neuroblastoma SH-SY5Y cell line used to reproduce Cd intoxication in humans. SH-SY5Y cells were pre-treated with BCP (25, 50, and 100 μM) for 24 h. The day after, cells were challenged with cadmium chloride (CdCl2; 10 μM) for 24 h to induce neuronal toxicity. CdCl2 increased ROS accumulation, and BCP treatment significantly reduced ROS production at concentrations of 50 and 100 μM. In addition, CdCl2 significantly decreased the protein level of nuclear factor erythroid 2-related factor 2 (Nrf2) compared to unstimulated cells; the treatment with BCP at a concentration of 50 μM markedly increased Nrf2 expression, thus confirming the BCP anti-oxidant effect. Moreover, BCP treatment preserved cells from death, regulated the apoptosis pathway, and showed a significant anti-inflammatory effect, thus reducing the pro-inflammatory cytokines increased by the CdCl2 challenge. The results indicated that BCP preserved neuronal damage induced by Cd and might represent a future candidate for protection in neurotoxic conditions.

Cannabinoids in Medicine: A Multifaceted Exploration of Types, Therapeutic Applications, and Emerging Opportunities in Neurodegenerative Diseases and Cancer Therapy

In this review article, we embark on a thorough exploration of cannabinoids, compounds that have garnered considerable attention for their potential therapeutic applications. Initially, this article delves into the fundamental background of cannabinoids, emphasizing the role of endogenous cannabinoids in the human body and outlining their significance in studying neurodegenerative diseases and cancer. Building on this foundation, this article categorizes cannabinoids into three main types: phytocannabinoids (plant-derived cannabinoids), endocannabinoids (naturally occurring in the body), and synthetic cannabinoids (laboratory-produced cannabinoids). The intricate mechanisms through which these compounds interact with cannabinoid receptors and signaling pathways are elucidated. A comprehensive overview of cannabinoid pharmacology follows, highlighting their absorption, distribution, metabolism, and excretion, as well as their pharmacokinetic and pharmacodynamic properties. Special emphasis is placed on the role of cannabinoids in neurodegenerative diseases, showcasing their potential benefits in conditions such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. The potential antitumor properties of cannabinoids are also investigated, exploring their potential therapeutic applications in cancer treatment and the mechanisms underlying their anticancer effects. Clinical aspects are thoroughly discussed, from the viability of cannabinoids as therapeutic agents to current clinical trials, safety considerations, and the adverse effects observed. This review culminates in a discussion of promising future research avenues and the broader implications for cannabinoid-based therapies, concluding with a reflection on the immense potential of cannabinoids in modern medicine.

CB2 receptor in the CNS: from immune and neuronal modulation to behavior

Despite low levels of cannabinoid receptor type 2 (CB2R) expression in the central nervous system in human and rodents, a growing body of evidence shows CB2R involvement in many processes at the behavioral level, through both immune and neuronal modulations. Recent in vitro and in vivo evidence have highlighted the complex role of CB2R under physiological and inflammatory conditions. Under neuroinflammatory states, its activation seems to protect the brain and its functions, making it a promising target in a wide range of neurological disorders. Here, we provide a complete and updated overview of CB2R function in the central nervous system of rodents, spanning from modulation of immune function in microglia but also in other cell types, to behavior and neuronal activity, in both physiological and neuroinflammatory contexts.

G protein-coupled receptors in neurodegenerative diseases and psychiatric disorders

Neuropsychiatric disorders are multifactorial disorders with diverse aetiological factors. Identifying treatment targets is challenging because the diseases are resulting from heterogeneous biological, genetic, and environmental factors. Nevertheless, the increasing understanding of G protein-coupled receptor (GPCR) opens a new possibility in drug discovery. Harnessing our knowledge of molecular mechanisms and structural information of GPCRs will be advantageous for developing effective drugs. This review provides an overview of the role of GPCRs in various neurodegenerative and psychiatric diseases. Besides, we highlight the emerging opportunities of novel GPCR targets and address recent progress in GPCR drug development.

Altered glial expression of the cannabinoid 1 receptor in the subiculum of a mouse model of Alzheimer's disease

The alteration of the endocannabinoid tone usually associates with changes in the expression and/or function of the cannabinoid CB₁ receptor. In Alzheimer's disease (AD), amyloid beta (Aβ)-containing aggregates induce a chronic inflammatory response leading to reactivity of both microglia and astrocytes. However, how this glial response impacts on the glial CB₁ receptor expression in the subiculum of a mouse model of AD, a brain region particularly affected by large accumulation of plaques and concomitant subcellular changes in microglia and astrocytes, is unknown. The CB₁ receptor localization in both glial cells was investigated in the subiculum of male 5xFAD/CB₂ ^EGFP/f/f (AD model) and CB₂ ^EGFP/f/f mice by immuno-electron microscopy. The findings revealed that glial CB₁ receptors suffer remarkable changes in the AD mouse. Thus, CB₁ receptor expression increases in reactive microglia in 5xFAD/CB₂ ^EGFP/f/f , but remains constant in astrocytes with CB₁ receptor labeling rising proportionally to the perimeter of the reactive astrocytes. Not least, the CB₁ receptor localization in microglial processes in the subiculum of controls and closely surrounding amyloid plaques and dystrophic neurites of the AD model, supports previous suggestions of the presence of the CB₁ receptor in microglia. These findings on the correlation between glial reactivity and the CB₁ receptor expression in microglial cells and astrocytes, contribute to the understanding of the role of the endocannabinoid system in the pathophysiology of Alzheimer's disease.

The impact of cannabinoids on inflammasome signaling in HIV-1 infection

Human immunodeficiency virus type 1 (HIV-1) is a chronic disease that afflicts over 38 million people worldwide without a known cure. The advent of effective antiretroviral therapies (ART) has significantly decreased the morbidity and mortality associated with HIV-1 infection in people living with HIV-1 (PWH), thanks to durable virologic suppression. Despite this, people with HIV-1 experience chronic inflammation associated with co-morbidities. While no single known mechanism accounts for chronic inflammation, there is significant evidence to support the role of the NLRP3 inflammasome as a key driver. Numerous studies have demonstrated therapeutic impact of cannabinoids, including exerting modulatory effects on the NLRP3 inflammasome. Given the high rates of cannabinoid use in PWH, it is of great interest to understand the intersecting biology of the role of cannabinoids in HIV-1-associated inflammasome signaling. Here we describe the literature of chronic inflammation in people with HIV, the therapeutic impact of cannabinoids in PWH, endocannabinoids in inflammation, and HIV-1-associated inflammation. We describe a key interaction between cannabinoids, the NLRP3 inflammasome, and HIV-1 viral infection, which supports further investigation of the critical role of cannabinoids in HIV-1 infection and inflammasome signaling.

