Modulation of transmitter release via presynaptic cannabinoid receptors

Potential anti-epileptic phytoconstituents: An updated review

ETHNOPHARMACOLOGICAL RELEVANCE

Epilepsy is one of the most commonly occurring non-communicable neurological disorder that affects people of all age groups. Around 50 million people globally are epileptic, with 80% cases in developing countries due to lack of access to treatments determined by high cost and poor availability or it can be defined by the fraction of active epileptic patients who are not appropriately being treated. The availability of antiepileptic drugs and their adjuvant therapy in such countries is less than 50% and these are highly susceptible to drug interactions and severe adverse effects. As a result, the use of herbal medicine is increasingly becoming popular.

AIM OF THE STUDY

To provide pharmacological information on the active constituents evaluated in the preclinical study to treat epilepsy with potential to be used as an alternative therapeutic option in future. It also provides affirmation for the development of novel antiepileptic drugs derived from medicinal plants.

MATERIALS AND METHODS

Relevant information on the antiepileptic potential of phytoconstituents in the preclinical study (in-vitro, in-vivo) is provided based on their effect on screening parameters. Besides, relevant information on pharmacology of phytoconstituents, the traditional use of their medicinal plants related to epilepsy and status of phytoconstituents in the clinical study were derived from online databases, including PubMed, Clinicaltrial. gov, The Plant List (TPL, www.theplantlist.org), Science Direct. Articles identified using preset searching syntax and inclusion criteria are presented.

RESULTS

More than 70% of the phytoconstituents reviewed in this paper justified the traditional use of their medicinal plant related to epilepsy by primarily acting on the GABAergic system. Amongst the phytoconstituents, only cannabidiol and tetrahydrocannabinol have been explored for clinical application in epilepsy.

CONCLUSION

The preclinical and clinical data of the phytoconstituents to treat epilepsy and its associated comorbidities provides evidence for the discovery and development of novel antiepileptic drugs from medicinal plants. In terms of efficacy and safety, further randomized and controlled clinical studies are required to understand the complete pharmacodynamic and pharmacokinetic picture of phytoconstituents. Also, specific botanical source evaluation is needed.

Distribution of the Cannabinoid Receptor Type 1 in the Brain of the Genetically Audiogenic Seizure-Prone Hamster GASH/Sal

The endocannabinoid system modulates epileptic seizures by regulating neuronal excitability. It has become clear that agonist activation of central type I cannabinoid receptors (CB1R) reduces epileptogenesis in pre-clinical animal models of epilepsy. The audiogenic seizure-prone hamster GASH/Sal is a reliable experimental model of generalized tonic-clonic seizures in response to intense sound stimulation. However, no studies hitherto had investigated CB1R in the GASH/Sal. Although the distribution of CB1R has been extensively studied in mammalian brains, their distribution in the Syrian golden hamster brain also remains unknown. The objective of this research is to determine by immunohistochemistry the differential distribution of CB1R in the brains of GASH/Sal animals under seizure-free conditions, by comparing the results with wild-type Syrian hamsters as controls. CB1R in the GASH/Sal showed a wide distribution in many nuclei of the central nervous system. These patterns of CB1R-immunolabeling are practically identical between the GASH/Sal model and control animals, varying in the intensity of immunostaining in certain regions, being slightly weaker in the GASH/Sal than in the control, mainly in brain regions associated with epileptic networks. The RT-qPCR analysis confirms these results. In summary, our study provides an anatomical basis for further investigating CB1R in acute and kindling audiogenic seizure protocols in the GASH/Sal model as well as exploring CB1R activation via exogenously administered cannabinoid compounds.

In it together? The case for endocannabinoid-noradrenergic interactions in fear extinction

Anxiety and trauma-related disorders, such as post-traumatic stress disorder (PTSD), are debilitating mental illnesses with great personal and socioeconomic costs. Examining memory formation and relevant behavioural responding associated with aversive stimuli may improve our understanding of the neurobiology underlying fear memory processing and PTSD treatment. The neurocircuitry underpinning learned fear and its inhibition through extinction is complex, involving synergistic interactions between different neurotransmitter systems in inter-connected brain areas. Endocannabinoid and noradrenergic transmission have both been implicated separately in fear memory processing and PTSD, but potential interactions between these systems in relation to fear extinction have received little attention to date. Their receptors are expressed together in brain areas crucial for fear extinction, which is enhanced by both cannabinoid and noradrenergic receptor activation in these areas. Moreover, cannabinoid signalling modulates the activity of locus coeruleus noradrenaline (NA) neurons and the release of NA in the medial prefrontal cortex, a brain area that is crucial for fear extinction. Interestingly, endocannabinoid-noradrenergic system interactions have been shown to regulate the encoding and retrieval of fear memory. Thus, noradrenergic regulation of fear extinction may also be driven indirectly in part via cannabinoid receptor signalling. In this perspective paper, we collate the available relevant literature and propose a synergistic role for the endocannabinoid and noradrenergic systems in regulating fear extinction, the study of which may further our understanding of the neurobiological substrates of PTSD and its treatment.

Serotonin 2A receptors and cannabinoids

Accumulating evidence has proven that both exogenous cannabinoids as well as imbalances in the endocannabinoid system are involved in the onset and development of mental disorders such as anxiety, depression, or schizophrenia. Extensive recent research in this topic has mainly focused on the molecular mechanisms by which cannabinoid agonists may contribute to the pathophysiology of these disorders. Initially, serotonin neurotransmitter garnered most attention due to its relationship to mood disorders and mental diseases, with little attention to specific receptors. To date, the focus has redirected toward the understanding of different serotonin receptors, through a demonstration of its versatile pharmacology and synergy with different modulators. Serotonin 2A receptors are a good example of this phenomenon, and the complex signaling that they trigger appears of high relevance in the context of mental disorders, especially in schizophrenia. This chapter will analyze most relevant attributes of serotonin 2A receptors and the endocannabinoid system, and will highlight the evidence toward the functional bidirectional interaction between these elements in the brain as well as the impact of the endocannabinoid system dysregulation on serotonin 2A receptors functionality.

Cannabis and Inflammatory Mediators

INTRODUCTION

Although the recreational cannabis use is expressive worldwide, the literature about medical potential of cannabis extracts, including its anti-inflammatory properties, remains inconclusive.

METHODS

We screened all articles, published on the PubMed database, on inflammatory mediators and any information about cannabis use from 1980 to March 2019.

RESULTS

Six studies were included, and the main findings were as follows: (i) among healthy volunteers and cannabis users, cannabinoids seemed to decrease the inflammatory response, thus decreasing the immune response, which led to a higher risk of infections; (ii) among patients with multiple sclerosis, cannabinoids seemed to have little impact on the inflammatory markers' levels.

DISCUSSION

Although cannabis use can produce immune inflammatory suppression in healthy people, this effect is not robust enough to change inflammatory mediators' levels in situations of highly dysfunctional inflammatory activation. Nevertheless, the impact of cannabinoids in clinical outcomes of these conditions remains to be determined.

Cannabinoid receptor modulation changes the accumbal neuronal responses to morphine in the reinstatement of morphine-induced conditioned place preference

The nucleus accumbens (NAc) is a central component of the brain reward system. It has been known that most of the drugs of abuse such as opioids and cannabinoids affect the NAc. Although cannabinoids can modulate different stages of morphine encounter such as the reinstatement of morphine-induced conditioned place preference (CPP), there is no evidence for the NAc neurons' response to prove it. That is why the present study was designed. The procedure was as follows: The rats were entered to CPP by sc 5 mg/kg morphine in three consecutive days. During the extinction period or in the reinstatement phase, icv WIN 55,212-2 (10mM/5 μL dimethyl sulfoxide [DMSO] 10%) or AM251 (0.5mM/5-μL DMSO 10%) was infused in separate groups. Also, the NAc neurons' response to cannabinoid modulation in reinstatement to morphine was investigated by extracellular single unit recording. As a result, the cannabinoid in the reinstatement phase decreased the NAc neuronal activity. The CB1 receptor inhibition during the extinction period increased the NAc firing rate after ip 1 mg/kg morphine. Also, the inhibition of this receptor in the reinstatement phase increased the NAc neurons' firing rate. The inhibitory effect of cannabinoid on the NAc neuronal activity in the reinstatement has indicated the possible potency of cannabinoid to induce reinstatement of morphine-induced CPP alone and in the absence of a priming dose of morphine. Also, the different effects of the CB1 agonist during the extinction period in the reinstatement phase suggest different mechanisms underlying these two parts.

