Cannabinoid-mediated modulation of neuropathic pain and microglial accumulation in a model of murine type I diabetic peripheral neuropathic pain

The effects of a brand-specific, hemp-derived cannabidiol product on physiological, biochemical, and psychometric outcomes in healthy adults: a double-blind, randomized clinical trial

BACKGROUND

Cannabidiol (CBD) is a non-psychoactive phyto-cannabinoid derived from the Cannabis sativa plant. CBD exhibits various interactions at receptor sites, prompting the research of its potential anti-inflammatory, immunomodulatory, psychological, and pain-relieving effects. This study aimed to investigate the physiological, biochemical, and psychometric effects of a brand-specific, hemp-derived CBD product in healthy adults over a 12-week observation period.

METHODS

54 healthy males and females (age = 25 ± 7y; BMI = 24.82 ± 3.25 kg/m2) recruited from a large Southeastern University completed the study. Participants arrived at the laboratory after > 8 h of fasting, and > 48 h without alcohol consumption and vigorous exercise. Following baseline measurements (height, weight, blood pressure, electrocardiogram (ECG), and blood work), participants were stratified by sex and randomized to either CBD or placebo groups. Products were administered double-blinded, with both given in liquid form containing medium-chain triglyceride oil, while the CBD product specifically contained 50 mg/mL of CBD. Participants were instructed to consume 1 mL of their product twice daily and were given enough product to last until their next laboratory visit. Data were collected at baseline and on days 30 ± 3, 60 ± 3, and 90 ± 3. Blood was drawn for analysis of immune and inflammatory biomarkers. Chronic pain among participants was calculated using urine samples according to the foundational pain index (FPI). Self-reported psychometric questionnaires were utilized (Cohen's Perceived Stress Scale, Pittsburgh Sleep Quality Index, Profile of Mood States,10-item Likert scale for perceived pain) to assess stress, sleep quality, mood state, and body discomfort. To determine overall wellbeing, participants completed a daily survey indicating if they missed work or school due to illness. Change from baseline was calculated for each measure, and mixed effects models were used to determine differences between groups over time while adjusting for baseline values (α = 0.05). Data are presented as mean ± standard deviation.

RESULTS

There were no Group-by-Time interactions or Group or Time main effects for immune or inflammatory biomarkers (p > 0.05). Analyses revealed no Group-by-Time interactions or main effects observed for perceived stress, sleep quality, overall mood disturbance, and all the profile of mood state subscales (p > 0.05), except "vigor-activity." A Time main effect was found for the sub-score for "vigor-activity" (p = 0.007; Pre CBD = 19.5 ± 5.2, Post CBD = 17.3 ± 5.3; Pre PL = 19.0 ± 5.7, Post PL = 17.9 ± 7.1), which decreased from Visit 3 to Visit 4 (p = 0.025) and from Visit 3 to Visit 5 (p = 0.014). There was a Group main effect for FPI (p = 0.028; Pre CBD = 11.9 ± 14.4, Post CBD = 8.8 ± 10.9; Pre PL = 9.0 ± 14.2, Post PL = 12.9 ± 11.5), indicating that the placebo group had greater increases in pain over the intervention compared to the CBD group. No significant differences were found between groups in the incidence and prevalence of "colds or flus" (p > 0.05).

DISCUSSION

CBD was safe and well tolerated in healthy adults. These findings show pain was lower in the CBD group, suggesting a potentially positive effect for consumption of CBD. "Vigor-activity" decreased across the intervention, which may be a confounding effect of the academic semester. While the dosage chosen was safe, more research may be warranted using higher doses as these may be needed to observe further therapeutic effects in healthy populations.

Topical Cannabidiol for Established Chemotherapy-Induced Neuropathy: A Pilot Randomized Placebo-Controlled Trial

Background: Patients have been known to use cannabinoids for treating established chemotherapy-induced peripheral neuropathy (CIPN) based on anecdotal information and retrospective reports suggesting that such might be beneficial. In response, a double-blinded, placebo-controlled, randomized, pilot clinical trial was developed to evaluate whether resultant data would support a phase III trial for testing whether a cannabidiol (CBD) cream might improve CIPN. Methods: Forty patients with established CIPN were randomized, in a double-blinded manner, to topical CBD or a placebo cream. The study product was applied for 2 weeks, followed by a crossover for 2 weeks. Neuropathy was evaluated using the European Organization of Research and Treatment of Cancer (EORTC)-CIPN20, the Chemotherapy-Induced Peripheral Neuropathy Assessment Tool, and the Global Impression of Change instruments. Side effects were recorded by symptom diaries. Results: The EORTC-CIPN20 scores were similar in the patients receiving CBD versus the placebo. Likewise, the toxicity scores were similar in patients who received the CBD versus the placebo. Conclusions: This pilot trial did not support that the studied CBD isolate cream improved painful established CIPN. It was well tolerated overall. Clinical Trial Registration Number: NCT05388058.

Cannabidiol and pain

Chronic pain presents significant personal, psychological, and socioeconomic hurdles, impacting over 30% of adults worldwide and substantially contributing to disability. Unfortunately, current pharmacotherapy often proves inadequate, leaving fewer than 70% of patients with relief. This shortfall has sparked a drive to seek alternative treatments offering superior safety and efficacy profiles. Cannabinoid-based pharmaceuticals, notably cannabidiol (CBD), hold promise in pain management, driven by their natural origins, versatility, and reduced risk of addiction. As we navigate the opioid crisis, ongoing research plunges into CBD's therapeutic potential, buoyed by animal studies revealing its pain-relieving prowess through various system tweaks. However, the efficacy of cannabis in chronic pain management remains a contentious and stigmatized issue. The International Association for the Study of Pain (IASP) presently refrains from endorsing cannabinoid use for pain relief. Nevertheless, evidence indicates their potential in alleviating cancer-related, neuropathic, arthritis, and musculoskeletal pain, necessitating further investigation. Crucially, our comprehension of CBD's role in pain management is a journey still unfolding, with animal studies illustrating its analgesic effects through interactions with the endocannabinoid, inflammatory, and nociceptive systems. As the plot thickens, it's clear: the saga of chronic pain and CBD's potential offers a compelling narrative ripe for further exploration and understanding.

Cannabidiol Treatment Shows Therapeutic Efficacy in a Rodent Model of Social Transfer of Pain in Pair-Housed Male Mice

Introduction: Prosocial behavior refers to sharing emotions and sensations such as pain. Accumulated data indicate that cannabidiol (CBD), a nonpsychotomimetic component of the Cannabis sativa plant, attenuates hyperalgesia, anxiety, and anhedonic-like behavior. Nevertheless, the role of CBD in the social transfer of pain has never been evaluated. In this study, we investigated the effects of acute systemic administration of CBD in mice that cohabited with a conspecific animal suffering from chronic constriction injury. Furthermore, we assessed whether repeated CBD treatment decreases hypernociception, anxiety-like behavior, and anhedonic-like responses in mice undergoing chronic constriction injury and whether this attenuation would be socially transferred to the partner. Materials and Methods: Male Swiss mice were Housed in pairs for 28 days. On the 14th day of living together, animals were then divided into two groups: cagemate nerve constriction (CNC), in which one animal of each partner was subjected to sciatic nerve constriction; and cagemate sham (CS), subjected to the same surgical procedure but without suffering nerve constriction. In Experiments 1, 2, and 3 on day 28 of living together, the cagemates (CNC and CS) animals received a single systemic injection (intraperitoneally) of vehicle or CBD (0.3, 1, 10, or 30 mg/kg). After 30 min, the cagemates were subjected to the elevated plusmaze followed by exposure to the writhing and sucrose splash tests. For chronic treatment (Exp. 4), sham and chronic constriction injury animals received a repeated systemic injection (subcutaneous) of vehicle or CBD (10 mg/kg) for 14 days after the sciatic nerve constriction procedure. On days 28 and 29 sham and chronic constriction injury animals and their cagemates were behaviorally tested. Results and Conclusion: Acute CBD administration attenuated anxiety-like behavior, pain hypersensitivity, and anhedonic-like behavior in cagemates that cohabited with a pair in chronic pain. In addition, repeated CBD treatment reversed the anxiety-like behavior induced by chronic pain and enhanced the mechanical withdrawal thresholds in Von Frey filaments and the grooming time in the sucrose splash test. Moreover, repeated CBD treatment effects were socially transferred to the chronic constriction injury cagemates.

