Peripheral Cannabinoid Receptor Activation Attenuates Frostbite-Induced Chronic Pain via Modulation of TRP Channels, Neuroinflammation, and Autophagy

“Frostbite injury is a debilitating cold injury encountered in extreme high-altitude and subzero environments, frequently resulting in persistent chronic pain even after tissue healing. Using our previously validated frostbite-induced chronic pain model, we further investigated the contribution of neuroimmune, excitatory mechanisms and evaluated the therapeutic efficacy of peripheral cannabinoid receptor activation.

Frostbite produced significant mechanical allodynia, mechanical hyperalgesia, and cold hypersensitivity, along with increased spontaneous nocifensive behaviors.

Local peripheral administration of CB13, a peripherally acting CB1/CB2 receptor dual agonist, dose-dependently attenuated both mechanical and cold allodynia without impairing locomotor activity, indicating a lack of central nervous system side effects.

At the molecular level, frostbite induced marked peripheral and spinal sensitization, demonstrated by elevated expression of TRPV1, TRPA1, TRPV4, and TRPM8 channels, increased levels of pro-inflammatory cytokines, and enhanced c-Fos expression as an indicator of heightened neuronal activation in pain-relevant regions. These alterations were accompanied by pronounced microglial activation and upregulation of the NLRP3 inflammasome.

CB13 treatment significantly reversed these pathological changes and concurrently restored Beclin-1-associated autophagy signaling, suggesting engagement of both neuroimmune resolution and intracellular homeostasis pathways. Notably, frostbite injury was associated with marked oxidative and nitrosative stress in the sciatic nerve, as evidenced by reduced glutathione depletion and elevated lipid peroxidation and nitrite levels, which were significantly normalized by CB13 treatment.

Collectively, these findings demonstrate that peripheral cannabinoid receptor activation effectively inhibit frostbite induced chronic pain through modulation of nociceptive, neuroinflammatory, redox, and cellular stress pathways.

This work highlights peripherally selective cannabinoid receptor agonists as promising, safer therapeutic strategies for chronic pain associated with cold injuries.”

https://pubmed.ncbi.nlm.nih.gov/41802611

“This study demonstrates that peripheral cannabinoid receptor activation via CB13 effectively alleviates frostbite-induced chronic pain by targeting multiple pathological mechanisms, including nociceptor hyperexcitability, spinal neuronal activation, neuroinflammation, inflammasome signaling, oxidative stress, and impaired autophagy.”

https://www.sciencedirect.com/science/article/abs/pii/S0891584926001565?via%3Dihub

Effect of Δ9-tetrahydrocannabinol and cannabidiol on myofascial pain modulation in patients with temporomandibular disorder: a prospective crossover study

Background: Temporomandibular Disorder (TMD) often causes chronic orofacial pain and functional limitations, with conventional treatments providing suboptimal results. Phytocannabinoids such as Δ9-Tetrahydrocannabinol (Δ9-THC) and Cannabidiol (CBD) have analgesic and anti-inflammatory properties, but evidence in TMD is scarce.

Objective: To evaluate the efficacy of Δ9-THC/CBD therapy in reducing pain and improving mandibular function in TMD patients.

Methods: Twenty adults with chronic myofascial pain (DC/TMD diagnosis) participated in a blinded, crossover, non-randomized study. Participants underwent two consecutive 90-day phases: placebo followed by Δ9-THC/CBD therapy (1:1 ratio, starting with a dose of 2 mg/day in the first week, gradually adjusting an increase of 2 mg/week until reaching 10 mg/day in the fifth week, sublingually), without washout. Outcomes included pain intensity (VAS), muscle sensitivity (algometry), mandibular function (mouth opening, protrusion, laterality) and pain sensitivity (allodynia/hyperalgesia). Data were analyzed using linear mixed models for repeated measures.

Results: Δ9-THC/CBD improved all outcomes versus baseline and post-placebo (p < 0.001; Cohen’s d > 0.8). Mouth opening increased from 45.9 mm to 49.9 mm; VAS pain decreased from 7.35 to 3.50. Functional pain dropped by ∼90%, with near elimination of allodynia and hyperalgesia. Placebo effects were minimal.

