Category Archives: Pain

Modulation of Human Peripheral Blood Mononuclear Cell Signaling by Medicinal Cannabinoids.

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“Medical marijuana is increasingly prescribed as an analgesic for a growing number of indications, amongst which terminal cancer and multiple sclerosis.

In this study we aimed to investigate the immune-cell modulatory properties of medical cannabis.

Healthy volunteers were asked to ingest medical cannabis, and kinome profiling was used to generate comprehensive descriptions of the cannabis challenge on inflammatory signal transduction in the peripheral blood of these volunteers.

Results were related to both short term and long term effects in patients experimentally treated with a medical marijuana preparation for suffering from abdominal pain as a result of chronic pancreatitis or other causes.

The results reveal an immunosuppressive effect of cannabinoid preparations via deactivation of signaling through the pro-inflammatory p38 MAP kinase and mTOR pathways and a concomitant deactivation of the pro-mitogenic ERK pathway. However, long term cannabis exposure in two patients resulted in reversal of this effect.

While these data provide a powerful mechanistic rationale for the clinical use of medical marijuana in inflammatory and oncological disease, caution may be advised with sustained use of such preparations.”

https://www.ncbi.nlm.nih.gov/pubmed/28174520

http://journal.frontiersin.org/article/10.3389/fnmol.2017.00014/full

Use of medical cannabis to reduce pain and improve quality of life in cancer patients.

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“Early attention to pain and symptoms in those with cancer improves both quality of life and survival. Opioid medications are the mainstay treatment of cancer-related pain.

Cannabinoids are increasingly used as adjunctive treatments for cancer pain, but clinical evidence supporting their use as an “opioid sparing agent” or to improve quality of life is as yet unknown. Our study sought to determine if the addition of cannabinoids (medical cannabis) resulted in the reduction of the average opioid dose required for pain control, and improve self-reported quality of life indices.

CONCLUSIONS:

Patients with cancer pain benefited from the addition of cannabinoids. The average opioid dose decreased following access to medical cannabis. Self-reported ratings of several quality of life indicators showed statistically significant improvement. Our study shows a signal that cannabinoids may reduce cancer patients’ reliance on opioids to control pain. Further prospective controlled studies are needed to further elucidate the role of cannabinoids in the treatment of cancer pain.”

https://www.ncbi.nlm.nih.gov/pubmed/28148191

Antihyperalgesic effect of CB1 receptor activation involves the modulation of P2X3 receptor in the primary afferent neuron.

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“Cannabinoid system is a potential target for pain control.

Cannabinoid receptor 1 (CB1) activation play a role in the analgesic effect of cannabinoids once it is expressed in primary afferent neurons.

This study investigates whether the anti-hyperalgesic effect of CB1receptor activation involves P2×3 receptor in primary afferent neurons.

Our data suggest that the analgesic effect of CB1 receptor activation is mediated by a negative modulation of the P2×3 receptor in the primary afferent neurons.”

https://www.ncbi.nlm.nih.gov/pubmed/28131783

Compensatory Activation of Cannabinoid CB2 Receptor Inhibition of GABA Release in the Rostral Ventromedial Medulla in Inflammatory Pain.

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“The rostral ventromedial medulla (RVM) is a relay in the descending pain modulatory system and an important site of endocannabinoid modulation of pain.

Our data provide evidence that CB2 receptor function emerges in the RVM in persistent inflammation and that selective CB2 receptor agonists may be useful for treatment of persistent inflammatory pain.

SIGNIFICANCE STATEMENT:

These studies demonstrate that endocannabinoid signaling to CB1 and CB2 receptors in adult rostral ventromedial medulla is altered in persistent inflammation. The emergence of CB2 receptor function in the rostral ventromedial medulla provides additional rationale for the development of CB2 receptor-selective agonists as useful therapeutics for chronic inflammatory pain.”

https://www.ncbi.nlm.nih.gov/pubmed/28100744

Synergistic attenuation of chronic pain using mu opioid and cannabinoid receptor 2 agonists.

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“The misuse of prescription opiates is on the rise with combination therapies (e.g. acetaminophen or NSAIDs) resulting in severe liver and kidney damage. In recent years, cannabinoid receptors have been identified as potential modulators of pain and rewarding behaviors associated with cocaine, nicotine and ethanol in preclinical models. Yet, few studies have identified whether mu opioid agonists and CB2 agonists act synergistically to inhibit chronic pain while reducing unwanted side effects including reward liability.

We determined if analgesic synergy exists between the mu-opioid agonist morphine and the selective CB2 agonist, JWH015, in rodent models of acute and chronic inflammatory, post-operative, and neuropathic pain using isobolographic analysis. We also investigated if the MOR-CB2 agonist combination decreased morphine-induced conditioned place preference (CPP) and slowing of gastrointestinal transit. Co-administration of morphine with JWH015 synergistically inhibited preclinical inflammatory, post-operative and neuropathic-pain in a dose- and time-dependent manner; no synergy was observed for nociceptive pain. Opioid-induced side effects of impaired gastrointestinal transit and CPP were significantly reduced in the presence of JWH015.

Here we show that MOR + CB2 agonism results in a significant synergistic inhibition of preclinical pain while significantly reducing opioid-induced unwanted side effects.

The opioid sparing effect of CB2 receptor agonism strongly supports the advancement of a MOR-CB2 agonist combinatorial pain therapy for clinical trials.”

https://www.ncbi.nlm.nih.gov/pubmed/28007501

Compensatory activation of cannabinoid CB2 receptor inhibition of GABA release in the rostral ventromedial medulla (RVM) in inflammatory pain.

