Cannabidiol enhances morphine antinociception, diminishes NMDA-mediated seizures and reduces stroke damage via the sigma 1 receptor

Cannabidiol for Pain Treatment: Focus on Pharmacology and Mechanism of Action

Cannabis has a long history of medical use. Although there are many cannabinoids present in cannabis, Δ9tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) are the two components found in the highest concentrations. CBD itself does not produce typical behavioral cannabimimetic effects and was thought not to be responsible for psychotropic effects of cannabis. Numerous anecdotal findings testify to the therapeutic effects of CBD, which in some cases were further supported by research findings. However, data regarding CBD’s mechanism of action and therapeutic potential are abundant and omnifarious. Therefore, we review the basic research regarding molecular mechanism of CBD’s action with particular focus on its analgesic potential. Moreover, this article describes the detailed analgesic and anti-inflammatory effects of CBD in various models, including neuropathic pain, inflammatory pain, osteoarthritis and others. The dose and route of the administration-dependent effect of CBD, on the reduction in pain, hyperalgesia or allodynia, as well as the production of pro and anti-inflammatory cytokines, were described depending on the disease model. The clinical applications of CBD-containing drugs are also mentioned. The data presented herein unravel what is known about CBD’s pharmacodynamics and analgesic effects to provide the reader with current state-of-art knowledge regarding CBD’s action and future perspectives for research.

Endogenous Opiates and Behavior: 2018

This paper is the forty-first consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2018 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (2), the roles of these opioid peptides and receptors in pain and analgesia in animals (3) and humans (4), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (5), opioid peptide and receptor involvement in tolerance and dependence (6), stress and social status (7), learning and memory (8), eating and drinking (9), drug abuse and alcohol (10), sexual activity and hormones, pregnancy, development and endocrinology (11), mental illness and mood (12), seizures and neurologic disorders (13), electrical-related activity and neurophysiology (14), general activity and locomotion (15), gastrointestinal, renal and hepatic functions (16), cardiovascular responses (17), respiration and thermoregulation (18), and immunological responses (19).

The Use of Vitamins, Supplements, Herbs, and Essential Oils in Rehabilitation

The term, dietary supplement, refers to a broad category of products, including herbal or plant-based extracts, micronutrients, and food-based nutraceuticals. The use of supplements in clinical rehabilitation requires clear communication from patients and health care providers to understand the types of products used and their effects on health. Providers should distinguish between using micronutrient supplementation for therapeutic purposes and treatment of nutritional deficiency in patients with malnutrition syndromes. Evidence supports micronutrient and nutraceutical supplementation use to improve pain, functional status, and inflammation. There is little evidence on the use of herbal or plant-based extracts in therapeutic rehabilitation; larger studies are warranted.

Receptors and Channels Possibly Mediating the Effects of Phytocannabinoids on Seizures and Epilepsy

Epilepsy contributes to approximately 1% of the global disease burden. By affecting especially young children as well as older persons of all social and racial variety, epilepsy is a present disorder worldwide. Currently, only 65% of epileptic patients can be successfully treated with antiepileptic drugs. For this reason, alternative medicine receives more attention. Cannabis has been cultivated for over 6000 years to treat pain and insomnia and used since the 19th century to suppress epileptic seizures. The two best described phytocannabinoids, (−)-trans-Δ⁹-tetrahydrocannabinol (THC) and cannabidiol (CBD) are claimed to have positive effects on different neurological as well as neurodegenerative diseases, including epilepsy. There are different cannabinoids which act through different types of receptors and channels, including the cannabinoid receptor 1 and 2 (CB₁, CB₂), G protein-coupled receptor 55 (GPR55) and 18 (GPR18), opioid receptor µ and δ, transient receptor potential vanilloid type 1 (TRPV1) and 2 (TRPV2), type A γ-aminobutyric acid receptor (GABA_AR) and voltage-gated sodium channels (VGSC). The mechanisms and importance of the interaction between phytocannabinoids and their different sites of action regarding epileptic seizures and their clinical value are described in this review.