Antidepressant and Neuroprotective Effects of 3-Hydroxy Paroxetine, an Analog of Paroxetine in Rats

BACKGROUND

Paroxetine (PX) is a widely used antidepressant with side effects such as weakness, dizziness, and trouble sleeping. In search of novel compounds with better efficacy and fewer side effects, we synthesized 3HPX, a hydroxylated analog of PX, and compared the 2 in silico for their pharmacokinetic and binding properties and in vivo for their antidepressant and potential neuroprotective effects.

METHODS

In silico studies compared pharmacological properties as well as interactions of PX and 3HPX with the serotonin transporter. In vivo studies utilized an animal model of comorbid depression-Parkinson disease. Adult male Wistar rats were injected (sterotaxically) with lipopolysaccharide in the striatum (unilaterally), followed by 14 days of once-daily injections (i.p.) of 10 mg/kg PX or 3HPX. Animals were tested for motor asymmetry and locomotor activity as well as indices of anhedonia and helplessness using sucrose preference and forced swim tests, respectively. Brains of these animals were collected after the last test, and tyrosine hydroxylase-positive neurons in substantia nigra pars compacta and Iba-1-positive stained microglia in ipsilateral striatum were measured.

RESULTS

In silico findings indicated that 3HPX could bind stronger to serotonin transporter and also have a better clearance and hence less toxicity compared with PX. In vivo results revealed a more effective reversal of immobility in the swim test, substantial increase in tyrosine hydroxylase-positive cells in the substantia nigra pars compacta, and more ramified Iba-1+ cells by 3HPX compared with PX.

CONCLUSION

The findings suggest superior effectiveness of 3HPX as an antidepressant and neuroprotectant compared with PX and hence potential utility in Parkinson disease depression co-morbidity.

The role of MACF1 on acute myeloid leukemia cell proliferation is involved in Runx2-targeted PI3K/Akt signaling

Acute myeloid leukemia (AML) is a type of hematologic diseases, which is related to abnormal genes. The aberrant microtubule actin cross-linking factor 1 (MACF1) is associated with progression of multiple tumors by initiating cell proliferation. Nevertheless, the function and action mechanism of MACF1 in AML cell proliferation remain mostly unknown. Our study aimed to explore the influence of MACF1 on AML cell proliferation by CCK-8 and EdU staining assays. Moreover, we aimed to explore the effect of MACF1 on downstream Runx2 and the PI3K/Akt signaling. MACF1 expression in AML patients was predicted by bioinformatics analysis. Cells were transfected with si-con, si-MACF1 or Runx2 using Lipofectamine 2000. Upregulated MACF1 was found in AML patients and predicted worse overall survival. MACF1 expression was upregulated in AML cells compared with that in hematopoietic stem and progenitor cells. MACF1 silencing reduced AML cell proliferation. Runx2 level was increased in AML cells, and decreased by silencing MACF1. Runx2 upregulation rescued MACF1 silencing-mediated inhibition of proliferation. MACF1 downregulation inhibited activation of the PI3K/Akt pathway by decreasing Runx2. Activation of the PI3K/Akt pathway abrogated the suppressive role of MACF1 downregulation in AML cell proliferation. In conclusion, MACF1 knockdown decreased AML cell proliferation by reducing Runx2 and inactivating the PI3K/Akt signaling.

Microglial Cannabinoid CB2 Receptors in Pain Modulation

Pain, especially chronic pain, can strongly affect patients' quality of life. Cannabinoids ponhave been reported to produce potent analgesic effects in different preclinical pain models, where they primarily function as agonists of G_i/o protein-coupled cannabinoid CB₁ and CB₂ receptors. The CB₁ receptors are abundantly expressed in both the peripheral and central nervous systems. The central activation of CB₁ receptors is strongly associated with psychotropic adverse effects, thus largely limiting its therapeutic potential. However, the CB₂ receptors are promising targets for pain treatment without psychotropic adverse effects, as they are primarily expressed in immune cells. Additionally, as the resident immune cells in the central nervous system, microglia are increasingly recognized as critical players in chronic pain. Accumulating evidence has demonstrated that the expression of CB₂ receptors is significantly increased in activated microglia in the spinal cord, which exerts protective consequences within the surrounding neural circuitry by regulating the activity and function of microglia. In this review, we focused on recent advances in understanding the role of microglial CB₂ receptors in spinal nociceptive circuitry, highlighting the mechanism of CB₂ receptors in modulating microglia function and its implications for CB₂ receptor- selective agonist-mediated analgesia.

Cannabinoid receptor 2 evolutionary gene loss makes parrots more susceptible to neuroinflammation

In vertebrates, cannabinoids modulate neuroimmune interactions through two cannabinoid receptors (CNRs) conservatively expressed in the brain (CNR1, syn. CB1) and in the periphery (CNR2, syn. CB2). Our comparative genomic analysis indicates several evolutionary losses in the CNR2 gene that is involved in immune regulation. Notably, we show that the CNR2 gene pseudogenized in all parrots (Psittaciformes). This CNR2 gene loss occurred because of chromosomal rearrangements. Our positive selection analysis suggests the absence of any specific molecular adaptations in parrot CNR1 that would compensate for the CNR2 loss in the modulation of the neuroimmune interactions. Using transcriptomic data from the brains of birds with experimentally induced sterile inflammation we highlight possible functional effects of such a CNR2 gene loss. We compare the expression patterns of CNR and neuroinflammatory markers in CNR2-deficient parrots (represented by the budgerigar, Melopsittacus undulatus and five other parrot species) with CNR2-intact passerines (represented by the zebra finch, Taeniopygia guttata). Unlike in passerines, stimulation with lipopolysaccharide resulted in neuroinflammation in the parrots linked with a significant upregulation of expression in proinflammatory cytokines (including interleukin 1 beta (IL1B) and 6 (IL6)) in the brain. Our results indicate the functional importance of the CNR2 gene loss for increased sensitivity to brain inflammation.

Endocannabinoid System of the Blood-Brain Barrier: Current Understandings and Therapeutic Potentials

The endocannabinoid system (ECS) has been found at the blood-brain barrier (BBB), as Cannabinoid receptors were characterized in human brain microvascular endothelial cells and astrocytes. In several in vitro and in vivo studies, cannabinoids decreased BBB permeability and enhanced membrane integrity, which may be achieved through endothelial tight junctions and other mechanisms. These permeability regulation effects of cannabinoids suggested that the ECS may protect the brain by enhancing barrier integrity. Related questions about cannabinoid-drug interaction and drug distribution across the BBB are also raised. Specifically, can cannabinoids significantly reduce drug bioavailability to the brain? More in-depth and systematic investigations are needed to characterize and quantify these effects of cannabinoids on brain microvasculature physiopathology. Therefore, this review summarizes literatures from different disciplines to promote more research on assessing the therapeutic benefits and risks of using cannabinoids to protect BBB from dysfunctions or breakdown, and to avoid consequent brain damages due to inflammation, neurodegenerations, hemorrhage, ischemia, or other causes.

