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

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“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.”

https://pubmed.ncbi.nlm.nih.gov/36355044/

https://www.liebertpub.com/doi/10.1089/can.2022.0096

Medical Cannabis Use and Inflammatory Cytokines and Chemokines Among Adult Chronic Pain Patients

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“Background: Utilizing cannabis as a therapeutic option for chronic pain (CP) has increased significantly. However, data regarding the potential immunomodulatory effects of cannabis in CP patients remain scarce. We aimed at exploring the relationship between cannabis use and inflammatory cytokines and chemokines among a cohort of CP patients. 

Methods: Adult patients with a CP diagnosis and medical authorization of cannabis were enrolled. Patients completed validated clinical questionnaires and self-reported the effectiveness of cannabis for symptom management. Patients’ blood and cannabis samples were analyzed for the presence of four major cannabinoids, two major cannabinoid metabolites, 29 different cytokines/chemokines, and cortisol. The multivariable linear regression model was used to identify cannabis and patient factors associated with immune markers. 

Results: Fifty-six patients (48±15 years; 64% females) were included, with dried cannabis (53%) being the most common type of cannabis consumed. Seventy percent of products were considered delta-9-tetrahydrocannabinol (Δ9-THC)-dominant. The majority of patients (96%) self-reported effective pain management, and 76% reported a significant decrease in analgesic medication usage (p≤0.001). Compared with males, female patients had higher plasma levels of cannabidiol (CBD), cannabidiolic acid, Δ9-THC, and 11-hydroxy-Δ9-tetrahydrocannabinol but lower concentrations of delta-9-tetrahydrocannabinolic acid and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). Females had significantly lower eotaxin levels (p=0.04) in comparison to male patients. The regression analysis indicated that high cannabis doses were related to increased levels of interleukin (IL)-12p40 (p=0.02) and IL-6 (p=0.01), whereas female sex was associated with decreased eotaxin (p≤0.01) concentrations. Blood CBD levels were associated with lower vascular endothelial growth factor (p=0.04) concentrations, and THC-COOH was a factor related to decreased tumor necrosis factor alpha (p=0.02) and IL-12p70 (p=0.03). 

Conclusion: This study provides further support for the patient-perceived effectiveness of cannabis in managing CP symptoms and reducing analgesic medication consumption. The results suggest a potential sex difference in metabolizing cannabinoids, and the varying immune marker concentrations may support a possible immunomodulatory effect associated with patient sex and cannabis product type. These preliminary findings provide grounds for further validation using larger, well-designed studies with longer follow-up periods.”

https://pubmed.ncbi.nlm.nih.gov/36342776/

https://www.liebertpub.com/doi/10.1089/can.2022.0143

” Flower Power”: Controlled Inhalation of THC-Predominant Cannabis Flos Improves Health-Related Quality of Life and Symptoms of Chronic Pain and Anxiety in Eligible UK Patients

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“In November 2018, the UK’s Home Office established a legal route for eligible patients to be prescribed cannabis-based products for medicinal use in humans (CBPMs) as unlicensed medicines. These include liquid cannabis extracts for oral administration (“oils”) and dried flowers for inhalation (“flos”). Smoking of CBPMs is expressly prohibited. To date, THC-predominant cannabis flowers remain the most prescribed CBPMs in project Twenty21 (T21), the first multi-center, prospective, observational UK cannabis patient registry. This observational, prospective data review analyzes patient-reported outcome measures (PROMS) collected by T21 associated with the inhalation of KHIRON 20/1, the most prescribed CBPM in the project. PROMS collected at baseline and at subsequent 3-month follow-up included health-related quality of life (HRQoL), general mood, and sleep. Condition-specific measures of illness severity were performed with the Brief Pain Inventory Short Form (BPI-SF) and the Generalized Anxiety Disorder 7-Item Scale (GAD-7). Participants (N = 344) were mostly males (77.6%, average age = 38.3) diagnosed mainly with chronic pain (50.9%) and anxiety-related disorders (25.3%). Inhalation of KHIRON 20/1 was associated with a marked increase in self-reported HRQoL, general mood, and sleep (N = 344; p < 0.001). Condition-specific assessments showed significant improvements in pain severity (T = 6.67; p < 0.001) and interference (T = 7.19; p < 0.001) in patients using KHIRON 20/1 for chronic pain (N = 174). Similar results were found for patients diagnosed with anxiety-related disorders (N = 107; T = 12.9; p < 0.001). Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos is associated with a significant improvement in patient-reported pain scores, mood, anxiety, sleep disturbances and overall HRQoL in a treatment-resistant clinical population.”

