Cannabidiol increases the nociceptive threshold in a preclinical model of Parkinson’s disease.

Neuropharmacology

“Medications that improve pain threshold can be useful in the pharmacotherapy of Parkinson’s disease (PD). Pain is a prevalent PD’s non-motor symptom with a higher prevalence of analgesic drugs prescription for patients. However, specific therapy for PD-related pain are not available.

Since the endocannabinoid system is expressed extensively in different levels of pain pathway, drugs designed to target this system have promising therapeutic potential in the modulation of pain. Thus, we examined the effects of the 6-hydroxydopamine- induced PD on nociceptive responses of mice and the influence of cannabidiol (CBD) on 6-hydroxydopamine-induced nociception.

Further, we investigated the pathway involved in the analgesic effect of the CBD through the co-administration with a fatty acid amide hydrolase (FAAH) inhibitor, increasing the endogenous anandamide levels, and possible targets from anandamide, i.e., the cannabinoid receptors subtype 1 and 2 (CB1 and CB2) and the transient receptor potential vanilloid type 1 (TRPV1).

We report that 6-hydroxydopamine- induced parkinsonism decreases the thermal and mechanical nociceptive threshold, whereas CBD (acute and chronic treatment) reduces this hyperalgesia and allodynia evoked by 6-hydroxydopamine. Moreover, ineffective doses of either FAAH inhibitor or TRPV1 receptor antagonist potentialized the CBD-evoked antinociception while an inverse agonist of the CB1 and CB2 receptor prevented the antinociceptive effect of the CBD.

Altogether, these results indicate that CBD can be a useful drug to prevent the parkinsonism-induced nociceptive threshold reduction. They also suggest that CB1 and TRPV1 receptors are important for CBD-induced analgesia and that CBD could produce these analgesic effects increasing endogenous anandamide levels.”

https://www.ncbi.nlm.nih.gov/pubmed/31706993

“The CBD treatment decreases hyperalgesia and allodynia in experimental parkinsonism.”

https://www.sciencedirect.com/science/article/pii/S0028390819303703?via%3Dihub

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Cellular Distribution of Canonical and Putative Cannabinoid Receptors in Canine Cervical Dorsal Root Ganglia.

Image result for frontiers in veterinary science“Growing evidence indicates cannabinoid receptors as potential therapeutic targets for chronic pain.

Consequently, there is an increasing interest in developing cannabinoid receptor agonists for treating human and veterinary pain.

The present study may represent a morphological substrate to consider in order to develop therapeutic strategies against chronic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/31608295

“The anti-nociceptive potential of the endocannabinoid system has prompted the development of therapeutic cannabinoid receptors agonists or medical marjiuana to be used in pets in order to treat chronic pain.”

https://www.frontiersin.org/articles/10.3389/fvets.2019.00313/full

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Cannabinoid Receptor Type 1 and Its Role as an Analgesic: An Opioid Alternative?

 Publication Cover“Understanding how the body regulates pain is fundamental to develop rational strategies to combat the growing prevalence of chronic pain states, opioid dependency, and the increased financial burden to the medical care system.

Pain is the most prominent reason why Americans seek medical attention and extensive literature has identified the importance of the endocannabinoid pathway in controlling pain. Modulation of the endocannabinoid system offers new therapeutic opportunities for the selective control of excessive neuronal activity in several pain conditions (acute, inflammatory, chronic, and neuropathic).

Cannabinoids have a long history of medicinal use and their analgesic properties are well documented; however, there are major impediments to understanding cannabinoid pain modulation.

One major issue is the presence of psychotropic side effects associated with D9-tetrahydrocannabinol (THC) or synthetic derivatives, which puts an emphatic brake on their use. This dose-limiting effect prevents the appropriate degree of analgesia .

Animal studies have shown that the psychotropic effects are mediated via brain cannabinoid type 1 (CB1) receptors, while analgesic activity in chronic pain states may be mediated via CB1R action in the spinal cord, brainstem, peripheral sensory neurons, or immune cells.