Cannabidiol induces systemic analgesia through activation of the PI3Kγ/nNOS/NO/KATP signaling pathway in neuropathic mice. A KATP channel S-nitrosylation-dependent mechanism

BACKGROUND

Cannabidiol (CBD) is the second most abundant pharmacologically active component present in Cannabis sp. Unlike Δ-9-tetrahydrocannabinol (THC), it has no psychotomimetic effects and has recently received significant interest from the scientific community due to its potential to treat anxiety and epilepsy. CBD has excellent anti-inflammatory potential and can be used to treat some types of inflammatory and neuropathic pain. In this context, the present study aimed to evaluate the analgesic mechanism of cannabidiol administered systemically for the treatment of neuropathic pain and determine the endogenous mechanisms involved with this analgesia.

METHODS

Neuropathic pain was induced by sciatic nerve constriction surgery, and the nociceptive threshold was measured using the paw compression test in mice.

RESULTS

CBD produced dose-dependent antinociception after intraperitoneal injection. Selective inhibition of PI3Kγ dose-dependently reversed CBD-induced antinociception. Selective inhibition of nNOS enzymes reversed the antinociception induced by CBD, while selective inhibition of iNOS and eNOS did not alter this antinociception. However, the inhibition of cGMP production by guanylyl cyclase did not alter CBD-mediated antinociception, but selective blockade of ATP-sensitive K+ channels dose-dependently reversed CBD-induced antinociception. Inhibition of S-nitrosylation dose-dependently and completely reversed CBD-mediated antinociception.

CONCLUSION

Cannabidiol has an antinociceptive effect when administered systemically and this effect is mediated by the activation of PI3Kγ as well as by nitric oxide and subsequent direct S-nitrosylation of KATP channels on peripheral nociceptors.

Long-term Effects of Cannabidiol and/or Fentanyl Exposure in Rats Submitted to Neonatal Pain

The current study aimed to evaluate anxiety behavior, hippocampal ionized calcium-binding adaptor molecule 1 (Iba1) and cannabinoid receptor 1 (CB1) gene expression, and nociceptive response in adulthood after a combination of fentanyl and cannabidiol (CBD) for nociceptive stimuli induced during the first week of life in rats. Complete Freund's adjuvant-induced inflammatory nociceptive insult on postnatal day (PN) 1 and PN3. Both fentanyl and CBD were used alone or in combination from PN1 to PN7. Behavioral and nociceptive tests were performed at PN60 and PN62. The expression of the microglial calcium-binding proteins Iba1 and CB1 was detected in the hippocampus using reverse Quantitative polymerase chain reaction (qPCR) and immunohistochemistry. Our results suggest that the anxiety behavior response and immune activation in adult life depend on the CBD dose combined with fentanyl for the nociceptive stimuli induced during the first week of life. Treatment of neonatal nociceptive insult with CBD and opioids showed significant dose-dependent and male-female differences. The increased gene expression in the hippocampus of the analyzed cannabinoid gene supports this data. In addition, treatment with fentanyl led to an increase in CB1 protein expression. Moreover, the expression of Iba1 varied according to the administered dose of CBD and may or may not be associated with the opioid. A lower dose of CBD during the inflammatory period was associated with enhanced anxiety in adult life. PERSPECTIVE: The treatment of nociceptive stimuli with CBD and opioids during the first week of life demonstrated significant sex differences in adult life on anxiety behavior and supraspinal pain sensitivity.

An Overview of Cannabidiol

Cannabidiol (CBD) is one of the most interesting constituents of cannabis, garnering significant attention in the medical community in recent years due to its proven benefit for reducing refractory seizures in pediatric patients. Recent legislative changes in the United States have made CBD readily available to the general public, with up to 14% of adults in the United States having tried it in 2019. CBD is used to manage a myriad of symptoms, including anxiety, pain, and sleep disturbances, although rigorous evidence for these indications is lacking. A significant advantage of CBD over the other more well-known cannabinoid delta-9-tetrahydroncannabinol (THC) is that CBD does not produce a "high." As patients increasingly self-report its use to manage their medical conditions, and as the opioid epidemic continues to drive the quest for alternative pain management approaches, the aims of this narrative review are to provide a broad overview of the discovery, pharmacology, and molecular targets of CBD, its purported and approved neurologic indications, evidence for its analgesic potential, regulatory implications for patients and providers, and future research needs.

IUPHAR review- Preclinical models of neuropathic pain: Evaluating multifunctional properties of natural cannabinoid receptors ligands

Neuropathic pain remains prevalent and challenging to manage and is often comorbid with depression and anxiety. The new approach that simultaneously targets neuropathic pain and the associated comorbidities, such as depression and anxiety, is timely and critical, given the high prevalence and severity of neuropathic pain and the lack of effective analgesics. In this review, we focus on the animal models of neuropathic pain that researchers have used to investigate the analgesic effects of cannabidiol (CBD) and Beta-Caryophyllene (BCP) individually and in combination while addressing the impact of these compounds on the major comorbidity (e.g., depression, anxiety) associated with neuropathic pain. We also addressed the potential targets/mechanisms by which CBD and BCP produce analgesic effects in neuropathic pain models. The preclinical studies examined in this review support CBD and BCP individually and combined as potential alternative analgesics for neuropathic pain while showing beneficial effects on depression and anxiety.

Chronic wound-related pain, wound healing and the therapeutic potential of cannabinoids and endocannabinoid system modulation

Chronic wounds represent a significant burden on the individual, and the healthcare system. Individuals with chronic wounds report pain to be the most challenging aspect of living with a chronic wound, with current therapeutic options deemed insufficient. The cutaneous endocannabinoid system is an important regulator of skin homeostasis, with evidence of system dysregulation in several cutaneous disorders. Herein, we describe the cutaneous endocannabinoid system, chronic wound-related pain, and comorbidities, and review preclinical and clinical evidence investigating endocannabinoid system modulation for wound-related pain and wound healing. Based on the current literature, there is some evidence to suggest efficacy of endocannabinoid system modulation for promotion of wound healing, attenuation of cutaneous disorder-related inflammation, and for the management of chronic wound-related pain. However, there is 1) a paucity of preclinical studies using validated models, specific for the study of chronic wound-related pain and 2) a lack of randomised control trials and strong clinical evidence relating to endocannabinoid system modulation for wound-related pain. In conclusion, while there is some limited evidence of benefit of endocannabinoid system modulation in wound healing and wound-related pain management, further research is required to better realise the potential of targeting the endocannabinoid system for these therapeutic applications.