Colonization with the commensal fungus Candida albicans perturbs the gut-brain axis through dysregulation of endocannabinoid signaling

Anxiety disorders are the most prevalent mental health disorder worldwide, with a lifetime prevalence of 5-7 % of the human population. Although the etiology of anxiety disorders is incompletely understood, one aspect of host health that affects anxiety disorders is the gut-brain axis. Adolescence is a key developmental window in which stress and anxiety disorders are a major health concern. We used adolescent female mice in a gastrointestinal (GI) colonization model to demonstrate that the commensal fungus Candida albicans affects host health via the gut-brain axis. In mice, bacterial members of the gut microbiota can influence the host gut-brain axis, affecting anxiety-like behavior and the hypothalamus-pituitary-adrenal (HPA) axis which produces the stress hormone corticosterone (CORT). Here we showed that mice colonized with C. albicans demonstrated increased anxiety-like behavior and increased basal production of CORT as well as dysregulation of CORT production following acute stress. The HPA axis and anxiety-like behavior are negatively regulated by the endocannabinoid N-arachidonoylethanolamide (AEA). We demonstrated that C. albicans-colonized mice exhibited changes in the endocannabinoidome. Further, increasing AEA levels using the well-characterized fatty acid amide hydrolase (FAAH) inhibitor URB597 was sufficient to reverse both neuroendocrine phenotypes in C. albicans-colonized mice. Thus, a commensal fungus that is a common colonizer of humans had widespread effects on the physiology of its host. To our knowledge, this is the first report of microbial manipulation of the endocannabinoid (eCB) system that resulted in neuroendocrine changes contributing to anxiety-like behavior.

Investigation of Safety and Tolerability of ASP3652 Based on Clinical Studies of Cerebrospinal Fluid Transfer After Multiple Doses and Exposure After Single Doses at High Dose Levels

INTRODUCTION

The studies described here were conducted to investigate the central nervous system (CNS) transfer of ASP3652, a peripherally acting inhibitor of fatty acid amide hydrolase, after multiple doses at around the anticipated therapeutic dose and the safety, tolerability, and pharmacokinetics after single doses at corresponding supratherapeutic doses in healthy subjects.

METHODS

Study 1 was an open-label multiple dose study in which ASP3652 (300 mg bid) or matching placebo was administered in multiple doses to healthy subjects. Study 2 was a placebo-controlled, randomized 4 × 4 crossover study in which ASP3652 was given as three single ascending doses of ASP3652 (600-1800 mg) or matching placebo to healthy subjects. Levels of ASP3652 and endocannabinoids (eCBs) in plasma, cerebrospinal fluid (CSF) (study 1 only), and safety were evaluated.

RESULTS

In study 1, ASP3652 was readily absorbed to reach C_max at 1 h after dosing. AUC_tau and C_max of ASP3652 in CSF were approximately 0.2% and 0.06% of the AUC_tau and C_max in plasma after multiple doses of ASP3652 300 mg bid. At steady state the area under the response-time curve (AURC) from 0 to 12 h and the maximum response for anandamide in plasma were approximately 550-fold and 230-fold higher than those in CSF. In study 2, the C_max and AUC of ASP3652 increased higher than dose proportionally in subjects receiving 600-1800 mg ASP3652. For eCBs, although the AURC increased less than dose proportionally, maximum plasma levels were comparable across all treatment groups. The incidence of adverse events (AEs) was similar across all treatment groups including the placebo group. There was no evidence of CNS-related side effects.

CONCLUSIONS

ASP3652 showed low CNS penetration at the anticipated therapeutic dose and was well tolerable without any CNS-related AEs at supratherapeutic doses, supporting that the drug can be safely tested at the anticipated therapeutic dose.

TRIAL REGISTRATION

ClinicalTrials.gov identifier, NCT02034734 for study 1, NCT01815684 for study 2.

The Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of ASP3652 in First-in-Human and Ascending Multiple Oral Dose Studies in Healthy Subjects

INTRODUCTION

Inhibitors of fatty acid amide hydrolase (FAAH) increase the levels of endocannabinoids and have shown analgesic and anti-inflammatory activity in animal models. ASP3652 is a peripherally acting FAAH inhibitor in development for the treatment of chronic bladder and pelvic pain disorders. Here we describe the safety, pharmacokinetics, and pharmacodynamics of single and multiple oral doses of ASP3652 administered in healthy non-elderly and elderly male and female volunteers.

METHODS

Study 1 was a combined single-ascending dose and food-effect study in which ASP3652 was given as single doses (1-600 mg) or matching placebo in healthy subjects. Study 2 was a multiple ascending dose study in which ASP3652 or matching placebo was administered in multiple oral doses (10-300 mg bid and 600 mg qd for 14 days) to healthy subjects. In both studies, the levels of ASP3652, FAAH, endocannabinoids (eCBs) and safety were evaluated.

RESULTS

ASP3652 was readily absorbed to reach C_max at 1 h after a single dose. Steady state was reached within 3 days after the start of multiple dosing. The C_max and AUC of ASP3652 increased in a slightly more than dose-proportional manner after a single dose of ASP3652 at 30-600 mg. There was some accumulation (15-38%) based on C_max and AUC_12h upon multiple doses. C_max was 47% lower in combination with food. There was no significant effect of gender or age on the pharmacokinetics of ASP3652. FAAH activity was inhibited in a dose-dependent manner in all dose groups after single and multiple doses of ASP3652, paralleled by an increase in plasma levels of anandamide (AEA). The incidence of adverse events following multiple doses was similar across all treatment groups including the placebo group.

CONCLUSIONS

Single and multiple doses of ASP3652 were safe and well tolerated and increased endogenous cannabinoid plasma levels.

Molecular Pharmacology of Synthetic Cannabinoids: Delineating CB1 Receptor-Mediated Cell Signaling

Synthetic cannabinoids (SCs) are a class of new psychoactive substances (NPSs) that exhibit high affinity binding to the cannabinoid CB1 and CB2 receptors and display a pharmacological profile similar to the phytocannabinoid (-)-trans-Δ9-tetrahydrocannabinol (THC). SCs are marketed under brand names such as K2 and Spice and are popular drugs of abuse among male teenagers and young adults. Since their introduction in the early 2000s, SCs have grown in number and evolved in structural diversity to evade forensic detection and drug scheduling. In addition to their desirable euphoric and antinociceptive effects, SCs can cause severe toxicity including seizures, respiratory depression, cardiac arrhythmias, stroke and psychosis. Binding of SCs to the CB1 receptor, expressed in the central and peripheral nervous systems, stimulates pertussis toxin-sensitive G proteins (Gi/Go) resulting in the inhibition of adenylyl cyclase, a decreased opening of N-type Ca2+ channels and the activation of G protein-gated inward rectifier (GIRK) channels. This combination of signaling effects dampens neuronal activity in both CNS excitatory and inhibitory pathways by decreasing action potential formation and neurotransmitter release. Despite this knowledge, the relationship between the chemical structure of the SCs and their CB1 receptor-mediated molecular actions is not well understood. In addition, the potency and efficacy of newer SC structural groups has not been determined. To address these limitations, various cell-based assay technologies are being utilized to develop structure versus activity relationships (SAR) for the SCs and to explore the effects of these compounds on noncannabinoid receptor targets. This review focuses on describing and evaluating these assays and summarizes our current knowledge of SC molecular pharmacology.

[Central Effect of Components of Cannabis: Utility and Risk]

Cannabis contains over 700 known cannabinoids, terpenoids, flavonoids, and so on; however, the roles and importance of these components have yet to be fully understood. Δ⁹-Tetrahydrocannabinol (THC) is believed the most psychoactive component in cannabis, whereas cannabidiol (CBD), cannabinol, and cannabigerol are the most well-known non-psychoactive components. THC, but not CBD, has been shown to produce abnormal behavior in animals; these effects are caused, at least in part, by binding to cannabinoid receptor type 1 (CB₁) in the brain. Regarding the risks associated with cannabis use, acute effects of THC, such as a "high", cognitive deficits, and irritability, are considered more important than potential dependence. On the other hand, CBD has shown anticonvulsant, anti-inflammatory, immunosuppressive, analgesic, and anticancer effects. However, CBD has very low affinity (in the micromolar range) for the CB₁ receptor, as well as for the CB₂ receptor, and its underlying mechanism remains obscure. In this review, we demonstrate that THC induces abnormal behavior such as catalepsy-like immobilization, spatial memory impairment, and high and low sensitivity to ultrasonic vocalization after an aversive air-puff stimulus. Moreover, we demonstrate that THC and CBD improve brain injury in middle cerebral artery occlusion in a mouse model through different mechanisms. These findings suggest the need to discuss the recent development of "THC and CBD pharmacology" in animal studies, as well as the utility and risk of various cannabis components in humans.

