Endocannabinoid signaling in the brain

Impact of the Cannabinoid System in Alzheimer's Disease

Cannabinoids are compounds isolated from cannabis and are also widely present in both nervous and immune systems of animals. In recent years, with in-depth research on cannabinoids, their clinical medicinal value has been evaluated, and many exciting achievements have been continuously accumulating, especially in the field of neurodegenerative disease. Alzheimer's disease is the most common type of neurodegenerative disease that causes dementia and has become a global health problem that seriously impacts human health today. In this review, we discuss the therapeutic potential of cannabinoids for the treatment of Alzheimer's disease. How cannabinoids act on different endocannabinoid receptor subtypes to regulate Alzheimer's disease and the roles of the endocannabinoid system in Alzheimer's disease are outlined, and the underlying mechanisms are discussed. Finally, we summarize the most relevant opportunities of cannabinoid pharmacology related to Alzheimer's disease and discuss the potential usefulness of cannabinoids in the clinical treatment of Alzheimer's disease.

The interaction of membrane estradiol receptors and metabotropic glutamate receptors in adaptive and maladaptive estradiol-mediated motivated behaviors in females

Estrogen receptors were initially identified as intracellular, ligand-regulated transcription factors that result in genomic change upon ligand binding. However, rapid estrogen receptor signaling initiated outside of the nucleus was also known to occur via mechanisms that were less clear. Recent studies indicate that these traditional receptors, estrogen receptor α and estrogen receptor β, can also be trafficked to act at the surface membrane. Signaling cascades from these membrane-bound estrogen receptors (mERs) can rapidly alter cellular excitability and gene expression, particularly through the phosphorylation of CREB. A principal mechanism of neuronal mER action has been shown to occur through glutamate-independent transactivation of metabotropic glutamate receptors (mGlu), which elicits multiple signaling outcomes. The interaction of mERs with mGlu has been shown to be important in many diverse functions in females, including driving motivated behaviors. Experimental evidence suggests that a large part of estradiol-induced neuroplasticity and motivated behaviors, both adaptive and maladaptive, occurs through estradiol-dependent mER activation of mGlu. Herein we will review signaling through estrogen receptors, both "classical" nuclear receptors and membrane-bound receptors, as well as estradiol signaling through mGlu. We will focus on how the interactions of these receptors and their downstream signaling cascades are involved in driving motivated behaviors in females, discussing a representative adaptive motivated behavior (reproduction) and maladaptive motivated behavior (addiction).

Endocannabinoid signaling in synaptic function

In the last decades, astrocytes have emerged as important regulatory cells actively involved in brain function by exchanging signaling with neurons. The endocannabinoid (eCB) signaling is widely present in many brain areas, being crucially involved in multiple brain functions and animal behaviors. The present review presents and discusses current evidence demonstrating that astrocytes sense eCBs released during neuronal activity and subsequently release gliotransmitters that regulate synaptic transmission and plasticity. The eCB signaling to astrocytes and the synaptic regulation mediated by astrocytes activated by eCBs are complex phenomena that exhibit exquisite spatial and temporal properties, a wide variety of downstream signaling mechanisms, and a large diversity of functional synaptic outcomes. Studies investigating this topic have revealed novel regulatory processes of synaptic function, like the lateral regulation of synaptic transmission and the active involvement of astrocytes in the spike-timing dependent plasticity, originally thought to be exclusively mediated by the coincident activity of pre- and postsynaptic neurons, following Hebbian rules for associative learning. Finally, the critical influence of astrocyte-mediated eCB signaling on animal behavior is also discussed.

Heterogeneity in major depressive disorder: The need for biomarker-based personalized treatments

Major Depressive Disorder (MDD) or depression is a pathological mental condition affecting millions of people worldwide. Identification of objective biological markers of depression can provide for a better diagnostic and intervention criteria; ultimately aiding to reduce its socioeconomic health burden. This review provides a comprehensive insight into the major biomarker candidates that have been implicated in depression neurobiology. The key biomarker categories are covered across all the "omics" levels. At the epigenomic level, DNA-methylation, non-coding RNA and histone-modifications have been discussed in relation to depression. The proteomics system shows great promise with inflammatory markers as well as growth factors and neurobiological alterations within the endocannabinoid system. Characteristic lipids implicated in depression together with the endocrine system are reviewed under the metabolomics section. The chapter also examines the novel biomarkers for depression that have been proposed by studies in the microbiome. Depression affects individuals differentially and explicit biomarkers identified by robust research criteria may pave the way for better diagnosis, intervention, treatment, and prediction of treatment response.

Potential Utility of Cannabidiol in Stress-Related Disorders

Background: The endocannabinoid (eCB) system plays an important role in homeostatic regulation of anxiety and stress responses; however, the eCB system can be disrupted following traumatic stressors. Additionally, traumatic or chronic stressors that occur during adulthood or early life can cause long-lasting disturbances in the eCB system. These alterations interfere with hypothalamic-pituitary-adrenal axis function and may be involved in lifelong increased fear and anxiety behaviors as well as increased risk for development of post-traumatic stress disorder (PTSD). Methods: This review focuses on the implications of trauma and significant stressors on eCB functionality and neural pathways, both in adolescence and into adulthood, as well as the current state of testing for CBD efficacy in treating pediatric and adult patients suffering from stress-induced eCB dysregulation. Articles were searched via Pubmed and included studies examining eCB modulation of stress-related disorders in both clinical settings and preclinical models. Conclusion: Given the potential for lifelong alterations in eCB signaling that can mediate stress responsiveness, consideration of pharmaceutical or nutraceutical agents that impact eCB targets may improve clinical outcomes in stress-related disorders. However, caution may be warranted in utilization of medicinal cannabinoid products that contain delta-9-tetrahydrocannabinol due to pronounced euphorigenic effects and potential to exacerbate stress-related behaviors. Other cannabinoid products, such as cannabidiol (CBD), have shown promise in reducing stress-related behaviors in pre-clinical models. Overall, pre-clinical evidence supports CBD as a potential treatment for stress or anxiety disorders resulting from previously stressful events, particularly by reducing fearful behavior and promoting extinction of contextual fear memories, which are hallmarks of PTSD. However, very limited clinical research has been conducted examining the potential effectiveness of CBD in this regard and should be examined further.

Molecular Insights into Epigenetics and Cannabinoid Receptors

The actions of cannabis are mediated by G protein-coupled receptors that are part of an endogenous cannabinoid system (ECS). ECS consists of the naturally occurring ligands N-arachidonylethanolamine (anandamide) and 2-arachidonoylglycerol (2-AG), their biosynthetic and degradative enzymes, and the CB1 and CB2 cannabinoid receptors. Epigenetics are heritable changes that affect gene expression without changing the DNA sequence, transducing external stimuli in stable alterations of the DNA or chromatin structure. Cannabinoid receptors are crucial candidates for exploring their functions through epigenetic approaches due to their significant roles in health and diseases. Epigenetic changes usually promote alterations in the expression of genes and proteins that can be evaluated by various transcriptomic and proteomic analyses. Despite the exponential growth of new evidence on the critical functions of cannabinoid receptors, much is still unknown regarding the contribution of various genetic and epigenetic factors that regulate cannabinoid receptor gene expression. Recent studies have identified several immediate and long-lasting epigenetic changes, such as DNA methylation, DNA-associated histone proteins, and RNA regulatory networks, in cannabinoid receptor function. Thus, they can offer solutions to many cellular, molecular, and behavioral impairments found after modulation of cannabinoid receptor activities. In this review, we discuss the significant research advances in different epigenetic factors contributing to the regulation of cannabinoid receptors and their functions under both physiological and pathological conditions. Increasing our understanding of the epigenetics of cannabinoid receptors will significantly advance our knowledge and could lead to the identification of novel therapeutic targets and innovative treatment strategies for diseases associated with altered cannabinoid receptor functions.