The pharmacology and therapeutic role of cannabidiol in diabetes

In recent years, cannabidiol (CBD), a non-psychotropic cannabinoid, has garnered substantial interest in drug development due to its broad pharmacological activity and multi-target effects. Diabetes is a chronic metabolic disease that can damage multiple organs in the body, leading to the development of complications such as abnormal kidney function, vision loss, neuropathy, and cardiovascular disease. CBD has demonstrated significant therapeutic potential in treating diabetes mellitus and its complications owing to its various pharmacological effects. This work summarizes the role of CBD in diabetes and its impact on complications such as cardiovascular dysfunction, nephropathy, retinopathy, and neuropathy. Strategies for discovering molecular targets for CBD in the treatment of diabetes and its complications are also proposed. Moreover, ways to optimize the structure of CBD based on known targets to generate new CBD analogues are explored.

Cannabidiol for musculoskeletal regenerative medicine

Chronic musculoskeletal (MSK) pain is one of the most prevalent causes, which lead patients to a physician's office. The most common disorders affecting MSK structures are osteoarthritis, rheumatoid arthritis, back pain, and myofascial pain syndrome, which are all responsible for major pain and physical disability. Although there are many known management strategies currently in practice, phytotherapeutic compounds have recently begun to rise in the medical community, especially cannabidiol (CBD). This natural, non-intoxicating molecule derived from the cannabis plant has shown interesting results in many preclinical studies and some clinical settings. CBD plays vital roles in human health that go well beyond the classic immunomodulatory, anti-inflammatory, and antinociceptive properties. Recent studies demonstrated that CBD also improves cell proliferation and migration, especially in mesenchymal stem cells (MSCs). The foremost objective of this review article is to discuss the therapeutic potential of CBD in the context of MSK regenerative medicine. Numerous studies listed in the literature indicate that CBD possesses a significant capacity to modulate mammalian tissue to attenuate and reverse the notorious hallmarks of chronic musculoskeletal disorders (MSDs). The most of the research included in this review report common findings like immunomodulation and stimulation of cell activity associated with tissue regeneration, especially in human MSCs. CBD is considered safe and well tolerated as no serious adverse effects were reported. CBD promotes many positive effects which can manage detrimental alterations brought on by chronic MSDs. Since the application of CBD for MSK health is still undergoing expansion, additional randomized clinical trials are warranted to further clarify its efficacy and to understand its cellular mechanisms.

Establishment of a point of departure for CBD hepatotoxicity employing human HepaRG spheroids

The United States Food and Drug Administration recently approved the use of Cannabis sativa derived cannabidiol (CBD) in the treatment of Dravet Syndrome and Lennox-Gastaut Syndrome, under the trade name, Epidiolex. In double-blinded, placebo-controlled clinical trials, elevated ALT levels were observed in some patients, but these findings could not be uncoupled from the confounds of potential drug-drug interactions with co-administration of valproate and clobazam. Given the uncertainty of the potential hepatatoxic effects of CBD, the objective of the present study was to determine a point of departure for CBD, using human HepaRG spheroid cultures, followed by transcriptomic benchmark dose analysis. Treatment of HepaRG spheroids with CBD for 24 and 72 h, resulted in EC50 concentrations for cytotoxicity of 86.27 µM and 58.04 µM, respectively. Subsequent transcriptomic analysis at these timepoints demonstrated little alteration of gene and pathway data sets at a CBD concentration at or below 10 µM. Although this current analysis was conducted using liver cells, interestingly the findings at 72 h post CBD treatment showed suppression of many genes more commonly associated with immune regulation. Indeed, the immune system is a well-established target for CBD based on immune function assays. Collectively, in the present studies a point of departure was derived using transcriptomic changes produced by CBD in a human cell-based model system, which has been shown to accurately translate to human hepatotoxicity modeling.

Autophagy: An Emerging Target for Developing Effective Analgesics

Inadequate treatment of acute and chronic pain causes depression, anxiety, sleep disturbances, and increased mortality. Abuse and overdose of opioids and the side effects associated with chronic use of NSAID illustrate the need for development of safer and effective pain medication. Working toward this end, an in silico tool based on an emergent intelligence analytical platform that examines interactions between protein networks was used to identify molecular mechanisms involved in regulating the body's response to painful stimuli and drug treatments. Examining interactions between protein networks associated with the expression of over 20 different pain types suggests that the regulation of autophagy plays a central role in modulation of pain symptoms (see Materials and Methods). Using the topology of this regulatory scheme as an in silico screening tool, we identified that combinations of functions targeted by cannabidiol, myo-inositol, and fish oils with varying ratios of eicosapentaenoic and docosahexaenoic acids are projected to produce superior analgesia. For validating this prediction, we administered combinations of cannabidiol, myo-inositol, and fish oils to rats that received formalin injections in hind paws, prior to substance administration, and showed that analgesic effects produced by these combinations were comparable or superior to known NSAID analgesics, which suggests that these combinations have potential in treatment of pain.

Sinomenine alleviates diabetic peripheral neuropathic pain through inhibition of the inositol-requiring enzyme 1 alpha-X-box binding protein 1 pathway by downregulating prostaglandin-endoperoxide synthase 2

INTRODUCTION

We tried to show the effect of sinomenine (SIN) in diabetic peripheral neuropathic pain (DPNP) and the related underlying mechanism.

METHODS

Network pharmacological analysis and bioinformatics analysis were carried out for identification of the active ingredients of Sinomenium acutum and the related genes. The DPNP rat model was constructed and primary rat spinal cord microglial cells were isolated for in vitro cell experiments. The therapeutic role of SIN in DPNP was determined in vivo and in vitro through analysis of microglial cell activation and inflammatory response.

RESULTS

Therapeutic role of S. acutum in DPNP was mainly achieved by regulating 14 key genes, among which the target gene prostaglandin-endoperoxide synthase 2 (PTGS2) of SIN might be the key gene. An in vivo experiment showed that SIN inactivated the inositol-requiring enzyme 1 alpha-X-box binding protein 1 pathway by downregulating PTGS2, which relieved pain symptoms in DPNP rats. It was confirmed in vivo that SIN inhibited the pathway through PTGS2 to alleviate the activation of spinal cord microglial cells and inflammatory response.

CONCLUSION

SIN decreases the expression of PTGS2 to inactivate the inositol-requiring enzyme 1 alpha-X-box binding protein 1 signaling pathway, which inhibits microglial activation, as well as the release of inflammatory factors, thus alleviating DPNP.

The Effects of Long-Term Self-Dosing of Cannabidiol on Drowsiness, Testosterone Levels, and Liver Function

Introduction

Previous research indicated that cannabidiol (CBD) may result in low levels of male total testosterone (TT), elevations in liver tests (LTs), and daytime drowsiness (DD). We investigated the prevalences of TT and LT in a large adult sample self-administering CBD and determined the effect self-dosing of CBD has on the severity of DD.

Methods

Adult participants (18-75 years of age) who self-dose CBD orally for a minimum of 30 days were recruited for this decentralized observational study from companies that offer CBD products. Participants were sent their usual CBD regimen. A clinical study platform was used on a phone app to obtain consent and collect study data. Data included demographic information, reasons for self-dosing, dosage, current medications and dosage, medical history, adverse effects, effects on DD, and efficacy. After 30 days, LT and TT were obtained and follow-up LT was offered to participants who demonstrated elevated values of alanine transaminase (ALT).