Therapeutic potential of opioid/cannabinoid combinations in humans: Review of the evidence

The endogenous opioid and cannabinoid receptor systems are widely distributed and co-localized throughout central and peripheral nervous system regions. A large body of preclinical evidence suggests that there are functional interactions between these two systems that may be leveraged to address various health conditions. Numerous animal studies have shown that cannabinoid agonists (e.g., delta-9-tetrahydrocannabinol [Δ⁹-THC]) enhance the analgesic effects of µ-opioid analgesics as evidenced by decreasing the opioid dose required for analgesia (i.e., opioid sparing) and extending the duration of the opioid analgesia. In contrast, controlled human laboratory studies and clinical trials have not demonstrated robust analgesic or opioid-sparing effects from opioid-cannabinoid combinations. Meta-analyses of the literature (clinical trials, controlled laboratory studies; some non-controlled studies/case reports) have examined the effects of cannabis/cannabinoids for pain relief in those taking a wide variety of analgesics, including prescription opioid medications. These data do not strongly support the use of cannabinoids for chronic pain nor do prospective studies demonstrate significant cannabinoid-mediated opioid-sparing effects. Preclinical studies have also suggested a role for cannabinoids for the treatment of opioid withdrawal. Controlled laboratory and clinical studies suggest that there may be a modest signal for Δ⁹-THC to suppress some opioid signs and symptoms but they are not completely ameliorated and there may also be concerns around safety of Δ⁹-THC administration in a state of heightened autonomic arousal as occurs with opioid withdrawal. Despite anecdotal and correlational reports suggesting a benefit of cannabis on reducing opioid overdose, there is no strong data supporting this contention and emerging reports have conflicting results. In summary, there is a groundswell of public advocacy supporting the use of cannabis and cannabinoids to replace opioid analgesics or to reduce opioid use; however, the extant controlled clinical data do not support the role of cannabinoids for opioid replacement or opioid-sparing effects when treating opioid use disorder or chronic pain.

Orally consumed cannabinoids provide long-lasting relief of allodynia in a mouse model of chronic neuropathic pain

Chronic pain affects a significant percentage of the United States population, and available pain medications like opioids have drawbacks that make long-term use untenable. Cannabinoids show promise in the management of pain, but long-term treatment of pain with cannabinoids has been challenging to implement in preclinical models. We developed a voluntary, gelatin oral self-administration paradigm that allowed male and female mice to consume ∆9-tetrahydrocannabinol, cannabidiol, or morphine ad libitum. Mice stably consumed these gelatins over 3 weeks, with detectable serum levels. Using a real-time gelatin measurement system, we observed that mice consumed gelatin throughout the light and dark cycles, with animals consuming less THC-gelatin than the other gelatin groups. Consumption of all three gelatins reduced measures of allodynia in a chronic, neuropathic sciatic nerve injury model, but tolerance to morphine developed after 1 week while THC or CBD reduced allodynia over three weeks. Hyperalgesia gradually developed after sciatic nerve injury, and by the last day of testing, THC significantly reduced hyperalgesia, with a trend effect of CBD, and no effect of morphine. Mouse vocalizations were recorded throughout the experiment, and mice showed a large increase in ultrasonic, broadband clicks after sciatic nerve injury, which was reversed by THC, CBD, and morphine. This study demonstrates that mice voluntarily consume both cannabinoids and opioids via gelatin, and that cannabinoids provide long-term relief of chronic pain states. In addition, ultrasonic clicks may objectively represent mouse pain status and could be integrated into future pain models.

The Therapeutic Effectiveness of Full Spectrum Hemp Oil Using a Chronic Neuropathic Pain Model

BACKGROUND

Few models exist that can control for placebo and expectancy effects commonly observed in clinical trials measuring 'Cannabis' pharmacodynamics. We used the Foramen Rotundum Inflammatory Constriction Trigeminal Infraorbital Nerve injury (FRICT-ION) model to measure the effect of "full-spectrum" whole plant extracted hemp oil on chronic neuropathic pain sensitivity in mice.