Endocannabinoid system contributions to sex-specific adolescent neurodevelopment

With an increasing number of countries and states adopting legislation permitting the use of cannabis for medical purposes, there is a growing interest among health and research professionals into the system through which cannabinoids principally act, the endocannabinoid system (ECS). Much of the seminal research into the ECS dates back only 30 years and, although there has been tremendous development within the field during this time, many questions remain. More recently, investigations have emerged examining the contributions of the ECS to normative development and the effect of altering this system during important critical periods. One such period is adolescence, a unique period during which brain and behaviours are maturing and reorganizing in preparation for adulthood, including shifts in endocannabinoid biology. The purpose of this review is to discuss findings to date regarding the maturation of the ECS during adolescence and the consequences of manipulations of the ECS during this period to normative neurodevelopmental processes, as well as highlight sex differences in ECS function, important technical considerations, and future directions. Because most of what we know is derived from preclinical studies on rodents, we provide relevant background of this model and some commentary on the translational relevance of the research in this area.

Roles of the Cannabinoid System in the Basal Ganglia in Parkinson’s Disease

Parkinson’s disease (PD) is a neurodegenerative disease usually caused by neuroinflammation, oxidative stress and other etiologies. Recent studies have found that the cannabinoid system present in the basal ganglia has a strong influence on the progression of PD. Altering the cannabinoid receptor activation status by modulating endogenous cannabinoid (eCB) levels can exert an anti-movement disorder effect. Therefore, the development of drugs that modulate the endocannabinoid system may be a novel strategy for the treatment of PD. However, eCB regulation is complex, with diverse cannabinoid receptor functions and the presence of dopaminergic, glutamatergic, and γ-aminobutyric signals interacting with cannabinoid signaling in the basal ganglia region. Therefore, the study of eCB is challenging. Here, we have described the function of the cannabinoid system in the basal ganglia and its association with PD in three parts (eCBs, cannabinoid receptors, and factors regulating the cannabinoid metabolism) and summarized the mechanisms of action related to the cannabinoid analogs currently aimed at treating PD. The shortcomings identified from previous studies and the directions that should be explored in the future will provide insights into new approaches and ideas for the future development of cannabinoid-based drugs and the treatment of PD.

Crossroads of Drug Abuse and HIV Infection: Neurotoxicity and CNS Reservoir

Drug abuse is a common comorbidity in people infected with HIV. HIV-infected individuals who abuse drugs are a key population who frequently experience suboptimal outcomes along the HIV continuum of care. A modest proportion of HIV-infected individuals develop HIV-associated neurocognitive issues, the severity of which further increases with drug abuse. Moreover, the tendency of the virus to go into latency in certain cellular reservoirs again complicates the elimination of HIV and HIV-associated illnesses. Antiretroviral therapy (ART) successfully decreased the overall viral load in infected people, yet it does not effectively eliminate the virus from all latent reservoirs. Although ART increased the life expectancy of infected individuals, it showed inconsistent improvement in CNS functioning, thus decreasing the quality of life. Research efforts have been dedicated to identifying common mechanisms through which HIV and drug abuse lead to neurotoxicity and CNS dysfunction. Therefore, in order to develop an effective treatment regimen to treat neurocognitive and related symptoms in HIV-infected patients, it is crucial to understand the involved mechanisms of neurotoxicity. Eventually, those mechanisms could lead the way to design and develop novel therapeutic strategies addressing both CNS HIV reservoir and illicit drug use by HIV patients.

Spontaneous Activity of CB2 Receptors Attenuates Stress-Induced Behavioral and Neuroplastic Deficits in Male Mice

The monoaminergic theory of depression/anxiety disorders cannot fully explain the behavioral and neuroplastic changes observed after ADs chronic treatment. Endocannabinoid system, which comprises CB2 receptors, has been associated with the chronic effects of these drugs, especially in stressed mice. CB2-KO mice display more vulnerability to stressful stimuli. In the present study, we hypothesized that the behavioral and neuroplastic effects observed after repeated treatment with the AD escitalopram (Esc) in chronically stressed mice depend on CB2 receptor signaling. Male mice submitted to chronic unpredictable stress (CUS) paradigm (21 days) were treated daily with AM630 (0.01; 0.03 or 0.3 mg/kg, i.p) a CB2 receptor antagonist/inverse agonist. At e 19th day of the CUS protocol, mice were submitted to Open field test and Tail-suspension test to evaluate antidepressant-like behavior. At the end of the stress protocol, mice were submitted to Novel Suppressed Feeding test (day 22nd) to evaluate anxiety-like behavior. In a second series of experiments, male mice treated with Esc (10 mg/kg, daily, 21 days) in the presence or not of AM630 (0.30 mg/kg) were submitted to the same round of behavioral tests in the same conditions as performed in the dose-response curve protocol. Animals were then euthanized under deep anesthesia, and their brains/hippocampi removed for immunohistochemistry (Doublecortin-DCX) or Western Blot assay. Our results demonstrated that chronic treatment with AM630, a CB2 antagonist/inverse agonist, induces anxiolytic-like effects in stressed mice. Moreover, chronic reduction of CB2 receptor endogenous activity by AM630 attenuated the neuroplastic (potentiating stress-induced decreased expression of pro-BDNF, but enhanced pmTOR and DAGL expression in the hippocampus reduced in stressed mice), the antidepressant- but not the anxiolytic-like effects of Esc. AM630 alone or in combination with Esc decreased the expression of DCX + cell in both the subgranular and granular layers of the dentate gyrus (DG), indicating a general reduction of DCX + neuroblasts and a decrease in their migration through the DG layers. We suggest that the antidepressant-like behavior and the pro-neurogenic effect, but not the anxiolytic like behavior, promoted by Esc in stressed mice are, at least in part, mediated by CB2 receptors.

Neuroinflammation, Early-Life Adversity, and Brain Development

The overarching objective is to review how early exposure to adversity interacts with inflammation to alter brain maturation. Both adversity and inflammation are significant risk factors for psychopathology. Literature relevant to the effects of adversity in children and adolescents on brain development is reviewed. These studies are supported by research in animals exposed to species-relevant stressors during development. While it is known that exposure to adversity at any age increases inflammation, the effects of inflammation are exacerbated at developmental stages when the immature brain is uniquely sensitive to experiences. Microglia play a vital role in this process, as they scavenge cellular debris and prune synapses to optimize performance. In essence, microglia modify the synapse to match environmental demands, which is necessary for someone with a history of adversity. Overall, by piecing together clinical and preclinical research areas, what emerges is a picture of how adversity uniquely sculpts the brain. Microglia interactions with the inhibitory neurotransmitter GABA (specifically, the subtype expressing parvalbumin) are discussed within contexts of development and adversity. A review of inflammation markers in individuals with a history of abuse is combined with preclinical studies to describe their effects on maturation. Inconsistencies within the literature are discussed, with a call for standardizing methodologies relating to the age of assessing adversity effects, measures to quantify stress and inflammation, and more brain-based measures of biochemistry. Preclinical studies pave the way for interventions using anti-inflammation-based agents (COX-2 inhibitors, CB2 agonists, meditation/yoga) by identifying where, when, and how the developmental trajectory goes awry.