Results

A total of 28,121 individuals were contacted, 1,475 met the criteria and were enrolled, and 1,061 (female: 65.2%, male: 34.8%) completed the study. Most of the participants used full-spectrum CBD oil or CBD isolate with the mean ± SD daily dose of CBD for all users of 55.4 ± 37.8 mg. CBD use was associated with a significant decrease in DD and a decrease in the prevalence of low TT in males >40 years of age. The prevalences of elevations in ALT and aspartate aminotransferase were not significantly different from those of the general adult population, and the prevalences of elevated levels of alkaline phosphatase and bilirubin were less than those of a healthy adult population. There was no relationship between LT and CBD dose.

Conclusions

In this large-sample study, self-dosing CBD was not associated with an increased prevalence of elevation of LT or low levels of TT in men. Furthermore, CBD administration decreased DD and was associated with a lower prevalence of low testosterone levels in older men as compared to age-adjusted population norms.

Cannabinoids and terpenes for diabetes mellitus and its complications: from mechanisms to new therapies

The number of people diagnosed with diabetes mellitus and its complications is markedly increasing worldwide, leading to a worldwide epidemic across all age groups, from children to older adults. Diabetes is associated with premature aging. In recent years, it has been found that peripheral overactivation of the endocannabinoid system (ECS), and in particular cannabinoid receptor 1 (CB1R) signaling, plays a crucial role in the progression of insulin resistance, diabetes (especially type 2), and its aging-related comorbidities such as atherosclerosis, nephropathy, neuropathy, and retinopathy. Therefore, it is suggested that peripheral blockade of CB1R may ameliorate diabetes and diabetes-related comorbidities. The use of synthetic CB1R antagonists such as rimonabant has been prohibited because of their psychiatric side effects. In contrast, phytocannabinoids such as cannabidiol (CBD) and tetrahydrocannabivarin (THCV), produced by cannabis, exhibit antagonistic activity on CB1R signaling and do not show any adverse side effects such as psychoactive effects, depression, or anxiety, thereby serving as potential candidates for the treatment of diabetes and its complications. In addition to these phytocannabinoids, cannabis also produces a substantial number of other phytocannabinoids, terpenes, and flavonoids with therapeutic potential against insulin resistance, diabetes, and its complications. In this review, the pathogenesis of diabetes, its complications, and the potential to use cannabinoids, terpenes, and flavonoids for its treatment are discussed.

Chronic Pain and Cannabidiol in Animal Models: Behavioral Pharmacology and Future Perspectives

The incidence of chronic pain is around 8% in the general population, and its impact on quality of life, mood, and sleep exceeds the burden of its causal pathology. Chronic pain is a complex and multifaceted problem with few effective and safe treatment options. It can be associated with neurological diseases, peripheral injuries or central trauma, or some maladaptation to traumatic or emotional events. In this perspective, animal models are used to assess the manifestations of neuropathy, such as allodynia and hyperalgesia, through nociceptive tests, such as von Frey, Hargreaves, hot plate, tail-flick, Randall & Selitto, and others. Cannabidiol (CBD) has been considered a promising strategy for treating chronic pain and diseases that have pain as a consequence of neuropathy. However, despite the growing body of evidence linking the efficacy of CBD on pain management in clinical and basic research, there is a lack of reviews focusing on chronic pain assessments, especially when considering pre-clinical studies, which assess chronic pain as a disease by itself or as a consequence of trauma or peripheral or central disease. Therefore, this review focused only on studies that fit our inclusion criteria: (1) used treatment with CBD extract; (2) used tests to assess mechanical or thermal nociception in at least one of the following most commonly used tests (von Frey, hot plate, acetone, Hargreaves, tail-flick, Randall & Selitto, and others); and (3) studies that assessed pain sensitivity in chronic pain induction models. The current literature points out that CBD is a well-tolerated and safe natural compound that exerts analgesic effects, decreasing hyperalgesia, and mechanical/thermal allodynia in several animal models of pain and patients. In addition, CBD presents several molecular and cellular mechanisms of action involved in its positive effects on chronic pain. In conclusion, using CBD seems to be a promising strategy to overcome the lack of efficacy of conventional treatment for chronic pain.

Intrathecal Actions of the Cannabis Constituents Δ(9)-Tetrahydrocannabinol and Cannabidiol in a Mouse Neuropathic Pain Model

(1) Background: The psychoactive and non-psychoactive constituents of cannabis, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), synergistically reduce allodynia in various animal models of neuropathic pain. Unfortunately, THC-containing drugs also produce substantial side-effects when administered systemically. We examined the effectiveness of targeted spinal delivery of these cannabis constituents, alone and in combination. (2) Methods: The effect of acute intrathecal drug delivery on allodynia and common cannabinoid-like side-effects was examined in a mouse chronic constriction injury (CCI) model of neuropathic pain. (3) Results: intrathecal THC and CBD produced dose-dependent reductions in mechanical and cold allodynia. In a 1:1 combination, they synergistically reduced mechanical and cold allodynia, with a two-fold increase in potency compared to their predicted additive effect. Neither THC, CBD nor combination THC:CBD produced any cannabis-like side-effects at equivalent doses. The anti-allodynic effects of THC were abolished and partly reduced by cannabinoid CB1 and CB2 receptor antagonists AM281 and AM630, respectively. The anti-allodynic effects of CBD were partly reduced by AM630. (4) Conclusions: these findings indicate that intrathecal THC and CBD, individually and in combination, could provide a safe and effective treatment for nerve injury induced neuropathic pain.

Role of Cannabidiol and Tetrahydrocannabivarin on Paclitaxel-induced neuropathic pain in rodents

The purpose of this study was to evaluate if phytocannabinoids, synthetic cannabidiol (CBD), and tetrahydrocannabivarin (THCV), and their combination, could protect mice from Paclitaxel-induced peripheral neuropathy (PIPN). Six groups of C57BL/6J mice (n = 6) were used in this study. The mice were given paclitaxel (PTX) (8 mg/kg/day, i.p.) on days 1, 3, 5, and 7 to induce neuropathy. Mice were evaluated for behavioral parameters, and dorsal root ganglions (DRG) were collected from the animals and subjected to RNA sequencing and westernblot analysis at the end of the study. On cultured DRGs derived from adult male rats, immunocytochemistry and mitochondrial functional assays were also performed. When compared to individual treatments, the combination of CBD and THCV improved thermal and mechanical neurobehavioral symptoms in mice by twofold. Targets for CBD and THCV therapy were identified by KEGG (RNA sequencing). PTX reduced the expression of p-AMPK, SIRT1, NRF2, HO1, SOD2, and catalase while increasing the expression of PI3K, p-AKT, p-P38 MAP kinase, BAX, TGF-β, NLRP3 inflammasome, and caspase 3 in DRG homogenates of mice. Combination therapy outperformed monotherapy in reversing these protein expressions. The addition of CBD and THCV to DRG primary cultures reduced mitochondrial superoxides while increasing mitochondrial membrane potentials. WAY100135 and rimonabant altered the neuroprotective effects of CBD and THCV respectively by blocking 5-HT1A and CB1 receptors in mice and DRG primary cultures. The entourage effect of CBD and THCV against PIPN appears to protect neurons in mice via 5HT1A and CB1 receptors respectively.

Topical Cannabinoids for Treating Chemotherapy-Induced Neuropathy: A Case Series

BACKGROUND

Chemotherapy-induced peripheral neuropathy is a common and often severe side effect from many chemotherapeutic agents, with limited treatment options. There is no literature on the use of topical cannabinoids for chemotherapy-induced neuropathy.

