Category Archives: Pain

Reinforcing effects of opioid/cannabinoid mixtures in rhesus monkeys responding under a food/drug choice procedure.

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Psychopharmacology

“Cannabinoid receptor agonists such as delta-9-tetrahydrocannabinol (Δ9-THC) enhance the antinociceptive potency of mu opioid receptor agonists such as morphine, indicating that opioid/cannabinoid mixtures might be effective for treating pain. However, such enhancement will be beneficial only if cannabinoids do not also enhance adverse effects of opioids, including those related to abuse.

In rhesus monkeys, cannabinoids fail to enhance and often decrease self-administration of the mu opioid receptor agonist heroin, suggesting that opioid/cannabinoid mixtures do not have greater reinforcing effects (abuse potential) compared with opioids alone. Previous studies on the self-administration of opioid/cannabinoid mixtures used single-response procedures, which do not easily differentiate changes in reinforcing effects from other effects (e.g., rate decreasing).

CONCLUSION:

Overall, these results extend previous studies to include choice behavior and show that cannabinoids do not substantially enhance the reinforcing effects of mu opioid receptor agonists.”

 https://www.ncbi.nlm.nih.gov/pubmed/29860612
https://link.springer.com/article/10.1007%2Fs00213-018-4932-6

Including cannabinoids in the treatment of painful schwannomatosis.

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“A 47‐year‐old man, affected by Schwannomatosis, presented a very severe pain (10/10, NRS) with paroxysmal shooting episodes, allodynia, paresthesia, and dysesthesia; in parallel, the patient had lost weight (from 70 to 49 kg) and experienced fatigue and deep depression. The previous pain prescription, including opioids and antineutopathic drugs, was fully ineffective. We progressively substituted this therapy with 15 drops, 3 times/daily, of THC/CBD in a concentration ratio 5:1, equal to 15 mg of active substance each time, reaching improvement in pain intensity (6/10) and in several other aspects as mood and quality of life”

https://www.ncbi.nlm.nih.gov/pubmed/29845778  

https://onlinelibrary.wiley.com/doi/abs/10.1002/brb3.1011

“Schwannomatosis is a rare genetic disorder that results in tumors (called schwannomas) that grow on the peripheral nerves throughout the body. It is recognized most often in people over the age of 30. Schwannomatosis can cause severe, debilitating pain and neurological dysfunction.”  https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_clinics/neurofibromatosis/schwannomatosis/index.html

Ventilatory-depressant effects of opioids alone and in combination with cannabinoids in rhesus monkeys.

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“Pain is a serious health problem that is commonly treated with opioids, although the doses of opioids needed to treat pain are often similar to those that decrease respiration. Combining opioids with drugs that relieve pain through non-opioid mechanisms can decrease the doses of opioids needed for analgesia, resulting in an improved therapeutic window, but only if the doses of opioids that decrease respiration are not similarly decreased. Using small doses of opioids to treat pain has the potential to reduce the number of overdoses and deaths.

This study investigated whether the cannabinoid receptor agonists Δ9-tetrahydrocannabinol (Δ9-THC) and CP 55,940 modify the ventilatory-depressant effects of morphine and fentanyl in three monkeys.

In summary, cannabinoid receptor agonists, which increase the potency of opioids to produce antinociception, did not increase their potency to depress ventilation. Thus, the therapeutic window is greater for opioids when they are combined with cannabinoid receptor agonists, indicating a possible advantage for these drug mixtures in treating pain.”

https://www.ncbi.nlm.nih.gov/pubmed/29807027

https://www.sciencedirect.com/science/article/pii/S0014299918303108

Patterns of medicinal cannabis use, strain analysis, and substitution effect among patients with migraine, headache, arthritis, and chronic pain in a medicinal cannabis cohort.

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“Medicinal cannabis registries typically report pain as the most common reason for use. It would be clinically useful to identify patterns of cannabis treatment in migraine and headache, as compared to arthritis and chronic pain, and to analyze preferred cannabis strains, biochemical profiles, and prescription medication substitutions with cannabis.