Immunomodulatory Role of CB2 Receptors in Emotional and Cognitive Disorders

Emotional behavior, memory, and learning have been associated with alterations in the immune system in neuropsychiatric and neurodegenerative diseases. In recent years, several studies pointed out the involvement of the cannabinoid receptor 2 (CB2r) in the immune system and the regulation of inflammation. This receptor is widely distributed in different tissues and organs with higher expression in spleen and immune system cells. However, CB2r has also been detected in several brain areas and different brain cell types, such as neurons and glia. These findings suggest that CB2r may closely relate the immune system and the brain circuits regulating inflammation, mood, and cognitive functions. Therefore, we review the studies that may help elucidate the molecular bases of CB2r in regulating inflammation in different brain cells and its role in the pathophysiology of psychiatric and neurodegenerative disorders.

Reviewing the Role of the Endocannabinoid System in the Pathophysiology of Depression

Major depressive disorder is a high-impact, debilitating disease and it is currently considered the most prevalent mental illness. It is associated with disability, as well as increased morbidity and mortality. Despite its significant repercussions in our society, its exact pathophysiology remains unclear and therefore, available antidepressant treatment options are limited and, in some cases, ineffective. In the past years, research has focused on the development of a multifactorial theory of depression. Simultaneously, evidence supporting the role of the endocannabinoid system in the neurobiology of neuropsychiatric diseases has emerged. Studies have shown that the endocannabinoid system strongly impacts neurotransmission, and the neuroendocrine and neuroimmune systems, which are known to be dysfunctional in depressive patients. Accordingly, common antidepressants were shown to have a direct impact on the expression of cannabinoid receptors throughout the brain. Therefore, the relationship between the endocannabinoid system and major depressive disorder is worth consideration. Nevertheless, most studies focus on smaller pieces of what is undoubtedly a larger mosaic of interdependent processes. Therefore, the present review summarizes the existing literature regarding the role of the endocannabinoid system in depression aiming to integrate this information into a holistic picture for a better understanding of the relationship between the two.

Cannabinoid Receptor 1 and 2 Signaling Pathways Involved in Sepsis

ABSTRACT

Sepsis is defined as a life-threatening organ dysfunction, caused by a dysregulated host response to an infection and can progress to septic shock, which represents a major challenge in critical care with a high mortality rate. Currently, there is no definitive treatment available for the dysregulated immune response in sepsis. Therefore, a better understanding of the pathophysiological mechanisms may be useful for elucidating the molecular basis of sepsis and may contribute to the development of new therapeutic strategies. The endocannabinoid system is an emerging research topic for the modulation of the host immune response under various pathological conditions. Cannabinoid receptors include the cannabinoid type 1 receptor (CB1) and the cannabinoid type 2 receptor (CB2). This review addresses the main functionality of CB1 and CB2 in sepsis, which can contribute to a better understanding about the pathophysiology of sepsis. Specifically, we discuss the role of CB1 in the cardiovascular system which is one of the biological systems that are strongly affected by sepsis and septic shock. We are also reviewing the role of CB2 in sepsis, specially CB2 activation, which exerts anti-inflammatory activities with potential benefit in sepsis.

Cannabinoid receptor 2 selective agonists and Alzheimer's disease: An insight into the therapeutic potentials

Endocannabinoid system has been extensively studied in recent decades, particularly the cannabinoid receptors CB1 and CB2, due to their important role in neuroinflammation. Among these, CB2 has gained prominence due to its selective overexpression in glial cells during neuroinflammation. In contrast to CB1 agonists, CB2 agonists have no side effects such as ataxia, hypothermia, euphoria, psychological, or addiction liabilities. CB2 and its selective agonists' above-mentioned unique properties have become a research focus in neurodegenerative disorders such as Alzheimer's disease (AD). The review discusses the neuroprotective role of CB receptors, particularly CB2, in AD, as well as the significance and limitations of this research.

Medicinal Chemistry approach, pharmacology and neuroprotective benefits of CB2R modulators in neurodegenerative diseases

In the last decades, cannabinoid receptor 2 (CB₂R) has continued to receive attention as a key therapeutic target in neuroprotection. Indeed, several findings highlight the neuroprotective effects of CB₂R through suppression of both neuronal excitability and reactive microglia. Additionally, CB₂R seems to be a more promising target than cannabinoid receptor 1 (CB₁R) thanks to the lack of central side effects, its lower expression levels in the central nervous system (CNS), and its inducibility, since its expression enhances quickly in the brain following pathological conditions. This review aims to provide a thorough overview of the main natural and synthetic selective CB₂R modulators, their chemical classification and their potential therapeutic usefulness in neuroprotection, a crucial aspect for the treatment of neurodegenerative diseases.

Role of the Endocannabinoid System in the Adipose Tissue with Focus on Energy Metabolism

The endocannabinoid system is involved in a wide range of processes including the control of energy acquisition and expenditure. Endocannabinoids and their receptors are present in the central nervous system but also in peripheral tissues, notably the adipose tissues. The endocannabinoid system interacts with two main hormones regulating appetite, namely leptin and ghrelin. The inhibitory effect of the cannabinoid receptor 1 (CB₁) antagonist rimonabant on fat mass suggested that the endocannabinoid system can also have a peripheral action in addition to its effect on appetite reduction. Thus, several investigations have focused on the peripheral role of the endocannabinoid system in the regulation of metabolism. The white adipose tissue stores energy as triglycerides while the brown adipose tissue helps to dissipate energy as heat. The endocannabinoid system regulates several functions of the adipose tissues to favor energy accumulation. In this review we will describe the presence of the endocannabinoid system in the adipose tissue. We will survey the role of the endocannabinoid system in the regulation of white and brown adipose tissue metabolism and how the eCB system participates in obesity and metabolic diseases.

The Endocannabinoid System and Alcohol Dependence: Will Cannabinoid Receptor 2 Agonism be More Fruitful than Cannabinoid Receptor 1 Antagonism?