https://pubmed.ncbi.nlm.nih.gov/36289837/

“Our results indicate that controlled inhalation of pharmaceutical grade, THC-predominant cannabis flos was associated with a robust improvement in patient-reported pain scores, general mood, anxiety, sleep, and overall HRQoL in a treatment-resistant clinical population.”

https://www.mdpi.com/2227-9059/10/10/2576/htm

Cannabidiol as a modulator of α7 nicotinic receptors

SpringerLink

“Cannabidiol (CBD), an important terpenoid compound from marijuana with no psychoactive effects, has become of great pharmaceutical interest for several health conditions. As CBD is a multitarget drug, there is a need to establish the molecular mechanisms by which CBD may exert therapeutic as well as adverse effects. The α7 nicotinic acetylcholine receptor (α7 nAChR) is a cation-permeable ACh-gated channel present in the nervous system and in non-neuronal cells. It is involved in different pathological conditions, including neurological and neurodegenerative disorders, inflammation, and cancer. By high-resolution single-channel recordings and confocal microscopy, we here reveal how CBD modulates α7 nAChR ionotropic and metabotropic functions. CBD leads to a profound concentration-dependent decrease of α7 nAChR single-channel activity with an IC50 in the sub-micromolar range. The inhibition of α7 nAChR activity, which takes place through a membrane pathway, is neither mediated by receptor phosphorylation nor overcome by positive allosteric modulators and is compatible with CBD stabilization of resting or desensitized α7 nAChR conformational states. CBD modulation is complex as it also leads to the later appearance of atypical, low-frequency α7 nAChR channel openings. At the cellular level, CBD inhibits the increase in intracellular calcium triggered by α7 nAChR activation, thus decreasing cell calcium responses. The modulation of α7 nAChR is of pharmacological relevance and should be considered in the evaluation of CBD potential therapeutic uses. Thus, our study provides novel molecular information of CBD multiple actions and targets, which is required to set the basis for prospective applications in human health.”

https://pubmed.ncbi.nlm.nih.gov/36282426/

https://link.springer.com/article/10.1007/s00018-022-04600-y

“Targeting α7 nicotinic acetylcholine receptors for chronic pain”

https://pubmed.ncbi.nlm.nih.gov/36245927/

Efficacy and mechanism of the antinociceptive effects of cannabidiol on acute orofacial nociception induced by Complete Freund’s Adjuvant in male Mus musculus mice

Archives of Oral Biology

“Objectives: The objectives were to investigate the efficacy and mechanisms of cannabidiol on orofacial nociception induced by Complete Freund’s Adjuvant (CFA) in male Mus musculus mice.

Design: For the study of efficacy, mice were divided into seven groups: sham; inflammation; and cannabidiol 0.5, 1, 3, 5, and 10 mg. For the study of mechanisms of cannabidiol, mice were divided into six groups: sham, inflammation, calcitonin gene-related peptide (CGRP) antagonist with and without cannabidiol, and vanilloid receptor 1 antagonist with and without cannabidiol. Spontaneous pain-like behaviors, trigeminal nociception, and trigeminal modulating activity were investigated.

Results: CFA injected in the right masseter muscle significantly induced spontaneous pain-like behaviors and the trigeminal nociceptive pathway. This effect was inhibited by injection of 1, 3, 5, and 10 mg of cannabidiol. The 50 % inhibitory concentration of cannabidiol on antinociception was found to be 3 mg/kg. In addition, there was no difference in spontaneous pain-like behaviors with vanilloid receptor 1 antagonist injected before treatment with cannabidiol compared to saline control. Reduced c-fos expression was observed in the trigeminal nucleus caudalis and periaqueductal gray in the group injected with CGRP antagonist before treatment with cannabidiol.

