Mechanistic Potential and Therapeutic Implications of Cannabinoids in Nonalcoholic Fatty Liver Disease.

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“Nonalcoholic fatty liver disease (NAFLD) is comprised of nonalcoholic fatty liver (NAFL) and nonalcoholic steatohepatitis (NASH). It is defined by histologic or radiographic evidence of steatosis in the absence of alternative etiologies, including significant alcohol consumption, steatogenic medication use, or hereditary disorders.

NAFLD is now the most common liver disease, and when NASH is present it can progress to fibrosis and hepatocellular carcinoma. Different mechanisms have been identified as contributors to the physiology of NAFLD; insulin resistance and related metabolic derangements have been the hallmark of physiology associated with NAFLD.

The mainstay of treatment has classically involved lifestyle modifications focused on the reduction of insulin resistance. However, emerging evidence suggests that the endocannabinoid system and its associated cannabinoid receptors and ligands have mechanistic and therapeutic implications in metabolic derangements and specifically in NAFLD.

Cannabinoid receptor 1 antagonism has demonstrated promising effects with increased resistance to hepatic steatosis, reversal of hepatic steatosis, and improvements in glycemic control, insulin resistance, and dyslipidemia. Literature regarding the role of cannabinoid receptor 2 in NAFLD is controversial.

Exocannabinoids and endocannabinoids have demonstrated some therapeutic impact on metabolic derangements associated with NAFLD, although literature regarding direct therapeutic use in NAFLD is limited. Nonetheless, the properties of the endocannabinoid system, its receptors, substrates, and ligands remain a significant arena warranting further research, with potential for a pharmacologic intervention for a disease with an anticipated increase in economic and clinical burden.”

https://www.ncbi.nlm.nih.gov/pubmed/29843404

http://www.mdpi.com/2305-6320/5/2/47

The role of lipid signaling in the progression of malignant melanoma.

Cancer and Metastasis Reviews

“In the past decades, a vast amount of data accumulated on the role of lipid signaling pathways in the progression of malignant melanoma, the most metastatic/aggressive human cancer type. Genomic studies identified that PTEN loss is the leading factor behind the activation of the PI3K-signaling pathway in melanoma, mutations of which are one of the main resistance mechanisms behind target therapy failures. On the other hand, illegitimate expressions of megakaryocytic genes p12-lipoxyganse, cyclooxygenase-2, and phosphodiestherase-2/autotaxin (ATX) are mostly involved in the regulation of motility signaling in melanoma through various G-protein-coupled bioactive lipid receptors. Furthermore, endocannabinoid signaling can also be a novel paracrine survival factor in melanoma. Last but not least, prenylation inhibitors acting even on mutated small GTP-ases, such as NRAS of melanoma may offer novel therapeutic opportunities. As regards melanoma, the most effective therapy nowadays is immunotherapy, with the resistance mechanisms also possibly involving the lipid signaling activities of melanoma cells, which further supports the idea of their being therapeutic targets.”

∆9-tetrahydrocannabinol inhibits epithelial-mesenchymal transition and metastasis by targeting matrix metalloproteinase-9 in endometrial cancer.

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“Limited therapeutic interventions are clinically available for treating aggressive endometrial cancer (EC). Therefore, effective therapies are urgently required.

Therefore, the present study investigated the role of ∆9-tetrahydrocannabinol (THC), which is reported to impact proliferative and migratory activities during impairment of cancer progression.

In the present study, cell migration in response to THC was measured using transwell assays. Using western blot analysis, the levels of cannabinoid receptors in EC tissues were detected and pathways leading to the inhibition of cell migration by THC on human EC cells were determined.

Results suggested that cannabinoid receptors were highly expressed in EC tissues.

Furthermore, THC inhibited EC cell viability and motility by inhibiting epithelial-mesenchymal transition (EMT) and downregulating matrix metalloproteinase-9 (MMP-9) gene expression in aggressive human EC cells.

The results have the potential to promote the development of novel compounds for the treatment of EC metastasis. The present findings suggest that THC may inhibit human EC cell migration through regulating EMT and MMP-9 pathways.”

https://www.ncbi.nlm.nih.gov/pubmed/29805589

https://www.spandidos-publications.com/10.3892/ol.2018.8407

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

The Pharmacological Inhibition of Fatty Acid Amide Hydrolase Prevents Excitotoxic Damage in the Rat Striatum: Possible Involvement of CB1 Receptors Regulation.

Molecular Neurobiology

“The endocannabinoid system (ECS) actively participates in several physiological processes within the central nervous system.

