Category Archives: Neuropathic Pain

CB2 receptor deletion on myeloid cells enhanced mechanical allodynia in a mouse model of neuropathic pain.

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 Scientific Reports“Neuropathic pain can develop after nerve injury, leading to a chronic condition with spontaneous pain and hyperalgesia.

Pain is typically restricted to the side of the injured nerve, but may occasionally spread to the contralateral side, a condition that is often referred to as mirror-image pain.

Mechanisms leading to mirror-image pain are not completely understood, but cannabinoid CB2 receptors have been implicated.

In this study, we use genetic mouse models to address the question if CB2 receptors on neurons or on microglia/macrophages are involved.

We conclude that CB2 receptors on microglia and macrophages, but not on neurons, modulate neuropathic pain responses.”

https://www.ncbi.nlm.nih.gov/pubmed/31097758

https://www.nature.com/articles/s41598-019-43858-4

Analyzing the role of cannabinoids as modulators of Wnt/β-catenin signaling pathway for their use in the management of neuropathic pain.

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Bioorganic & Medicinal Chemistry Letters

“Neuropathic pain is a debilitating form of treatment-resistant chronic pain caused by damage to the nervous system. Cannabinoids have been known for suppressing neuropathic pain by modulating the endo cannabinoid system. Since the canonical Wnt/β-catenin signaling has recently been implicated in pain sensation, we investigated the impact of major cannabinoids (1-6) from the leaves of Cannabis sativa and an epoxy derivative of compound 2, here upon referred to as 2a, on modulating Wnt/β-catenin signaling pathway. The results presented in this study show that compound 1, 2 and 2a exhibited potent inhibitory activity against Wnt/β-catenin pathway in a dose-dependent manner. Compound 2a was seen to inhibit this pathway at slightly lower concentrations than its parent molecule 2, under similar conditions. Taken together, compound 1, 2 and 2a, by virtue of their inhibition of Wnt/β-catenin signaling pathway, could be developed as effective neuroprotective agents for the management of neuropathic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/30871771

https://www.sciencedirect.com/science/article/pii/S0960894X19301428?via%3Dihub

β-Caryophyllene, a Natural Sesquiterpene, Attenuates Neuropathic Pain and Depressive-Like Behavior in Experimental Diabetic Mice.

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 View details for Journal of Medicinal Food cover image“Neuropathic pain (NP) is associated with chronic hyperglycemia and emotional disorders such as depression in diabetic patients, complicating the course of treatment. Drugs currently used to treat NP have undesirable side effects, so research on other natural sources has been required.

β-caryophyllene (BCP), a natural sesquiterpene found in some food condiments and considered an agonist to cannabinoid receptor type 2, could have potential therapeutic effects to treat conditions such as NP and emotional disorders. For this reason, we assessed whether BCP modulates nociception, anxiety, and depressive-like behavior in streptozotocin (STZ)-induced experimental diabetic BALB/c female mice.

BCP was orally chronic administrated (10 mg/kg/60 μL). Pain developed with STZ was evaluated with von Frey filament test, SMALGO®, and hot plate test. Anxiety and depression-like behavior were assessed by marbles test, forced swim test, and tail suspension test. BCP significantly reduced glycemia in experimental diabetic mice. The pain was also mitigated by BCP administration. Depression-like behavior assessed with tail suspension test was attenuated with orally chronic BCP administration. Substance P and cytokines such as interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6) were also attenuated with BCP administration. NP was positively correlated with substance P and IL-6 and IL-1β release.

Our data using an orally chronic BCP administration in the STZ challenged mice to suggest that glycemia, diabetes-related NP, and depressive-like behavior could be prevented/reduced by dietary BCP.”

https://www.ncbi.nlm.nih.gov/pubmed/30864870

https://www.liebertpub.com/doi/10.1089/jmf.2018.0157

“β-caryophyllene (BCP) is a common constitute of the essential oils of numerous spice, food plants and major component in Cannabis.”   http://www.ncbi.nlm.nih.gov/pubmed/23138934

“Beta-caryophyllene is a dietary cannabinoid.”   https://www.ncbi.nlm.nih.gov/pubmed/18574142

Cannabinoids: a new approach for pain control?

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“To analyze available data related to the use of cannabinoids in medicine, with a special focus on pain management in cancer. The use of cannabis for medical purposes is growing but there are still numerous questions to be solved: effectiveness, safety, and specific indications.

RECENT FINDINGS:

There is considerable variation between countries in the approaches taken, reflecting a variety of historical and cultural factors and despite few randomized controlled studies using natural cannabinoids, there is a trend to state that the use of cannabis should be taken seriously as a potential treatment of cancer-related pain. Cannabidiol, a nontoxic phytocannabinoid with few side-effects is promising in various indications in medicine.

SUMMARY:

The endocannabinoid system is a potential therapeutic target. Cannabinoids may be considered as potential adjuvant in cancer-related pain management. Cannabidiol appears to be the drug of choice. Analgesic trial designs should evolve to get closer to real-life practice and to avoid biases.”

https://www.ncbi.nlm.nih.gov/pubmed/30789867

https://insights.ovid.com/crossref?an=00001622-900000000-00002

An Update of Current Cannabis-Based Pharmaceuticals in Pain Medicine.

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“Cannabis users have long reported therapeutic properties of the plant for a variety of conditions, some of which include nausea, emesis, seizures, cancer, neurogenic diseases and pain control. Research has elucidated many cannabinoid pharmacodynamic and pharmacokinetic properties, expanding the potential use of cannabinoids as a medical therapy.