CASE PRESENTATIONS

The current manuscript presents a case series of patients presenting in oncology clinics at Sutter Health, CA and Mayo Clinic, Rochester, MN from April 2019 to December 2020 with chemotherapy-induced peripheral neuropathy who used topical creams containing the cannabinoids delta-nine-tetrahydrocannabinol (THC) and/or cannabidiol (CBD).

CONCLUSIONS

This case series suggests that topical cannabinoids may be helpful for patients with chemotherapy-induced peripheral neuropathy. This paper also discusses the potential mechanisms of action by which topical cannabinoids might alleviate established CIPN symptoms. A randomized placebo-controlled trial using a standardized product is planned to study the actual efficacy of such treatment.

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

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

Sex Differences in Tolerance to Delta-9-Tetrahydrocannabinol in Mice With Cisplatin-Evoked Chronic Neuropathic Pain

Tolerance to the pain-relieving effects of cannabinoids limits the therapeutic potential of these drugs in patients with chronic pain. Recent preclinical research with rodents and clinical studies in humans has suggested important differences between males and females in the development of tolerance to cannabinoids. Our previous work found that male mice expressing a desensitization resistant form (S426A/S430A) of the type 1 cannabinoid receptor (CB₁R) show delayed tolerance and increased sensitivity to the antinociceptive effects of delta-9-tetrahydrocannabinol (∆⁹-THC). Sex differences in tolerance have been reported in rodent models with females acquiring tolerance to ∆⁹-THC faster than males. However, it remains unknown whether the S426A/S430A mutation alters analgesic tolerance to ∆⁹-THC in mice with chemotherapy-evoked chronic neuropathic pain, and also whether this tolerance might be different between males and females. Male and female S426A/S430A mutant and wild-type littermates were made neuropathic using four once-weekly injections of 5 mg/kg cisplatin and subsequently assessed for tolerance to the anti-allodynic effects of 6 and/or 10 mg/kg ∆⁹-THC. Females acquired tolerance to the anti-allodynic effects of both 6 and 10 mg/kg ∆⁹-THC faster than males. In contrast, the S426A/S430A mutation did not alter tolerance to ∆⁹-THC in either male or female mice. The anti-allodynic effects of ∆⁹-THC were blocked following pretreatment with the CB₁R antagonist, rimonabant, and partially blocked following pretreatment with the CB₂R inverse agonist, SR144528. Our results show that disruption of the GRK/β-arrestin-2 pathway of desensitization did not affect sensitivity and/or tolerance to ∆⁹-THC in a chronic pain model of neuropathy.

Therapeutic Prospects of Cannabinoids in the Immunomodulation of Prevalent Autoimmune Diseases

Introduction: Cannabinoids such as ▵-9-THC and CBD can downregulate the immune response by modulating the endocannabinoid system. This modulation is relevant for the treatment of prevalent autoimmune diseases (ADs), such as multiple sclerosis (MS), systemic lupus erythematosus (SLE), diabetes mellitus type 1 (DMT1), and rheumatoid arthritis (RA). These conditions require new therapeutic options with fewer side effects for the control of the autoimmune response. Objective: to conduct a literature review of preclinical scientific evidence that supports further clinical investigations for the use of cannabinoids (natural or synthetic) as potential immunomodulators of the immune response in ADs. Methodology: A systematic search was carried out in different databases using different MeSH terms, such as Cannabis sativa L., cannabinoids, immunomodulation, and ADs. Initially, 677 journal articles were found. After filtering by publication date (from 2000 to 2020 for SLE, DMT1, and RA; and 2010 to 2020 for MS) and removing the duplicate items, 200 articles were selected and analyzed by title and summary associated with the use of cannabinoids as immunomodulatory treatment for those diseases. Results: Evidence of the immunomodulatory effect of cannabinoids in the diseases previously mentioned, but SLE that did not meet the search criteria, was summarized from 24 journal articles. CBD was found to be one of the main modulators of the immune response. This molecule decreased the number of Th1 and Th17 proinflammatory cells and the production of the proinflammatory cytokines, interleukin (IL)-1, IL-12, IL-17, interferon (IFN)-γ, and tumor necrosis factor alpha, in mouse models of MS and DMT1. Additionally, new synthetic cannabinoid-like molecules, with agonist or antagonist activity on CB1, CB2, TRPV1, PPAR-α, and PPAR-γ receptors, have shown anti-inflammatory properties in MS, DMT1, and RA. Conclusion: Data from experimental animal models of AD showed that natural and synthetic cannabinoids downregulate inflammatory responses mediated by immune cells responsible for AD chronicity and progression. Although synthetic cannabinoid-like molecules were evaluated in just two clinical trials, they corroborated the potential use of cannabinoids to treat some ADs. Notwithstanding, new cannabinoid-based approaches are required to provide alternative treatments to patients affected by the large group of ADs.

The cannabinoid system and microglia in health and disease

Recent years have yielded significant advances in our understanding of microglia, the immune cells of the central nervous system (CNS). Microglia are key players in CNS development, immune surveillance, and the maintenance of proper neuronal function throughout life. In the healthy brain, homeostatic microglia have a unique molecular signature. In neurological diseases, microglia become activated and adopt distinct transcriptomic signatures, including disease-associated microglia (DAM) implicated in neurodegenerative disorders. Homeostatic microglia synthesise the endogenous cannabinoids 2-arachidonoylglycerol and anandamide and express the cannabinoid receptors CB1 and CB2 at constitutively low levels. Upon activation, microglia significantly increase their synthesis of endocannabinoids and upregulate their expression of CB2 receptors, which promote a protective microglial phenotype by enhancing their production of neuroprotective factors and reducing their production of pro-inflammatory factors. Here, we summarise the effects of the microglial cannabinoid system in the CNS demyelinating disease multiple sclerosis, the neurodegenerative diseases Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis, chronic inflammatory and neuropathic pain, and psychiatric disorders including depression, anxiety and schizophrenia. We discuss the therapeutic potential of cannabinoids in regulating microglial activity and highlight the need to further investigate their specific microglia-dependent immunomodulatory effects.

Oral efficacy of Δ(9)-tetrahydrocannabinol and cannabidiol in a mouse neuropathic pain model

The psychoactive and non-psychoactive constituents of cannabis, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD), have synergistic analgesic efficacy in animal models of neuropathic pain when injected systemically. However, the relevance of this preclinical synergy to clinical neuropathic pain studies is unclear because many of the latter use oral administration. We therefore examined the oral effectiveness of these phytocannabinoids and their interactions in a mouse chronic constriction injury (CCI) model of neuropathic pain. THC produced a dose-dependent reduction in mechanical and cold allodynia, but also induced side-effects with similar potency. CBD also reduced allodynia, albeit with lower potency than THC, but did not produce cannabinoid-like side-effects at any dose tested. Combination THC:CBD produced a dose-dependent reduction in allodynia, however, it displayed little to no synergy. Combination THC:CBD produced substantial, synergistic side-effects which increased with the proportion of CBD. These findings demonstrate that oral THC and CBD, alone and in combination, have analgesic efficacy in an animal neuropathic pain model. Unlike prior systemic injection studies, combination THC:CBD lacks analgesic synergy when delivered orally. Furthermore, both THC and combination THC:CBD display a relatively poor therapeutic window when delivered orally. This suggests that CBD provides a safer, albeit lower efficacy, oral treatment for nerve injury induced neuropathic pain than THC-containing preparations. This article is part of the special issue on 'Cannabinoids'.