The development of appropriate therapies is incumbent on our understanding of the role of peripheral versus central endocannabinoid-driven analgesia. Recent physiological, pharmacological, and anatomical studies provide evidence that one of the main roles of the endocannabinoid system is the regulation of gamma-aminobutyric acid (GABA) and/or glutamate release.

This article will review this evidence in the context of its implications for pain. We first provide a brief overview of CB1R’s role in the regulation of nociception, followed by a review of the evidence that the peripheral endocannabinoid system modulates nociception.

We then look in detail at regulation of central-mediated analgesia, followed up with evidence that cannabinoid mediated modulation of pain involves modulation of GABAergic and glutamatergic neurotransmission in key brain regions. Finally, we discuss cannabinoid action on non-neuronal cells in the context of inflammation and direct modulation of neurons.

This work stands to reveal long-standing controversies in the cannabinoid analgesia area that have had an impact on failed clinical trials and implementation of therapeutics targeting this system.”

https://www.ncbi.nlm.nih.gov/pubmed/31596190

https://www.tandfonline.com/doi/abs/10.1080/15504263.2019.1668100?journalCode=wjdd20

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Involvement of Spinal Cannabinoid CB2 Receptors in Exercise-Induced Antinociception.

Neuroscience“Muscle pain affects approximately 11-24% of the global population.

Several studies have shown that exercise is a non-pharmacological therapy to pain control. It has been suggested that the endocannabinoid system is involved in this antinociceptive effect.

The present study aimed to investigate whether spinal cannabinoid CB2 receptors participate in the exercise-induced antinociception.

The present study suggests that activation of spinal cannabinoid CB2 receptors and reduction of activated microglia are involved in exercise-induced antinociception.”

https://www.ncbi.nlm.nih.gov/pubmed/31473278

https://www.sciencedirect.com/science/article/abs/pii/S0306452219306165?via%3Dihub

“Exercise activates the endocannabinoid system.”  https://www.ncbi.nlm.nih.gov/pubmed/14625449

“The endocannabinoid system and pain.”  https://www.ncbi.nlm.nih.gov/pubmed/19839937

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Comparative studies of endocannabinoid modulation of pain.

Philosophical Transactions of the Royal Society B: Biological Sciences cover image

“Cannabinoid-based therapies have long been used to treat pain, but there remain questions about their actual mechanisms and efficacy. From an evolutionary perspective, the cannabinoid system would appear to be highly conserved given that the most prevalent endogenous cannabinoid (endocannabinoid) transmitters, 2-arachidonyl glycerol and anandamide, have been found throughout the animal kingdom, at least in the species that have been analysed to date. This review will first examine recent findings regarding the potential conservation across invertebrates and chordates of the enzymes responsible for endocannabinoid synthesis and degradation and the receptors that these transmitters act on. Next, comparisons of how endocannabinoids modulate nociception will be examined for commonalities between vertebrates and invertebrates, with a focus on the medicinal leech Hirudo verbana. Evidence is presented that there are distinct, evolutionarily conserved anti-nociceptive and pro-nociceptive effects. The combined studies across various animal phyla demonstrate the utility of using comparative approaches to understand conserved mechanisms for modulating nociception. This article is part of the Theo Murphy meeting issue ‘Evolution of mechanisms and behaviour important for pain’.”

https://www.ncbi.nlm.nih.gov/pubmed/31544609

https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0279

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Endocannabinoid modulation of inflammatory hyperalgesia in the IFN-α mouse model of depression.

Brain, Behavior, and Immunity“Depression is a well-recognised effect of long-term treatment with interferon-alpha (IFN-α), a widely used treatment for chronic viral hepatitis and malignancy. In addition to the emotional disturbances, high incidences of painful symptoms such as headache and joint pain have also been reported following IFN-α treatment.