Altered relationship between anandamide and glutamate in circulation after 30 min of arm cycling: A comparison of chronic pain subject with healthy controls

The insufficient knowledge of biochemical mechanisms behind the emergence and maintenance of chronic musculoskeletal pain conditions constrains the development of diagnostic and therapeutic tools for clinical use. However, physical activity and exercise may improve pain severity and physical function during chronic pain conditions. Nevertheless, the biochemical consequences of physical activity and exercise in chronic pain need to be elucidated to increase the precision of this therapeutic tool in chronic pain treatment. The endocannabinoid system has been suggested to play an important role in exercise-induced reward and pain inhibition. Moreover, glutamatergic signalling has been suggested as an important factor for sensation and transmission of pain. In addition, a link has been established between the endocannabinoid system and glutamatergic pathways. This study examines the effect of dynamic load arm cycling (30 min) on levels of lipid mediators related to the endocannabinoid system and glutamate in plasma of chronic pain subjects and pain-free controls. Pain assessments and plasma levels of arachidonoylethanolamide (anandamide), 2-aracidonoylglycerol, oleoylethanolamide, palmitoylethanolamide, stearoylethanolamide and glutamate from 21 subjects with chronic neck pain (chronic pain group) and 11 healthy controls were analysed pre and post intervention of dynamic load arm cycling. Pain intensity was significantly different between groups pre and post exercise. Post exercise, anandamide levels were significantly decreased in health controls but not in the chronic pain group. A strong positive correlation existed between anandamide and glutamate in the control group post exercise but not in the chronic pain group. Moreover, the glutamate/anandamide ratio increased significantly in the control group and differed significantly with the chronic pain group post exercise. The altered relationship between anandamide and glutamate after the intervention in the chronic pain group might reflect alterations in the endocannabinoid-glutamate mechanistic links in the chronic pain group compared to the pain-free control group.

The fatty acid amide hydrolase inhibitor URB597 modulates splenic catecholamines in chronically stressed female and male rats

The changes in sympathetic innervations in lymphoid organs could be a key factor in immune dysregulation. The endocannabinoid system has been shown to exhibit potent immunomodulatory effects that may differ between males and females, representing a potential therapeutic target for peripheral and central inflammatory disorders. Thus, in the present study, an examination was made of the effect of fatty acid amide hydrolase inhibitor URB597 treatment on splenic catecholamine content, synthesis, uptake and degradation in chronically unpredictably stressed (CUS) female and male rats. The results show that CUS increases anxiety-like behaviors and that URB597 had an anxiolytic effect on chronically stressed animals of both sexes. CUS induced the expression of plasma interleukin - 6 (IL-6), interleukin - 10 (IL-10) and IL-6 in the spleen, whereas the expression of IL-10 was reduced in the spleen of both sexes. URB597 treatment did not cause changes in IL-6 in plasma or the spleen, whereas it increased IL-10 in the spleen in CUS animals of both sexes. CUS caused a significant depletion of noradrenaline content in the spleen of female rats and a reduction in noradrenaline uptake in the spleen of female rats, while stressed males had a small but insignificant decrease of splenic noradrenaline levels and an enhanced uptake. The FAAH inhibitor URB597 enhances reduced noradrenaline content, affecting its uptake directly at the level of the spleen. It gives rise to the possibility that endocannabinoids exert a neurorestorative effect on the sympathetic nerve system and cell-mediated immune responses in the spleen of chronically stressed rats.

Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of ASP3652, a Reversible Fatty Acid Amide Hydrolase Inhibitor, in Healthy, Nonelderly, Japanese Men and Elderly, Japanese Men and Women: A Randomized, Double-blind, Placebo-controlled, Single and Multiple Oral Dose, Phase I Study

PURPOSE

This study aimed to evaluate the safety, tolerability, and pharmacokinetic and pharmacodynamic properties of ASP3652, a peripherally acting inhibitor of peripheral fatty acid amide hydrolase (FAAH) after 30-, 100-, 300-, 600-, and 900-mg single and 100- and 300-mg BID multiple oral dose in Japanese patients.

METHODS

This was a randomized, double-blind, placebo-controlled, single and multiple oral dose Phase I study in healthy, nonelderly men and elderly men and women. The study consisted of 2 parts: in the single oral dose part, 40 healthy, nonelderly men were randomized to receive placebo or ASP3652; in the multiple oral dose part, 48 enrolled nonelderly men and elderly men and women were randomized to receive placebo or ASP3652. In both parts, the investigator judged whether the individuals were healthy based on the results of physical examinations and screening. The safety profile was assessed by examining adverse events, defined as any untoward medical occurrence in an individual administered the study drug and that did not necessarily have a causal relationship with the study treatment; clinical laboratory evaluations; vital signs; the Profile of Mood States scale; and standard 12-lead ECGs and 12-lead ECGs for QT assessment. Pharmacokinetic parameters were estimated using unchanged ASP3652 concentrations in plasma and urine. Pharmacodynamic parameters were estimated using FAAH activity and plasma anandamide, oleoylethanolamide, and palmitoylethanolamide concentrations. Safety and tolerability profiles were compared with the placebo group.

FINDINGS

ASP3652 was rapidly absorbed to reach C_max in a single dose and near steady-state at approximately 3 days after the start of multiple dosing. The C_max and AUC of ASP3652 were slightly higher than dose proportional after a single dose of ASP3652 at 30-900 mg. There was no apparent accumulation based on C_max and AUC_0-12 after multiple doses. Although no differences were found in C_max or AUC_0-12 by age in men, C_max and AUC_0-12 were slightly higher in elderly women than elderly men. FAAH activity was inhibited in a dose-dependent manner, and plasma levels of anandamide, oleoylethanolamide, and palmitoylethanolamide increased in all dose groups after single and multiple doses of ASP3652. The incidence of adverse events after multiple doses, which ranged from 44.4% to 66.7%, was similar across all treatment groups, including the placebo group.

IMPLICATIONS

Single and multiple doses of ASP3652 were well tolerated and increased endogenous cannabinoids.

A critical inquiry into marble-burying as a preclinical screening paradigm of relevance for anxiety and obsessive-compulsive disorder: Mapping the way forward

Rodent marble-burying behavior in the marble-burying test (MBT) is employed as a model or measure to study anxiety- and compulsive-like behaviors or anxiolytic and anticompulsive drug action. However, the test responds variably to a range of pharmacological interventions, and little consensus exists regarding specific methodologies for its execution. Regardless, the test is widely applied to investigate the effects of pharmacological, genetic, and behavioral manipulations on purported behaviors related to the said neuropsychiatric constructs. Therefore, in the present review we attempt to expound the collective translational significance of the MBT. We do this by (1) reviewing burying behavior as a natural behavioral phenotype, (2) highlighting key aspects of anxiety and obsessive-compulsive disorder from a translational perspective, (3) reviewing the history and proof of concept of the MBT, (4) critically appraising potential methodological confounds in execution of the MBT, and (5) dissecting responses of the MBT to various pharmacological interventions. We conclude by underlining that the collective translational value of the MBT will be strengthened by contextually valid experimental designs and objective reporting of data.

The anti-inflammatory and analgesic effects of formulated full-spectrum cannabis extract in the treatment of neuropathic pain associated with multiple sclerosis

PURPOSE

Cannabis has been used for thousands of years in many cultures for the treatment of several ailments including pain. The benefits of cannabis are mediated largely by cannabinoids, the most prominent of which are tetrahydrocannabinol (THC) and cannabidiol (CBD). As such, THC and/or CBD have been investigated in clinical studies for the treatment of many conditions including neuropathic pain and acute or chronic inflammation. While a plethora of studies have examined the biochemical effects of purified THC and/or CBD, only a few have focused on the effects of full-spectrum cannabis plant extract. Accordingly, studies using purified THC or CBD may not accurately reflect the potential health benefits of full-spectrum cannabis extracts. Indeed, the cannabis plant produces a wide range of cannabinoids, terpenes, flavonoids, and other bioactive molecules which are likely to contribute to the different biological effects. The presence of all these bioactive molecules in cannabis extracts has garnered much attention of late especially with regard to their potential role in the treatment of neuropathic pain associated with multiple sclerosis.

METHODS

Literature review was performed to further understand the effect of clinically used full-spectrum cannabis extract in patients with multiple sclerosis.