Alcohol-use disorder (AUD) remains a major public health concern. In recent years, there has been a heightened interest in components of the endocannabinoid system for the treatment of AUD. Cannabinoid type 1 (CB1) receptors have been shown to modulate the rewarding effects of alcohol, reduce the abuse-related effects of alcohol, improve cognition, exhibit anti-inflammatory, and neuroprotective effects, which are all favorable properties of potential therapeutic candidates for the treatment of AUD. However, CB1 agonists have not been investigated for the treatment of AUD because they stimulate the motivational properties of alcohol, increase alcohol intake, and have the tendency to be abused. Preclinical data suggest significant potential for the use of CB1 antagonists to treat AUD; however, a clinical phase I/II trial with SR14716A (rimonabant), a CB1 receptor antagonist/inverse agonist showed that it produced serious neuropsychiatric adverse events such as anxiety, depression, and even suicidal ideation. This has redirected the field to focus on alternative components of the endocannabinoid system, including cannabinoid type 2 (CB2) receptor agonists as a potential therapeutic target for AUD. CB2 receptor agonists are of particular interest because they can modulate the reward pathway, reduce abuse-related effects of alcohol, reverse neuroinflammation, improve cognition, and exhibit anti-inflammatory and neuroprotective effects, without exhibiting the psychiatric side effects seen with CB1 antagonists. Accordingly, this article presents an overview of the studies reported in the literature that have investigated CB2 receptor agonists with regards to AUD and provides commentary as to whether this receptor is a worthy target for continued investigation.

Cannabinoid and Cannabinoid-Related Receptors in the Myenteric Plexus of the Porcine Ileum

An important piece of evidence has shown that molecules acting on cannabinoid receptors influence gastrointestinal motility and induce beneficial effects on gastrointestinal inflammation and visceral pain. The aim of this investigation was to immunohistochemically localize the distribution of canonical cannabinoid receptor type 1 (CB1R) and type 2 (CB2R) and the cannabinoid-related receptors transient potential vanilloid receptor 1 (TRPV1), transient potential ankyrin receptor 1 (TRPA1), and serotonin receptor 5-HT1a (5-HT1aR) in the myenteric plexus (MP) of pig ileum. CB1R, TRPV1, TRPA1, and 5-HT1aR were expressed, with different intensities in the cytoplasm of MP neurons. For each receptor, the proportions of the immunoreactive neurons were evaluated using the anti-HuC/HuD antibody. These receptors were also localized on nerve fibers (CB1R, TRPA1), smooth muscle cells of tunica muscularis (CB1R, 5-HT1aR), and endothelial cells of blood vessels (TRPV1, TRPA1, 5-HT1aR). The nerve varicosities were also found to be immunoreactive for both TRPV1 and 5-HT1aR. No immunoreactivity was documented for CB2R. Cannabinoid and cannabinoid-related receptors herein investigated showed a wide distribution in the enteric neurons and nerve fibers of the pig MP. These results could provide an anatomical basis for additional research, supporting the therapeutic use of cannabinoid receptor agonists in relieving motility disorders in porcine enteropathies.

Cannabinoid-Based Medicines and Multiple Sclerosis

The emerging role of the endocannabinoid system (ECS) in the control of symptoms and disease progression in multiple sclerosis (MS) has been highlighted by recent studies. MS is a chronic, immune-mediated, and demyelinating disorder of the central nervous system with no cure so far. It is widely reported that cannabinoids might be used to control MS symptoms and that they also might exert neuroprotective effects and slow down disease progression. The aim of this chapter is to give an overview of the main endogenous and synthetic cannabinoids used for the symptomatic amelioration of MS and their beneficial outcomes, providing new possible perspectives for the treatment of this disease.

The impact of cannabinoid type 2 receptors (CB2Rs) in neuroprotection against neurological disorders

Cannabinoids have long been used for their psychotropic and possible medical properties of symptom relief. In the past few years, a vast literature shows that cannabinoids are neuroprotective under different pathological situations. Most of the effects of cannabinoids are mediated by the well-characterized cannabinoid receptors, the cannabinoid type 1 receptor (CB1R) and cannabinoid type 2 receptor (CB2R). Even though CB1Rs are highly expressed in the central nervous system (CNS), the adverse central side effects and the development of tolerance resulting from CB1R activation may ultimately limit the clinical utility of CB1R agonists. In contrast to the ubiquitous presence of CB1Rs, CB2Rs are less commonly expressed in the healthy CNS but highly upregulated in glial cells under neuropathological conditions. Experimental studies have provided robust evidence that CB2Rs seem to be involved in the modulation of different neurological disorders. In this paper, we summarize the current knowledge regarding the protective effects of CB2R activation against the development of neurological diseases and provide a perspective on the future of this field. A better understanding of the fundamental pharmacology of CB2R activation is essential for the development of clinical applications and the design of novel therapeutic strategies.

Synthesis of the Major Mammalian Metabolites of THCV

A simple synthesis of the major oxidized metabolites in mammalian tissues of (-)-Δ⁹-tetrahydrocannabivarin (THCV) (1) has been accomplished by kinetic studies of allylic oxidation using SeO₂ on botanically derived THCV with the aim to yield primary and secondary allylic alcohols concurrently. This synthetic approach led to the preparation of numerous THCV derivatives, including two new compounds, 8α-hydroxy-Δ⁹-tetrahydrocannabivarin (2) and 8β-hydroxy-Δ⁹-tetrahydrocannabivarin (3), and the known compounds 11-hydroxy-Δ⁹-tetrahydrocannabivarin (4) and Δ⁹-tetrahydrocannabivarin-11-oic acid (5), without affecting the C-10a stereogenic center in the natural precursor and without formation of tricyclic dibenzopyran derivatives. This simple synthetic methodology could be useful to investigate the pharmacological role of THCV metabolites at, among others, the endocannabinoid CB1 and CB2 receptors for which THCV reportedly acts as respectively a neutral antagonist and partial agonist.

Cannabinoid CB2 receptors mediate the anxiolytic-like effects of monoacylglycerol lipase inhibition in a rat model of predator-induced fear

The endocannabinoid system is a key regulator of the response to psychological stress. Inhibitors of monoacylglycerol lipase (MGL), the enzyme that deactivates the endocannabinoid 2-arachidonoyl-sn-glycerol (2-AG), exert anxiolytic-like effects in rodent models via 2-AG-dependent activation of CB₁ cannabinoid receptors. In the present study, we examined whether the MGL inhibitor JZL184 might modulate persistent predator-induced fear in rats, a model that captures features of human post-traumatic stress disorder. Exposure to 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a volatile chemical that is innately aversive to some rodent species, produced in male rats a long-lasting anxiety-like state that was measured 7 days later in the elevated plus maze test. Systemic administration of JZL184 [4, 8 and 16 mg/kg, intraperitoneal (IP)] 4 h before testing caused dose-dependent inhibition of MGL activity and elevation of 2-AG content in brain tissue. Concomitantly, the inhibitor suppressed TMT-induced fear behaviors with a median effective dose (ED₅₀) of 4 mg/kg. A similar behavioral response was observed with another MGL inhibitor, KML29 (4 and 16 mg/kg, IP). Surprisingly, the effect of JZL184 was prevented by co-administration of the CB₂ inverse agonist AM630 (5 mg/kg, IP), but not the CB₁ inverse agonist rimonabant (1 mg/kg, IP). Supporting mediation of the response by CB₂ receptors, the CB₂ agonist JWH133 (0.3, 1 and 3 mg/kg, IP) also produced anxiolytic-like effects in TMT-stressed rats, which were suppressed by AM630. Notably, (i) JWH133 was behaviorally ineffective in animals that had no prior experience with TMT; and (ii) CB₂ mRNA levels in rat prefrontal cortex were elevated 7 days after exposure to the aversive odorant. The results suggest that JZL184 attenuates the behavioral consequences of predator stress through a mechanism that requires 2-AG-mediated activation of CB₂ receptors, whose transcription may be induced by the stress itself.