RESULTS:

Of 2032 patients, 21 illnesses were treated with cannabis. Pain syndromes accounted for 42.4% (n = 861) overall; chronic pain 29.4% (n = 598;), arthritis 9.3% (n = 188), and headache 3.7% (n = 75;). Across all 21 illnesses, headache was a symptom treated with cannabis in 24.9% (n = 505). These patients were given the ID Migraine™ questionnaire, with 68% (n = 343) giving 3 “Yes” responses, 20% (n = 102) giving 2 “Yes” responses (97% and 93% probability of migraine, respectively). Therefore, 88% (n = 445) of headache patients were treating probable migraine with cannabis. Hybrid strains were most preferred across all pain subtypes, with “OG Shark” the most preferred strain in the ID Migraine™ and headache groups. Many pain patients substituted prescription medications with cannabis (41.2-59.5%), most commonly opiates/opioids (40.5-72.8%). Prescription substitution in headache patients included opiates/opioids (43.4%), anti-depressant/anti-anxiety (39%), NSAIDs (21%), triptans (8.1%), anti-convulsants (7.7%), muscle relaxers (7%), ergots (0.4%).

CONCLUSIONS:

Chronic pain was the most common reason for cannabis use, consistent with most registries. The majority of headache patients treating with cannabis were positive for migraine. Hybrid strains were preferred in ID Migraine™, headache, and most pain groups, with “OG Shark”, a high THC (Δ9-tetrahydrocannabinol)/THCA (tetrahydrocannabinolic acid), low CBD (cannabidiol)/CBDA (cannabidiolic acid), strain with predominant terpenes β-caryophyllene and β-myrcene, most preferred in the headache and ID Migraine™ groups. This could reflect the potent analgesic, anti-inflammatory, and anti-emetic properties of THC, with anti-inflammatory and analgesic properties of β-caryophyllene and β-myrcene. Opiates/opioids were most commonly substituted with cannabis. Prospective studies are needed, but results may provide early insight into optimizing crossbred cannabis strains, synergistic biochemical profiles, dosing, and patterns of use in the treatment of headache, migraine, and chronic pain syndromes.”

 https://www.ncbi.nlm.nih.gov/pubmed/29797104
https://thejournalofheadacheandpain.springeropen.com/articles/10.1186/s10194-018-0862-2

Self-initiated use of topical cannabidiol oil for epidermolysis bullosa.

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“Epidermolysis bullosa is a rare blistering skin disorder that is challenging to manage because skin fragility and repeated wound healing cause itching, pain, limited mobility, and recurrent infections.

Cannabidiol, an active cannabinoid found in cannabis, is postulated to have antiinflammatory and analgesic effects.

We report 3 cases of self-initiated topical cannabidiol use in patients with epidermolysis bullosa in an observational study.

One patient was weaned completely off oral opioid analgesics. All 3 reported faster wound healing, less blistering, and amelioration of pain with cannabidiol use.

Although these results demonstrate promise, further randomized, double-blind clinical trials are necessary to provide scientific evidence of our observed benefits of cannabidiol for the treatment of epidermolysis bullosa.”

https://www.ncbi.nlm.nih.gov/pubmed/29786144

https://onlinelibrary.wiley.com/doi/abs/10.1111/pde.13545

Cannabinoid WIN-55,212-2 mesylate inhibits tumor necrosis factor-α-induced expression of nitric oxide synthase in dorsal root ganglion neurons.

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“Tumor necrosis factor-α (TNF-α) is an established pain modulator in the peripheral nervous system. Elevated levels of TNF-α in dorsal root ganglion (DRG) neurons reportedly is critical for neuropathic pain processing. It has been shown that the production of nitric oxide, a key player in the development and maintenance of nociception, depends on the expression of nitric oxide synthases (NOSs) and their activities.

Accumulating evidence also supports an important role of cannabinoids in modulating neuropathic pain.

In this study, we explored the effects and the underlying mechanisms of crosstalk between TNF-α and cannabinoid on the expression/activity of NOS in DRG neurons.

Our findings suggest that TNF-α induces the expression/activity of nNOS in DRG neurons by increasing its mRNA stability by a p38 MAPK-dependent mechanism; WIN-55 inhibits this effect of TNF-α by inhibiting p38 MAPK via CB2.

By linking the functions of TNF-α, NOS and cannabinoid in DRG neurons, this study adds new insights into the molecular mechanisms underlying the pharmacologic effects of cannabinoids on neuropathic pain as well as into the pathophysiology of neuropathic pain.”

https://www.ncbi.nlm.nih.gov/pubmed/29786105

https://www.spandidos-publications.com/10.3892/ijmm.2018.3687

Cannabinoids in the Management of Musculoskeletal Pain: A Critical Review of the Evidence