The Therapeutic Potential of the Endocannabinoid System in Age-Related Diseases

The endocannabinoid system (ECS) dynamically regulates many aspects of mammalian physiology. ECS has gained substantial interest since growing evidence suggests that it also plays a major role in several pathophysiological conditions due to its ability to modulate various underlying mechanisms. Furthermore, cannabinoids, as components of the cannabinoid system (CS), have proven beneficial effects such as anti-inflammatory, immunomodulatory, neuromodulatory, antioxidative, and cardioprotective effects. In this comprehensive review, we aimed to describe the complex interaction between CS and most common age-related diseases such as neuro-degenerative, oncological, skeletal, and cardiovascular disorders, together with the potential of various cannabinoids to ameliorate the progression of these disorders. Since chronic inflammation is postulated as the pillar of all the above-mentioned medical conditions, we also discuss in this paper the potential of CS to ameliorate aging-associated immune system dysregulation.

TRPV1: A Common Denominator Mediating Antinociceptive and Antiemetic Effects of Cannabinoids

The most common medicinal claims for cannabis are relief from chronic pain, stimulation of appetite, and as an antiemetic. However, the mechanisms by which cannabis reduces pain and prevents nausea and vomiting are not fully understood. Among more than 450 constituents in cannabis, the most abundant cannabinoids are Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD). Cannabinoids either directly or indirectly modulate ion channel function. Transient receptor potential vanilloid 1 (TRPV1) is an ion channel responsible for mediating several modalities of pain, and it is expressed in both the peripheral and the central pain pathways. Activation of TRPV1 in sensory neurons mediates nociception in the ascending pain pathway, while activation of TRPV1 in the central descending pain pathway, which involves the rostral ventral medulla (RVM) and the periaqueductal gray (PAG), mediates antinociception. TRPV1 channels are thought to be implicated in neuropathic/spontaneous pain perception in the setting of impaired descending antinociceptive control. Activation of TRPV1 also can cause the release of calcitonin gene-related peptide (CGRP) and other neuropeptides/neurotransmitters from the peripheral and central nerve terminals, including the vagal nerve terminal innervating the gut that forms central synapses at the nucleus tractus solitarius (NTS). One of the adverse effects of chronic cannabis use is the paradoxical cannabis-induced hyperemesis syndrome (HES), which is becoming more common, perhaps due to the wider availability of cannabis-containing products and the chronic use of products containing higher levels of cannabinoids. Although, the mechanism of HES is unknown, the effective treatment options include hot-water hydrotherapy and the topical application of capsaicin, both activate TRPV1 channels and may involve the vagal-NTS and area postrema (AP) nausea and vomiting pathway. In this review, we will delineate the activation of TRPV1 by cannabinoids and their role in the antinociceptive/nociceptive and antiemetic/emetic effects involving the peripheral, spinal, and supraspinal structures.

Impaired Membrane Lipid Homeostasis in Schizophrenia

BACKGROUND AND HYPOTHESIS

Multiple lines of clinical, biochemical, and genetic evidence suggest that disturbances of membrane lipids and their metabolism are probably involved in the etiology of schizophrenia (SCZ). Lipids in the membrane are essential to neural development and brain function, however, their role in SCZ remains largely unexplored.

STUDY DESIGN

Here we investigated the lipidome of the erythrocyte membrane of 80 patients with SCZ and 40 healthy controls using ultra-performance liquid chromatography-mass spectrometry. Based on the membrane lipids profiling, we explored the potential mechanism of membrane phospholipids metabolism.

STUDY RESULTS

By comparing 812 quantified lipids, we found that in SCZ, membrane phosphatidylcholines and phosphatidylethanolamines, especially the plasmalogen, were significantly decreased. In addition, the total polyunsaturated fatty acids (PUFAs) in the membrane of SCZ were significantly reduced, resulting in a decrease in membrane fluidity. The accumulation of membrane oxidized lipids and the level of peripheral lipid peroxides increased, suggesting an elevated level of oxidative stress in SCZ. Further study of membrane-phospholipid-remodeling genes showed that activation of PLA2s and LPCATs expression in patients, supporting the imbalance of unsaturated and saturated fatty acyl remodeling in phospholipids of SCZ patients.

CONCLUSIONS

Our results suggest that the mechanism of impaired membrane lipid homeostasis is related to the activated phospholipid remodeling caused by excessive oxidative stress in SCZ. Disordered membrane lipids found in this study may reflect the membrane dysfunction in the central nervous system and impact neurotransmitter transmission in patients with SCZ, providing new evidence for the membrane lipids hypothesis of SCZ.

Interactions between the Nicotinic and Endocannabinoid Receptors at the Plasma Membrane

Compartmentalization, together with transbilayer and lateral asymmetries, provide the structural foundation for functional specializations at the cell surface, including the active role of the lipid microenvironment in the modulation of membrane-bound proteins. The chemical synapse, the site where neurotransmitter-coded signals are decoded by neurotransmitter receptors, adds another layer of complexity to the plasma membrane architectural intricacy, mainly due to the need to accommodate a sizeable number of molecules in a minute subcellular compartment with dimensions barely reaching the micrometer. In this review, we discuss how nature has developed suitable adjustments to accommodate different types of membrane-bound receptors and scaffolding proteins via membrane microdomains, and how this "effort-sharing" mechanism has evolved to optimize crosstalk, separation, or coupling, where/when appropriate. We focus on a fast ligand-gated neurotransmitter receptor, the nicotinic acetylcholine receptor, and a second-messenger G-protein coupled receptor, the cannabinoid receptor, as a paradigmatic example.

Cannabinoids and PPAR Ligands: The Future in Treatment of Polycystic Ovary Syndrome Women with Obesity and Reduced Fertility

Cannabinoids (CBs) are used to treat chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis spasticity. Recently, the medicinal use of CBs has attracted increasing interest as a new therapeutic in many diseases. Data indicate a correlation between CBs and PPARs via diverse mechanisms. Both the endocannabinoid system (ECS) and peroxisome proliferator-activated receptors (PPARs) may play a significant role in PCOS and PCOS related disorders, especially in disturbances of glucose-lipid metabolism as well as in obesity and fertility. Taking into consideration the ubiquity of PCOS in the human population, it seems indispensable to search for new potential therapeutic targets for this condition. The aim of this review is to examine the relationship between metabolic disturbances and obesity in PCOS pathology. We discuss current and future therapeutic interventions for PCOS and related disorders, with emphasis on the metabolic pathways related to PCOS pathophysiology. The link between the ECS and PPARs is a promising new target for PCOS, and we examine this relationship in depth.