Recent cannabis use in HIV is associated with reduced inflammatory markers in CSF and blood

OBJECTIVE

To determine whether cannabis may reduce HIV-related persistent inflammation, we evaluated the relationship of cannabis use in people with HIV (PWH) to inflammatory cytokines in CSF and blood plasma.

METHODS

We measured a panel of proinflammatory cytokines (interleukin [IL]-16, C-reactive protein [CRP], IL-6, interferon gamma-induced protein [IP]-10, soluble CD14, and soluble tumor necrosis factor receptor type II [sTNFRII]) in CSF and blood plasma in PWH and HIV- individuals who did or did not use cannabis at various levels of exposure. Participants in this observational cohort were recruited from community sources and underwent lumbar puncture and phlebotomy. Cannabis use parameters were characterized by self-report based on a semistructured timeline follow-back interview. Cytokines were measured using commercially available immunoassays. Data were analyzed using factor analysis.

RESULTS

Participants were 35 PWH and 21 HIV- individuals, mean (SD) age 45.4 (14.5) years, 41 cannabis ever users, and 15 never users. PWH and HIV- were not different in recency, cumulative months, grams, or density of cannabis use. A factor analysis using CSF biomarkers yielded a factor loading on CRP, IL-16, and sTNFRII that was significantly associated with recency of cannabis use (more recent use associated with lower factor 1 values, reflecting less inflammation; r = 0.331 [95% CI 0.0175, 0.586]). In particular, more recent cannabis use was related to lower IL-16 levels (r = 0.549 [0.282, 0.737]). Plasma biomarkers yielded a factor loading on sTNFRII and IP-10 that was associated with more recent cannabis use (more recent use related to less inflammation; r = 0.374 [0.0660, 0.617]).

CONCLUSIONS

Recent cannabis use was associated with lower levels of inflammatory biomarkers, both in CSF and blood, but in different patterns. These results are consistent with compartmentalization of immune effects of cannabis. The principal active components of cannabis are highly lipid soluble and sequestered in brain tissue; thus, our findings are consistent with specific anti-neuroinflammatory effects that may benefit HIV neurologic dysfunction.

Microglial Phenotypes and Their Relationship to the Cannabinoid System: Therapeutic Implications for Parkinson's Disease

Parkinson’s disease is a neurodegenerative disorder, the motor symptoms of which are associated classically with Lewy body formation and nigrostriatal degeneration. Neuroinflammation has been implicated in the progression of this disease, by which microglia become chronically activated in response to α-synuclein pathology and dying neurons, thereby acquiring dishomeostatic phenotypes that are cytotoxic and can cause further neuronal death. Microglia have a functional endocannabinoid signaling system, expressing the cannabinoid receptors in addition to being capable of synthesizing and degrading endocannabinoids. Alterations in the cannabinoid system—particularly an upregulation in the immunomodulatory CB₂ receptor—have been demonstrated to be related to the microglial activation state and hence the microglial phenotype. This paper will review studies that examine the relationship between the cannabinoid system and microglial activation, and how this association could be manipulated for therapeutic benefit in Parkinson’s disease.

The therapeutic role of cannabinoid receptors and its agonists or antagonists in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease and its characteristic is the progressive degeneration of dopaminergic neurons within the substantia nigra (SN) of the midbrain. There is hardly any clinically proven efficient therapeutics for its cure in several recent preclinical advances proposed to treat PD. Recent studies have found that the endocannabinoid signaling system in particular the comprised two receptors, CB1 and CB2 receptors, has a significant regulatory function in basal ganglia and is involved in the pathogenesis of PD. Therefore, adding new insights into the biochemical interactions between cannabinoids and other signaling pathways may help develop new pharmacological strategies. Factors of the endocannabinoid system (ECS) are abundantly expressed in the neural circuits of basal ganglia, where they interact interactively with glutamatergic, γ-aminobutyric acid-ergic (GABAergic), and dopaminergic signaling systems. Although preclinical studies on PD are promising, the use of cannabinoids at the clinical level has not been thoroughly studied. In this review, we evaluated the available evidence and reviewed the involvement of ECS in etiologies, symptoms and treatments related to PD. Since CB1 and CB2 receptors are the two main receptors of endocannabinoids, we primarily put the focus on the therapeutic role of CB1 and CB2 receptors in PD. We will try to determine future research clues that will help understand the potential therapeutic benefits of the ECS in the treatment of PD, aiming to open up new strategies and ideas for the treatment of PD.

Cannabidiol Protects Dopaminergic Neuronal Cells from Cadmium

The protective effect of cannabidiol (CBD), the non-psychoactive component of Cannabis sativa, against neuronal toxicity induced by cadmium chloride (CdCl₂ 10 μM) was investigated in a retinoic acid (RA)-differentiated SH-SY5Y neuroblastoma cell line. CBD (1 μM) was applied 24 h before and removed during cadmium (Cd) treatment. In differentiated neuronal cells, CBD significantly reduced the Cd-dependent decrease of cell viability, and the rapid reactive oxygen species (ROS) increase. CBD significantly prevented the endoplasmic reticulum (ER) stress (GRP78 increase) and the subcellular distribution of the cytochrome C, as well as the overexpression of the pro-apoptotic protein BAX. Immunocytochemical analysis as well as quantitative protein evaluation by western blotting revealed that CBD partially counteracted the depletion of the growth associated protein 43 (GAP43) and of the neuronal specific class III β-tubulin (β3 tubulin) induced by Cd treatment. These data showed that Cd-induced neuronal injury was ameliorated by CBD treatment and it was concluded that CBD may represent a potential option to protect neuronal cells from the detrimental effects of Cd toxicity.

Druggable targets of the endocannabinoid system: Implications for the treatment of HIV-associated neurocognitive disorder

HIV-associated neurocognitive disorder (HAND) affects nearly half of all HIV-infected individuals. Synaptodendritic damage correlates with neurocognitive decline in HAND, and many studies have demonstrated that HIV-induced neuronal injury results from excitotoxic and inflammatory mechanisms. The endocannabinoid (eCB) system provides on-demand protection against excitotoxicity and neuroinflammation. Here, we discuss evidence of the neuroprotective and anti-inflammatory properties of the eCB system from in vitro and in vivo studies. We examine the pharmacology of the eCB system and evaluate the therapeutic potential of drugs that modulate eCB signaling to treat HAND. Finally, we provide perspective on the need for additional studies to clarify the role of the eCB system in HIV neurotoxicity and speculate that strategies that enhance eCB signaling might slow cognitive decline in HAND.