METHODS

Male BALBc mice were submitted to the FRICT-ION chronic neuropathic pain model with oral insertion through an incision in the buccal/cheek crease of 3 mm of chromic gut suture (4-0). The suture, wedged along the V2 trigeminal nerve branch, creates a continuous irritation that develops into secondary mechanical hypersensitivity on the snout. Von Frey filament stimuli on the mouse whisker pad was used to assess the mechanical pain threshold from 0-6 h following dosing among animals (n = 6) exposed to 5 μL of whole plant extracted hemp oil combined with a peanut butter vehicle (0.138 mg/kg), the vehicle alone (n = 3) 7 weeks post-surgery, or a naïve control condition (n = 3).

RESULTS

Mechanical allodynia was alleviated within 1 h (d = 2.50, p < 0.001) with a peak reversal effect at 4 h (d = 7.21, p < 0.001) and remained significant throughout the 6 h observation window. There was no threshold change on contralateral whisker pad after hemp oil administration, demonstrating the localization of anesthetic response to affected areas.

CONCLUSION

Future research should focus on how whole plant extracted hemp oil affects multi-sensory and cognitive-attentional systems that process pain.

Cannabidiol attenuates methamphetamine-induced conditioned place preference via the Sigma1R/AKT/GSK-3β/CREB signaling pathway in rats

Methamphetamine (METH) is a highly addictive psychostimulant. Cannabidiol (CBD) is an exogenous cannabinoid without psychostimulating activity, which has potential therapeutic effects on opioid addiction. However, it is unclear whether CBD has therapeutic effects on METH-induced motivational effects. The present study examines whether CBD has a protective effect on METH-induced conditioned place preference (CPP) in rats by regulating the Sigma1R and AKT-GSK3β-CREB signaling pathway. Seventy rats were equally and randomly divided into seven groups. The rat CPP model was established via the intraperitoneal injection (IP) of 2 mg/kg of METH. Next, the intraperitoneal injection of 10, 20, 40, and 80 mg/kg CBD was performed 1 h prior to the injection of saline or METH. The protein expression levels of Sigma1R, AKT, p-AKT, GSK-3β, p-GSK-3β, CREB, and p-CREB in the rats' prefrontal cortex, nucleus accumbens, and hippocampus and ventral tegmental were detected using western blot analysis. CBD was found to inhibit METH-induced CPP in a dose-dependent fashion. The expression levels of Sigma1R, p-AKT, p-GSK3β, and p-CREB increased significantly in the METH-induced CPP model. Treatment involving different doses of CBD caused differential inhibitory responses in the cellular protein abundance of Sigma1R, p-AKT, p-GSK3β, and p-CREB across various brain regions. The present study found that METH can induce CPP in rats. When a pretreatment of CBD is applied, the CBD can weaken CPP in METH-induced rats by regulating the SigmaR1/AKT/GSK-3β/CREB signaling pathway. The results of this study indicate that CBD has a potential therapeutic effect on METH-induced rewarding effects.

Fenfluramine acts as a positive modulator of sigma-1 receptors

OBJECTIVE

Adjunctive fenfluramine hydrochloride, classically described as acting pharmacologically through a serotonergic mechanism, has demonstrated a unique and robust clinical response profile with regard to its magnitude, consistency, and durability of effect on seizure activity in patients with pharmacoresistant Dravet syndrome. Recent findings also support long-term improvements in executive functions (behavior, emotion, cognition) in these patients. The observed clinical profile is inconsistent with serotonergic activity alone, as other serotonergic medications have not been demonstrated to have these clinical effects. This study investigated a potential role for σ1 receptor activity in complementing fenfluramine's serotonergic pharmacology.

METHODS

Radioligand binding assays tested the affinity of fenfluramine for 47 receptors associated with seizures in the literature, including σ receptors. Cellular function assays tested fenfluramine and norfenfluramine (its major metabolite) activity at various receptors, including adrenergic, muscarinic, and serotonergic receptors. The σ1 receptor activity was assessed by the mouse vas deferens isometric twitch and by an assay of dissociation of the σ1 receptor from the endoplasmic reticulum stress protein binding immunoglobulin protein (BiP). In vivo mouse models assessed fenfluramine activity at σ1 receptors in ameliorating dizocilpine-induced learning deficits in spatial and nonspatial memory tasks, alone or in combination with the reference σ1 receptor agonist PRE-084.