Conclusion: Δ9-THC/CBD therapy provided substantial analgesic and functional benefits in TMD patients, supporting its potential as a therapeutic alternative. Larger randomized studies are recommended to validate these findings and explore underlying mechanisms.”

https://pubmed.ncbi.nlm.nih.gov/41740529

“Cannabinoid therapy was effective in reducing painful symptoms in TMD patients, associated with relevant functional improvements in mandibular opening, protrusion, and laterality compared to placebo.”

https://www.sciencedirect.com/science/article/pii/S1807593226000268?via%3Dihub

Potential effects of cannabidiol on formalin-induced inflammatory pain in morphine-dependent rats

“Chronic morphine exposure leads to tolerance and dependence, complicating pain management and reducing the efficacy of opioid analgesics.

Cannabidiol (CBD), a non-psychoactive constituent of Cannabis sativa, has been recognized for its anti-inflammatory and analgesic potential.

This study examined the effects of CBD on acute and inflammatory phases of formalin-induced nociception in morphine-dependent and non-dependent rats.

Eighty-four male Wistar rats were divided into the control (non-dependent) and dependent groups. Morphine dependence was induced through an oral escalating-dose regimen in drinking water containing 3% sucrose (to mask bitterness) for 14 days, while controls received only sucrose. CBD (25-200μg/5 μL, ICV) was administered prior to the formalin test. Formalin injection produced a clear biphasic nociceptive response (P < 0.001 in both phases), confirming the model’s validity.

Morphine dependence alone did not significantly affect baseline pain responses (P > 0.05). However, CBD produced a significant, dose-dependent reduction in pain behaviors during both the early (0-5 min) and the late (20-50 min) phases (P<0.001 vs. vehicle). The 100 μg/5 μL and 200 μg/5 μL doses showed the most robust and consistent antinociceptive effect.

CBD produced robust antinociceptive effects in both morphine-treated and non-treated rats, with no statistically significant difference between groups. Open-field results indicated no significant differences in locomotor activity, confirming that the observed analgesia was not related to motor impairment.

These findings demonstrate that CBD effectively attenuates both acute and inflammatory pain. Moreover, it maintains its effectiveness in animals treated with morphine. This highlights its potential as a non-opioid supplementary therapy for managing pain in individuals with opioid dependence.”

https://pubmed.ncbi.nlm.nih.gov/41747636

https://www.sciencedirect.com/science/article/abs/pii/S0022395626001263?via%3Dihub

Age differences in endocannabinoid tone are ameliorated after recent cannabis use

“An age-related decline in endocannabinoid system (ECS) activity may contribute to conditions such as chronic pain and Alzheimer’s disease. Although cannabis is increasingly used by older adults to alleviate age-related conditions, it remains unclear how cannabinoids affect ECS activity across the lifespan.

The present study assayed levels of seven endocannabinoids (AEA, 2-AG, DEA, LEA, PEA, SEA, and OEA) in a sample of adults (N = 142; younger 21-24 years, n = 38; midlife 25-54, n = 73; older 55-71, n = 31) assayed before cannabis use (baseline [pre-use]) and ~ 1 h after flower or ~ 2 h after edible cannabis use.

At baseline, older adults exhibited lower AEA and DEA than younger adults, and lower LEA than midlife adults.

Acute cannabis use increased AEA, DEA, LEA, PEA, SEA, and OEA across all age groups (all p < .001). 2-AG showed no increase. For AEA and DEA, increases were larger in older adults (Time×Age).

These findings indicate broad endocannabinoid elevations after cannabis use regardless of age, alongside age-related differences at baseline and in acute responses.”

https://pubmed.ncbi.nlm.nih.gov/41580496

https://www.nature.com/articles/s41598-025-27618-1

The psychoactive cannabinoid THC inhibits peripheral nociceptors by targeting NaV1.7 and NaV1.8 nociceptive sodium channels

“Δ⁹-Tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis, is widely recognized for its central effects mediated by cannabinoid receptors. Here, we uncover a distinct peripheral mechanism by which THC inhibits the excitability of nociceptive neurons.