Due to the inconsistent delivery and control of the active components involved with smoking, pharmaceutical companies are investigating and prioritizing routes other than smoke inhalation for therapeutic use of cannabinoids. In this relatively new field of pharmaceutical development, ongoing drug development promises great benefit from targeted endocannabinoid receptor agonism.

Available in Canada and Europe, nabiximols, a specific extract from the Cannabis plant, has demonstrated great benefit in the treatment of pain related to spasticity in multiple sclerosis, cancer and otherwise chronic pain conditions.

The cannabidiol oral solution Epidiolex®, which is available in the USA, is indicated for management of refractory epilepsy but may offer therapeutic relief to chronic pain conditions as well.

Current investigative drugs, such as those developed by Cara Therapeutics and Zynerba Pharmaceuticals, are synthetic cannabinoids which show promise to specifically target neuropsychiatric conditions and chronic pain symptoms such as neuropathy and allodynia.

The objective of this review is to provide clinicians with an update of currently available and promising developmental cannabis pharmaceutical derivatives which may stand to greatly benefit patients with otherwise difficult-to-treat chronic conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/30721403

https://link.springer.com/article/10.1007%2Fs40122-019-0114-4

A Cost-Effectiveness Model for Adjunctive Smoked Cannabis in the Treatment of Chronic Neuropathic Pain

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“A recent meta-analysis affirmed the benefit of medicinal cannabis for chronic neuropathic pain, a disabling and difficult-to-treat condition. As medicinal cannabis use is becoming increasingly prevalent among Americans, an exploration of its economic feasibility is warranted. We present this cost-effectiveness analysis of adjunctive cannabis pharmacotherapy for chronic peripheral neuropathy.

A growing body of scientific literature demonstrates reproducible efficacy of cannabis in the treatment of several medical conditions, including chronic neuropathic pain. Clinical trials of oral, smoked, and vaporized cannabis and cannabinoids have all demonstrated analgesic benefit of medicinal cannabis in the treatment of this costly and disabling condition. A recent meta-analysis of individual patient data from five randomized controlled trials of inhaled cannabis demonstrated pain relief comparable to gabapentin. Treatment guidelines for neuropathic pain recommend consideration of cannabinoids as third-line agents.

As recently proposed willingness-to-pay thresholds for the United States health marketplace range from $110,000 to $300,000 per QALY, cannabis appears cost-effective when augmenting second-line treatment for painful neuropathy. Further research is warranted to explore the long-term benefit of smoked cannabis and standardization of its dosing for chronic neuropathic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/30944870

https://www.liebertpub.com/doi/10.1089/can.2018.0027

“New study analyzes cost effectiveness of smoked cannabis to treat chronic neuropathic pain” https://www.eurekalert.org/pub_releases/2019-01/mali-nsa012919.php

Cannabinoids-induced peripheral analgesia depends on activation of BK channels.

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 Brain Research“The endogenous cannabinoid system is involved in the physiological inhibitory control of pain and is of particular interest for the development of therapeutic approaches for pain management.

Selective activation of the peripheral CB1 cannabinoid receptor has been shown to suppress the heightened firing of primary afferents, which is the peripheral mechanism underlying neuropathic pain after nerve injury. However, the mechanism underlying this effect of CB1 receptor remains unclear.

The large-conductance calcium-activated potassium (BK) channels have been reported to participate in anticonvulsant and vasorelaxant effects of cannabinoids. We asked whether BK channels participate in cannabinoids-induced analgesia and firing-suppressing effects in primary afferents after nerve injury.

Here, using mice with chronic constriction injury(CCI)-induced neuropathic pain, antinociception action and firing-suppressing effect of HU210 were measured before and after BK channel blocker application. We found that local peripheral application of HU210 alleviated CCI-induced pain behavior and suppressed the heightened firing of injured fibers. Co-administration of IBTX with HU210 significantly reversed the analgesia and the firing-suppressing effect of HU210.

This result indicated that the peripheral analgesic effects of cannabinoids depends on activation of BK channels.”

https://www.ncbi.nlm.nih.gov/pubmed/30615887

https://www.sciencedirect.com/science/article/pii/S0006899319300071?via%3Dihub

Cannabinoids and Pain: New Insights From Old Molecules.

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“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.”

https://www.ncbi.nlm.nih.gov/pubmed/30542280

https://www.frontiersin.org/articles/10.3389/fphar.2018.01259/full

Cannabidiol modulates serotonergic transmission and reverses both allodynia and anxiety-like behavior in a model of neuropathic pain

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“Clinical studies indicate that cannabidiol (CBD), the primary nonaddictive component of cannabis that interacts with the serotonin (5-HT)1A receptor, may possess analgesic and anxiolytic effects.

Overall, repeated treatment with low-dose CBD induces analgesia predominantly through TRPV1 activation, reduces anxiety through 5-HT1A receptor activation, and rescues impaired 5-HT neurotransmission under neuropathic pain conditions.”

https://www.ncbi.nlm.nih.gov/pubmed/30157131

https://insights.ovid.com/crossref?an=00006396-900000000-98870

THC and gabapentin interactions in a mouse neuropathic pain model.

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Neuropharmacology

“Clinical studies have shown that the major psychoactive ingredient of Cannabis sativa Δ9-tetrahydrocannabinol (THC) has some analgesic efficacy in neuropathic pain states.

However, THC has a significant side effect profile. We examined whether the profile of THC could be improved by co-administering it with the first-line neuropathic pain medication gabapentin.

These findings indicate that gabapentin synergistically enhances the anti-allodynic actions of THC and improves its therapeutic window.

Thus, THC may represent a potential adjuvant for neuropathic pain medications such as gabapentin.”

https://www.ncbi.nlm.nih.gov/pubmed/30312630

https://www.sciencedirect.com/science/article/pii/S0028390818307779?via%3Dihub