RESULTS

Fenfluramine and norfenfluramine bound ≥30% to β2-adrenergic, muscarinic M1, serotonergic 5-HT1A, and σ receptors, as well as sodium channels, with a Ki between 266 nM (σ receptors) and 17.5 μM (β-adrenergic receptors). However, only σ1 receptor isometric twitch assays showed a positive functional response, with weak stimulation by fenfluramine and inhibition by norfenfluramine. Fenfluramine, but not the 5-HT2C agonist lorcaserin, showed a positive modulation of the PRE-084-induced dissociation of σ1 protein from BiP. Fenfluramine also showed dose-dependent antiamnesic effects against dizocilpine-induced learning deficits in spontaneous alternation and passive avoidance responses, which are models of σ1 activation. Moreover, low doses of fenfluramine synergistically potentiated the low-dose effect of PRE-084, confirming a positive modulatory effect at the σ1 receptor. Finally, all in vivo effects were blocked by the σ1 receptor antagonist NE-100.

SIGNIFICANCE

Fenfluramine demonstrated modulatory activity at σ1 receptors in vitro and in vivo in addition to its known serotonergic activity. These studies identify a possible new σ1 receptor mechanism underpinning fenfluramine's central nervous system effects, which may contribute to its antiseizure activity in Dravet syndrome and positive effects observed on executive functions in clinical studies.

Is cannabidiol a drug acting on unconventional targets to control drug-resistant epilepsy?

Cannabis has been considered as a therapeutic strategy to control intractable epilepsy. Several cannabis components, especially cannabidiol (CBD), induce antiseizure effects. However, additional information is necessary to identify the types of epilepsies that can be controlled by these components and the mechanisms involved in these effects. This review presents a summary of the discussion carried out during the 2nd Latin American Workshop on Neurobiology of Epilepsy entitled "Cannabinoid and epilepsy: myths and realities." This event was carried out during the 10th Latin American Epilepsy Congress in San José de Costa Rica (September 28, 2018). The review focuses to discuss the use of CBD as a new therapeutic strategy to control drug-resistant epilepsy. It also indicates the necessity to consider the evaluation of unconventional targets such as P-glycoprotein, to explain the effects of CBD in drug-resistant epilepsy.

Safety Assessment of a Hemp Extract using Genotoxicity and Oral Repeat-Dose Toxicity Studies in Sprague-Dawley Rats

Cannabinoids are extracted from Cannabis sativa L. and are used for a variety of medicinal purposes. Recently, there has been a focus on the cannabinoid Cannabidiol (CBD) and its potential benefits. This study investigated the safety of a proprietary extract of C. sativa, consisting of 9% hemp extract (of which 6.27% is CBD) and 91% olive oil. The mutagenic potential of the hemp extract was evaluated with the AMES assay inclusive of a hepatic drug metabolizing mix (S9) rich in CYP enzymes. The test article did not elicit evidence of bacterial mutagenicity. GLP compliant 14-day and a 90-day toxicity study were conducted. Olive oil was used as a control. The 90-day study had a 28-day recovery period. Treatments for the 14-day non-recovery range-finding study were 0, 1000, 2000 and 4000 mg test article/kg body weight (bw)/day for 14 days. There was a non-statistically significant (p > 0.05) decrease in body weights for the male and female rats receiving the test article. Hypoactivity, hyperactivity, reduced food consumption and piloerection were observed in the rats receiving 4000 mg test article/kg bw. Histopathology showed an increase in the size of liver cells (hypertrophy) around the central vein (centrilobular) in Groups 3 (3/10) and 4 (5/10) that correlated with increased liver weights. In the 90-day study, 8 groups of rats were dosed with 0, 200, 400 and 800 mg test article/kg bw/day. Groups 5 to 8 had a 28-day recovery. There were no test article-linked changes in clinical observations, physical examinations, Functional Observation Battery, ophthalmology, Motor Activity Assessment, hematology, clinical chemistries and macropathology (all groups). With the exception of the liver and adrenal gland, no test article-linked pathology was observed. For all rats receiving the test article, histopathology showed hypertrophy of liver cells around the central vein. The increase of liver weight is most likely caused by hypertrophy due to up-regulation of the hepatic drug metabolizing enzymes. The hepatocellular hypertrophy was completely reversed in 28 days and was not considered to be an adverse effect. Vacuolization of the adrenal zona fasciculata was observed in the control and 800 mg test article/kg bw groups. The vacuolization of the zona fasciculata was of the same incidence and severity in treatment and control male rats and correlated with an increased in the weights of the adrenal glands. In addition, a statistically significant increase (p<0.05) in adrenal-to-body weight ratios was observed for females receiving 800 mg test article/kg bw. This increase in adrenal-to-body weight ratio did not correlate with any of the pathology findings. The NOAEL for the test article is 800 mg/kg bw/day for female and 400 mg/kg bw/day for male Sprague Dawley rats.