Conclusion: The antinociceptive effects of cannabidiol induced by acute orofacial nociception is mediated by vanilloid receptor 1 but not by CGRP. Cannabidiol can act with peripheral nonpeptidergic neurons and can be used as an alternative drug or as a synergistic medication in pain treatment.”

https://pubmed.ncbi.nlm.nih.gov/36265395/

“Our results may imply that cannabidiol can be used as an alternative drug or as synergistic medication in orofacial pain treatment.”

https://www.sciencedirect.com/science/article/abs/pii/S0003996922002278?via%3Dihub

Medical Cannabis Patients Report Improvements in Health Functioning and Reductions in Opiate Use

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“Purpose: Opioid use rates have dropped as North American patients gain access to medical cannabis, indicating a harm reduction role, yet health outcomes remain mostly unexplored. This study presents self-reported medical cannabis use, perceptions of health functioning, and changes in opioid pain medication use in Florida medical cannabis patients.

Methods: Patients (n = 2,183) recruited from medical dispensaries across Florida completed a 66-item cross-sectional survey that included demographic, health, and medication usage items, along with items from the Medical Outcomes Survey (SF-36) to assess health functioning before and after cannabis initiation.

Results: Most participants were between the ages of 20 and 70 years of age (95%), over 54% were female, 47% were employed, and most (85%) were white. Commonly reported ailment groups were Pain and Mental Health combined (47.92%), Mental Health (28.86%) or Pain (9.07%). Health domains of bodily pain, physical functioning, and social functioning improved while limitations due to physical and emotional problems were unchanged. Most patients rated medical cannabis as being important to their quality of life. Many (60.98%) reported using pain medications prior to medical cannabis, 93.36% of these reported a change in pain medication after medical cannabis. The majority of participants (79%) reported either cessation or reduction in pain medication use following initiation of medical cannabis and 11.47% described improved functioning.

Conclusions: The findings suggest that some medical cannabis patients decreased opioid use without harming quality of life or health functioning, soon after the legalization of medical cannabis. The public health implications of medical cannabis as an alternative pain medication are discussed.”

https://pubmed.ncbi.nlm.nih.gov/36168127/

“In conclusion, some patients may reduce or even cease use of OBPM upon access to medical cannabis, potentially without harming quality of life or health functioning. This is suggestive of the harm reduction role and opioid-sparing effects of medical cannabis in a quality-controlled and regulated medical-use only state. Given the great individual and societal costs associated with the opioid crisis (Florence et al., 2021; National Institute on Drug Abuse, n.d.), the public health implications of these findings are important to consider.”

https://www.tandfonline.com/doi/full/10.1080/10826084.2022.2107673

Cannabidiol and Delta-9-Tetrahydrocannabinol Interactions in Male and Female Rats with Persistent Inflammatory Pain

The Journal of Pain

“Cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC), two of the primary constituents of cannabis, are used by some individuals to self-treat chronic pain. It is unclear whether the pain-relieving effects of CBD alone and in combination with THC are consistent across genders and among types of pain.

The present study compared the effects of CBD and THC given alone and in combination in male and female rats with Complete Freund’s adjuvant-induced inflammatory pain.

After induction of hindpaw inflammation, vehicle, CBD (0.05-2.5 mg/kg), THC (0.05-2.0 mg/kg), or a CBD:THC combination (3:1, 1:1, or 1:3 dose ratio) was administered i.p. twice daily for three days. Then on day four, mechanical allodynia, thermal hyperalgesia, weight-bearing, and locomotor activity were assessed 0.5-4 h after administration of the same dose combination. Hindpaw edema and open field (anxiety-like) behaviors were measured thereafter.

THC alone was anti-allodynic and anti-hyperalgesic, and decreased paw thickness, locomotion, and open field behaviors. CBD alone was anti-allodynic and anti-hyperalgesic. When combined with THC, CBD tended to decrease THC effects on pain-related behaviors and exacerbate THC-induced anxiety-like behaviors, particularly in females.