Fatty Acid-Binding Protein 5 Modulates Brain Endocannabinoid Tone and Retrograde Signaling in the Striatum

The endocannabinoid (eCB) anandamide (AEA) and 2-arachidonoylglycerol (2-AG) are endogenous lipid neurotransmitters that regulate an array of physiological functions, including pain, stress homeostasis, and reward. Fatty acid-binding protein 5 (FABP5) is a key modulator of intracellular eCB transport and inactivation. Recent evidence suggests that FABP5 controls synaptic 2-AG signaling at excitatory synapses in the dorsal raphe nucleus. However, it is currently not known whether this function extends to other brain areas. To address this, we first profiled eCB levels across several brain areas in FABP5 knockout mice and wild-type controls and report that FABP5 deletion elevates AEA levels in the striatum, prefrontal cortex, midbrain, and thalamus, as well as midbrain 2-AG levels. The expression of eCB biosynthetic and catabolic enzymes was largely unaltered in these regions, although minor sex and region-specific changes in the expression of 2-AG catabolic enzymes were observed in female FABP5 KO mice. Robust FABP5 expression was observed in the striatum, a region where both AEA and 2-AG control synaptic transmission. Deletion of FABP5 impaired tonic 2-AG and AEA signaling at striatal GABA synapses of medium spiny neurons, and blunted phasic 2-AG mediated short-term synaptic plasticity without altering CB1R expression or function. Collectively, these results support the role of FABP5 as a key regulator of eCB signaling at excitatory and inhibitory synapses in the brain.

Deficiency in endocannabinoid synthase DAGLB contributes to early onset Parkinsonism and murine nigral dopaminergic neuron dysfunction

Endocannabinoid (eCB), 2-arachidonoyl-glycerol (2-AG), the most abundant eCB in the brain, regulates diverse neural functions. Here we linked multiple homozygous loss-of-function mutations in 2-AG synthase diacylglycerol lipase β (DAGLB) to an early onset autosomal recessive Parkinsonism. DAGLB is the main 2-AG synthase in human and mouse substantia nigra (SN) dopaminergic neurons (DANs). In mice, the SN 2-AG levels were markedly correlated with motor performance during locomotor skill acquisition. Genetic knockdown of Daglb in nigral DANs substantially reduced SN 2-AG levels and impaired locomotor skill learning, particularly the across-session learning. Conversely, pharmacological inhibition of 2-AG degradation increased nigral 2-AG levels, DAN activity and dopamine release and rescued the locomotor skill learning deficits. Together, we demonstrate that DAGLB-deficiency contributes to the pathogenesis of Parkinsonism, reveal the importance of DAGLB-mediated 2-AG biosynthesis in nigral DANs in regulating neuronal activity and dopamine release, and suggest potential benefits of 2-AG augmentation in alleviating Parkinsonism.

Cannabinoid Receptor Type 1 in Parkinson's Disease: A Positron Emission Tomography Study with [18 F]FMPEP-d2

Background

The endocannabinoid system is a widespread neuromodulatory system affecting several biological functions and processes. High densities of type 1 cannabinoid (CB1) receptors and endocannabinoids are found in basal ganglia, which makes them an interesting target group for drug development in basal ganglia disorders such as Parkinson's disease (PD).

Objective

The aim of this study was to investigate CB1 receptors in PD with [¹⁸F]FMPEP‐d₂ positron emission tomography (PET) and the effect of dopaminergic medication on the [¹⁸F]FMPEP‐d₂ binding.

Methods

The data consisted of 16 subjects with PD and 10 healthy control subjects (HCs). All participants underwent a [¹⁸F]FMPEP‐d₂ high‐resolution research tomograph PET examination for the quantitative assessment of cerebral binding to CB1 receptors. To investigate the effect of dopaminergic medication on the [¹⁸F]FMPEP‐d₂ binding, 15 subjects with PD underwent [¹⁸F]FMPEP‐d₂ PET twice, both on and off antiparkinsonian medication.

Results

[¹⁸F]FMPEP‐d₂ distribution volume was significantly lower in the off scan compared with the on scan in basal ganglia, thalamus, hippocampus, and amygdala (P < 0.05). Distribution volume was lower in subjects with PD off than in HCs globally (P < 0.05), but not higher than in HCs in any brain region.

Conclusions

Subjects with PD have lower CB1 receptor availability compared with HCs. PD medication increases CB1 receptor toward normal levels. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Exploration of Multiverse Activities of Endocannabinoids in Biological Systems

Over the last 25 years, the human endocannabinoid system (ECS) has come into the limelight as an imperative neuro-modulatory system. It is mainly comprised of endogenous cannabinoid (endocannabinoid), cannabinoid receptors and the associated enzymes accountable for its synthesis and deterioration. The ECS plays a proven role in the management of several neurological, cardiovascular, immunological, and other relevant chronic conditions. Endocannabinoid or endogenous cannabinoid are endogenous lipid molecules which connect with cannabinoid receptors and impose a fashionable impact on the behavior and physiological processes of the individual. Arachidonoyl ethanolamide or Anandamide and 2-arachidonoyl glycerol or 2-AG were the endocannabinoid molecules that were first characterized and discovered. The presence of lipid membranes in the precursor molecules is the characteristic feature of endocannabinoids. The endocannabinoids are released upon rapid enzymatic reactions into the extracellular space via activation through G-protein coupled receptors, which is contradictory to other neurotransmitter that are synthesized beforehand, and stock up into the synaptic vesicles. The current review highlights the functioning, synthesis, and degradation of endocannabinoid, and explains its functioning in biological systems.

Cross state-dependent memory retrieval between cannabinoid CB1 and serotonergic 5-HT1A receptor agonists in the mouse dorsal hippocampus

Understanding the neurobiological mechanisms of drug-related learning and memory formation may help the treatment of cognitive disorders. Dysfunction of the cannabinoid and serotonergic systems has been demonstrated in learning and memory disorders. The present paper investigates the phenomenon called state-dependent memory (SDM) induced by ACPA (a selective cannabinoid CB1 receptor agonist) and 8-OH-DPAT (a nonselective 5-HT1A receptor agonist) with special focus on the role of the 5-HT1A receptor in the effects of both ACPA and 8-OH-DPAT SDM and cross state-dependent memory retrieval between ACPA and 8-OH-DPAT in a step-down inhibitory avoidance task. The dorsal hippocampal CA1 regions of adult male NMRI mice were bilaterally cannulated, and all drugs were microinjected into the intended injection sites. A single-trial step-down inhibitory avoidance task was used to assess memory retrieval and state-dependence. Post-training and/or pre-test microinjections of ACPA (1 and 2 ng/mouse) and 8-OH-DPAT (0.5 and 1 μg/mouse) dose-dependently induced amnesia. Pre-test administration of the same doses of ACPA and 8-OH-DPAT reversed the post-training ACPA- and 8-OH-DPAT-induced amnesia, respectively. This phenomenon has been named SDM. 8-OH-DPAT (1 μg/mouse) reversed the amnesia induced by ACPA (0.5, 1, and 2 ng/mouse) and induced ACPA SDM. ACPA (2 ng/mouse) reversed the amnesia induced by 8-OH-DPAT (0.25, 0.5, and 1 μg/mouse) and induced 8-OH-DPAT SDM. Pre-test administration of a 5-HT1A receptor antagonist, (S)-WAY 100135 (0.25 and 0.5 μg/mouse), 5 min before ACPA and 8-OH-DPAT dose-dependently inhibited ACPA- and 8-OH-DPAT-induced SDM, respectively. The present study results demonstrated ACPA- and 8-OH-DPAT- induced SDM. Overall, the data revealed that dorsal hippocampal 5-HT1A receptor mechanisms play a pivotal role in modulating cross state-dependent memory retrieval between ACPA and 8-OH-DPAT.