A new mechanism for cannabidiol in regulating the one-carbon cycle and methionine levels in Dictyostelium and in mammalian epilepsy models

BACKGROUND AND PURPOSE

Epidiolex™, a form of highly purified cannabidiol (CBD) derived from Cannabis plants, has demonstrated seizure control activity in patients with Dravet syndrome, without a fully elucidated mechanism of action. We have employed an unbiased approach to investigate this mechanism at a cellular level.

EXPERIMENTAL APPROACH

We use a tractable biomedical model organism, Dictyostelium, to identify a protein controlling the effect of CBD and characterize this mechanism. We then translate these results to a Dravet syndrome mouse model and an acute in vitro seizure model.

KEY RESULTS

CBD activity is partially dependent upon the mitochondrial glycine cleavage system component, GcvH1 in Dictyostelium, orthologous to the human glycine cleavage system component H protein, which is functionally linked to folate one-carbon metabolism (FOCM). Analysis of FOCM components identified a mechanism for CBD in directly inhibiting methionine synthesis. Analysis of brain tissue from a Dravet syndrome mouse model also showed drastically altered levels of one-carbon components including methionine, and an in vitro rat seizure model showed an elevated level of methionine that is attenuated following CBD treatment.

CONCLUSIONS AND IMPLICATIONS

Our results suggest a novel mechanism for CBD in the regulating methionine levels and identify altered one-carbon metabolism in Dravet syndrome and seizure activity.

Achyranthes bidentata polypeptides prevent apoptosis by inhibiting the glutamate current in cultured hippocampal neurons

Glutamate-induced excitotoxicity plays a critical role in the neurological impairment caused by middle cerebral artery occlusion. Achyranthes bidentata polypeptides have been shown to protect against neurological functional damage caused by middle cerebral artery occlusion, but the underlying neuroprotective mechanisms and the relationship to glutamate-induced excitotoxicity remain unclear. Therefore, in the current study, we investigated the protective effects of Achyranthes bidentata polypeptides against glutamate-induced excitotoxicity in cultured hippocampal neurons. Hippocampal neurons were treated with Mg²⁺-free extracellular solution containing glutamate (300 µM) for 3 hours as a model of glutamate-mediated excitotoxicity (glutamate group). In the normal group, hippocampal neurons were incubated in Mg²⁺-free extracellular solution. In the Achyranthes bidentata polypeptide group, hippocampal neurons were incubated in Mg²⁺-free extracellular solution containing glutamate (300 µM) and Achyranthes bidentata polypeptide at different concentrations. At 24 hours after exposure to the agents, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and Hoechst 33258 staining were used to assess neuronal viability and nuclear morphology, respectively. Caspase-3 expression and activity were evaluated using western blot assay and colorimetric enzymatic assay, respectively. At various time points after glutamate treatment, reactive oxygen species in cells were detected by H2DCF-DA, and mitochondrial membrane potential was detected by rhodamine 123 staining. To examine the effect of Achyranthes bidentata polypeptides on glutamate receptors, electrophysiological recording was used to measure the glutamate-induced inward current in cultured hippocampal neurons. Achyranthes bidentata polypeptide decreased the percentage of apoptotic cells and reduced the changes in caspase-3 expression and activity induced by glutamate. In addition, Achyranthes bidentata polypeptide attenuated the amplitude of the glutamate-induced current. Furthermore, the glutamate-induced increase in intracellular reactive oxygen species and reduction in mitochondrial membrane potential were attenuated by Achyranthes bidentata polypeptide treatment. These findings collectively suggest that Achyranthes bidentata polypeptides exert a neuroprotective effect in cultured hippocampal neurons by suppressing the overactivation of glutamate receptors and inhibiting the caspase-3-dependent mitochondrial apoptotic pathway. All animal studies were approved by the Animal Care and Use Committee, Nantong University, China (approval No. 20120216-001) on February 16, 2012.