RESULTS

Herein, the current knowledge about the potential beneficial effects of existing products of full-spectrum cannabis extract in clinical studies involving patients with multiple sclerosis is extensively reviewed. In addition, the possible adverse effects associated with cannabis use is discussed along with how the method of extraction and the delivery mechanisms of different cannabis extracts contribute to the pharmacokinetic and biological effects of full-spectrum cannabis extracts.Herein, the current knowledge about the potential beneficial effects of existing products of full-spectrum cannabis extract in clinical studies involving patients with multiple sclerosis is extensively reviewed. In addition, the possible adverse effects associated with cannabis use is discussed along with how the method of extraction and the delivery mechanisms of different cannabis extracts contribute to the pharmacokinetic and biological effects of full-spectrum cannabis extracts.

The molecular mechanisms that underpin the biological benefits of full-spectrum cannabis extract in the treatment of neuropathic pain and inflammation

Cannabis has been shown to be beneficial in the treatment of pain and inflammatory diseases. The biological effect of cannabis is mainly attributed to two major cannabinoids, tetrahydrocannabinol and cannabidiol. In the majority of studies to-date, a purified tetrahydrocannabinol and cannabidiol alone or in combination have been extensively examined in many studies for the treatment of numerous disorders including pain and inflammation. However, few studies have investigated the biological benefits of full-spectrum cannabis plant extract. Given that cannabis is known to generate a large number of cannabinoids along with numerous other biologically relevant products including terpenes, studies involving purified tetrahydrocannabinol and/or cannabidiol do not consider the potential biological benefits of the full-spectrum cannabis extracts. This may be especially true in the case of cannabis as a potential treatment of pain and inflammation. Herein, we review the pre-clinical physiological and molecular mechanisms in biological systems that are affected by cannabis.

Role of cannabis in inflammatory bowel diseases

For many centuries, cannabis (marijuana) has been used for both recreational and medicinal purposes. Currently, there are about 192 million cannabis users worldwide, constituting approximately 3.9% of the global population. Cannabis comprises more than 70 aromatic hydrocarbon compounds known as cannabinoids. Endogenous circulating cannabinoids, or endocannabinoids, such as anandamide and 2-arachidonoyl-glycerol, their metabolizing enzymes (fatty acid amide hydrolase and monoacylglycerol lipase) and 2 G-protein coupled cannabinoid receptors, CB1 and CB2, together represent the endocannabinoid system and are present throughout the human body. In the gastrointestinal (GI) tract, the activated endocannabinoid system reduces gut motility, intestinal secretion and epithelial permeability, and induces inflammatory leukocyte recruitment and immune modulation through the cannabinoid receptors present in the enteric nervous and immune systems. Because of the effects of cannabinoids on the GI tract, attempts have been made to investigate their medicinal properties, particularly for GI disorders such as pancreatitis, hepatitis, and inflammatory bowel diseases (IBD). The effects of cannabis on IBD have been elucidated in several small observational and placebo-controlled studies, but with varied results. The small sample size and short follow-up duration in these studies make it difficult to show the clear benefits of cannabis in IBD. However, cannabis is now being considered as a potential drug for inflammatory GI conditions, particularly IBD, because of its spreading legalization in the United States and other countries and the growing trend in its use. More high-quality controlled studies are warranted to elucidate the mechanism and benefits of cannabis use as a possible option in IBD management.

Do the effects of cannabis on the hippocampus and striatum increase risk for psychosis?

Cannabis use is associated with increased risk of psychotic symptoms and in a small number of cases it can lead to psychoses. This review examines the neurobiological mechanisms that mediate the link between cannabis use and psychosis risk. We use an established preclinical model of psychosis, the methylazoxymethanol acetate (MAM) rodent model, as a framework to examine if psychosis risk in some cannabis users is mediated by the effects of cannabis on the hippocampus, and this region's role in the regulation of mesolimbic dopamine. We also examine how cannabis affects excitatory neurotransmission known to regulate hippocampal neural activity and output. Whilst there is clear evidence that cannabis/cannabinoids can affect hippocampal and medial temporal lobe function and structure, the evidence that cannabis/cannabinoids increase striatal dopamine function is less robust. There is limited evidence that cannabis use affects cortical and striatal glutamate levels, but there are currently too few studies to draw firm conclusions. Future work is needed to test the MAM model in relation to cannabis using multimodal neuroimaging approaches.

Cannabis use disorders may protect against certain disorders of the digestive organs in people with schizophrenia but not in healthy controls

BACKGROUND

Previous studies have shown a potential for cannabis in disorders of the digestive organs. We aimed to investigate whether cannabis use disorders (CUD) would decrease the risk of incident disorders of the digestive organs, in people with schizophrenia and population controls.

METHODS

We combined nationwide Danish registers to identify 21 066 cases with schizophrenia and 176 935 sex-and-age-matched controls. Two models were analyzed for the associations between CUD and digestive disorders in time-varying Cox regressions: one adjusted for sex, year of birth, and calendar year; and one further adjusted for alcohol and other substance use disorders and parental education.

RESULTS

CUD was associated with a decreased risk of developing disorders of gut-brain interaction (e.g. irritable bowel syndrome, dyspepsia, etc.) among cases with schizophrenia (HR = 0.84, 95% CI 0.74-0.94, p = 0.003). CUD was associated with decreased risk of inflammatory bowel disease (HR = 0.70, 95% CI 0.49-0.99, p = 0.045) in the basically adjusted model, dropping just below statistical significance in the fully adjusted model (HR = 0.71, 95% CI 0.48-1.03, p = 0.07). CUD displayed a tendency toward a decreased risk of serious disorders of the digestive organs among cases with schizophrenia (HR = 0.89, 95% CI 0.77-1.02, p = 0.09) in the fully adjusted model. No associations were observed among controls.

CONCLUSIONS

In people with schizophrenia, but not in controls, CUD is associated with decreased risk of disorders of gut-brain interaction and inflammatory bowel disease, and possibly other serious disorders of the digestive organs. Our findings could lead to new targets for treatment and prevention of disorders of the digestive organs.

Abnormal Cannabidiol Affects Production of Pro-Inflammatory Mediators and Astrocyte Wound Closure in Primary Astrocytic-Microglial Cocultures

Abnormal cannabidiol (abn-CBD) exerts neuroprotective effects in vivo and in vitro. In the present study, we investigated the impact of abn-CBD on the glial production of proinflammatory mediators and scar formation within in vitro models. Primary astrocytic-microglial cocultures and astrocytic cultures from neonatal C57BL/6 mice and CB2 receptor knockout mice were stimulated with lipopolysaccharide (LPS), and the concentrations of tumor necrosis factor α (TNFα), interleukin-6 (IL-6) and nitrite were determined. Furthermore, we performed a live cell microscopy-based scratch-wound assay. After LPS stimulation, TNFα, IL-6 and nitrite production was more strongly increased in cocultures than in isolated astrocytes. Abn-CBD treatment attenuated the LPS-induced production of TNFα and nitrite in cocultures, while IL-6 production remained unaltered. In isolated astrocytes, only LPS-induced TNFα production was reduced by abn-CBD. Similar effects were observed after abn-CBD application in cocultures of CB2 knockout mice. Interestingly, LPS-induced TNFα and nitrite levels were far lower in CB2 knockout cultures compared to wildtypes, while IL-6 levels did not differ. In the scratch-wound assay, treatment with abn-CBD decelerated wound closure when microglial cells were present. Our data shows a differential role of abn-CBD for modulation of glial inflammation and astrocytic scar formation. These findings provide new explanations for mechanisms behind the neuroprotective potential of abn-CBD.

Phytocannabinoids: Useful Drugs for the Treatment of Obesity? Special Focus on Cannabidiol

Currently, an increasing number of diseases related to insulin resistance and obesity is an alarming problem worldwide. It is well-known that the above states can lead to the development of type 2 diabetes, hypertension, and cardiovascular diseases. An excessive amount of triacylglycerols (TAGs) in a diet also evokes adipocyte hyperplasia and subsequent accumulation of lipids in peripheral organs (liver, cardiac muscle). Therefore, new therapeutic methods are constantly sought for the prevention, treatment and alleviation of symptoms of the above mentioned diseases. Currently, much attention is paid to Cannabis derivatives-phytocannabinoids, which interact with the endocannabinoid system (ECS) constituents. Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and cannabidiol (CBD) are the most abundant compounds of Cannabis plants and their therapeutic application has been suggested. CBD is considered as a potential therapeutic agent due to its anti-inflammatory, anti-oxidant, anti-tumor, neuroprotective, and potential anti-obesity properties. Therefore, in this review, we especially highlight pharmacological properties of CBD as well as its impact on obesity in different tissues.