A fluorescent sensor for spatiotemporally resolved imaging of endocannabinoid dynamics in vivo

Endocannabinoids (eCBs) are retrograde neuromodulators with important functions in a wide range of physiological processes, but their in vivo dynamics remain largely uncharacterized. Here we developed a genetically encoded eCB sensor called GRAB_eCB2.0. GRAB_eCB2.0 consists of a circular-permutated EGFP and the human CB1 cannabinoid receptor, providing cell membrane trafficking, second-resolution kinetics with high specificity for eCBs, and shows a robust fluorescence response at physiological eCB concentrations. Using GRAB_eCB2.0, we monitored evoked and spontaneous changes in eCB dynamics in cultured neurons and acute brain slices. We observed spontaneous compartmentalized eCB transients in cultured neurons and eCB transients from single axonal boutons in acute brain slices, suggesting constrained, localized eCB signaling. When GRAB_eCB2.0 was expressed in the mouse brain, we observed foot shock-elicited and running-triggered eCB signaling in the basolateral amygdala and hippocampus, respectively. In a mouse model of epilepsy, we observed a spreading wave of eCB release that followed a Ca²⁺ wave through the hippocampus. GRAB_eCB2.0 is a robust probe for eCB release in vivo.

Immunohistochemical assessment of cannabinoid type-1 receptor (CB1R) and its correlation with clinicopathological parameters in glioma

Background

Glioma is the most frequent primary brain tumor and one of the most aggressive forms of cancer. Recently, numerous studies have focused on cannabinoids as a new therapeutic approach due to their antineoplastic effects through activation of the cannabinoid receptors. This study aimed to investigate the immunohistochemical expression level of cannabinoid type-1 receptors (CB1R) in human glioma samples and evaluate its clinicopathologic significance.

Materials and methods

We analyzed the expression of CB1R in 61 paraffin-embedded glioma and 4 normal brain tissues using automated immunohistochemical assay. CB1R expression was categorized into high versus low expression levels. Statistical analyses were performed to evaluate the association between CB1R and phosphorylated extracellular signal-related kinase (p-ERK) expression levels and the clinicopathologic features of glioma.

Results

Our results showed that CB1R immunopositivity was seen in 59 of 61 cases (96.7%). CB1R was down-expressed in glioma compared to normal brain tissues. However, CB1R expression was not correlated with clinicopathological parameters except for p-ERK.

Conclusion

Our findings indicate the down-expression of CB1R in glioma tissues when compared to non-cancerous brain tissues. This change in CB1R expression in gliomas should be further tested regardless of the clinicopathological findings to provide a therapeutic advantage in glioma patients.

Cannabinoid Receptor 1 Expression in Human Dorsal Root Ganglia and CB13-Induced Bidirectional Modulation of Sensory Neuron Activity

Cannabinoid receptors have been identified as potential targets for analgesia from studies on animal physiology and behavior, and from human clinical trials. Here, we sought to improve translational understanding of the mechanisms of cannabinoid-mediated peripheral analgesia. Human lumbar dorsal root ganglia were rapidly recovered from organ donors to perform physiological and anatomical investigations into the potential for cannabinoids to mediate analgesia at the level of the peripheral nervous system. Anatomical characterization of in situ gene expression and immunoreactivity showed that 61 and 53% of human sensory neurons express the CB1 gene and receptor, respectively. Calcium influx evoked by the algogen capsaicin was measured by Fura-2AM in dissociated human sensory neurons pre-exposed to the inflammatory mediator prostaglandin E2 (PGE2) alone or together with CB13 (1 μM), a cannabinoid agonist with limited blood–brain barrier permeability. Both a higher proportion of neurons and a greater magnitude of response to capsaicin were observed after exposure to CB13, indicating cannabinoid-mediated sensitization. In contrast, membrane properties measured by patch-clamp electrophysiology demonstrated that CB13 suppressed excitability and reduced action potential discharge in PGE2-pre-incubated sensory neurons, suggesting the suppression of sensitization. This bidirectional modulation of sensory neuron activity suggests that cannabinoids may suppress overall membrane excitability while simultaneously enhancing responsivity to TRPV1-mediated stimuli. We conclude that peripherally restricted cannabinoids may have both pro- and anti-nociceptive effects in human sensory neurons.

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.

Cannabis and Cannabis Derivatives for Abdominal Pain Management in Inflammatory Bowel Disease

For centuries, cannabis and its components have been used to manage a wide variety of symptoms associated with many illnesses. Gastrointestinal (GI) diseases are no exception in this regard. Individuals suffering from inflammatory bowel disease (IBD) are among those who have sought out the ameliorating properties of this plant. As legal limitations of its use have eased, interest has grown from both patients and their providers regarding the potential of cannabis to be used in the clinical setting. Similarly, a growing number of animal and human studies have been undertaken to evaluate the impact of cannabis and cannabinoid signaling elements on the natural history of IBD and its associated complications. There is little clinical evidence supporting the ability of cannabis or related products to treat the GI inflammation underlying these disorders. However, 1 recurring theme from both animal and human studies is that these agents have a significant impact on several IBD-related symptoms, including abdominal pain. In this review, we discuss the role of cannabis and cannabinoid signaling in visceral pain perception, what is currently known regarding the efficacy of cannabis and its derivatives for managing pain, related symptoms and inflammation in IBD, and what work remains to effectively utilize cannabis and its derivatives in the clinical setting.

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.

Cannabis use and medication nonadherence in bipolar disorder: A nationwide inpatient sample database analysis

BACKGROUND

Medication nonadherence among bipolar disorder (BD) is often linked with comorbid substance use disorders. This study aims to investigate cannabis use disorder (CUD) association with medication noncompliance in hospitalized BD patients.

METHODS

Using data on 266,303 BD hospitalizations between 2010 and 2014 from the US Nationwide Inpatient Sample database, we obtained medication noncompliance rates stratified by demographics and CUD. Logistic regression was used to evaluate factors associated with medication noncompliance.

RESULTS

Overall mean age, the prevalence of CUD, and medication nonadherence were 41.58 (± 0.11) years, 15.0% and 16.1%, respectively. There were 56.6% females in the overall population. There was a significant difference in the characteristics of those in the medication nonadherence vs adherence groups, including age, sex, race, comorbid substance use, income, insurance type, hospital region, and hospital teaching status (p < 0.001). After adjusting for other variables using multivariate analysis, there remained a statistically significant association of medication nonadherence in BD hospitalization and CUD (OR 1.42, 95% CI 1.36-1.48).

LIMITATION

Confounding multiple substance use could not be accounted for, and the retrospective nature of the database which includes only inpatients is prone to possible selection and reporting bias.

CONCLUSION

CUD statistically predicts increased rates of medication nonadherence among patients with BD. Given the possible association of CUD with medication nonadherence among BD patients, collaborative work between general adult psychiatry and addiction services is imperative in improving the management outcome of patients with BD and comorbid CUD.

Cannabidiol reverses memory impairments and activates components of the Akt/GSK3β pathway in an experimental model of estrogen depletion

Clinical and preclinical evidence has indicated that estrogen depletion leads to memory impairments and increases the susceptibility to neural damage. Here, we have sought to investigate the effects of Cannabidiol (CBD) a non-psychotomimetic compound from Cannabis sativa, on memory deficits induced by estrogen depletion in rats, and its underlying mechanisms. Adult rats were subjected to bilateral ovariectomy, an established estrogen depletion model in rodents, or sham surgery and allowed to recover for three weeks. After that, they received daily injections of CBD (10 mg/kg) for fourteen days. Rats were tested in the inhibitory avoidance task, a type of emotionally-motivated memory. After behavioral testing they were euthanized, and their hippocampi were isolated for analysis of components of the Akt/GSK3β survival pathway and the antiapoptotic protein Bcl2. Results revealed that ovariectomy impaired avoidance memory, and CBD was able to completely reverse estrogen depletion-induced memory impairment. Ovariectomy also reduced Akt/GSK3β pathway's activation by decreasing the phosphorylation levels of Akt and GSK3β and Bcl2 levels, which were ameliorated by CBD. The present results indicate that CBD leads to a functional recovery accompanied by the Akt/GSK3β survival pathway's activation, supporting its potential as a treatment for estrogen decline-induced deterioration of neural functioning and maintenance.