Vapor inhalation of cannabidiol (CBD) in rats

RATIONALE

Cannabidiol (CBD), a compound found in many strains of the Cannabis genus, is increasingly available in e-cigarette liquids as well as other products. CBD use has been promoted for numerous purported benefits which have not been rigorously assessed in preclinical studies.

OBJECTIVE

To further validate an inhalation model to assess CBD effects in the rat. The primary goal was to determine plasma CBD levels after vapor inhalation and compare that with the levels observed after injection. Secondary goals were to determine if hypothermia is produced in male Sprague-Dawley rats and if CBD affects nociception measured by the warm water tail-withdrawal assay.

METHODS

Blood samples were collected from rats exposed for 30 min to vapor generated by an e-cigarette device using CBD (100, 400 mg/mL in the propylene glycol vehicle). Separate experiments assessed the body temperature response to CBD in combination with nicotine (30 mg/mL) and the anti-nociceptive response to CBD.

RESULTS

Vapor inhalation of CBD produced concentration-related plasma CBD levels in male and female Wistar rats that were within the range of levels produced by 10 or 30 mg/kg, CBD, i.p. Dose-related hypothermia was produced by CBD in male Sprague-Dawley rats, and nicotine (30 mg/mL) inhalation enhanced this effect. CBD inhalation had no effect on anti-nociception alone or in combination with Δ9-tetrahydrocannabinol inhalation.

CONCLUSIONS

The vapor-inhalation approach is a suitable pre-clinical model for the investigation of the effects of inhaled CBD. This route of administration produces hypothermia in rats, while i.p. injection does not, at comparable plasma CBD levels.

Effects of cannabidiol (CBD) in neuropsychiatric disorders: A review of pre-clinical and clinical findings

Cannabis sativa (cannabis) is one of the oldest plants cultivated by men. Cannabidiol (CBD) is the major non-psychomimetic compound derived from cannabis. It has been proposed to have a therapeutic potential over a wide range of neuropsychiatric disorders. In this narrative review, we have summarized a selected number of pre-clinical and clinical studies, examining the effects of CBD in neuropsychiatric disorders. In some pre-clinical studies, CBD was demonstrated to potentially exhibit anti-epileptic, anti-oxidant, anti-inflammatory anti-psychotic, anxiolytic and anti-depressant properties. Moreover, CBD was shown to reduce addictive effects of some drugs of abuse. In clinical studies, CBD was shown to be safe, well-tolerated and efficacious in mitigating the symptoms associated with several types of seizure disorders and childhood epilepsies. Given that treatment with CBD alone was insufficient at managing choreic movements in patients with Huntington's disease, other cannabis-derived treatments are currently being investigated. Patients with Parkinson's disease (PD) have reported improvements in sleep and better quality of life with CBD; however, to fully elucidate the therapeutic potential of CBD on the symptoms of PD-associated movement disorders, larger scale, randomized, placebo-controlled studies still need to be conducted in the future. Currently, there are no human studies that investigated the effects of CBD in either Alzheimer's disease or unipolar depression, warranting further investigation in this area, considering that CBD was shown to have effects in pre-clinical studies. Although, anxiolytic properties of CBD were reported in the Social Anxiety Disorder, antipsychotic effects in schizophrenia and anti-addictive qualities in alcohol and drug addictions, here too, larger, randomized, placebo-controlled trials are needed to evaluate the therapeutic potential of CBD.