Cannabis induced increase in striatal glutamate associated with loss of functional corticostriatal connectivity

Cannabis is the most commonly used illicit drug and is known to alter state of consciousness and impair neurocognitive function. However, the mechanisms underlying these effects have yet to be fully elucidated. Rodent studies suggest that Δ9-tetrahydrocannabinol (THC) activates dopaminergic neurons in the limbic system, subsequently enhancing dopamine, which is implicated in the rewarding effects of cannabis. Additional evidence suggests that THC may act indirectly on dopamine firing by modulating GABA and glutamate release. This double-blind, placebo-controlled study assessed the acute influence of two doses of THC on brain kinetics of glutamate, GABA, and dopamine, in relation to behavioral outcomes, by using magnetic resonance spectroscopy and functional magnetic resonance imaging. Twenty occasional cannabis users received acute doses of cannabis (300 µg/kg THC) and placebo, in one of two dose regimes (full dose and divided dose), during two separate testing days. Administration of THC increased striatal glutamate concentrations, and dopamine as indicated by a reduction in functional connectivity (FC) between the nucleus accumbens (NAc) and cortical areas. Alterations in glutamate and FC were dose dependent and evident in the full dose group where THC serum concentrations exceeded 2 ng/ml at T-max. Average glutamate changes correlated strongly with FC alterations. Additionally, THC induced changes in FC correlated with feelings of subjective high and decreased performance on an attention task. Taken together, this suggests that THC elicits subjective and cognitive alterations via increased striatal dopaminergic activity and loss of corticostriatal connectivity, which is associated with an increase in striatal glutamate.

Cannabidiol and Cannabinoid Compounds as Potential Strategies for Treating Parkinson's Disease and L-DOPA-Induced Dyskinesia

Parkinson's disease (PD) and L-DOPA-induced dyskinesia (LID) are motor disorders with significant impact on the patient's quality of life. Unfortunately, pharmacological treatments that improve these disorders without causing severe side effects are not yet available. Delay in initiating L-DOPA is no longer recommended as LID development is a function of disease duration rather than cumulative L-DOPA exposure. Manipulation of the endocannabinoid system could be a promising therapy to control PD and LID symptoms. In this way, phytocannabinoids and synthetic cannabinoids, such as cannabidiol (CBD), the principal non-psychotomimetic constituent of the Cannabis sativa plant, have received considerable attention in the last decade. In this review, we present clinical and preclinical evidence suggesting CBD and other cannabinoids have therapeutic effects in PD and LID. Here, we discuss CBD pharmacology, as well as its neuroprotective effects and those of other cannabinoids. Finally, we discuss the modulation of several pro- or anti-inflammatory factors as possible mechanisms responsible for the therapeutic/neuroprotective potential of Cannabis-derived/cannabinoid synthetic compounds in motor disorders.

Bones and Joints: The Effects of Cannabinoids on the Skeleton

CONTEXT

The endocannabinoid system uses tissue-specific lipid ligands and G protein‒coupled transmembrane receptors to regulate neurologic, metabolic, and immune responses. Recent studies demonstrate that the endocannabinoid system influences bone metabolism. With the increasing use of endocannabinoid mimetics (e.g., tetrahydrocannabinol and cannabidiol), the involvement of endocannabinoids in bone growth and remodeling has become clinically relevant.

EVIDENCE ACQUISITION

This literature review is based on a search of PubMed and Google Scholar databases as of June 2019 for all English-language publications relating to cannabinoids and bone. We evaluated retrieved articles for relevance, experimental design, data acquisition, statistical analysis, and conclusions.

EVIDENCE SYNTHESIS

Preclinical studies establish a role for endocannabinoids in bone metabolism. These studies yield complex and often contradictory results attributed to differences in the specific experimental model examined. Studies using human cells or subjects are limited.

CONCLUSIONS

In vitro and animal models document that endocannabinoids are involved in bone biology. The relevance of these observations to humans is not clear. The increasing long-term use of medical and recreational cannabis underscores the need to better understand the role of endocannabinoids in human bone metabolism. Moreover, it is important to evaluate the role of endocannabinoids as a therapeutic target to prevent and treat disorders associated with bone loss.

Effects of Cannabinoids on Female Sexual Function

INTRODUCTION

With the legalization of both medical and recreational marijuana in some countries and a few US states, its use has become more widely prevalent. Both exogenous cannabinoids such as tetrahydrocannabinol (THC) and endogenous cannabinoids (endocannabinoids) have been shown to affect female gonadotropin pathways and female sexuality. Yet, our understanding of the mechanisms and effects on female sexual function is limited.

AIM

To review the literature regarding the effects of both endogenous and exogenous cannabinoids on female sexual function in both animals and humans.

METHODS

We performed a PubMed search for English-language articles in peer-reviewed journals between 1970 and 2019. We used the following search terms: "cannabinoids," "endocannabinoids," "marijuana," "cannabis," and "female sexual function" or "sexual function." The main outcomes of the papers were reviewed.

MAIN OUTCOME MEASURE

The main outcome measure was sexual function in females.

RESULTS

A total of 12 human studies and 8 animal studies that evaluated the relationship between cannabinoids and female sexual function were included. Study types in animals were blinded, prospective, placebo-controlled trials. Human studies were based primarily on questionnaire data. The data indicate dose-dependent effects on female sexual desire and receptivity, such that low doses generally facilitate or have no effect but high doses inhibit.

CONCLUSIONS

More research is needed to develop a better understanding of the effects of cannabinoids on female sexual function. There does appear to be an effect on both animals and humans, but whether the effect is positive or negative along dose and species lines requires more study. With the legalization of marijuana occurring in more countries and more US states, there needs to be more well-controlled studies evaluating the effects. Lynn B, Gee A, Zhang L, et al. Effects of Cannabinoids on Female Sexual Function. Sex Med Rev 2020;8:18-27.

WIN 55,212-2 Reverted Pilocarpine-Induced Status Epilepticus Early Changes of the Interaction among 5-HT2C/NMDA/CB1 Receptors in the Rat Hippocampus

The molecular basis for temporal lobe epileptogenesis  remains poorly defined. Recent evidence shows that serotonin 2C receptors (5-HT_2CRs), NR2A and NR2B subunit-containing N-methyl-d-aspartate receptors (NMDARs) and cannabinoid 1 receptors (CB₁Rs) may be involved in the progression of the epileptic disorders. Moreover, CB₁R activation has been reported to modulate the activity of 5-HT_2C and NMDA receptors. Here, we treated Sprague-Dawley rats with the pro-convulsant agent pilocarpine (PILO) to induce status epilepticus (SE) in order to study the effect, with regards to receptor signaling and their interactions, of the preactivation of the CB₁Rs on early changes that occur 24 h from the initial insult in the hippocampus. Pretreatment with the synthetic CB_1/2R agonist WIN 55,212-2 (2 mg/kg, ip) counteracted PILO-induced 5-HT_2CR downregulation. Moreover, WIN 55,212-2 uncoupled PILO-induced 5-HT_2CR/NR2A and prevented NR2A^Tyr1325 phosphorylation indirectly since no 5-HT_2CR/CB₁R interactions were observed. WIN 55,212-2 treatment also prevented PILO-mediated impairment of CB₁R/NR2B interactions and NR2B subunit internalization, suggesting a possible role of CB₁R in NR2B-containing NMDAR turn over. All the effects observed in animals treated with WIN 55,212-2 were blocked by pretreatment with the selective CB₁R antagonist AM251 (1 mg/kg, ip) given 45 min before PILO injection. These results, obtained in vivo in post-PILO-induced SE, provide new insights on the early cellular responses during epileptogenesis and identify new CB₁R-mediated mechanisms by which cannabinoids may prevent the development of chronic epilepsy.

Elevation of endocannabinoids in the brain by synthetic cannabinoid JWH-018: mechanism and effect on learning and memory

The impairment of learning and memory is a well-documented effect of both natural and synthetic cannabinoids. In the present study, we aimed to investigate the effect of acute administration of JWH-018, a synthetic cannabinoid, on the hippocampal metabolome to assess biochemical changes in vivo. JWH-018 elevated levels of the endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG). The increase of endocannabinoid levels in response to JWH-018 could be inhibited by co-administration of AM251, a CB1 receptor antagonist. Biochemical analyses revealed that this was the result of suppression of two hydrolases involved in endocannabinoid degradation (fatty acid amide hydrolase [FAAH] and monoacylglycerol lipase [MAGL]). Additionally, we showed that JWH-018 causes a reduction in the levels of brain-derived neurotrophic factor (BDNF), which is known to modulate synaptic plasticity and adaptive processes underlying learning and memory. The decrease of BDNF following JWH-018 treatment was also rescued by co-administration of AM251. As both endocannabinoids and BDNF have been shown to modulate learning and memory in the hippocampus, the alteration of their levels in response to JWH-018 may explain the contribution of synthetic cannabinoids to impairment of memory.

