The Endocannabinoid System in Endometriosis-Associated Pain: Mechanisms, Molecular Targets, and Therapeutic Implications

A new 2026 review published in Reproductive Sciences examines the endocannabinoid system (ECS) as a therapeutic target for endometriosis-associated pain, a condition that can cause severe pelvic pain, painful menstruation, painful intercourse, and other chronic symptoms. The authors highlight the ECS because of its established roles in regulating pain, inflammation, and immune activity.

The review found that cannabinoids may influence three major mechanisms involved in endometriosis-associated pain: inflammation, pain signaling and sensitization, and the growth of endometriotic lesions. Cannabinoids interact with both cannabinoid and non-cannabinoid receptors found in endometriotic tissue, while also reducing inflammatory signaling from immune cells such as mast cells and macrophages.

The researchers conclude that the endocannabinoid system is a promising therapeutic target for endometriosis-associated pain, with cannabinoid therapies showing potential to regulate nociception, inflammation, and lesion proliferation. They call for clinical trials to further evaluate cannabinoid-based treatments for people living with endometriosis.

“Endometriosis is a chronic gynecological disorder affecting approximately 10% of reproductive-age women, characterized by the ectopic growth of endometrial tissue and severe pain, including dysmenorrhea, chronic pelvic pain, dyspareunia, dysuria, and dyschezia. Current treatments are limited in efficacy and associated with significant side effects, underscoring the urgent need for novel therapeutic strategies.

The endocannabinoid system (ECS) has emerged as a promising therapeutic target, given its well-established roles in pain modulation, inflammation, and immune regulation. Epidemiological evidence demonstrates that women with endometriosis increasingly use cannabis for symptom self-management, yet the underlying mechanisms remain poorly characterized.

This review integrates preclinical and human evidence to comprehensively evaluate the mechanistic basis of cannabinoid efficacy in endometriosis-associated pain. Evidence from in vitro studies and animal models indicates that cannabinoids target three main mechanisms of endometriosis-associated pain, including inflammation, nociceptive signaling, and lesion proliferation.

Cannabinoids suppress pain signaling and sensitization by interacting with cannabinoid and non-cannabinoid receptors expressed in endometriotic lesions. Cannabinoids attenuate endometriosis-induced inflammation by inhibiting proinflammatory cytokine signaling and reducing the release of inflammatory mediators by mast cells and peritoneal macrophages. Cannabinoids also exert antiproliferative effects in endometriosis models, thereby suppressing the growth of endometriotic lesions.

In conclusion, the ECS is a promising therapeutic target for endometriosis-associated pain, as it regulates nociception, inflammation, and proliferation. These promising findings highlight the potential therapeutic benefits of cannabinoids for endometriosis-associated pain, warranting the need for clinical trials to evaluate the safety and effectiveness of cannabinoid therapies in endometriosis.”

https://pubmed.ncbi.nlm.nih.gov/42745018

https://link.springer.com/article/10.1007/s43032-026-02201-9

Unveiling the mechanism of action behind the anti-cancer properties of cannabinoids in ER + breast cancer cells: impact on aromatase and steroid receptors

The Journal of Steroid Biochemistry and Molecular Biology“Breast cancer is the leading cause of cancer-related death in women worldwide. In the last years, cannabinoids have gained attention in the clinical setting and clinical trials with cannabinoid-based preparations are underway. However, contradictory anti-tumour properties have also been reported. Thus, the elucidation of the molecular mechanisms behind their anti-tumour efficacy is crucial to better understand its therapeutic potential.

Considering this, our work aims to clarify the molecular mechanisms underlying the anti-cancer properties of the endocannabinoid anandamide (AEA) and of the phytocannabinoids, cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC), in estrogen receptor-positive (ER+) breast cancer cells that overexpress aromatase (MCF-7aro). Their in vitro effects on cell proliferation, cell death and activity/expression of aromatase, ERα, ERβ and AR were investigated.

Our results demonstrated that cannabinoids disrupted MCF-7aro cell cycle progression. Unlike AEA and THC that induced apoptosis, CBD triggered autophagy to promote apoptotic cell death. Interestingly, all cannabinoids reduced aromatase and ERα expression levels in cells. On the other hand, AEA and CBD not only exhibited high anti-aromatase activity but also induced up-regulation of ERβ. Therefore, all cannabinoids, albeit by different actions, target aromatase and ERs, impairing, in that way, the growth of ER+ breast cancer cells, which is dependent on estrogen signalling.