Metabolic effects of medical cannabis treatment

Cannabis has a wide range of favorable clinical effects on pain, sleep, mood, gastrointestinal symptom, appetite and physical activity, factors that may affect the metabolic profile of the consumer. In this study, we prospectively evaluated patients recently starting medical cannabis treatment. All patients from the rheumatology clinic, who were just approved for medical cannabis treatment for resistant chronic pain, were recruited. After consent, demographic and clinical parameters were documented, including indication for medical cannabis treatment, way of consumption, type of cannabis and monthly dose of medical cannabis. Fasting morning blood glucose, hemoglobin A1c, insulin, lipid profile, cortisol and uric acid levels, in addition to body weight, were obtained just prior to and 3 months following cannabis consumption. Wilcoxon' sign rank test was used to compare baseline levels to those obtained 3 months later. Twenty-eight patients completed the study. Mean age of the patients was 47.8±9.1 years and ~70% were female patients. 75% of all the patients had fibromyalgia. Mean monthly consumed cannabis amount was 22.21±3.6 g, and 21 (75%) patients used extracts (oil). There was no significant change in any parameter evaluated. The results of our study seem to indicate that medical cannabis, mainly extracts, have no significant effect on any parameter of the metabolic profile of patients with chronic pain syndrome, during 3 months of initial use.

Possible actions of cannabidiol in obsessive-compulsive disorder by targeting the WNT/β-catenin pathway

Obsessive-compulsive disorder (OCD) is a neuropsychiatric disorder characterized by recurrent and distinctive obsessions and/or compulsions. The etiologies remain unclear. Recent findings have shown that oxidative stress, inflammation, and glutamatergic pathways play key roles in the causes of OCD. However, first-line therapies include cognitive-behavioral therapy but only 40% of the patients respond to this first-line therapy. Research for new treatment is mandatory. This review focuses on the potential effects of cannabidiol (CBD), as a potential therapeutic strategy, on OCD and some of the presumed mechanisms by which CBD provides its benefit properties. CBD medication downregulates GSK-3β, the main inhibitor of the WNT/β-catenin pathway. The activation of the WNT/β-catenin could be associated with the control of oxidative stress, inflammation, and glutamatergic pathway and circadian rhythms dysregulation in OCD. Future prospective clinical trials could focus on CBD and its different and multiple interactions in OCD.

New Insights in the Involvement of the Endocannabinoid System and Natural Cannabinoids in Nicotine Dependence

Nicotine, the main psychoactive component in tobacco smoke, plays a major role in tobacco addiction, producing a high morbidity and mortality in the world. A great amount of research has been developed to elucidate the neural pathways and neurotransmitter systems involved in such a complex addictive behavior. The endocannabinoid system, which has been reported to participate in the addictive properties of most of the prototypical drugs of abuse, is also implicated in nicotine dependence. This review summarizes and updates the main behavioral and biochemical data involving the endocannabinoid system in the rewarding properties of nicotine as well as in nicotine withdrawal and relapse to nicotine-seeking behavior. Promising results from preclinical studies suggest that manipulation of the endocannabinoid system could be a potential therapeutic strategy for treating nicotine addiction.

Parkinson's disease related alterations in cannabinoid transmission

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic (DAergic) neurons of the substantia nigra pars compacta (SNc) by neurodegeneration. Recent findings in animal models of PD propose tonic inhibition of the remaining DA neurons through GABA release from reactive glial cells. Movement dysfunctions could be ameliorated by promotion of activity in dormant DA cells. The endocannabinoid system (ECS) is extensively present in basal ganglia (BG) and is known as an indirect modulator of DAergic neurotransmission, thus drugs designed to target this system have shown promising therapeutic potential in PD patients. Interestingly, down/up-regulation of cannabinoid receptors (CBRs) varies across the different stages of PD, suggesting that some of the motor/ non-motor deficits may be related to changes in CBRs. Determination of the profile of changes of these receptors across the different stages of PD as well as their neural distribution within the BG could improve understanding of PD and identify pathways important in disease pathobiology. In this review, we focus on temporal and spatial alterations of CBRs during PD in the BG. At present, as inconclusive, but suggestive results have been obtained, future investigations should be conducted to extend preclinical studies examining CBRs changes within each stage in controlled clinical trials in order to determine the potential of targeting CBRs in management of PD.

Spatial synaptic modulation through IP3 diffusion triggered by ECB: a computational study with an astrocyte-neurons model

Recently, functional interactions between neurons and astrocytes have been steadily clarified. In particular, the effects of presynaptic depolarization-induced suppression of excitation (DSE) through endocannabinoid (ECB) and endocannabinoids-mediated synaptic potentiation (eSP) by an astrocyte have been used as an evidence of global heterosynaptic modulation. However, the mechanism of occurrence of spatial modulation in a neural network remains unknown. Although the Ca²⁺ density in astrocytes is strongly related to eSP through ECB, the mechanism of the rise in the ECB receptor in Ca²⁺ remains unclear. Since Ca²⁺ is closely related to inositol-1,4,5-trisphosphate (IP₃), it is believed that the released IP₃ affects Ca²⁺ in astrocytes that receive ECB. Therefore, this study approximately showed the spatial distribution of DSE or eSP with astrocyte-neuron computational models, assuming that the IP₃ caused by ECB is transmitted in an astrocyte. The results showed doughnut-shaped DSE, eSP, and DSE regions from the central ECB released points to the surroundings. They suggested that IP₃ diffusion plays an important role in mediating this synaptic modulation.

Brain is modulated by neuronal plasticity during postnatal development

Neuroplasticity is referred to the ability of the nervous system to change its structure or functions as a result of former stimuli. It is a plausible mechanism underlying a dynamic brain through adaptation processes of neural structure and activity patterns. Nevertheless, it is still unclear how the plastic neural systems achieve and maintain their equilibrium. Additionally, the alterations of balanced brain dynamics under different plasticity rules have not been explored either. Therefore, the present article primarily aims to review recent research studies regarding homosynaptic and heterosynaptic neuroplasticity characterized by the manipulation of excitatory and inhibitory synaptic inputs. Moreover, it attempts to understand different mechanisms related to the main forms of synaptic plasticity at the excitatory and inhibitory synapses during the brain development processes. Hence, this study comprised surveying those articles published since 1988 and available through PubMed, Google Scholar and science direct databases on a keyword-based search paradigm. All in all, the study results presented extensive and corroborative pieces of evidence for the main types of plasticity, including the long-term potentiation (LTP) and long-term depression (LTD) of the excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs).