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“The rostral ventromedial medulla (RVM) is a relay in the descending pain modulatory system and an important site of endocannabinoid modulation of pain.

These studies demonstrate that endocannabinoid signaling to CB1- and CB2-receptors in adult RVM is altered in persistent inflammation.

The emergence of CB2 receptor function in the RVM provides additional rationale for the development of CB2 receptor-selective agonists as useful therapeutics for chronic inflammatory pain.”

https://www.ncbi.nlm.nih.gov/pubmed/27940994

A novel inhibitor of endocannabinoid catabolic enzymes sheds light on behind the scene interplay between chronic pain, analgesic tolerance, and heroin dependence.

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“From the Aristotelian ancient Greece, pain has been associated with appetites or emotions and is opposite to pleasure. Reward and addiction is also linked to pleasure and compulsive drug seeking reinstates pleasure.

Alleviation of chronic pain can induce a euphoric phase similar to what is found in addiction. Both chronic pain and addiction are recognized as a disease of the central nervous system. They share many characteristics and brain regions/mechanisms.

Evidence points to the usefulness of cannabinoids as a new class of agents to add to the pharmaceutical toolbox in the management of chronic pain.

Wilkerson and colleagues, in this issue, examine SA-57, an inhibitor of two different endocannabinoid catabolic enzymes FAAH and MAGL, demonstrating its analgesic effectiveness and morphine-sparing properties in a chronic pain model, as well as its ability to reduce heroin seeking behavior in a self-administration paradigm in mice.

This timely study emphasizes the need for development of more efficacious chronic pain therapeutics with minimized abuse potential and/or reinforcing properties. It also highlights the need for better understanding of the overlapping circuitry of chronic pain, reward, and addiction.”

https://www.ncbi.nlm.nih.gov/pubmed/27890603

The endocannabinoid hydrolysis inhibitor SA-57: Intrinsic antinociceptive effects, augmented morphine-induced antinociception, and attenuated heroin seeking behavior in mice.

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“Although opioids are highly efficacious analgesics, their abuse potential and other untoward side effects diminish their therapeutic utility. The addition of non-opioid analgesics offers a promising strategy to reduce required antinociceptive opioid doses that concomitantly reduce opioid-related side effects.

Inhibitors of the primary endocannabinoid catabolic enzymes fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) show opioid-sparing effects in preclinical models of pain. As simultaneous inhibition of these enzymes elicits enhanced antinociceptive effects compared with single enzyme inhibition, the present study tested whether the dual FAAH-MAGL inhibitor SA-57 [4-[2-(4-chlorophenyl)ethyl]-1-piperidinecarboxylic acid 2-(methylamino)-2-oxoethyl ester] produces morphine-sparing antinociceptive effects, without major side effects associated with either drug class.

Although high doses of SA-57 alone were required to produce antinociception, low doses of this compound, which elevated AEA and did not affect 2-AG brain levels, augmented the antinociceptive effects of morphine, but lacked cannabimimetic side effects.

Because of the high abuse liability of opioids and implication of the endocannabinoid system in the reinforcing effects of opioids, the final experiment tested whether SA-57 would alter heroin seeking behavior. Strikingly, SA-57 reduced heroin-reinforced nose poke behavior and the progressive ratio break point for heroin.

In conclusion, the results of the present study suggest that inhibition of endocannabinoid degradative enzymes represents a promising therapeutic approach to decrease effective doses of opioids needed for clinical pain control, and may also possess therapeutic potential to reduce opioid abuse.”

https://www.ncbi.nlm.nih.gov/pubmed/27890602

State of the evidence: Cannabinoids and cancer pain-A systematic review.

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“Cannabinoids are widely used to alleviate intractable symptoms such as pain, nausea, and muscle spasticity. The purpose of this review was to ascertain the current state of the science regarding use of cannabinoids for cancer pain.

CONCLUSIONS:

Eight randomized control trials met the inclusion criteria for review. Most trials found analgesic effects from cannabinoids when compared to placebo, although not all associations reached statistical significance. The analgesic effects of cannabinoids were also limited by dose-dependent side effects. Side effects most commonly reported were changes in cognition, sedation, and dizziness.

IMPLICATIONS FOR PRACTICE:

There is evidence that cannabinoids are effective adjuvants for cancer pain not completely relieved by opioid therapy, but there is a dearth of high-quality studies to support a stronger conclusion. Cannabinoids appear to be safe in low and medium doses. Methodological limitations of the trials limited the ability to make sound conclusions. Further research is warranted before efficacy, safety, and utility of cannabinoids for cancer pain can be determined.”

https://www.ncbi.nlm.nih.gov/pubmed/27863159

The central cannabinoid receptor type-2 (CB2) and chronic pain.

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“Cannabinoid receptor type-2 (CB2, CB2 Receptor, or CB2-R) mediates analgesia, via two mechanisms. CB2 receptors contained in peripheral immune tissue mediates analgesia by altering cytokine profiles, and thus has little adverse effects on central nervous systems. CB2 is also expressed in the neurons and glial cells of the Central Nervous System (CNS). This neuronal expression may also contribute to pain attenuation. The CB2 receptor has been proposed as a potential target in treating chronic pain of several etiologies.”

https://www.ncbi.nlm.nih.gov/pubmed/27842450