The endocannabinoid system plays an important role in emotional and nociceptive processing, however it is unknown whether repeated IFN-α administration induces alterations in this system.

The present study investigated nociceptive responding in the IFN-α-induced mouse model of depression and associated changes in the endocannabinoid system. Furthermore, the effects of modulating peripheral endocannabinoid tone on inflammatory pain-related behaviour in the IFN-α model was examined.

In summary, increasing peripheral endocannabinoid tone attenuates inflammatory hyperalgesia induced following repeated IFN-α administration. These data provide support for the endocannabinoid system in mediating and modulating heightened pain responding associated with IFNα-induced depression.”

https://www.ncbi.nlm.nih.gov/pubmed/31505257

“Inflammatory hyperalgesia is associated with altered endocannabinoid levels. Enhancing peripheral endocannabinoid tone attenuates IFN-α related hyperalgesia.”

https://www.sciencedirect.com/science/article/pii/S0889159119306063?via%3Dihub

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The effects of cannabis, cannabinoids, and their administration routes on pain control efficacy and safety: A systematic review and network meta-analysis.

“To determine the effects of cannabis, cannabinoids, and their administration routes on pain and adverse euphoria events.

Randomized controlled trials investigating the effects of cannabis or cannabinoids on pain reduction.

RESULTS:

A total of 25 studies involving 2270 patients were included. We found that delta-9-tetrahydrocannabinol/cannabidiol (THC/CBD) (oromucosal route), THC (oromucosal route), and standardized dried cannabis (with THC; SCT; inhalation route) could reduce neuropathic pain score (SMD -0.41, 95% CI -0.7 to -0.1; -0.61, 95% CI -1.2 to -0.02; and -0.77, 95% CI -1.4 to -0.2; respectively). For nociceptive pain, only standardized cannabis extract (with THC; SCET) via oral route could reduce pain score (SMD -1.8, 95% C; -2.4 to -1.2). In cancer pain, THC/CBD via oromucosal route and THC via oral or oromucosal route could reduce pain score (SMD -0.7, 95% CI -1.2 to -0.2; and -2.1, 95% CI -2.8 to -1.4; respectively). No study was observed for THC/CBD via oral route or inhalation or THC via inhalation for cancer and nociceptive pain, SCET via oromucosal route or inhalation for neuropathic and cancer pain, THC via oromucosal route for nociceptive pain, and SCT via oromucosal or oral route for neuropathic, cancer, and nociceptive pain. Statistically significant increased risks of euphoria were observed in THC/CBD (oromucosal), THC (oromucosal), and SCT (inhalation).

CONCLUSION:

The use of cannabis and cannabinoids via certain administration routes could reduce different types of pain. Product developers could consider our findings as part of their product design so that the effective route of cannabis and cannabinoids for pain control can be achieved.”

https://www.ncbi.nlm.nih.gov/pubmed/31495691

https://www.japha.org/article/S1544-3191(19)30353-X/fulltext

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Opioid-enhancing antinociceptive effects of delta-9-tetrahydrocannabinol and amitriptyline in rhesus macaques.

Cover image for Experimental and Clinical Psychopharmacology“Cannabinoids can enhance the antinociceptive effects of opioids in a synergistic manner, potentially reducing the analgesic dosage of opioids and improving pain therapy. This strategy has also been used as a rationale to combine certain antidepressants and opioids.

In this experiment, opioid-induced thermal antinociception was assessed in rhesus macaques using a warm-water tail-withdrawal procedure with 3 water temperatures (40, 50, and 55 °C). In general, the acute antinociceptive effects of intramuscular (i.m.) cumulative doses of heroin were studied alone or in combination with i.m. (-)-trans-delta-9-tetrahydrocannabinol (THC), cannabinol (CBN), or the tricyclic antidepressant amitriptyline.