Immunomodulation by cannabinoids: Current uses, mechanisms, and identification of data gaps to be addressed for additional therapeutic application

The endocannabinoid system plays a critical role in immunity and therefore its components, including cannabinoid receptors 1 and 2 (CB₁ and CB₂), are putative druggable targets for immune-mediated diseases. Whether modulating endogenous cannabinoid levels or interacting with CB₁ or CB₂ receptors directly, cannabinoids or cannabinoid-based therapeutics (CBTs) show promise as anti-inflammatory or immune suppressive agents. Herein we provide an overview of cannabinoid effects in animals and humans that provide support for the use of CBTs in immune-mediated disease such as multiple sclerosis (MS), inflammatory bowel disease (IBD), asthma, arthritis, diabetes, human immunodeficiency virus (HIV), and HIV-associated neurocognitive disorder (HAND). This is not an exhaustive review of cannabinoid effects on immune responses, but rather provides: (1) key studies in which initial and/or novel observations were made in animal studies; (2) critical human studies including meta-analyses and randomized clinical trials (RCTs) in which CBTs have been assessed; and (3) evidence for the role of CB₁ or CB₂ receptors in immune-mediated diseases through genetic analyses of single nucleotide polymorphisms (SNPs) in the CNR1 and CNR2 genes that encode CB₁ or CB₂ receptors, respectively. Perhaps most importantly, we provide our view of data gaps that exist, which if addressed, would allow for more rigorous evaluation of the efficacy and risk to benefit ratio of the use of cannabinoids and/or CBTs for immune-mediated diseases.

Effects of Cannabidiol and Beta-Caryophyllene Alone or in Combination in a Mouse Model of Permanent Ischemia

Current treatments for stroke, which account for 6.5 million global deaths annually, remain insufficient for treatment of disability and mortality. One targetable hallmark of stroke is the inflammatory response following infarct, which leads to significant damage post-infarct. Cannabinoids and their endogenous targets within the CNS have emerged as potential treatments for neuroinflammatory indications. We and others have previously shown that synthetic agonists of the cannabinoid CB2 receptor reduce infarct size and microglial activation in rodent models of stroke. The non-cannabinoid receptor mediated effects of the phytocannabinoid cannabidiol (CBD) have also shown effectiveness in these models. The present aim was to determine the single and combined effects of the cannabis-derived sesquiterpene and putative CB2 receptor agonist β-caryophyllene (BCP) and CBD on permanent ischemia without reperfusion using a mouse model of photothrombosis. Because BCP and CBD likely work through different sites of action but share common mechanisms of action, we sought to determine whether combinations of BCP and CBD were more potent than either compound alone. Therefore we determined the effect of BCP (3-30 mg/kg IP) and CBD (3-30 mg/kg IP), given alone or in combination (30:3, 30:10, and 30:30 BCP:CBD), on infarct size, microglial activation, and motor performance.

Therapeutic Agents for the Treatment of Temporomandibular Joint Disorders: Progress and Perspective

Temporomandibular joint disorders (TMD) are a common health condition caused by the structural or functional disorders of masticatory muscles and the temporomandibular joint (TMJ). Abnormal mandibular movement in TMD patients may cause pain, chronic inflammation, and other discomfort, which could be relieved by a variety of drugs through various delivery systems. In this study, we summarized commonly used therapeutic agents in the management of TMD as well as novel bioactive molecules in preclinical stage and clinical trials. The emerging therapy strategies such as novel intra-TMJ delivery systems and implants based on tissue engineering are also discussed. This comprehensive review will strengthen our understanding of pharmacological approaches for TMD therapy.

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.

Acupuncture attenuates the development of diabetic peripheral neuralgia by regulating P2X4 expression and inflammation in rat spinal microglia

Diabetic peripheral neuropathy (DPN) is a chronic microvascular complication of diabetes. The purpose of this study is to find the underlying mechanism for the effects of acupuncture in DPN rats. Rats were rendered diabetic with a single injection of 35 mg/kg streptozotocin (STZ). These STZ-diabetic rats were treated with acupuncture for 20 min once daily. The therapeutic efficacy of acupuncture was assessed using mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) evaluations. After 14 days treatment, acupuncture markedly reduced the pathological injury in STZ-diabetic rats. Moreover, it significantly down-regulated P2X4 and OX42 expression along with the reduced levels of inflammatory factors (CXCR3, TNF-α, IL-1β, IL-6), GSP and lipid metabolisms in the spinal cord of the DPN rats. Acupuncture could relieve DPN in rats by regulating P2X4 expression and inflammation in spinal microglia.

Mechanisms of Cannabinoids and Potential Applicability to Skin Diseases

The legalisation of cannabis in a growing number of jurisdictions has led to increasing interest in its potential therapeutic effects in a range of disorders, including cutaneous conditions. Cannabinoids have been used as natural medicines for centuries; however, their biological activity in the skin is a new area of study. Recent data suggest that cannabinoids are involved in neuro-immuno-endocrine modulation of skin functioning, yet their effect on the features of dermatologic conditions is unclear. This article sought to review the mechanisms by which cannabinoids regulate skin functioning through the lens of relevance to treatment of dermatologic diseases looking at the effects of cannabinoids on a range of cellular activities and dermatologic conditions both in vitro and in vivo. We identified studies demonstrating an inhibitory effect of cannabinoids on skin inflammation, proliferation, fibrosis, pain, and itch-biological mechanisms involved in the pathogenesis of many dermatologic conditions. Cannabinoids have the potential to expand the therapeutic repertoire of a wide spectrum of skin disorders. Given their widespread unregulated use by the general public, basic and clinical studies are required to elucidate the effectiveness and long-term effects of topical and systemic cannabinoids in cutaneous disorders.

Cannabidiol and Sports Performance: a Narrative Review of Relevant Evidence and Recommendations for Future Research

Cannabidiol (CBD) is a non-intoxicating cannabinoid derived from Cannabis sativa. CBD initially drew scientific interest due to its anticonvulsant properties but increasing evidence of other therapeutic effects has attracted the attention of additional clinical and non-clinical populations, including athletes. Unlike the intoxicating cannabinoid, Δ9-tetrahydrocannabinol (Δ9-THC), CBD is no longer prohibited by the World Anti-Doping Agency and appears to be safe and well-tolerated in humans. It has also become readily available in many countries with the introduction of over-the-counter "nutraceutical" products. The aim of this narrative review was to explore various physiological and psychological effects of CBD that may be relevant to the sport and/or exercise context and to identify key areas for future research. As direct studies of CBD and sports performance are is currently lacking, evidence for this narrative review was sourced from preclinical studies and a limited number of clinical trials in non-athlete populations. Preclinical studies have observed robust anti-inflammatory, neuroprotective and analgesic effects of CBD in animal models. Preliminary preclinical evidence also suggests that CBD may protect against gastrointestinal damage associated with inflammation and promote healing of traumatic skeletal injuries. However, further research is required to confirm these observations. Early stage clinical studies suggest that CBD may be anxiolytic in "stress-inducing" situations and in individuals with anxiety disorders. While some case reports indicate that CBD improves sleep, robust evidence is currently lacking. Cognitive function and thermoregulation appear to be unaffected by CBD while effects on food intake, metabolic function, cardiovascular function, and infection require further study. CBD may exert a number of physiological, biochemical, and psychological effects with the potential to benefit athletes. However, well controlled, studies in athlete populations are required before definitive conclusions can be reached regarding the utility of CBD in supporting athletic performance.