As aromatase and ERs are key targets for ER+ breast cancer treatment, cannabinoids can be considered as potential and attractive therapeutic compounds for this type of cancer, being CBD the most promising one. Thus, from an in vitro perspective, this work may contribute to the growing mass of evidence of cannabinoids and cannabinoids-based medicines as potential anti-cancer drugs.”

https://pubmed.ncbi.nlm.nih.gov/33722705/

“AEA and THC induce apoptosis in ER+ breast cancer cells, while CBD trigger autophagy to promote apoptosis. AEA, THC and CBD impair growth of ER+ breast cancer cells, by disrupting cycle progression. AEA, THC and CBD affect aromatase and ERα expression levels in ER+ breast cancer cells. AEA and CBD strongly inhibited aromatase activity and up-regulated ERβ levels. Cannabinoids are considered potential therapeutic compounds for ER+ breast cancer, being CBD the most promising one.”

https://www.sciencedirect.com/science/article/abs/pii/S0960076021000698?via%3Dihub

Endocannabinoids and Stroke Prevention: Review of Clinical Studies.

View details for Cannabis and Cannabinoid Research cover image“The societal burden of ischemic stroke suggests a need for additional therapeutic categories in stroke prevention.

Modulation of the endocannabinoid system (ECS) is a rational target for stroke prevention because of its effects on inflammation, vascular tone, and metabolic balance, all well-described stroke risk factors.

In this article, we summarize the existing ECS clinical studies in human subjects’ research as they relate to conventional vascular risk factors associated with ischemic stroke.”

https://www.ncbi.nlm.nih.gov/pubmed/32322672

https://www.liebertpub.com/doi/10.1089/can.2018.0066

“The endocannabinoid system and stroke: A focused review. This review seeks to summarize the recent evidence for the role of the endocannabinoid signaling system in stroke pathophysiology, as well as the evidence from preclinical studies regarding the efficacy of cannabinoids as neuroprotective therapies in the treatment of stroke.” https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6458776/

The effects of cannabinoids in exemestane-resistant breast cancer cells: PS181.

“Exemestane is one of the aromatase inhibitors (AI) used as first line treatment for estrogen-receptor positive breast cancer in post-menopausal women. Exemestane acts by inhibiting aromatase, the enzyme responsible for the conversion of androgens to estrogens and also by promoting apoptosis of breast cancer cells. Nevertheless, despite its therapeutic success, this AI, after prolonged treatment, can induce acquired resistance, which causes tumor relapse. Therefore, it is important to find new strategies to overcome resistance in order to improve breast cancer treatment.

Considering that the development of resistance is the main reason for endocrine treatment failure, our group decided to explore the ability of three cannabinoids, Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD) and anandamide (AEA), to reverse resistance to exemestane. The THC and CBD are phytocannabinoids derived from the plant Cannabis sativa (marijuana) whereas AEA is an endocannabinoid. For that, it was used LTEDaro cells, a long-term estrogen deprived ER+ breast cancer cell line that mimics resistance to exemestane. These cells were treated with exemestane in combination with two phytocannabinoids, CBD and THC, and the endocannabinoid AEA.

The presence of CB1 and CB2 in LTEDaro cells was confirmed by Western blot analysis and the effects of the combination of cannabinoids with exemestane were evaluated by MTT and LDH assays. Cell morphology was analyzed by Giemsa and Hoechst staining.

Results: Our results demonstrate that all the cannabinoids induce a decrease in viability of exemestane-resistant cells, in a dose- and time-dependent manner, without LDH release. These results indicate that the studied cannabinoids, mainly THC and AEA, revert the resistance to exemestane, probably by inducing apoptosis, as observed in Giemsa/Hoechst stain by the presence of typical morphological features of apoptosis.

Conclusion: This study highlights the efficacy of using cannabinoids as a potential adjuvant treatment to revert resistance to AIs.”

https://www.ncbi.nlm.nih.gov/pubmed/32258721

https://journals.lww.com/pbj/fulltext/2017/09000/The_effects_of_cannabinoids_in.118.aspx

Editorial: The Canonical and Non-Canonical Endocannabinoid System as a Target in Cancer and Acute and Chronic Pain

frontiers in pharmacology – Retraction Watch“The endocannabinoid system (ECS) comprises the canonical receptor subtypes CB1R and CB2R and endocannabinoids (anandamide, AEA and 2-arachidonoylglycerol, 2-AG), and a “non-canonical” extended signaling network consisting of: (i) other fatty acid derivatives; (ii) the defined “ionotropic cannabinoid receptors” (TRP channels); other GPCRs (GPR55, PPARα); (iii) enzymes involved in the biosynthesis and degradation of endocannabinoids (FAAH and MAGL); and (iv) protein transporters (FABP family).The ECS is currently a hot topic due to its involvement in cancer and pain.