Development of Oxygen-Bridged Pyrazole-Based Structures as Cannabinoid Receptor 1 Ligands

In this work, the synthesis of the cannabinoid receptor 1 neutral antagonists 8-chloro-1-(2,4-dichlorophenyl)-N-piperidin-1-yl-4,5-dihydrobenzo-1H-6-oxa-cyclohepta[1,2-c]pyrazole-3-carboxamide 1a and its deaza N-cyclohexyl analogue 1b has led to a deepening of the structure-activity studies of this class of compounds. A series of novel 4,5-dihydrobenzo-oxa-cycloheptapyrazoles analogues of 1a,b, derivatives 1c–j, was synthesized, and their affinity towards cannabinoid receptors was determined. Representative terms were evaluated using in vitro tests and isolated organ assays. Among the derivatives, 1d and 1e resulted in the most potent CB₁ receptor ligands (K_iCB₁ = 35 nM and 21.70 nM, respectively). Interestingly, both in vitro tests and isolated organ assays evidenced CB₁ antagonist activity for the majority of the new compounds, excluding compound 1e, which showed a CB₁ partial agonist behaviour. CB₁ antagonist activity of 1b was further confirmed by a mouse gastrointestinal transit assay. Significant activity of the new CB₁ antagonists towards food intake was showed by preliminary acute assays, evidencing the potentiality of these new derivatives in the treatment of obesity.

Cannabinoids: Potential Role in Inflammatory and Neoplastic Skin Diseases

The endocannabinoid system is a complex and nearly ubiquitous network of endogenous ligands, enzymes, and receptors that can also be stimulated by exogenous compounds such as those derived from the marijuana plant, Cannabis sativa. Recent data have shown that the endocannabinoid system is fully functional in the skin and is responsible for maintaining many aspects of skin homeostasis, such as proliferation, differentiation, and release of inflammatory mediators. Because of its role in regulating these key processes, the endocannabinoid system has been studied for its modulating effects on both inflammatory disorders of the skin and skin cancer. Although legal restrictions on marijuana as a Schedule I drug in the USA have made studying cannabinoid compounds unfavorable, an increasing number of studies and clinical trials have focused on the therapeutic uses of cannabinoids. This review seeks to summarize the current, and rapidly expanding field of research on the broad potential uses of cannabinoids in inflammatory and neoplastic diseases of the skin.

The Relationship between Marijuana Use Prior to Sex and Sexual Function in Women

INTRODUCTION

Scientific research on the effects of marijuana on sexual functioning in women, including libido, arousal, orgasm, and satisfaction, is limited.

AIM

To evaluate women's perceptions of the effect of marijuana use before sexual activity.

METHODS

A cross-sectional design, from March 2016-February 2017, within a single, academic, obstetrics and gynecology practice, was performed. Patients were given a questionnaire at their visit and asked to complete it anonymously and place it in a locked box after their visit.

MAIN OUTCOME MEASURES

The primary outcome was satisfaction in the sexual domains of drive, orgasm, lubrication, dyspareunia, and overall sexual experience. The secondary outcome was the effect of the frequency of marijuana use on satisfaction.

RESULTS

Of the 373 participants, 34.0% (n = 127) reported having used marijuana before sexual activity. Most women reported increases in sex drive, improvement in orgasm, decrease in pain, but no change in lubrication. After adjusting for race, women who reported marijuana use before sexual activity had 2.13 higher odds of reporting satisfactory orgasms (adjusted odds ratio = 2.13; 95% CI = 1.05, 4.35) than women who reported no marijuana use. After adjusting for race and age, women with frequent marijuana use, regardless of use before sex or not, had 2.10 times higher odds of reporting satisfactory orgasms than those with infrequent marijuana use (adjusted odds ratio = 2.10; 95% CI = 1.01-4.44).

CONCLUSION

Marijuana appears to improve satisfaction with orgasm. A better understanding of the role of the endocannabinoid system in women is important, because there is a paucity of literature, and it could help lead to development of treatments for female sexual dysfunction. Lynn BK, López JD, Miller C, et al. The Relationship between Marijuana Use Prior to Sex and Sexual Function in Women. Sex Med 2019;7:192-197.

Brain activity of anandamide: a rewarding bliss?

Anandamide is a lipid mediator that acts as an endogenous ligand of CB1 receptors. These receptors are also the primary molecular target responsible for the pharmacological effects of Δ9-tetrahydrocannabinol, the psychoactive ingredient in Cannabis sativa. Several studies demonstrate that anandamide exerts an overall modulatory effect on the brain reward circuitry. Several reports suggest its involvement in the addiction-producing actions of other abused drugs, and it can also act as a behavioral reinforcer in animal models of drug abuse. Importantly, all these effects of anandamide appear to be potentiated by pharmacological inhibition of its metabolic degradation. Enhanced brain levels of anandamide after treatment with inhibitors of fatty acid amide hydrolase, the main enzyme responsible for its degradation, seem to affect the rewarding and reinforcing actions of many drugs of abuse. In this review, we will provide an overview from a preclinical perspective of the current state of knowledge regarding the behavioral pharmacology of anandamide, with a particular emphasis on its motivational/reinforcing properties. We will also discuss how modulation of anandamide levels through inhibition of enzymatic metabolic pathways could provide a basis for developing new pharmaco-therapeutic tools for the treatment of substance use disorders.

Sexual interaction is essential for the transformation of non-copulating rats into sexually active animals by the endocannabinoid anandamide

The endocannabinoid anandamide (AEA) transforms half of the population of previously non-copulating (NC) rats into sexually active animals in a long-lasting manner. The aim of this work was to explore the nature of this transformation. We identified the dose range in which AEA induces mating behavior in previously NC rats, which evidenced a dose-based, biphasic profile for AEA to induce the transformation of NC rats. We demonstrate that the sexual interaction with a receptive female, involving at least an intromission, is essential for AEA to induce the transformation of NC rats. This AEA-induced conversion is centrally mediated and involves the activation of CB1 receptors. Results indicate that the sexual impairment of this population of NC rats relies on their incapacity to initiate sexual activity and that an unidentified brain inhibitory influence on sexual behavior expression is removed by AEA treatment, allowing previously NC rats to show copulatory behavior in a long-lasting manner. The inhibitory influence is not removed by AEA treatment when animals are not allowed to have sexual contact with the female immediately after AEA injection. The same result was found for the opioid receptor antagonist naloxone, the other treatment reported to induce copulation in rats classified as NC. These data suggest that sexual behavior expression could depend on two different neural mechanisms at two different moments: one involved in the display of the first copulatory response and another responsible for maintaining subsequent sexual behavior responding.

Gene expression analysis indicates reduced memory and cognitive functions in the hippocampus and increase in synaptic reorganization in the frontal cortex 3 weeks after MDMA administration in Dark Agouti rats

BACKGROUND

3,4-methylenedioxymethamphetamine (MDMA, "ecstasy") is a widely used entactogenic drug known to impair cognitive functions on the long-run. Both hippocampal and frontal cortical regions have well established roles in behavior, memory formation and other cognitive tasks and damage of these regions is associated with altered behavior and cognitive functions frequently described in otherwise healthy MDMA users. Meanwhile, in post-traumatic stress disorder (PTSD) patients seem to benefit from therapeutic application of the drug, where damage in hippocampal cue extinction may play a role. The aim of this study was to examine the hippocampus, frontal cortex and dorsal raphe of Dark Agouti rats with gene expression arrays (Illumina RatRef bead arrays) looking for possible mechanisms and new candidates contributing to the consequences of a single dose of MDMA (15 mg/kg) 3 weeks earlier.

RESULTS

The number of differentially expressed genes in the hippocampus, frontal cortex and the dorsal raphe were 481, 155, and 15, respectively. Gene set enrichment analysis of the microarray data revealed reduced expression of 'memory' and 'cognition', 'dendrite development' and 'regulation of synaptic plasticity' gene sets in the hippocampus, parallel to the downregulation of CaMK II subunits, glutamate-, CB1 cannabinoid- and EphA4, EphA5, EphA6 receptors. Downregulated gene sets in the frontal cortex were related to protein synthesis, chromatin organization, transmembrane transport processes, while 'dendrite development', 'regulation of synaptic plasticity' and 'positive regulation of synapse assembly' gene sets were upregulated besides elevated levels of a CaMK II subunit and NMDA2B glutamate receptor. Changes in the dorsal raphe region were mild and in most cases not significant.