Use of cannabidiol (CBD) for the treatment of chronic pain

Chronic pain can be recurrent or constant pain that lasts for longer than 3 months and can result in disability, suffering, and a physical disturbance. Related to the complex nature of chronic pain, treatments have a pharmacological and non-pharmacological approach. Due to the opioid epidemic, alternative therapies have been introduced, and components of the plant Cannabis Sativa, Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have gained recent interest as a choice of treatment. The exact mechanism for CBD is currently unknown, but unlike the CBD's psychoactive counterpart, THC, the side effects of CBD itself have been shown to be overall much more benign. The current pharmaceutical products for the treatment of chronic pain are known as nabiximols, and they contain a ratio of THC combined with CBD, which has been promising. This review focuses on the treatment efficacy of CBD, THC: CBD-based treatments for chronic pain and adverse events with each.

A Balanced Approach for Cannabidiol Use in Chronic Pain

Cannabidiol (CBD), the major non-psychoactive constituent of Cannabis sativa L., has gained traction as a potential treatment for intractable chronic pain in many conditions. Clinical evidence suggests that CBD provides therapeutic benefit in certain forms of epilepsy and imparts analgesia in certain conditions, and improves quality of life. CBD continues to be Schedule I or V on the list of controlled substances of the Drug Enforcement Agency of the United States. However, preparations labeled CBD are available publicly in stores and on the streets. However, use of CBD does not always resolve pain. CBD purchased freely entails the risk of adulteration by potentially hazardous chemicals. As well, CBD use by pregnant women is rising and poses a major health-hazard for future generations. In this mini-review, we present balanced and unbiased pre-clinical and clinical findings for the beneficial effects of CBD treatment on chronic pain and its deleterious effects on prenatal development.

The Effectiveness of Topical Cannabidiol Oil in Symptomatic Relief of Peripheral Neuropathy of the Lower Extremities

Background:

Peripheral neuropathy can significantly impact the quality of life for those who are affected, as therapies from the current treatment algorithm often fail to deliver adequate symptom relief. There has, however, been an increasing body of evidence for the use of cannabinoids in the treatment of chronic, noncancer pain. The efficacy of a topically delivered cannabidiol (CBD) oil in the management of neuropathic pain was examined in this four-week, randomized and placebocontrolled trial.

Methods:

In total, 29 patients with symptomatic peripheral neuropathy were recruited and enrolled. 15 patients were randomized to the CBD group with the treatment product containing 250 mg CBD/3 fl. oz, and 14 patients were randomized to the placebo group. After four weeks, the placebo group was allowed to crossover into the treatment group. The Neuropathic Pain Scale (NPS) was administered biweekly to assess the mean change from baseline to the end of the treatment period.

Results:

The study population included 62.1% males and 37.9% females with a mean age of 68 years. There was a statistically significant reduction in intense pain, sharp pain, cold and itchy sensations in the CBD group when compared to the placebo group. No adverse events were reported in this study.

Conclusions:

Our findings demonstrate that the transdermal application of CBD oil can achieve significant improvement in pain and other disturbing sensations in patients with peripheral neuropathy. The treatment product was well tolerated and may provide a more effective alternative compared to other current therapies in the treatment of peripheral neuropathy.

Cannabis sativa: Much more beyond Δ9-tetrahydrocannabinol

Cannabis is the most used illicit drug worldwide and its medicinal use is under discussion, being regulated in several countries. However, the psychotropic effects of Δ⁹-tetrahydrocannabinol (THC), the main psychoactive compound of Cannabis sativa, are of concern. Thus, the interest in the isolated constituents without psychotropic activity, such as cannabidiol (CBD) and cannabidivarin (CBDV) is growing. CBD and CBDV are lipophilic molecules with poor oral bioavailability and are mainly metabolized by cytochrome P450 (CYP450) enzymes. The pharmacodynamics of CBD is the best explored, being able to interact with diverse molecular targets, like cannabinoid receptors, G protein-coupled receptor-55, transient receptor potential vanilloid 1 channel and peroxisome proliferator-activated receptor-γ. Considering the therapeutic potential, several clinical trials are underway to study the efficacy of CBD and CBDV in different pathologies, such as neurodegenerative diseases, epilepsy, autism spectrum disorders and pain conditions. The anti-cancer properties of CBD have also been demonstrated by several pre-clinical studies in different types of tumour cells. Although less studied, CBDV, a structural analogue of CBD, is receiving attention in the last years. CBDV exhibits anticonvulsant properties and, currently, clinical trials are underway for the treatment of autism spectrum disorders. Despite the benefits of these phytocannabinoids, it is important to highlight their potential interference with relevant physiologic mechanisms. In fact, CBD interactions with CYP450 enzymes and with drug efflux transporters may have serious consequences when co-administered with other drugs. This review summarizes the therapeutic advances of CBD and CBDV and explores some aspects of their pharmacokinetics, pharmacodynamics and possible interactions. Moreover, it also highlights the therapeutic potential of CBD and CBDV in several medical conditions and clinical applications.

Immune Responses Regulated by Cannabidiol

Introduction: Cannabidiol (CBD) as Epidiolex^® (GW Pharmaceuticals) was recently approved by the U.S. Food and Drug Administration (FDA) to treat rare forms of epilepsy in patients 2 years of age and older. Together with the increased societal acceptance of recreational cannabis and CBD oil for putative medical use in many states, the exposure to CBD is increasing, even though all of its biological effects are not understood. Once such example is the ability of CBD to be anti-inflammatory and immune suppressive, so the purpose of this review is to summarize effects and mechanisms of CBD in the immune system. It includes a consideration of reports identifying receptors through which CBD acts, since the “CBD receptor,” if a single one exists, has not been definitively identified for the myriad immune system effects. The review then provides a summary of in vivo and in vitro effects in the immune system, in autoimmune models, with a focus on experimental autoimmune encephalomyelitis, and ends with identification of knowledge gaps.

Conclusion: Overall, the data overwhelmingly support the notion that CBD is immune suppressive and that the mechanisms involve direct suppression of activation of various immune cell types, induction of apoptosis, and promotion of regulatory cells, which, in turn, control other immune cell targets.

Cytokines in Pain: Harnessing Endogenous Anti-Inflammatory Signaling for Improved Pain Management

Current pain therapeutics offer inadequate relief to patients with chronic pain. A growing literature supports that pro-inflammatory cytokine signaling between immune, glial, and neural cells is integral to the development of pathological pain. Modulation of these communications may hold the key to improved pain management. In this review we first offer an overview of the relationships between pro-inflammatory cytokine and chemokine signaling and pathological pain, with a focus on the actions of cytokines and chemokines in communication between glia (astrocytes and microglia), immune cells (macrophages and T cells), and neurons. These interactions will be discussed in relation to both peripheral and central nervous system locations. Several novel non-neuronal drug targets for controlling pain are emerging as highly promising, including non-viral IL-10 gene therapy, which offer the potential for substantial pain relief through localized modulation of targeted cytokine pathways. Preclinical investigation of the mechanisms underlying the success of IL-10 gene therapy revealed the unexpected discovery of the powerful anti-nociceptive anti-inflammatory properties of D-mannose, an adjuvant in the non-viral gene therapeutic formulation. This review will include gene therapeutic approaches showing the most promise in controlling pro-inflammatory signaling via increased expression of anti-inflammatory cytokines like interleukin-10 (IL-10) or IL-4, or by directly limiting the bioavailability of specific pro-inflammatory cytokines, as with tumor necrosis factor (TNF) by the TNF soluble receptor (TNFSR). Approaches that increase endogenous anti-inflammatory signaling may offer additional opportunities for pain therapeutic development in patients not candidates for gene therapy. Promising novel avenues discussed here include the disruption of lymphocyte function-associated antigen (LFA-1) activity, antagonism at the cannabinoid 2 receptor (CB2R), and toll-like receptor 4 (TLR4) antagonism. Given the partial efficacy of current drugs, new strategies to manipulate neuroimmune and cytokine interactions hold considerable promise.