The current Research Topic highlights various ways the endocannabinoid system (ECS) can impact cancer and pain. Ramer et al. review the anticancer potential of the canonical and noncanonical endocannabinoid system. Morales and Jagerovic provide a much needed summary of cannabinoid ligands as promising antitumor agents in a wide variety of tumors, in contrast to their palliative applications. In their article, the authors classify cannabinoids with anticancer potential in endocannabinoids, phytocannabinoids, and synthetic cannabinoids. Moreno et al. in their review explored the value of cannabinoid receptor heteromers as potential new targets for anti-cancer therapies and as prognostic biomarkers, showing the potential of the endocannabinoid network in the anti-cancer setting as well as the clinical and ethical pitfalls behind it.

As an ensemble, these studies provide further fuel to the discussion and underline the potential for targeting the ECS at multiple levels to treat certain cancers and for pain relief. Importantly, they also help to move the focal point of the discussion beyond THC, CBD, and the cannonical receptors. Several of these reports either review or provide data to support the use of/targeting of other members of the ECS system as well as alternative natural products beyond THC and CBD.”

https://www.frontiersin.org/articles/10.3389/fphar.2020.00312/full

Endocannabinoid system and cardiometabolic risk factors: A comprehensive systematic review insight into the mechanistic effects of omega-3 fatty acids.

Life Sciences“Increased levels of endocannabinoids, 2-arachidonoylglycerol (2-AG) and arachidonoyl ethanolamide (AEA) have a pathophysiological role in the setting of cardiometabolic diseases. This systematic review was carried out to appraise the effect of omega-3 on cardiometabolic risk factors by highlighting the mediating effect of endocannabinoids.

Eleven animal studies and two human studies showed a marked reduction in 2-AG and AEA levels following intake of omega-3 which correlated with decreased adiposity, weight gain and improved glucose homeostasis. Moreover, endocannabinoids were elevated in three studies that replaced omega-3 with omega-6.

Omega-3 showed anti-inflammatory properties due to reduced levels of inflammatory cytokines, regulation of T-cells function and increased levels of eicosapentaenoyl ethanolamide, docosahexaenoyl ethanolamide and oxylipins; however, a limited number of studies examined a correlation between inflammatory cytokines and endocannabinoids following omega-3 administration.

In conclusion, omega-3 modulates endocannabinoid tone, which subsequently attenuates inflammation and cardiometabolic risk factors. However, further randomized clinical trials are needed before any recommendations are made to target the ECS using omega-3 as an alternative therapy to drugs for cardiometabolic disease improvement.”

https://www.ncbi.nlm.nih.gov/pubmed/32184122

“Endocannabinoid system (ECS) may mediate favorable effects of omega-3 fatty acids in cardiometabolic disorders. Omega-3 fatty acids showed anti-inflammatory effects due to increased levels of ethanolamide and oxylipins. Plant-derived omega-3 may be as effective as animal-derived omega-3 in ECS modulation. Omega-3 may have a potential to be an alternative to drugs for cardiometabolic disease improvement.”

https://www.sciencedirect.com/science/article/abs/pii/S0024320520303040?via%3Dihub

Influence of cannabinoids upon nerve-evoked skeletal muscle contraction.

Neuroscience Letters“Endocannabinoids play important roles in regulating CNS synaptic function and peripheral metabolism, but cannabinoids can also act acutely to modulate contraction strength in skeletal muscle.

Nerve terminals and the skeletal muscle sarcolemma express components of the cannabinoid signaling system.

Endocannabinoids, N-arachidonylethanolamine (anandamide, AEA) and 2-arachidonoyl-glycerol (2-AG), are produced by skeletal muscle. They may be involved in the acute regulation of neuromuscular transmission, by adjusting the parameters for quantal acetylcholine release from the motor nerve terminal. Downstream of neuromuscular transmission, cannabinoids may also act to limit the efficiency of excitation-contraction coupling.

Improved understanding of the distinct signaling actions of particular cannabinoid compounds and their receptor/transduction systems will help advance our understanding of the role of endocannabinoids in skeletal muscle physiology.

Cannabinoids might also offer the potential to develop new pharmacotherapeutics to treat neuromuscular disorders that affect muscle strength.”

https://www.ncbi.nlm.nih.gov/pubmed/32156612

https://www.sciencedirect.com/science/article/abs/pii/S0304394020301701?via%3Dihub

Stress-induced modulation of endocannabinoid signaling leads to delayed strengthening of synaptic connectivity in the amygdala.