Monoacylglycerol lipase inhibition as potential treatment for interstitial cystitis

Interstitial cystitis is a chronic inflammatory condition of the urinary bladder with an unclear etiology. Currently, there are no widely accepted long-term treatment options available for patients with IC, with the European Association of Urology (EAU, 2017 guidelines), American Urology Association (AUA, 2014 guidelines), and the Royal College of Obstetricians and Gynaecologists (RCOG, 2016 guidelines) all suggesting various different conservative, pharmacological, intravesical, and surgical interventions. The endocannabinoid system represents a potential target for IC treatment and management. Activation of cannabinoid receptor 2 (CBR2) with various agonists has previously been shown to reduce leukocyte differentiation and migration, in addition to inhibiting the release of pro-inflammatory cytokines at the site of inflammation. These receptors have been identified in the detrusor and sensory nerves of the urothelium in various mammalian species, including humans. We hypothesize that by inhibiting the enzymes responsible for the catabolism of endogenous cannabinoids locally, bladder concentrations of CBR2 agonists will increase, particularly 2-arachidonyl glycerol, resulting in a diminished inflammatory response.

Alzheimer's Disease Research Using Human Microglia

Experimental studies of neuroinflammation in Alzheimer's disease (AD) have mostly investigated microglia, the brain-resident macrophages. This review focused on human microglia obtained at rapid autopsies. Studies employing methods to isolate and culture human brain microglia in high purity for experimental studies were discussed. These methods were employed to isolate human microglia for investigation of a number of features of neuroinflammation, including activation phenotypes, neurotoxicity, responses to abnormal aggregated proteins such as amyloid beta, phagocytosis, and the effects of aging and disease on microglia cellular properties. In recent years, interest in human microglia and neuroinflammation has been renewed due to the identification of inflammation-related AD genetic risk factors, in particular the triggering receptor expressed on myeloid cells (TREM)-2. Because of the difficulties in developing effective treatments for AD, there has been a general need for greater understanding of the functions of microglia in normal and AD brains. While most experimental studies on neuroinflammation have employed rodent microglia, this review considered the role of human microglia in experimental studies. This review focused on the development of in vitro methodology for the culture of postmortem human microglia and the key findings obtained from experimental studies with these cells.

Cytochrome c can be released into extracellular space and modulate functions of human astrocytes in a toll-like receptor 4-dependent manner

BACKGROUND

Chronic activation of glial cells contributes to neurodegenerative diseases. Cytochrome c (CytC) is a soluble mitochondrial protein that can act as a damage-associated molecular pattern (DAMP) when released into the extracellular space from damaged cells. CytC causes immune activation of microglia in a toll-like receptor (TLR) 4-dependent manner. The effects of extracellular CytC on astrocytes are unknown. Astrocytes, which are the most abundant glial cell type in the brain, express TLR 4 and secrete inflammatory mediators; therefore, we hypothesized that extracellular CytC can interact with the TLR 4 of astrocytes inducing their release of inflammatory molecules and cytotoxins.

METHOD

Experiments were conducted using primary human astrocytes, U118 MG human astrocytic cells, BV-2 murine microglia, and SH-SY5Y human neuronal cells.

RESULTS

Extracellularly applied CytC increased the secretion of interleukin (IL)-1β, granulocyte-macrophage colony stimulating factor (GM-CSF) and IL-12 p70 by cultured primary human astrocytes. Anti-TLR 4 antibodies blocked the CytC-induced secretion of IL-1β and GM-CSF by astrocytes. Supernatants from CytC-activated astrocytes were toxic to human SH-SY5Y neuronal cells. We also demonstrated CytC release from damaged glial cells by measuring CytC in the supernatants of BV-2 microglia after their exposure to cytotoxic concentrations of staurosporine, amyloid-β peptides (Aβ42) and tumor necrosis factor-α.

CONCLUSION

CytC can be released into the extracellular space from damaged glial cells causing immune activation of astrocytes in a TLR 4-dependent manner.

GENERAL SIGNIFICANCE

Astrocyte activation by CytC may contribute to neuroinflammation and neuronal death in neurodegenerative diseases. Astrocyte TLR 4 could be a potential therapeutic target in these diseases.

Low mRNA expression and activity of monoacylglycerol lipase in human SH-SY5Y neuroblastoma cells

Relatively little is known about the endocannabinoid system in human neuroblastoma cell lines. In the present study, we have investigated the expression of the genes coding for the enzymes involved in the synthesis and catabolism of endocannabinoids in the SH-SY5Y cell line. The expression of MGLL, the gene coding for the 2-arachidonoylglycerol hydrolytic enzyme monoacylglycerol lipase (MAGL), was found to be 85 and 340 fold lower than the expression levels for the genes coding for alpha/beta-hydrolase domain containing 6 and 12 (ABHD6, ABHD12), which are alternative hydrolytic enzymes for this endocannabinoid. In comparison, mRNA levels of MGLL were 1.5 fold higher than ABHD6 and 2 fold lower than the levels of ABHD12 in DU-145 human prostate cells. In functional assays, the hydrolysis of the 2-arachidonoylglycerol homologue 2-oleoylglycerol by intact SH-SY5Y cells was partially inhibited by the ABHD6 inhibitor WWL70, but not by the MAGL inhibitor JZL184, whereas the reverse was true in DU-145 cells. The combination of JZL184 + WWL70 did, however produce a significantly greater inhibition of 2-OG hydrolysis than seen with WWL70 alone in the SH-SY5Y cells. The low MGLL expression in the SH-SY5Y cells was not due to epigenetic silencing, since levels were not affected by treatment with the methylation inhibitor 5-aza-2'-deoxycytidine and/or the histone acetylase inhibitor trichostatin A. The low MGLL expression in SH-SY5Y cells should be taken into account when using these cells in experiments investigating the involvement of the endocannabinoid system in models of physiological and pathological processes.