Electrophysiological study of the interactive role of the cannabinoid breakdown inhibitors and L-type calcium channels on granular neurons in the hippocampal dentate gyrus in rats

The interaction between L-type voltage-dependent Ca²⁺ channels and the endocannabinoid system (eCs) in synaptic plasticity is controversial. In the present research, the impact of acute administration of URB597, as an endocannabinoid breakdown inhibitor, was evaluated after chronic injection of verapamil, as a Ca²⁺ channels blocker, on inducing long-term potentiation (LTP) in the rat's hippocampal dentate gyrus (DG). Treatment of male Wistar rats was done using intraperitoneal(i.p) injection of verapamil hydrochloride (n = 8) and saline (n = 10), as the solvent of verapamil once a day within 13 days. Anesthetization was done by i.p injection of urethane and the rats were located in the stereotaxic apparatus for surgery, electrode implantation, and field potential recording. After observing a steady-state baseline response, saline or URB597 were injected (n = 9). Measurement of the population spike (PS) amplitude and slope of field excitatory postsynaptic potentials (fEPSPs) in the DG region was performed as a result of perforant pathway (PP) stimulation. Our treatments could inhibit LTP. Our results indicated that the chronic administration of verapamil produced a significant decrease in the slope of fEPSP and PS amplitude. Also, acute URB597 administration decreased the slope of fEPSP and PS amplitude compared to the saline group. Moreover, URB597 administration in combination with chronic administration of verapamil produced a greater decrease in fEPSP slope and PS amplitude than the saline group. These findings indicated that verapamil and URB597 disrupted LTP induction in the DG. Moreover, an interaction was observed between Ca²⁺ channels and eCs. Therefore, the eCs possibly play a selective role in synaptic plasticity.

The current understanding of the benefits, safety, and regulation of cannabidiol in consumer products

The popularity of cannabidiol (CBD) in consumer products is soaring as consumers are using CBD for general health and well-being as well as to seek relief from ailments especially pain, inflammation, anxiety, depression, and sleep disorders. However, there are limited data currently in the public domain that provide support for these benefits. By contrast, a significant amount of safety evaluation data for CBD have been obtained recently from pre-clinical and clinical studies of the CBD therapeutic Epidiolex®. Yet some key data gaps concerning the safe use of CBD still remain. Furthermore, current regulations on CBD use in consumer products remain uncertain and often conflict between the state and federal level. In light of the rapidly expanding popularity of CBD-related products in the marketplace, here we review the current understanding of the benefits, safety, and regulations surrounding CBD in consumer products. This review does not advocate for or against the use of CBD in consumer products. Rather this review seeks to assess the state-of-the-science on the health effects and safety of CBD, to identify critical knowledge gaps for future studies, and to raise the awareness of the current regulations that govern CBD use in consumer products.

Cannabis use and resting state functional connectivity in adolescent bipolar disorder

BACKGROUND

Adolescents with bipolar disorder have high rates of cannabis use, and cannabis use is associated with increased symptom severity and treatment resistance in bipolar disorder. Studies have identified anomalous resting-state functional connectivity among reward networks in bipolar disorder and cannabis use independently, but have yet to examine their convergence.

METHODS

Participants included 134 adolescents, aged 13 to 20 years: 40 with bipolar disorder and lifetime cannabis use, 31 with bipolar disorder and no history of cannabis use, and 63 healthy controls without lifetime cannabis use. We used a seed-to-voxel analysis to assess the restingstate functional connectivity of the amygdala, the nucleus accumbens and the orbitofrontal cortex, regions implicated in bipolar disorder and cannabis use. We used a generalized linear model to explore bivariate correlations for each seed, controlling for age and sex.

RESULTS

We found 3 significant clusters. Resting-state functional connectivity between the left nucleus accumbens seed and the left superior parietal lobe was negative in adolescents with bipolar disorder and no history of cannabis use, and positive in healthy controls. Resting-state functional connectivity between the right orbitofrontal cortex seed and the right lateral occipital cortex was positive in adolescents with bipolar disorder and lifetime cannabis use, and negative in healthy controls and adolescents with bipolar disorder and no history of cannabis use. Resting-state functional connectivity between the right orbitofrontal cortex seed and right occipital pole was positive in adolescents with bipolar disorder and lifetime cannabis use, and negative in adolescents with bipolar disorder and no history of cannabis use.

LIMITATIONS

The study did not include a cannabis-using control group.

CONCLUSION

This study provides preliminary evidence of cannabis-related differences in functional reward circuits in adolescents with bipolar disorder. Further studies are necessary to evaluate whether the present findings reflect consequences of or predisposition to cannabis use.

Obesity as a Condition Determined by Food Addiction: Should Brain Endocannabinoid System Alterations Be the Cause and Its Modulation the Solution?

Obesity is a complex disorder, and the number of people affected is growing every day. In recent years, research has confirmed the hypothesis that food addiction is a determining factor in obesity. Food addiction is a behavioral disorder characterized by disruptions in the reward system in response to hedonic eating. The endocannabinoid system (ECS) plays an important role in the central and peripheral control of food intake and reward-related behaviors. Moreover, both obesity and food addiction have been linked to impairments in the ECS function in various brain regions integrating peripheral metabolic signals and modulating appetite. For these reasons, targeting the ECS could be a valid pharmacological therapy for these pathologies. However, targeting the cannabinoid receptors with inverse agonists failed when used in clinical contexts as a consequence of the induction of affective disorders. In this context, new classes of drugs acting either on CB1 and/or CB2 receptors or on synthetic and degradation enzymes of endogenous cannabinoids are being studied. However, further investigation is necessary to find safe and effective treatments that can exert anti-obesity effects, normalizing reward-related behaviors without causing important adverse mood effects.

β-caryophyllene, an FDA-Approved Food Additive, Inhibits Methamphetamine-Taking and Methamphetamine-Seeking Behaviors Possibly via CB2 and Non-CB2 Receptor Mechanisms

Recent research indicates that brain cannabinoid CB2 receptors are involved in drug reward and addiction. However, it is unclear whether β-caryophyllene (BCP), a natural product with a CB2 receptor agonist profile, has therapeutic effects on methamphetamine (METH) abuse and dependence. In this study, we used animal models of self-administration, electrical brain-stimulation reward (BSR) and in vivo microdialysis to explore the effects of BCP on METH-taking and METH-seeking behavior. We found that systemic administration of BCP dose-dependently inhibited METH self-administration under both fixed-ratio and progressive-ratio reinforcement schedules in rats, indicating that BCP reduces METH reward, METH intake, and incentive motivation to seek and take METH. The attenuating effects of BCP were partially blocked by AM 630, a selective CB2 receptor antagonist. Genetic deletion of CB2 receptors in CB2-knockout (CB2-KO) mice also blocked low dose BCP-induced reduction in METH self-administration, suggesting possible involvement of a CB2 receptor mechanism. However, at high doses, BCP produced a reduction in METH self-administration in CB2-KO mice in a manner similar as in WT mice, suggesting that non-CB2 receptor mechanisms underlie high dose BCP-produced effects. In addition, BCP dose-dependently attenuated METH-enhanced electrical BSR and inhibited METH-primed and cue-induced reinstatement of drug-seeking in rats. In vivo microdialysis assays indicated that BCP alone did not produce a significant reduction in extracellular dopamine (DA) in the nucleus accumbens (NAc), while BCP pretreatment significantly reduced METH-induced increases in extracellular NAc DA in a dose-dependent manner, suggesting a DA-dependent mechanism involved in BCP action. Together, the present findings suggest that BCP might be a promising therapeutic candidate for the treatment of METH use disorder.