Image result for pnas“Even a brief exposure to severe stress strengthens synaptic connectivity days later in the amygdala, a brain area implicated in the affective symptoms of stress-related psychiatric disorders. However, little is known about the synaptic signaling mechanisms during stress that eventually culminate in its delayed impact on the amygdala. Hence, we investigated early stress-induced changes in amygdalar synaptic signaling in order to prevent its delayed effects.

Whole-cell recordings in basolateral amygdala (BLA) slices from rats revealed higher frequency of miniature excitatory postsynaptic currents (mEPSCs) immediately after 2-h immobilization stress. This was replicated by inhibition of cannabinoid receptors (CB1R), suggesting a role for endocannabinoid (eCB) signaling.

Stress also reduced N-arachidonoylethanolamine (AEA), an endogenous ligand of CB1R. Since stress-induced activation of fatty acid amide hydrolase (FAAH) reduces AEA, we confirmed that oral administration of an FAAH inhibitor during stress prevents the increase in synaptic excitation in the BLA soon after stress.

Although stress also caused an immediate reduction in synaptic inhibition, this was not prevented by FAAH inhibition. Strikingly, FAAH inhibition during the traumatic stressor was also effective 10 d later on the delayed manifestation of synaptic strengthening in BLA neurons, preventing both enhanced mEPSC frequency and increased dendritic spine-density.

Thus, oral administration of an FAAH inhibitor during a brief stress prevents the early synaptic changes that eventually build up to hyperexcitability in the amygdala. This framework is of therapeutic relevance because of growing interest in targeting eCB signaling to prevent the gradual development of emotional symptoms and underlying amygdalar dysfunction triggered by traumatic stress.”

https://www.ncbi.nlm.nih.gov/pubmed/31843894

https://www.pnas.org/content/early/2019/12/13/1910322116

The endocannabinoid system: Novel targets for treating cancer induced bone pain.

Biomedicine & Pharmacotherapy“Treating Cancer-induced bone pain (CIBP) continues to be a major clinical challenge and underlying mechanisms of CIBP remain unclear.

Recently, emerging body of evidence suggested the endocannabinoid system (ECS) may play essential roles in CIBP. Here, we summarized the current understanding of the antinociceptive mechanisms of endocannabinoids in CIBP and discussed the beneficial effects of endocannabinoid for CIBP treatment.

Targeting non-selective cannabinoid 1 receptors or selective cannabinoid 2 receptors, and modulation of peripheral AEA and 2-AG, as well as the inhibition the function of fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL) have produced analgesic effects in animal models of CIBP.

Management of ECS therefore appears to be a promising way for the treatment of CIBP in terms of efficacy and safety. Further clinical studies are encouraged to confirm the possible translation to humans of the very promising results already obtained in the preclinical studies.”

https://www.ncbi.nlm.nih.gov/pubmed/31627091

“Thus, cannabinoids may be clinically useful for treating chronic pain and CIBP.”

https://www.sciencedirect.com/science/article/pii/S075333221933731X?via%3Dihub

Endocannabinoid system and the expression of endogenous ceramides in human hepatocellular carcinoma.

 Journal Cover“The endogenous lipid metabolism network is associated with the occurrence and progression of malignancies.

Endocannabinoids and ceramides have demonstrated their anti-proliferative and pro-apoptotic properties in a series of cancer studies.

The aim of the present study was to evaluate the expression patterns of endocannabinoids and endogenous ceramides in 67 pairs of human hepatocellular carcinoma (HCC) tissues and non-cancerous counterpart controls.

Anandamide (AEA), the major endocannabinoid, was reduced in tumor tissues, probably due to the high expression and activity of fatty acid amide hydrolase. Another important endocannabinoid, 2-arachidonylglycerol (2-AG), was elevated in tumor tissues compared with non-tumor controls, indicating that the biosynthesis of 2-AG is faster than the degradation of 2-AG in tumor cells.

Furthermore, western blot analysis demonstrated that cannabinoid receptor 1 was downregulated, while cannabinoid receptor 2 was elevated in HCC tissues, in accordance with the alterations in the levels of AEA and 2-AG, respectively. For HCC tissues, the expression levels of C18:0, 20:0 and 24:0-ceramides decreased significantly, whereas C12:0, 16:0, 18:1 and 24:1-ceramides were upregulated, which may be associated with cannabinoid receptor activation and stearoyl-CoA desaturase protein downregulation.

The exact role of endocannabinoids and ceramides in regulating the fate of HCC cells requires further investigation.”

https://www.ncbi.nlm.nih.gov/pubmed/31423220

https://www.spandidos-publications.com/10.3892/ol.2019.10399