Inflammation and oxidative stress are key mediators in AKB48-induced neurotoxicity in vitro

Synthetic cannabinoids were introduced into market in early 2000s; since these "legal highs" are dramatically popular among youth, it becomes a deadly problem. Synthetic cannabinoids have high affinity to cannabinoid receptors; leading to various clinical symptoms. AKB48 (Apinaca) has been classified as a third-generation synthetic cannabinoid for the first time in 2014. The toxicity profile of AKB48 is unclear due to little information that mainly obtained from clinical and forensic cases; however, it is believed to be similar with other psychoactive substances. Thus, we aimed to investigate the possible toxicity mechanisms of AKB48 in SH-SY5Y (human bone marrow neuroblastoma) cell line. IC₅₀ value of AKB48 was calculated as 160.91 μM by MTT assay. AKB48 treatment enhanced (≥1.2-fold) the fluorescence intensity indicating increased reactive oxygen species production; however, glutathione levels did not changed in the range of 25-200 μM exposure concentrations. Cannabinoid type-1 receptor (CB1) expression was increased ≥15-fold in the range of 25-50 μM of AKB48, while cannabinoid type-2 receptor (CB2) did not expressed in SH-SY5Y cells. Interleukin-6 (IL-6) and tumor necrosis factor-α (TNF- α) were up-regulated with a dose-dependent manner, and the profiles were almost identical; however, mitogen-activated protein kinase 8 (MAPK 8) was only upregulated with 25 μM of AKB48 and nuclear factor kappa B (NF-ĸB) did not change. Our results should raise the concerns about the safety associated with synthetic cannabinoids uses.

Medical Cannabis

Medicolegal realities surrounding "medical marijuana" or "medical cannabis" are rapidly evolving in the United States. Clinicians are increasingly being asked by patients to share information about or certify them for medical cannabis. In order to engage in informed discussions with patients or be comfortable certifying them in states with medical cannabis laws, clinicians may benefit from an understanding of the current state of medical knowledge about medical cannabis. Intended for the generalist and subspecialist, this review provides an overview of the legal status, pharmacology, benefits, risks, and abuse liability of medical cannabis along with a general framework for counseling patients.

Traditional Uses of Cannabinoids and New Perspectives in the Treatment of Multiple Sclerosis

Recent findings highlight the emerging role of the endocannabinoid system in the control of symptoms and disease progression in multiple sclerosis (MS). MS is a chronic, immune-mediated, demyelinating disorder of the central nervous system with no cure so far. It is widely reported in the literature that cannabinoids might be used to control MS symptoms and that they also might exert neuroprotective effects and slow down disease progression. This review aims to give an overview of the principal cannabinoids (synthetic and endogenous) used for the symptomatic amelioration of MS and their beneficial outcomes, providing new potentially possible perspectives for the treatment of this disease.

Neuroprotection in Oxidative Stress-Related Neurodegenerative Diseases: Role of Endocannabinoid System Modulation

SIGNIFICANCE

Redox imbalance may lead to overproduction of reactive oxygen and nitrogen species (ROS/RNS) and subsequent oxidative tissue damage, which is a critical event in the course of neurodegenerative diseases. It is still not fully elucidated, however, whether oxidative stress is the primary trigger or a consequence in the process of neurodegeneration. Recent Advances: Increasing evidence suggests that oxidative stress is involved in the propagation of neuronal injury and consequent inflammatory response, which in concert promote development of pathological alterations characteristic of most common neurodegenerative diseases.

CRITICAL ISSUES

Accumulating recent evidence also suggests that there is an important interplay between the lipid endocannabinoid system [ECS; comprising the main cannabinoid 1 and 2 receptors (CB1 and CB2), endocannabinoids, and their synthetic and metabolizing enzymes] and various key inflammatory and redox-dependent processes.

FUTURE DIRECTIONS

Targeting the ECS to modulate redox state-dependent cell death and to decrease consequent or preceding inflammatory response holds therapeutic potential in a multitude of oxidative stress-related acute or chronic neurodegenerative disorders from stroke and traumatic brain injury to Alzheimer's and Parkinson's diseases and multiple sclerosis, just to name a few, which will be discussed in this overview. Antioxid. Redox Signal. 29, 75-108.

Activation of the Cannabinoid Type 2 Receptor by a Novel Indazole Derivative Normalizes the Survival Pattern of Lymphoblasts from Patients with Late-Onset Alzheimer's Disease

BACKGROUND

Alzheimer's disease is a multifactorial disorder for which there is no disease-modifying treatment yet. CB2 receptors have emerged as a promising therapeutic target for Alzheimer's disease because they are expressed in neuronal and glial cells and their activation has no psychoactive effects.

OBJECTIVE

The aim of this study was to investigate whether activation of the CB2 receptor would restore the aberrant enhanced proliferative activity characteristic of immortalized lymphocytes from patients with late-onset Alzheimer's disease. It is assumed that cell-cycle dysfunction occurs in both peripheral cells and neurons in patients with Alzheimer's disease, contributing to the instigation of the disease.

METHODS

Lymphoblastoid cell lines from patients with Alzheimer's disease and age-matched control individuals were treated with a new, in-house-designed dual drug PGN33, which behaves as a CB2 agonist and butyrylcholinesterase inhibitor. We analyzed the effects of this compound on the rate of cell proliferation and levels of key regulatory proteins. In addition, we investigated the potential neuroprotective action of PGN33 in β-amyloid-treated neuronal cells.

RESULTS

We report here that PGN33 normalized the increased proliferative activity of Alzheimer's disease lymphoblasts. The compound blunted the calmodulin-dependent overactivation of the PI3K/Akt pathway, by restoring the cyclin-dependent kinase inhibitor p27 levels, which in turn reduced the activity of the cyclin-dependent kinase/pRb cascade. Moreover, this CB2 agonist prevented β-amyloid-induced cell death in neuronal cells.

CONCLUSION

Our results suggest that the activation of CB2 receptors could be considered a useful therapeutic approach for Alzheimer's disease.

Cannabinoid CB1 and CB2 Receptors, and Monoacylglycerol Lipase Gene Expression Alterations in the Basal Ganglia of Patients with Parkinson's Disease

Previous studies suggest that the endocannabinoid system plays an important role in the neuropathological basis of Parkinson's disease (PD). This study was designed to detect potential alterations in the cannabinoid receptors CB1 (CB1r) and CB2 (A isoform, CB2Ar), and in monoacylglycerol lipase (MAGL) gene expression in the substantia nigra (SN) and putamen (PUT) of patients with PD. Immunohistochemical studies were performed to identify precise CB2r cellular localization in the SN of control and PD patients. To ensure the validity and reliability of gene expression data, the RNA integrity number (RIN) was calculated. CB1r, CB2Ar, and MAGL gene expressions were evaluated by real-time polymerase chain reaction (real-time PCR) using Taqman assays. Immunohistochemical experiments with in situ proximity ligation assay (PLA) were used to detect the precise cellular localization of CB2r in neurons, astrocytes, and/or microglia. All RIN values from control and PD postmortem brain samples were > 6. CB1r gene expression was unchanged in the SN but significantly higher in the PUT of patients with PD. CB2Ar gene expression was significantly increased (4-fold) in the SN but decreased in the PUT, whereas MAGL gene expression was decreased in the SN and increased in the PUT. Immunohistochemical analyses revealed that CB2r co-localize with astrocytes but not with neurons or microglial cells in the SN. The results of the present study suggest that CB1r, CB2r, and MAGL are closely related to the neuropathological processes of PD. Therefore, the pharmacological modulation of these targets could represent a new potential therapeutic tool for the management of PD.