CONCLUSION

The present data raise the possibility of new synapse formation / synaptic reorganization in the frontal cortex 3 weeks after a single neurotoxic dose of MDMA. In contrast, a prolonged depression of new neurite formation in the hippocampus is proposed by downregulations of members in long-term potentiation pathway and synaptic plasticity emphasizing the particular vulnerability of this brain region and proposing a mechanism responsible for cognitive problems in healthy individuals. At the same time, these results underpin benefits of MDMA in PTSD, where the drug may help memory extinction.

Pharmacokinetics and Tolerability of Δ9-THC-Hemisuccinate in a Suppository Formulation as an Alternative to Capsules for the Systemic Delivery of Δ9-THC

The objectives of this study were: (1) to assess the safety, tolerability, and pharmacokinetics of ascending doses of Δ⁹-tetrahydrocannabinol-hemisuccinate (THC-HS) after rectal administration as suppositories in male volunteers; and (2) to compare the pharmacokinetics of oral administration of Δ⁹-tetrahydrocannabinol (Δ⁹-THC) with an equivalent amount of Δ⁹-THC delivered as THC-HS via the suppository formulation. In support of the pharmacokinetic evaluations, an analytical method was developed and validated for the determination of Δ⁹-THC and for its major circulating metabolites 11-hydroxy-Δ⁹-tetrahydrocannabinol (11-OH-THC) and 11-nor-Δ⁹-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) in human plasma. Δ⁹-THC, 11-OH-THC, and THC-COOH were extracted from plasma using solid phase extraction and analyzed by liquid chromatography-tandem mass spectrometry. The limits of detection and quantitation for all 3 analytes were 0.25 and 0.5 ng/mL, respectively. The method was validated over the range of 0.5-25 ng/mL. This method was used to quantify Δ⁹-THC and any THC-HS as Δ⁹-THC due to the inclusion of a hydrolysis step as part of the extraction procedure. Therefore, Δ⁹-THC measured was the total THC (free Δ⁹-THC plus Δ⁹-THC derived from THC-HS). The assay was reproducible for the measurement of all 3 analytes, with a variability of 7.2, 13.7, and 8.3%, respectively, at the 1 ng/mL level. The method was then used to assess the pharmacokinetics of Δ⁹-THC and metabolites from the suppository dosage form in doses equivalent to 1.25, 2.5, 5, 10, and 20 mg Δ⁹-THC per suppository as THC-HS. Systemic exposure to Δ⁹-THC, administered as THC-HS suppository, increased broadly dose proportionally. Systemic exposure and C_{max (obs)} estimates for 11-OH-THC and THC-COOH generally increased subproportionally. The pharmacokinetic profiles of Δ⁹-THC and metabolites were also compared after oral administration of 10 mg Δ⁹-THC (as dronabinol capsules) and after administration of 10 mg equivalents of Δ⁹-THC as THC-HS in suppository form. Total systemic exposure to Δ⁹-THC was considerably higher following rectal administration of THC-HS than after oral administration. The Δ⁹-THC area under the plasma concentration versus time curve (AUC_(0-∞)) for THC-HS was 2.44-fold higher (90% confidence interval: 1.78, 3.35) than for the capsule administration.

Cannabinoid-induced increase of quantal size and enhanced neuromuscular transmission

Cannabinoids exert dynamic control over many physiological processes including memory formation, cognition and pain perception. In the central nervous system endocannabinoids mediate negative feedback of quantal transmitter release following postsynaptic depolarization. The influence of cannabinoids in the peripheral nervous system is less clear and might have broad implications for the therapeutic application of cannabinoids. We report a novel cannabinoid effect upon the mouse neuromuscular synapse: acutely increasing synaptic vesicle volume and raising the quantal amplitudes. In a mouse model of myasthenia gravis the cannabinoid receptor agonist WIN 55,212 reversed fatiguing failure of neuromuscular transmission, suggesting future therapeutic potential. Our data suggest an endogenous pathway by which cannabinoids might help to regulate transmitter release at the neuromuscular junction.

Pooled analysis of three randomized, double-blind, placebo controlled trials with rimonabant for smoking cessation

Despite the withdrawal of CB₁ antagonists, such as rimonabant, from the market and from active clinical development because of concerns about their side effect profiles, research suggests that the endocannabinoid system may play an important role in modulating nicotine's effects. We report the combined results, using a pooled analysis, of three previously unpublished trials assessing rimonabant as a smoking cessation pharmacotherapy conducted between 2002 and 2004. Smokers (n = 2097) motivated to quit were enrolled in three randomized, double-blind, placebo-controlled trials, STRATUS EU, US, and META, which consisted of a 10-week treatment period with either rimonabant 20 mg (n = 789), 5 mg (n = 518; used in only two of the three studies), or placebo (n = 790), in conjunction with brief counseling. The impact of drug on prolonged abstinence and adverse events was examined at 8 weeks (end-of-treatment) and at 48 weeks (available for STRATUS EU and US) after the targeted quit date. Rimonabant 20 mg resulted in significantly higher abstinence at end-of-treatment and at 48 weeks post-targeted quit date compared with placebo, while rimonabant 5 mg and placebo did not differ. Serious AEs did not differ by drug group. The 20 mg rimonabant dose, compared with placebo, produced increased nausea, diarrhea, anxiety symptoms, hyporexia, and vomiting, and decreased headache, constipation, and cough. These results support rimonabant 20 mg as a modestly effective aid for smoking cessation. Although work on CB₁ antagonists such as rimonabant has mostly been stopped because of unacceptable adverse events, these results may inform and spur the development of other endocannabinoids for smoking cessation.

Surprising outcomes in cannabinoid CB1/CB2 receptor double knockout mice in two models of ischemia

AIMS

We tested the hypothesis that CB1/CB2 receptor double knockout would produce significant increases in infarct size and volume and significant worsening in clinical score, using two mouse models, one of permanent ischemia and one of ischemia/reperfusion.

MAIN METHODS

Focal cerebral infarcts were created using either photo induced permanent injury or transient middle cerebral artery occlusion. Infarct volume and motor function were evaluated in cannabinoid receptor 1/cannabinoid receptor 2 double knockout mice.

KEY FINDINGS

The results surprisingly revealed that CB1/CB2 double knockout mice showed improved outcomes, with the most improvements in the mouse model of permanent ischemia.

SIGNIFICANCE

Although the number of individuals suffering from stroke in the United States and worldwide will continue to grow, therapeutic intervention for treatment following stroke remains frustratingly limited. Both the cannabinoid 1 receptor (CB1R) and the cannabinoid 2 receptor (CB2R) have been studied in relationship to stroke. Deletion of the CB2R has been shown to worsen outcome, while selective CB2R agonists have been demonstrated to be neuroprotective following stroke. Although initial studies of CB1R knockout mice demonstrated increased injury following stroke, indicating that activation of the CB1R was neuroprotective, later studies of selective antagonists of the CB1R also demonstrated a protective effect. Surprisingly the double knockout animals had improved outcome. Since the phenotype of the double knockout is not dramatically changed, significant changes in the contribution of other homeostatic pathways in compensation for the loss of these two important receptors may explain these apparently contradictory results.

The interaction between hippocampal GABA-B and cannabinoid receptors upon spatial change and object novelty discrimination memory function

RATIONALE

Previous studies have postulated functional links between GABA and cannabinoid systems in the hippocampus. The aim of the present study was to investigate any possible interaction between these systems in spatial change and object novelty discrimination memory consolidation in the dorsal hippocampus (CA1 region) of NMRI mice.

METHODS

Assessment of the spatial change and object novelty discrimination memory function was carried out in a non-associative task. The experiment comprised mice exposure to an open field containing five objects followed by the examination of their reactivity to object displacement (spatial change) and object substitution (object novelty) after three sessions of habituation.

RESULTS

Our results showed that the post-training intraperitoneal administration of the higher dose of ACPA (0.02 mg/kg) impaired both spatial change and novelty discrimination memory functions. Meanwhile, the higher dose of GABA-B receptor agonist, baclofen, impaired the spatial change memory by itself. Moreover, the post-training intra-CA1 microinjection of a subthreshold dose of baclofen increased the ACPA effect on spatial change and novelty discrimination memory at a lower and higher dose, respectively. On the other hand, the lower and higher but not mid-level doses of GABA-B receptor antagonist, phaclofen, could reverse memory deficits induced by ACPA. However, phaclofen at its mid-level dose impaired the novelty discrimination memory and whereas the higher dose impaired the spatial change memory.