We show that THC directly targets the nociceptive voltage-gated sodium channels NaV1.7 and NaV1.8 through the conserved local anesthetic binding site. This interaction reduces sodium currents and suppresses action potential generation in peripheral sensory neurons.

Our findings demonstrate that, beyond its central psychoactivity, THC exerts direct peripheral nociceptor inhibition via modulation of NaV1.7 and NaV1.8, offering new insight into cannabinoid-based analgesia independent of cannabinoid receptor signaling.”

https://pubmed.ncbi.nlm.nih.gov/41565997

“Cannabis has been used for centuries for its analgesic properties, and its clinical relevance in pain management continues to grow.”

 “These findings reveal a previously unrecognized mechanism for THC-mediated peripheral analgesia and establish a non-canonical molecular pathway through which the psychoactive cannabinoid can inhibit nociceptor excitability and thereby pain.”

https://www.nature.com/articles/s41386-026-02355-9

The Evidence for Medical Cannabis in Chronic Musculoskeletal Pain Management

“Chronic musculoskeletal pain (CMP) is a pervasive condition that can impair daily functioning and quality of life. Traditional pharmaceutical therapies, including non-steroidal anti-inflammatory drugs, gabapentinoids, and opioids, often yield suboptimal results and carry notable risks, such as adverse side effects and dependence.

Increasing interest has turned toward medical cannabis, particularly combined formulations of cannabidiol (CBD) and tetrahydrocannabinol (THC), as a potential alternative or complement to current pain management strategies.

Evidence suggests that cannabinoids interact with the endocannabinoid system to modulate nociception and inflammation, offering meaningful pain relief and possibly reducing opioid requirements.

However, heterogeneity in study designs, product formulations, and regulatory frameworks presents challenges in drawing definitive conclusions. Additionally, while most adverse effects, such as fatigue, dizziness, and mild cognitive changes, are generally reported as tolerable, concerns remain about long-term safety and standardization of dosing.

Taken together, the existing literature points to a promising role for medical cannabis in CMP management, underscoring the need for further high-quality research to establish best practices, clarify patient selection, and guide clinicians in safe and effective cannabinoid therapy.”

“This scoping review highlights the potential role of medical cannabis in managing musculoskeletal pain. Evidence suggests it may reduce pain, enhance well-being, and improve quality of life, particularly as an alternative or adjunct to opioids. Adverse effects are typically mild, supporting its use as a safer long-term option. However, data on long-term efficacy, especially for CBD, remain limited.

Given the risks of opioid dependence, cannabis offers a promising therapeutic alternative.”

https://surgicoll.scholasticahq.com/article/138573-the-evidence-for-medical-cannabis-in-chronic-musculoskeletal-pain-management

Cannabidiol reduces oxycodone self-administration while preserving its analgesic efficacy in a rat model of neuropathic pain

“Prescription opioid misuse is a significant public health concern among individuals with chronic pain. Treating severe pain often requires high doses of opioids, increasing the risk of developing an opioid use disorder.

Cannabidiol (CBD) is a non-intoxicating component of cannabis that has shown therapeutic potential without abuse liability.

This study investigated the effects of CBD on oxycodone self-administration and hyperalgesia in an animal model of chronic neuropathic pain.

Adult male rats were trained to self-administer intravenous oxycodone (0.06 mg/kg/infusion). Subsequently, they underwent chronic constriction injury (CCI) of the sciatic nerve or received sham surgery. Paw withdrawal latency was measured using the Hargreaves test as an indicator of thermal pain sensitivity. CBD (0, 1, 3, and 10 mg/kg, IP) was administered before the self-administration sessions, and pain testing was conducted afterward. The rats acquired oxycodone self-administration, as indicated by more active than inactive lever presses. CCI surgery decreased the paw withdrawal latency, confirming the induction of neuropathic pain. CCI alone did not affect oxycodone self-administration, suggesting that neuropathic pain does not substantially influence opioid intake at the dose tested.