Endocannabinoids Released in the Ventral Tegmental Area During Copulation to Satiety Modulate Changes in Glutamate Receptors Associated With Synaptic Plasticity Processes

Endocannabinoids modulate mesolimbic (MSL) dopamine (DA) neurons firing at the ventral tegmental area (VTA). These neurons are activated by copulation, increasing DA release in nucleus accumbens (NAcc). Copulation to satiety in male rats implies repeated ejaculation within a short period (around 2.5 h), during which NAcc dopamine concentrations remain elevated, suggesting continuous neuronal activation. During the 72 h that follow copulation to satiety, males exhibit long-lasting changes suggestive of brain plasticity processes. Enhanced DA neuron activity triggers the synthesis and release of endocannabinoids (eCBs) in the VTA, which participate in several long-term synaptic plasticity processes. Blockade of cannabinoid type 1 receptors (CB1Rs) during copulation to satiety interferes with the appearance of the plastic changes. Glutamatergic inputs to the VTA express CB1Rs and contribute to DA neuron burst firing and synaptic plasticity. We hypothesized that eCBs, released during copulation to satiety, would activate VTA CB1Rs and modulate synaptic plasticity processes involving glutamatergic transmission. To test this hypothesis, we determined changes in VTA CB1R density, phosphorylation, and internalization in rats that copulated to satiety 24 h earlier as compared both to animals that ejaculated only once and to sexually experienced unmated males. Changes in glutamate AMPAR and NMDAR densities and subunit composition and in ERK1/2 activation were determined in the VTA of males that copulated to satiety in the presence or absence of AM251, a CB1R antagonist. The CB1R density decreased and the proportion of phosphorylated CB1Rs increased in the animals that copulated compared to control rats. The CB1R internalization was detected only in sexually satiated males. A decrease in α-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor (AMPAR) density, blocked by AM251 pretreatment, and an increase in the proportion of GluA2-AMPARs occurred in sexually satiated rats. GluN2A- N-methyl-D-aspartate receptor (NMDAR) expression decreased, and GluN2B-NMDARs increased in these animals, both of which were prevented by AM251 pre-treatment. An increase in phosphorylated ERK1/2 emerged in males copulating to satiety in the presence of AM251. Results demonstrate that during copulation to satiety, eCBs activate CB1Rs in the VTA, producing changes in glutamate receptors compatible with a reduced neuronal activation. These changes could play a role in the induction of the long-lasting physiological changes that characterize sexually satiated rats.

Sphingolipid and Endocannabinoid Profiles in Adult Attention Deficit Hyperactivity Disorder

Genes encoding endocannabinoid and sphingolipid metabolism pathways were suggested to contribute to the genetic risk towards attention deficit hyperactivity disorder (ADHD). The present pilot study assessed plasma concentrations of candidate endocannabinoids, sphingolipids and ceramides in individuals with adult ADHD in comparison with healthy controls and patients with affective disorders. Targeted lipid analyses of 23 different lipid species were performed in 71 mental disorder patients and 98 healthy controls (HC). The patients were diagnosed with adult ADHD (n = 12), affective disorder (major depression, MD n = 16 or bipolar disorder, BD n = 6) or adult ADHD with comorbid affective disorders (n = 37). Canonical discriminant analysis and CHAID analyses were used to identify major components that predicted the diagnostic group. ADHD patients had increased plasma concentrations of sphingosine-1-phosphate (S1P d18:1) and sphinganine-1-phosphate (S1P d18:0). In addition, the endocannabinoids, anandamide (AEA) and arachidonoylglycerol were increased. MD/BD patients had increased long chain ceramides, most prominently Cer22:0, but low endocannabinoids in contrast to ADHD patients. Patients with ADHD and comorbid affective disorders displayed increased S1P d18:1 and increased Cer22:0, but the individual lipid levels were lower than in the non-comorbid disorders. Sphingolipid profiles differ between patients suffering from ADHD and affective disorders, with overlapping patterns in comorbid patients. The S1P d18:1 to Cer22:0 ratio may constitute a diagnostic or prognostic tool.

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.

Rapamycin prevents the long-term impairing effects of adolescence Δ-9-tetrahydrocannabinol on memory and plasticity in male rats

Long-lasting cognitive impairment is one of the most central negative consequences related to the exposure to cannabis during adolescence and particularly of Δ-9-tetrahydrocannabinol (THC). The aim of this study was to compare the protracted effects of adolescent versus late-adolescent chronic exposure to THC on short-term memory and plasticity and to examine whether rapamycin, a blocker of the mammalian target of rapamycin (mTOR) pathway, can restore THC-induced deficits in memory and plasticity. Male rats were injected with ascending doses of THC [2.5, 5, 10 mg/kg; intraperitoneally (i.p.)] during adolescence and late-adolescence (post-natal days 30-41 and 45-56, respectively), followed by daily injections of rapamycin (1 mg/kg, i.p.) during the first 10 days of cessation from THC. Thirty days after the last injection, rats were tested for short-term and working memory, anxiety-like behaviour, and plasticity in the pathways projecting from the ventral subiculum (vSub) of the hippocampus to the prefrontal cortex (PFC) and nucleus accumbens (NAc). THC exposure in adolescence, but not late-adolescence, was found to induce long-term deficits in object recognition short-term memory and synaptic plasticity in the hippocampal-accumbens pathway. Importantly, rapamycin rescued these persistent effects of THC administered during adolescence. Our findings show that some forms of memory and plasticity are sensitive to chronic THC administration during adolescence and that rapamycin administered during THC cessation may restore cognitive function and plasticity, thus potentially protecting against the possible long-term harmful effects of THC.

Memantine Prevents the WIN 55,212-2 Evoked Cross-Priming of Ethanol-Induced Conditioned Place Preference (CPP)

The activation of the endocannabinoid system controls the release of many neurotransmitters involved in the brain reward pathways, including glutamate. Both endocannabinoid and glutamate systems are crucial for alcohol relapse. In the present study, we hypothesize that N-methyl-D-aspartate (NMDA) glutamate receptors regulate the ability of a priming dose of WIN 55,212-2 to cross-reinstate ethanol-induced conditioned place preference (CPP). To test this hypothesis, ethanol-induced (1.0 g/kg, 10% w/v, i.p.) CPP (unbiased method) was established using male adult Wistar rats. After CPP extinction, one group of animals received WIN 55,212-2 (1.0 and 2.0 mg/kg, i.p.), the cannabinoid receptor 1 (CB1) agonist, or ethanol, and the other group received memantine (3.0 or 10 mg/kg, i.p.), the NMDA antagonist and WIN 55,212-2 on the reinstatement day. Our results showed that a priming injection of WIN 55,212-2 (2.0 mg/kg, i.p.) reinstated (cross-reinstated) ethanol-induced CPP with similar efficacy to ethanol. Memantine (3.0 or 10 mg/kg, i.p.) pretreatment blocked this WIN 55,212-2 effect. Furthermore, our experiments indicated that ethanol withdrawal (7 days withdrawal after 10 days ethanol administration) down-regulated the CNR1 (encoding CB1), GRIN1/2A (encoding GluN1 and GluN2A subunit of the NMDA receptor) genes expression in the prefrontal cortex and dorsal striatum, but up-regulated these in the hippocampus, confirming the involvement of these receptors in ethanol rewarding effects. Thus, our results show that the endocannabinoid system is involved in the motivational properties of ethanol, and glutamate may control cannabinoid induced relapse into ethanol seeking behavior.

BDNF Impact on Biological Markers of Depression-Role of Physical Exercise and Training

Depression is the most common and devastating psychiatric disorder in the world. Its symptoms, especially during the pandemic, are observed in all age groups. Exercise training (ET) is well known as a non-pharmacological strategy to alleviate clinical depression. The brain-derived neurotrophic factor (BDNF) is one of the biological factors whose expression and secretion are intensified in response to ET. BDNF is also secreted by contracted skeletal muscle that likely exerts para-, auto- and endocrine effects, supporting the crosstalk between skeletal muscle and other distant organs/tissues, such as the nervous system. This finding suggests that they communicate and work together to induce improvements on mood, cognition, and learning processes as BDNF is the main player in the neurogenesis, growth, and survival of neurons. Therefore, BDNF has been recognized as a therapeutic factor in clinical depression, especially in response to ET. The underlying mechanisms through which ET impacts depression are varied. The aim of this review was to provide information of the biological markers of depression such as monoamines, tryptophan, endocannabinoids, markers of inflammatory processes (oxidative stress and cytokines) stress and sex hormones and their relationship to BDNF. In addition, we reviewed the effects of ET on BNDF expression and how it impacts depression as well as the potential mechanisms mediating this process, providing a better understanding of underlying ET-related mechanisms in depression.