Molecular Interplay Between the Sigma-1 Receptor, Steroids, and Ion Channels

Cell excitability is tightly regulated by the activity of ion channels that allow for the passage of ions across cell membranes. Ion channel activity is controlled by different mechanisms that change their gating properties, expression or abundance in the cell membrane. The latter can be achieved by forming complexes with a diversity of proteins like chaperones such as the Sigma-1 receptor (Sig-1R), which is one with unique features and exhibits a role as a ligand-operated chaperone. This molecule also displays high intracellular mobility according to its activation level since, depletion of internal Ca⁺² stores or the presence of specific ligands, produce Sig-1R’s mobilization from the endoplasmic reticulum toward the plasma membrane or nuclear envelope. The function of the Sig-1R as a chaperone is regulated by synthetic and endogenous ligands, with some of these compounds being a steroids and acting as key endogenous modifiers of the actions of the Sig-1R. There are cases in the literature that exemplify the close relationship between the actions of steroids on the Sig-1R and the resulting negative or positive effects on ion channel function/abundance. Such interactions have been shown to importantly influence the physiology of mammalian cells leading to changes in their excitability. The present review focuses on describing how the Sig-1R regulates the functional properties and the expression of some sodium, calcium, potassium, and TRP ion channels in the presence of steroids and the physiological consequences of these interplays at the cellular level are also discussed.

The endocannabinoid system and stroke: A focused review

Stroke is an important cause of morbidity and mortality worldwide. Development of novel neuroprotectants is of paramount importance. This review seeks to summarize the recent evidence for the role of the endocannabinoid signaling system in stroke pathophysiology, as well as the evidence from preclinical studies regarding the efficacy of cannabinoids as neuroprotective therapies in the treatment of stroke. Recent evidence from rodent models implicating cannabinoid 1 receptor (CB1R), cannabinoid 2 receptor (CB2R), and CB1R and CB2R co-antagonism as neuroprotective strategies in stroke are reviewed. Rodent evidence for the therapeutic role of the endocannabinoid system in treating poststroke depression is reviewed. Finally, evidence for the role of cannabidiol, a publicly available cannabinoid that does not bind directly to known endocannabinoid receptors, as a stroke neuroprotectant is also reviewed. The review closes with a consideration of the role of human cannabinoid abuse in stroke and considers future directions for research on endocannabinoid-based stroke therapeutics.

An Update of Current Cannabis-Based Pharmaceuticals in Pain Medicine

Cannabis users have long reported therapeutic properties of the plant for a variety of conditions, some of which include nausea, emesis, seizures, cancer, neurogenic diseases and pain control. Research has elucidated many cannabinoid pharmacodynamic and pharmacokinetic properties, expanding the potential use of cannabinoids as a medical therapy. Due to the inconsistent delivery and control of the active components involved with smoking, pharmaceutical companies are investigating and prioritizing routes other than smoke inhalation for therapeutic use of cannabinoids. In this relatively new field of pharmaceutical development, ongoing drug development promises great benefit from targeted endocannabinoid receptor agonism. Available in Canada and Europe, nabiximols, a specific extract from the Cannabis plant, has demonstrated great benefit in the treatment of pain related to spasticity in multiple sclerosis, cancer and otherwise chronic pain conditions. The cannabidiol oral solution Epidiolex®, which is available in the USA, is indicated for management of refractory epilepsy but may offer therapeutic relief to chronic pain conditions as well. Current investigative drugs, such as those developed by Cara Therapeutics and Zynerba Pharmaceuticals, are synthetic cannabinoids which show promise to specifically target neuropsychiatric conditions and chronic pain symptoms such as neuropathy and allodynia. The objective of this review is to provide clinicians with an update of currently available and promising developmental cannabis pharmaceutical derivatives which may stand to greatly benefit patients with otherwise difficult-to-treat chronic conditions.