Treatment with CBD reduced oxycodone self-administration in both the sham and CCI rats. Oxycodone self-administration in the CCI rats reversed the CCI-induced decrease in paw withdrawal latency. However, CBD did not affect the antinociceptive effect of oxycodone in CCI rats.

Taken together, these findings demonstrate that CBD reduces oxycodone self-administration without affecting the antinociceptive effects of oxycodone in neuropathic pain.

This study supports the potential of CBD to reduce opioid use and misuse, regardless of pain status.”

https://pubmed.ncbi.nlm.nih.gov/41521216

https://www.nature.com/articles/s41598-025-31828-y

Cross-sectional comparison of cannabis use in adults with neuropathic versus non-neuropathic pain

Introduction: Cannabis has been decriminalized by many states and shows promise in treating both neuropathic and non-neuropathic pain through its interaction with the endocannabinoid system and anti-inflammatory effects. This study examines differences in cannabis use for adults whose most bothersome chronic pain condition is neuropathic vs. non-neuropathic.

Materials and methods: Survey data were collected from adults receiving care at a pain clinic. Participants completed demographic questions and standardized self-report measures (PROMIS Pain Intensity/Interference and the ID-Pain tool). Participants’ most bothersome pain condition(s) were categorized as neuropathic or non-neuropathic pain based on ID-Pain scores. Linear regression models assessed differences in frequency and duration of cannabis product use between groups, adjusting for age and sex.

Results: A total of 113 individuals were recruited; following exclusions and missing data, 104 participants (61.5% female) were included in the final analysis. Of these, 36.5% reported neuropathic pain as their most bothersome, and 63.5% reported non-neuropathic pain. Those with neuropathic pain reported significantly more days per month of Tetrahydrocannabinol/Cannabidiol (THC/CBD) combination (b = 5.96, p = 0.02), Cannabidiol-only (CBD-only) (b = 8.82, p = 0.03), and Tetrahydrocannabinol-only (THC-only) products (b = 7.04, p = 0.02). They also used THC-only (b = 0.97, p < 0.05) and THC/CBD (b = 1.09, p < 0.01) products more frequently per day. Neuropathic pain was positively associated with pain intensity (b = 4.10, p < 0.001) and interference (b = 4.95, p < 0.001).

Discussion: Adults whose most bothersome pain condition(s) were neuropathic used cannabis, especially THC and THC/CBD combination products, more frequently than those whose most bothersome pain was non-neuropathic. Participants with neuropathic pain also reported higher levels of pain intensity and interference. Further longitudinal research is needed to confirm whether increased use of THC-rich cannabis provides symptom relief for adults with neuropathic pain.”

https://pubmed.ncbi.nlm.nih.gov/41487383

“Cannabis interacts with the endocannabinoid system, making it a potential treatment for neuropathic pain.”

“Because previous studies found THC products to be more effective in managing neuropathic pain by interacting with the endocannabinoid system, it is possible that our participants also experienced benefit; this could explain their higher use of THC containing products.

https://www.frontiersin.org/journals/pain-research/articles/10.3389/fpain.2025.1677391/full

Effect of patient marijuana use on perioperative opioid requirements

“The effect of chronic marijuana use on patients is unknown, including in the surgical setting. Marijuana produces many effects on the body, which should be considered when providing medical care.

Chronic marijuana use may affect surgical opioid requirements. To explore this possibility, an observational study was completed by conducting a retrospective chart review of patients who underwent surgery with general anesthesia.

Patients were identified in the electronic medical record via self-reporting as marijuana users (users) or nonmarijuana users (nonusers). Users and nonusers were case-matched based on age, gender, weight, and procedure. After case matching, 570 patients’ charts were analyzed, and intraoperative opioid, intraoperative propofol, and post-anesthesia care unit opioid requirements were compared.