“Plants of the Gods” and their hallucinogenic powers in neuropharmacology — A review of two books

“Plants of the Gods” is a term referring to the religious meaning members of many primitive cultures worldwide attribute to plants containing hallucinogenic or mind-altering substances. The plants are customarily considered sacred and consumed in religious rituals in an attempt to reach and communicate with gods or revered ancestors. They are frequently used in healing rites. Occasionally, they are used for purely recreational purposes, this being their main use in the modern societies of both industrialized and underdeveloped nations. However, it must be noted that the hallucinogenic or psychedelic experiences, recreational, are not always euphoric. Plants of the Gods: Their Sacred, Healing, and Hallucinogenic Powers is well-written, fully illustrated with color photographs, and contains a good index. It is an effective compilation of ethnographic, historic, and neuropharmacologic information on the hallucinogenic plants of planet Earth and the psychological and sociological impact they have, particularly in primitive societies. The behavioral side effects and toxic manifestations that may be associated with transient or permanent neurological deficits or psychiatric conditions place them in the realm of neuropsychiatry, when affected individuals present to the emergency room or are referred for medical consultation.

Female Sex as a Protective Factor in the Effects of Chronic Cannabis Use on Verbal Learning and Memory

OBJECTIVE

The variability of findings in studies examining the effects of chronic cannabis use on neuropsychological functioning highlights the importance of examining contributing factors. Few studies examine the role of sex in the relationship between cannabis and neuropsychological functioning, despite known neurobiological structural differences between males and females. This study examined whether males and females experience differential cognitive effects of chronic cannabis use.

METHOD

Chronic cannabis users (3+ days per week for >12 months, n = 110, 72% male) and non-users (n = 71, 39% male) completed a neuropsychological test battery. Two multivariate analyses of covariance (MANCOVAs) examined for sex differences in performance within users and non-users on neuropsychological tests, controlling for potential confounding variables. Bonferroni corrections were applied to adjust for multiple comparisons.

RESULTS

Male and female cannabis users did not differ in cannabis use variables. Female cannabis users performed better than males on multiple subtests of the California Verbal Learning Test-II (CVLT-II), a verbal learning and memory test. Male cannabis users performed better than female users on Trial 1 of the CVLT-II (p = .002), and Trail Making Test B (p = .001), which measure attention and cognitive flexibility, respectively. Non-user males and females performed comparably, with the exception of Trail Making Test B (p = .001).

CONCLUSIONS

Results suggest that chronic cannabis use differentially impacts males and females, with females exhibiting better verbal learning and memory despite males demonstrating better attention and cognitive flexibility. Further research is needed to understand the potential protective mechanism of female sex on learning and memory effects of cannabis use.

Marijuana and β-estradiol interactions on spatial learning and memory in young female rats: Lack of role of the G protein-coupled estrogen receptor (GPR30)

It has been shown that 17β-estradiol (E2) hormone is an essential biological factor for increasing the sensitivity of women to drug abuse. Recent studies have shown a potential overlap between the molecular pathways of cannabinoids and ovarian hormones. The current study evaluated the interference between the marijuana and E2 effect on spatial learning and memory and the role of the G protein-coupled estrogen receptor (GPR30) in young female rats. The animals were separated into two main groups: intact-ovary and ovariectomized (OVX) rats. The latter group received intraperitoneal injections of E2, G-1 (GPR30 agonist), G-15 (GPR30 antagonist), marijuana, and different combinations of these substances for 28 days. Spatial learning and memory were evaluated by the Morris water maze (MWM) test. We also assessed the BDNF (brain-derived neurotrophic factor) concentration and the hippocampal level of GPR30. The results showed a significant reduction of spatial learning and memory in OVX rats compared to intact-ovary rats, which were restored by E2 replacement. Moreover, treatment with G-1 mimicked E2 effects on spatial learning and memory. Marijuana impaired spatial learning and memory in intact-ovary rats, while improved in OVX rats. We also found that treatment with M + E2 induced significant impairment in spatial learning and memory; however, treatment with M + G1 and M + G15 + E2 showed no significant difference. No significant differences in BDNF expression were observed in experimental groups. These results suggest that marijuana and E2 interact in their effect on spatial learning and memory in young female rats, but GPR30 seems to play no role in this interaction.

Maternal Supply of Both Arachidonic and Docosahexaenoic Acids Is Required for Optimal Neurodevelopment

During the last trimester of gestation and for the first 18 months after birth, both docosahexaenoic acid,22:6n-3 (DHA) and arachidonic acid,20:4n-6 (ARA) are preferentially deposited within the cerebral cortex at a rapid rate. Although the structural and functional roles of DHA in brain development are well investigated, similar roles of ARA are not well documented. The mode of action of these two fatty acids and their derivatives at different structural-functional roles and their levels in the gene expression and signaling pathways of the brain have been continuously emanating. In addition to DHA, the importance of ARA has been much discussed in recent years for fetal and postnatal brain development and the maternal supply of ARA and DHA. These fatty acids are also involved in various brain developmental processes; however, their mechanistic cross talks are not clearly known yet. This review describes the importance of ARA, in addition to DHA, in supporting the optimal brain development and growth and functional roles in the brain.

Cannabinoid Modulation of Dopamine Release During Motivation, Periodic Reinforcement, Exploratory Behavior, Habit Formation, and Attention

Motivational and attentional processes energize action sequences to facilitate evolutionary competition and promote behavioral fitness. Decades of neuropharmacology, electrophysiology and electrochemistry research indicate that the mesocorticolimbic DA pathway modulates both motivation and attention. More recently, it was realized that mesocorticolimbic DA function is tightly regulated by the brain's endocannabinoid system and greatly influenced by exogenous cannabinoids-which have been harnessed by humanity for medicinal, ritualistic, and recreational uses for 12,000 years. Exogenous cannabinoids, like the primary psychoactive component of cannabis, delta-9-tetrahydrocannabinol, produce their effects by acting at binding sites for naturally occurring endocannabinoids. The brain's endocannabinoid system consists of two G-protein coupled receptors, endogenous lipid ligands for these receptor targets, and several synthetic and metabolic enzymes involved in their production and degradation. Emerging evidence indicates that the endocannabinoid 2-arachidonoylglycerol is necessary to observe concurrent increases in DA release and motivated behavior. And the historical pharmacology literature indicates a role for cannabinoid signaling in both motivational and attentional processes. While both types of behaviors have been scrutinized under manipulation by either DA or cannabinoid agents, there is considerably less insight into prospective interactions between these two important signaling systems. This review attempts to summate the relevance of cannabinoid modulation of DA release during operant tasks designed to investigate either motivational or attentional control of behavior. We first describe how cannabinoids influence DA release and goal-directed action under a variety of reinforcement contingencies. Then we consider the role that endocannabinoids might play in switching an animal's motivation from a goal-directed action to the search for an alternative outcome, in addition to the formation of long-term habits. Finally, dissociable features of attentional behavior using both the 5-choice serial reaction time task and the attentional set-shifting task are discussed along with their distinct influences by DA and cannabinoids. We end with discussing potential targets for further research regarding DA-cannabinoid interactions within key substrates involved in motivation and attention.