A nonantinociceptive dose of THC (1 mg/kg) shifted the ED50 for the heroin dose-effect curve 3.6-fold leftward at 50 °C and 1.9-fold leftward at 55 °C compared with heroin alone. When the cannabinoid type-1 receptor (CB1R) antagonist, rimonabant, was administered prior to the most effective THC-heroin combination, rimonabant blocked the THC enhancement of heroin antinociception. When CBN (1-3.2 mg/kg) was administered prior to heroin, or 1 mg/kg of CBN was administered prior to a combination of 0.32 mg/kg of THC and heroin, no shifts were evident in the heroin dose-effect curves at either temperature.

However, similar to THC, amitriptyline (0.32-1 mg/kg) administered prior to heroin significantly shifted the heroin dose-effect curve leftward. Heroin produced both dose- and temperature-dependent thermal antinociception in nonhuman primates and THC produced opioid-enhancing effects in a CB1R-dependent manner. These effects of THC were not shared by cannabinol, but were quantitatively similar to that of amitriptyline.”

https://www.ncbi.nlm.nih.gov/pubmed/31464475

https://psycnet.apa.org/doiLanding?doi=10.1037%2Fpha0000313

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Cannabis Use Motivations among Adults Prescribed Opioids for Pain versus Opioid Addiction.

Pain Management Nursing“Cannabis has been linked to reduced opioid use, although reasons for cannabis use among adults prescribed opioids are unclear.

The purpose of this study was to determine whether motivations for cannabis use differ between adults prescribed opioids for persistent pain versus those receiving opioids as medication-assisted treatment for opioid use disorder.

RESULTS:

More than half the sample (n = 122) reported current, daily cannabis use and 63% reported pain as a motivation for use. Adults with persistent pain were more likely to be older, female, and have higher levels of education (p < .05). Adults with opioid use disorder were more likely to report “enhancement” (p < .01) and relief of drug withdrawal symptoms (p < .001) as motivations for cannabis use. The most common reasons for cannabis use in both populations were social and recreational use and pain relief.

CONCLUSIONS:

Both studied populations have unmet health needs motivating them to use cannabis and commonly use cannabis for pain. Persistent pain participants were less likely to use cannabis for euphoric effects or withdrawal purposes. Nurses should assess for cannabis use, provide education on known risks and benefits, and offer options for holistic symptom management.”

https://www.ncbi.nlm.nih.gov/pubmed/31375419

https://www.painmanagementnursing.org/article/S1524-9042(19)30096-7/fulltext

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Cannabinoids reduce hyperalgesia and inflammation via interaction with peripheral CB1 receptors.

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“Central antinociceptive effects of cannabinoids have been well documented.

Our results indicate that cannabinoids produce antihyperalgesia via interaction with a peripheral CB1 receptor.

This hypothesis is supported by the finding that anandamide inhibited capsaicin-evoked release of calcitonin gene-related peptide from isolated hindpaw skin.

Collectively, these results indicate that cannabinoids reduce inflammation via interaction with a peripheral CB1 receptor.”

“The Endocannabinoid System and Pain. Cannabis has been used for more than twelve thousand years and for many different purposes (i.e. fiber, medicinal, recreational). However, the endocannabinoid signaling system has only recently been the focus of medical research and considered a potential therapeutic target. Cannabinoid receptors and their endogenous ligands are present at supraspinal, spinal and peripheral levels. Cannabinoids suppress behavioral responses to noxious stimulation and suppress nociceptive processing through activation of cannabinoid CB1 and CB2 receptor subtypes. These studies suggest that manipulation of peripheral endocannabinoids may be promising strategy for the management of pain.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2834283/

“The Analgesic Potential of Cannabinoids. Historically and anecdotally cannabinoids have been used as analgesic agents. Moreover, cannabinoids act synergistically with opioids and act as opioid sparing agents, allowing lower doses and fewer side effects from chronic opioid therapy. Thus, rational use of cannabis based medications deserves serious consideration to alleviate the suffering of patients due to severe pain.”  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3728280/
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