Marijuana users required less intraoperative opioids (mean [standard deviation (SD)] 27.2 [20.5] morphine milligram equivalents [MMEs]) compared to those who were marijuana nonusers (31.3 [22.1] MME).

These results show a statistically significant difference in the intraoperative opioid requirement between case-matched users and nonusers (p = 0.02), with p = 0.013 after statistical adjustment for racial differences between the marijuana user and nonuser cohorts. Users and nonusers required similar amounts of intraoperative propofol (242.2 [220.2] and 257.8 [250.9], respectively) and post-operative opioids (7.3 [6.0] and 8.0 [9.0], respectively). The differences in intraoperative propofol and post-operative opioid requirements were not different statistically with p-values of 0.43 and 0.31, respectively.

Based on this study population, marijuana users required less intraoperative opioids when compared to case-matched marijuana nonusers, with no difference in intraoperative propofol or post-operative opioid requirements.

Perspective: Typical preoperative screening includes queries about patient substance use including marijuana, but details such as frequency and length of use are infrequently asked. The addition of these details to the assessment may provide improved understanding of a patient’s surgical opioid requirements.”

https://pubmed.ncbi.nlm.nih.gov/41123263

https://wmpllc.org/ojs/index.php/jom/article/view/3918

Medical Cannabis and Opioid Receipt Among Adults With Chronic Pain

Question  Is participation in the New York State (NYS) medical cannabis program associated with reduced prescription opioid receipt among adults with chronic pain?

Findings  In this cohort study of 204 adults with chronic pain, participation in the NYS medical cannabis program, defined as monthly dispensation of medical cannabis reported by the dispensary pharmacist, was associated with significantly reduced prescription opioid receipt.

Meaning  These findings suggest that participation in a pharmacist-directed medical cannabis program may help reduce prescription opioid receipt among adults with chronic pain.

Abstract

Importance  Medical cannabis is increasingly considered a substitute for prescription opioid medications for chronic pain, driven by the urgent need for opioid alternatives to combat the ongoing epidemic.

Objective  To determine the association between participation in the New York State (NYS) medical cannabis program and prescription opioid receipt among adults with chronic pain.

Design, Setting, and Participants  This cohort study used data from the NYS Prescription Monitoring Program (PMP) from September 2018 through July 2023. Adults prescribed opioids for chronic pain who were newly certified for medical cannabis use in NYS were recruited from a large academic medical center and nearby medical cannabis dispensaries in the Bronx, New York. Monthly dispensation of medical cannabis to study participants was monitored for 18 months. Data analyses were performed from February 3, 2025, to July 15, 2025.

Exposure  Portion of days covered each month by pharmacist report of dispensed medical cannabis.

Main Outcomes and Measures  Prescription opioid receipt, defined as NYS PMP-reported prescription monthly opioid dispensation (mean daily dose in morphine milliequivalents [MME]), was assessed with marginal structural models adjusted for time-invariant and time-varying confounders, including self-reported unregulated cannabis use. Nonprescribed opioid use was also assessed during the study period.

Results  Among 204 participants, the mean (SD) age at baseline was 56.8 (12.8) years, and 113 (55.4%) were female. At baseline, participants’ mean (SD) pain severity score was 6.6 (1.8) out of 10, and mean (SD) pain interference score was 6.8 (1.9) out of 10. Baseline mean (SD) daily MME was 73.3 (133.0). During the 18-month follow-up period, participants’ mean (SD) daily MME decreased to 57.4 (127.8). This reduction in mean daily MME was associated with the monthly portion of days covered with medical cannabis; compared with no medical cannabis dispensed, participants dispensed a 30-day supply of medical cannabis were exposed to 3.53 fewer MME per day (β = −3.53; 95% CI, −6.68 to −0.04; P = .03).

Conclusions and Relevance  In this cohort study, participation in NYS’s medical cannabis program was associated with reduced prescription opioid receipt during 18 months of prospective follow-up, accounting for unregulated cannabis use.”

https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2842414