Psychotropic Drugs for the Management of Chronic Pain and Itch

Clinical observations have shown that patients with chronic neuropathic pain or itch exhibit symptoms of increased anxiety, depression and cognitive impairment. Such patients need corrective therapy with antidepressants, antipsychotics or anticonvulsants. It is known that some psychotropic drugs are also effective for the treatment of neuropathic pain and pruritus syndromes due to interaction with the secondary molecular targets. Our own clinical studies have identified antipruritic and/or analgesic efficacy of the following compounds: tianeptine (atypical tricyclic antidepressant), citalopram (selective serotonin reuptake inhibitor), mianserin (tetracyclic antidepressant), carbamazepine (anticonvulsant), trazodone (serotonin antagonist and reuptake inhibitor), and chlorprothixene (antipsychotic). Venlafaxine (serotonin-norepinephrine reuptake inhibitor) is known to have an analgesic effect too. The mechanism of such effect of these drugs is not fully understood. Herein we review and correlate the literature data on analgesic/antipruritic activity with pharmacological profile of these compounds.

Cannabinoids and Pain: New Insights From Old Molecules

Cannabis has been used for medicinal purposes for thousands of years. The prohibition of cannabis in the middle of the 20th century has arrested cannabis research. In recent years there is a growing debate about the use of cannabis for medical purposes. The term ‘medical cannabis’ refers to physician-recommended use of the cannabis plant and its components, called cannabinoids, to treat disease or improve symptoms. Chronic pain is the most commonly cited reason for using medical cannabis. Cannabinoids act via cannabinoid receptors, but they also affect the activities of many other receptors, ion channels and enzymes. Preclinical studies in animals using both pharmacological and genetic approaches have increased our understanding of the mechanisms of cannabinoid-induced analgesia and provided therapeutical strategies for treating pain in humans. The mechanisms of the analgesic effect of cannabinoids include inhibition of the release of neurotransmitters and neuropeptides from presynaptic nerve endings, modulation of postsynaptic neuron excitability, activation of descending inhibitory pain pathways, and reduction of neural inflammation. Recent meta-analyses of clinical trials that have examined the use of medical cannabis in chronic pain present a moderate amount of evidence that cannabis/cannabinoids exhibit analgesic activity, especially in neuropathic pain. The main limitations of these studies are short treatment duration, small numbers of patients, heterogeneous patient populations, examination of different cannabinoids, different doses, the use of different efficacy endpoints, as well as modest observable effects. Adverse effects in the short-term medical use of cannabis are generally mild to moderate, well tolerated and transient. However, there are scant data regarding the long-term safety of medical cannabis use. Larger well-designed studies of longer duration are mandatory to determine the long-term efficacy and long-term safety of cannabis/cannabinoids and to provide definitive answers to physicians and patients regarding the risk and benefits of its use in the treatment of pain. In conclusion, the evidence from current research supports the use of medical cannabis in the treatment of chronic pain in adults. Careful follow-up and monitoring of patients using cannabis/cannabinoids are mandatory.

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

Cannabidiol (CBD), the major non-psychotomimetic compound present in the Cannabis sativa plant, exhibits therapeutic potential for various human diseases, including chronic neurodegenerative diseases, such as Alzheimer's and Parkinson's, ischemic stroke, epilepsy and other convulsive syndromes, neuropsychiatric disorders, neuropathic allodynia and certain types of cancer. CBD does not bind directly to endocannabinoid receptors 1 and 2, and despite research efforts, its specific targets remain to be fully identified. Notably, sigma 1 receptor (σ1R) antagonists inhibit glutamate N-methyl-D-aspartate acid receptor (NMDAR) activity and display positive effects on most of the aforesaid diseases. Thus, we investigated the effects of CBD on three animal models in which NMDAR overactivity plays a critical role: opioid analgesia attenuation, NMDA-induced convulsive syndrome and ischemic stroke. In an in vitro assay, CBD disrupted the regulatory association of σ1R with the NR1 subunit of NMDAR, an effect shared by σ1R antagonists, such as BD1063 and progesterone, and prevented by σ1R agonists, such as 4-IBP, PPCC and PRE084. The in vivo administration of CBD or BD1063 enhanced morphine-evoked supraspinal antinociception, alleviated NMDA-induced convulsive syndrome, and reduced the infarct size caused by permanent unilateral middle cerebral artery occlusion. These positive effects of CBD were reduced by the σ1R agonists PRE084 and PPCC, and absent in σ1R-/- mice. Thus, CBD displays antagonist-like activity toward σ1R to reduce the negative effects of NMDAR overactivity in the abovementioned experimental situations.

Photobiomodulation induces antinociception, recovers structural aspects and regulates mitochondrial homeostasis in peripheral nerve of diabetic mice

Diabetic peripheral neuropathy (DPN) is a nervous disorder caused by diabetes mellitus, affecting about 50% of patients in clinical medicine. Chronic pain is one of the major and most unpleasant symptoms developed by those patients, and conventional available treatments for the neuropathy, including the associated pain, are still unsatisfactory and benefit only a small number of patients. Photobiomodulation (PBM) has been gaining clinical acceptance once it is able to promote early nerve regeneration resulting in significant improvement in peripheral nerves disabilities. In this work, the effects of PBM (660 nm, 30 mW, 1.6 J/cm² , 0.28 cm² , 15 s in a continuous frequency) on treating DPN-induced pain and nerve damage were evaluated in an experimental model of diabetic-neuropathy induced by streptozotocin in mice. PBM-induced antinociception in neuropathic-pain mice was dependent on central opioids release. After 21 consecutive applications, PBM increased nerve growth factor levels and induced structural recovery increasing mitochondrial content and regulating Parkin in the sciatic nerve of DPN-mice. Taking together, these data provide new insights into the mechanisms involved in the effects of PBM-therapy emphasizing its therapeutic potential in the treatment of DPN.

Plant-Based Cannabinoids for the Treatment of Chronic Neuropathic Pain

Chronic neuropathic pain is a prevalent condition that places a heavy burden on individuals and the healthcare system. Current medications have limitations and new approaches are needed, particularly given the current opioid crisis. There is some clinical evidence that the plant Cannabis sativa produces relief from neuropathic pain. However, current meta-analyses suggest that this efficacy is limited and there are problems with side effects. Most of this clinical research has examined whole cannabis, the psychoactive phytocannabinoid 9-tetrahydrocannabinol (THC), and nabiximols, which are a mixture of THC and the non-psychoactive phytocannabinoid cannabidiol. In the past, there has been little evidence based, preclinical animal research to guide clinical studies on phytocannabinoids. Recent animal studies indicate that while THC and high dose nabiximols are effective in animal neuropathic pain models, significant pain relief is only achieved at doses that produce substantial side effects. By contrast, cannabidiol and low dose nabiximols have moderate pain relieving efficacy, but are devoid of cannabinoid-like side effects. This animal data suggests that cannabidiol and low dose nabiximols warrant consideration for clinical studies, at least as adjuvants to current drugs. Preclinical research is also required to identify other phytocannabinoids that have therapeutic potential.