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  • “The purposes of the present scoping review were to identify (1) the available studies regarding the efficacy of cannabinoids for the management of musculoskeletal pain and related conditions and (2) the knowledge gaps and opportunities in this area of research.
  • There is little high-quality evidence for medical cannabis in the core orthopaedic areas of arthritis, postoperative pain, back pain, and trauma-related pain.
  • The “best available” evidence suggests cannabis can be effective for managing arthritis pain, back pain, and trauma-related pain, although the quality of the evidence is poor.
  • Evidence regarding the use of cannabinoids for the management of postoperative pain is mixed.
  • Research on pain control in patients with arthritis, conditions related to the spine, and traumatic injuries represents major under-represented areas of study for the role of cannabinoids, and high-quality Level-I studies are needed.”

https://journals.lww.com/jbjsreviews/Abstract/latest/Cannabinoids_in_the_Management_of_Musculoskeletal.99892.aspx

A peripherally restricted cannabinoid 1 receptor agonist as a novel analgesic in cancer-induced bone pain.

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“Many malignant cancers, including breast cancer, have a propensity to invade bones, leading to excruciating bone pain.

Opioids are the primary analgesics used to alleviate this cancer-induced bone pain (CIBP) but are associated with numerous severe side effects, including enhanced bone degradation, which significantly impairs patients’ quality of life.

In contrast, agonists activating only peripheral CB1 receptors (CB1Rs) have been shown to effectively alleviate multiple chronic pain conditions with limited side effects, yet no studies have evaluated their role(s) in CIBP.

Here, we demonstrate for the first time that a peripherally selective CB1R agonist can effectively suppress CIBP.

Overall, our studies demonstrate that CIBP can be effectively managed by using a peripherally restricted CB1R agonist, PrNMI, without inducing dose-limiting central side effects.

Thus, targeting peripheral CB1Rs could be an alternative therapeutic strategy for the treatment of CIBP.”

 https://www.ncbi.nlm.nih.gov/pubmed/29781960
https://insights.ovid.com/crossref?an=00006396-900000000-98957

Endogenous systems involved in exercise-induced analgesia.

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“Exercise-induced analgesia is a phenomenon discussed worldwide. This effect began to be investigated in the early 1970s in healthy individuals and rodents during and after an acute or chronic session of running or swimming. Thereafter, studies found this effect was also induced by resistance exercises. Over the years, many studies have demonstrated the importance of exercise-induced analgesia in relieving pain caused by different conditions, such as fibromyalgia, low back pain, neuropathy, and osteoarthritis. This review aims to provide the reader with an in-depth description of the main endogenous systems, substances, neurotransmitters, receptors and enzymes that are thought to be involved in the analgesic effect induced by exercise. Many hypotheses have been proposed to elucidate the mechanisms responsible for exercise-induced analgesia. One of the most accepted hypotheses has been the activation of several endogenous systems described as analgesics. Studies have demonstrated that during and after exercise different endogenous systems are activated, which release substances or neurotransmitters, such as opioids, nitric oxide, serotonin, catecholamines and endocannabinoids, that may modulate the pain perception.”  https://www.ncbi.nlm.nih.gov/pubmed/29769416

http://www.jpp.krakow.pl/journal/archive/02_18/pdf/jpp.2018.1.01.pdf

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

Cannabinoid 1 receptors are expressed in nociceptive primary sensory neurons.

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 Neuroscience

“Expression of cannabinoid 1 (CB1) and vanilloid 1 (VR1) receptor proteins was studied in adult, cultured rat dorsal root ganglion neurons. Immunostaining of CB1 receptors alone produced labelling in 57+/-2% of the cultured dorsal root ganglion neurons (n=3 cultures). The area of the labelled cells was between 200 and 800 microm(2) with an average of 527+/-68 microm(2). VR1 immunolabelling revealed immunopositivity in 42+/-6% of the total population of dorsal root ganglion neurons. Cells showing VR1-like immunopositivity had an area between 200 and 600 microm(2). The mean area of the VR1-like immunopositive neurons was 376+/-61 microm(2). Double immunostaining with antisera raised against the CB1 and VR1 receptor proteins, showed a high degree of co-expression between CB1 and VR1 receptors. An average of 82+/-3% of the CB1-like immunopositive cells also showed VR1-like immunoreactivity (n=3 cultures) while 98+/-2% of the VR1-like immunolabelled neurons showed CB1 receptor-like immunostaining (n=3 cultures). Our data suggests that nociceptive primary sensory neurons co-express CB1 and VR1 receptors to a very high degree. We propose that this may provide an anatomical basis for a powerful combination of VR1 mediated excitation and CB1-mediated inhibition of nociceptive responses at central and peripheral terminals of nociceptive primary afferents.”

https://www.ncbi.nlm.nih.gov/pubmed/11036202

https://www.sciencedirect.com/science/article/abs/pii/S0306452200003894