CONCLUSIONS

Based on our findings, GABA-B receptors in the CA1 region appear to modulate the ACPA-induced cannabinoid CB1 signaling upon spatial change and novelty discrimination memory functions.

The CB1 Receptor as the Cornerstone of Exostasis

The type-1 cannabinoid receptor (CB1) is the main effector of the endocannabinoid system (ECS), which is involved in most brain and body functions. In this Perspective, we provide evidence indicating that CB1 receptor functions are key determinants of bodily coordinated exostatic processes. First, we will introduce the concepts of endostasis and exostasis as compensation or accumulation for immediate or future energy needs and discuss how exostasis has been necessary for the survival of species during evolution. Then, we will argue how different specific biological functions of the CB1 receptor in the body converge to provide physiological exostatic processes. Finally, we will introduce the concept of proactive evolution-induced diseases (PEIDs), which helps explain the seeming paradox that an evolutionary-selected physiological function can become the cause of epidemic pathological conditions, such as obesity. We propose here a possible unifying theory of CB1 receptor functions that can be tested by future experimental studies.

Effects of oral Δ9-tetrahydrocannabinol on the cerebral processing of olfactory input in healthy non-addicted subjects

BACKGROUND

Considering the increasing acknowledgment of the human sense of smell as a significant component of the quality of life, olfactory drug effects gain potential clinical importance. A recent observation in a human experimental context indicated that Δ⁹-tetrahydrocannabinol (THC) impaired the subject's performance in olfactory tests. To further analyze the role of THC in human olfaction, the present report addresses its effects on the central processing of olfactory stimuli.

METHODS

Employing a placebo-controlled randomized crossover design, an oral dose of 20 mg THC was administered in 15 healthy volunteers. The central processing of olfactory input, consisting of short pulses of gaseous vanillin or hydrogen sulfide, and for comparison, of non-odorous but painful carbon dioxide, were investigated before and after administration of THC or placebo in a pharmacological functional magnet resonance imaging study.

RESULTS

Following THC administration, the vanillin stimuli lost their pleasantness and became hedonically inert. This observation had its functional correlate in reduced stimulus-associated brain activations located in the left amygdala, the hippocampus and superior temporal pole (peak MNI coordinates x = - 27, y = - 1, z = - 26 mm p = 0.039). Differences in amygdala activations were significantly correlated with the corresponding differences in vanillin pleasantness (p = 0.025). By contrast, no effects were observed on the perception of processing of H₂S stimuli.

CONCLUSIONS

The results support that THC induced a modulation of the central processing of olfactory input. The THC-induced reduction in the pleasantness of a pleasurable odor was accompanied by reduced activations in the limbic system. Results agree with previous observation of negative effects of cannabinoids on the human sense of smell and strengthen the evidence that THC-based medications will be among drugs with olfactory side effects.

History of cannabis use is associated with altered gait

BACKGROUND

Despite evidence that cannabinoid receptors are located in movement-related brain regions (e.g., basal ganglia, cerebral cortex, and cerebellum), and that chronic cannabis use is associated with structural and functional brain changes, little is known about the long-term effect of cannabis use on human movement. The aim of the current study was to investigate balance and walking gait in adults with a history of cannabis use. We hypothesised that cannabis use is associated with subtle changes in gait and balance that are insufficient in magnitude for detection in a clinical setting.

METHODS

Cannabis users (n=22, 24±6years) and non-drug using controls (n=22, 25±8years) completed screening tests, a gait and balance test (with a motion capture system and in-built force platforms), and a clinical neurological examination of movement.

RESULTS

Compared to controls, cannabis users exhibited significantly greater peak angular velocity of the knee (396±30 versus 426±50°/second, P=0.039), greater peak elbow flexion (53±12 versus 57±7°, P=0.038) and elbow range of motion (33±13 versus 36±10°, P=0.044), and reduced shoulder flexion (41±19 versus 26±16°, P=0.007) during walking gait. However, balance and neurological parameters did not significantly differ between the groups.

CONCLUSIONS

The results suggest that history of cannabis use is associated with long-lasting changes in open-chain elements of walking gait, but the magnitude of change is not clinically detectable. Further research is required to investigate if the subtle gait changes observed in this population become more apparent with aging and increased cannabis use.

Cannabinoids and Vanilloids in Schizophrenia: Neurophysiological Evidence and Directions for Basic Research

Much of our knowledge of the endocannabinoid system in schizophrenia comes from behavioral measures in rodents, like prepulse inhibition of the acoustic startle and open-field locomotion, which are commonly used along with neurochemical approaches or drug challenge designs. Such methods continue to map fundamental mechanisms of sensorimotor gating, hyperlocomotion, social interaction, and underlying monoaminergic, glutamatergic, and GABAergic disturbances. These strategies will require, however, a greater use of neurophysiological tools to better inform clinical research. In this sense, electrophysiology and viral vector-based circuit dissection, like optogenetics, can further elucidate how exogenous cannabinoids worsen (e.g., tetrahydrocannabinol, THC) or ameliorate (e.g., cannabidiol, CBD) schizophrenia symptoms, like hallucinations, delusions, and cognitive deficits. Also, recent studies point to a complex endocannabinoid-endovanilloid interplay, including the influence of anandamide (endogenous CB₁ and TRPV₁ agonist) on cognitive variables, such as aversive memory extinction. In fact, growing interest has been devoted to TRPV₁ receptors as promising therapeutic targets. Here, these issues are reviewed with an emphasis on the neurophysiological evidence. First, we contextualize imaging and electrographic findings in humans. Then, we present a comprehensive review on rodent electrophysiology. Finally, we discuss how basic research will benefit from further combining psychopharmacological and neurophysiological tools.

Revisiting the flip side: Long-term depression of synaptic efficacy in the hippocampus

Synaptic plasticity is widely regarded as a putative biological substrate for learning and memory processes. While both decreases and increases in synaptic strength are seen as playing a role in learning and memory, long-term depression (LTD) of synaptic efficacy has received far less attention than its counterpart long-term potentiation (LTP). Never-the-less, LTD at synapses can play an important role in increasing computational flexibility in neural networks. In addition, like learning and memory processes, the magnitude of LTD can be modulated by factors that include stress and sex hormones, neurotrophic support, learning environments, and age. Examining how these factors modulate hippocampal LTD can provide the means to better elucidate the molecular underpinnings of learning and memory processes. This is in turn will enhance our appreciation of how both increases and decreases in synaptic plasticity can play a role in different neurodevelopmental and neurodegenerative conditions.

Caffeine and Cannabis Effects on Vital Neurotransmitters and Enzymes in the Brain Tissue of Juvenile Experimental Rats

BACKGROUND

Caffeine and cannabis are globally consumed and abused psychoactive substances. While caffeine is legally used in various forms, including in tea and coffee as beverages, it is also consumed in soda and energy drinks as additives. Cannabis, on the other hand, is considered illegal in most countries; albeit, it is being consumed globally particularly by adolescents.

PURPOSE

The adolescent stage marks a critical stage of brain development and maturation. Influences of agents on the brain at this stage may affect neuronal structural and functional attributes. To this end, the current experiment considered the effects of cannabis and caffeine on selected key neurotransmitters and enzymes in the brain tissues after regimented caffeine and cannabis treatment for 21 days.

METHODS

A total of 72 juvenile Wistar rats that were approximately 40 days old were divided into 6 groups A-F. The group A served as the control. Other groups were administered various dosages of caffeine or cannabis in distilled water, using oral gavages as follows: group B animals received 100 mg/kg body weight of caffeine, group C animals received 50 mg/kg body weight of caffeine, group D animals received 500 mg/kg body weight of cannabis, group E animals received 200 mg/kg body weight of cannabis, and group F received a low dose of cannabis (200 mg/kg body weight) plus a low dose of caffeine (50 mg/kg body weight). The animals were killed by cervical dislocation 24 h after the last administration. The brain tissues were excised and homogenized. The enzymes cytochrome C oxidase and glucose-6-phosphate dehydrogenase were assayed to observe tissue energy metabolism while the neurotransmitters gamma-amino butyric acid (GABA), glutamate, and dopamine were assayed to observe the effects of the psychoactive substances on their activities relative to mental activities.

RESULTS

GABA, glutamate, and dopamine were generally higher in the treated groups of animals. The levels of G-6-PDH were higher in all treated animals' brains. Caffeine produced quite more significant effects relative to cannabis and the combination of both increased the level of G-6-PDH significantly.

CONCLUSION

Results showed that caffeine and cannabis influenced the activities of the enzymes and neurotransmitters in the brain. Both stimulants altered brain chemistry relative to the tested enzymes and neurotransmitters.