These results suggest that at the doses tested, CBD-THC combinations may be less beneficial than THC alone for the treatment of chronic inflammatory pain.

PERSPECTIVE: The present study compared CBD and THC effects alone and in combination in male and female rats with persistent inflammatory pain. This study could help clinicians who prescribe cannabis-based medicines for inflammatory pain conditions determine which cannabis constituents may be most beneficial.”

https://pubmed.ncbi.nlm.nih.gov/36122809/

“THC and CBD each reduced chronic inflammatory pain (allodynia and hyperalgesia) in rats.”

https://www.jpain.org/article/S1526-5900(22)00392-3/fulltext

[Cannabinoids for the treatment of chronic pain – an overview of current medical knowledge]

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“Cannabis has been used in medicine for thousands of years, yet its use for therapeutic purposes is still controversial. Meta-analysis of the literature has shown the effectiveness of cannabinoids only in some diseases. Researchers are particularly interested in their use in chronic pain management, which analgesic effect has been proved in many studies. A review of the literature indicates that cannabinoid preparations may be effective in the treatment of some chronic pain disorders, particularly in neuropathic pain, and should be considered as a possible therapeutic choice in the absence of a satisfactory analgesic effect with standard medications. The increasing number of countries approving cannabinoids for medical use creates an opportunity to conduct more clinical trials and collect better-quality data necessary to establish clear guidelines and consistent recommendations for specific pain disorders.”

https://pubmed.ncbi.nlm.nih.gov/36086988/

Long-term effects of a diet supplement containing Cannabis sativa oil and Boswellia serrata in dogs with osteoarthritis following physiotherapy treatments: a randomised, placebo-controlled and double-blind clinical trial

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“Dogs are commonly affected by Osteoarthritis (OA). Different approaches can be used to alleviate animals’ symptoms. In this randomised, placebo-controlled and double-blind clinical trial, we performed a three months follow-up study assessing the efficacy of a food supplement containing natural ingredients (Cannabis sativa oil, Boswellia serrata Roxb. Phytosome® and Zingiber officinale extract) in dogs with OA after the interruption of physiotherapy that was performed during the previous three months. Inflammation and oxidative stress were reduced in the treated group (higher glutathione (GSH) and lower C-reactive protein [CRP] levels in blood) as well as chronic pain.”

https://pubmed.ncbi.nlm.nih.gov/36067506/

https://www.tandfonline.com/doi/abs/10.1080/14786419.2022.2119967?journalCode=gnpl20

Cannabidivarin alleviates neuroinflammation by targeting TLR4 co-receptor MD2 and improves morphine-mediated analgesia

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“Toll-like receptor 4 (TLR4) is a pattern-recognition receptor (PRR) that regulates the activation of immune cells, which is a target for treating inflammation.

In this study, Cannabidivarin (CBDV), an active component of Cannabis, was identified as an antagonist of TLR4. In vitro, intrinsic protein fluorescence titrations revealed that CBDV directly bound to TLR4 co-receptor myeloid differentiation protein 2 (MD2). Cellular thermal shift assay (CETSA) showed that CBDV binding decreased MD2 stability, which is consistent with in silico simulations that CBDV binding increased the flexibility of the internal loop of MD2.

Moreover, CBDV was found to restrain LPS-induced activation of TLR4 signaling axes of NF-κB and MAPKs, therefore blocking LPS-induced pro-inflammatory factors NO, IL-1β, IL-6 and TNF-α. Hot plate test showed that CBDV potentiated morphine-induced antinociception. Furthermore, CBDV attenuated morphine analgesic tolerance as measured by the formalin test by specifically inhibiting chronic morphine-induced glial activation and pro-inflammatory factors expression in the nucleus accumbent.

This study confirms that MD2 is a direct binding target of CBDV for the anti-neuroinflammatory effect and implies that CBDV has great translational potential in pain management.”

https://pubmed.ncbi.nlm.nih.gov/36032146/

“The results imply that CBDV could be a potential therapeutic agent for improving morphine-mediated analgesia.”

https://www.frontiersin.org/articles/10.3389/fimmu.2022.929222/full