Among such, its involvement in the downregulation of the N-methyl-D-aspartate receptor (NMDAr) through a modulatory input at the cannabinoid receptors (CBr) has been established. After its production via the kynurenine pathway (KP), quinolinic acid (QUIN) can act as an excitotoxin through the selective overactivation of NMDAr, thus participating in the onset and development of neurological disorders.

In this work, we evaluated whether the pharmacological inhibition of fatty acid amide hydrolase (FAAH) by URB597, and the consequent increase in the endogenous levels of anandamide, can prevent the excitotoxic damage induced by QUIN. URB597 (0.3 mg/kg/day × 7 days, administered before, during and after the striatal lesion) exerted protective effects on the QUIN-induced motor (asymmetric behavior) and biochemical (lipid peroxidation and protein carbonylation) alterations in rats.

URB597 also preserved the structural integrity of the striatum and prevented the neuronal loss (assessed as microtubule-associated protein-2 and glutamate decarboxylase localization) induced by QUIN (1 μL intrastriatal, 240 nmol/μL), while modified the early localization patterns of CBr1 (CB1) and NMDAr subunit 1 (NR1).

Altogether, these findings support the concept that the pharmacological manipulation of the endocannabinoid system plays a neuroprotective role against excitotoxic insults in the central nervous system.”

Endocannabinoid CB1 receptors are involved in antiepileptogenic effect of low frequency electrical stimulation during perforant path kindling in rats.

Epilepsy Research

“Administration of low-frequency electrical stimulation (LFS) at the kindling site has an antiepileptogenic effect. In the present study, we investigated the role of cannabinoid receptors type 1 (CB1) in mediating the inhibitory effects of LFS on the development of perforant path kindled seizures.

RESULTS:

Application of LFS had inhibitory effect on development of kindled seizures (kindling rate). Microinjection of AM281 (0.5 μg/μl) immediately after the last kindling stimulation (before LFS application) reduced the inhibitory effect of LFS on the kindling rate and suppressed the effects of LFS on potentiation (increasing the magnitude) of both population spike amplitude and population excitatory postsynaptic potential slope during kindling acquisition. AM281 pretreatment also prevented the effects of LFS on kindling-induced increase in early and late paired pulse depression. The higher dose of AM281 (2 μg/μl) failed to exert the effects observed with its lower dose (0.5 μg/μl). In addition, there was a decreased CB1 receptors immunostaining in kindled animals compared to control. However, application of LFS following kindling stimulations led to overexpression of CB1 receptors in the dentate gyrus.

CONCLUSION:

Obtained results showed that activation of overexpressed cannabinoid CB1 receptors by endogenous cannabinoids may have a role in mediating the inhibitory effect of LFS on perforant path kindled seizures.”

https://www.ncbi.nlm.nih.gov/pubmed/29800824

https://www.sciencedirect.com/science/article/pii/S0920121117304291?via%3Dihub

Computational investigation on the binding modes of Rimonabant analogues with CB1 and CB2.

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“The human cannabinoid G protein coupled receptor 1 (CB1) is highly expressed in central nervous system. CB1-selective antagonists show therapeutic promise in a wide range of disorders, such as obesity-related metabolic disorders, dyslipidemia, drug abuse and type 2 diabetes.

Rimonabant (SR141716A), MJ08 and MJ15 are selective CB1 antagonists with selectivity >1000 folds over CB2 despite of 42% sequence identity between CB1 and CB2. The integration of homology modeling, automated molecular docking and molecular dynamics simulation were used to investigate the binding modes of these selective inverse agonists/antagonists with CB1 and CB2 and their selectivity.

Our analyses showed that the hydrophobic interactions between ligands and hydrophobic pockets of CB1 account for the main binding affinity. In addition, instead of interacting with ligands directly as previously reported, the Lys1923.28in CB1 was engaged in indirect interactions with ligands to keep inactive-state CB1 stable by forming the salt bridge with Asp1762.63 . Lastly, our analyses indicated that the selectivity of these antagonists came from the difference in geometry shapes of binding pockets of CB1 and CB2.

The present study could guide future experimental works on these receptors and has the guiding significance for the design of functionally selective drugs targeting CB1 or CB2 receptors.”

https://www.ncbi.nlm.nih.gov/pubmed/29797785

https://onlinelibrary.wiley.com/doi/abs/10.1111/cbdd.13337

Cannabinoid CB2 receptors in the mouse brain: relevance for Alzheimer’s disease.

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“Because of their low levels of expression and the inadequacy of current research tools, CB2 cannabinoid receptors (CB2R) have been difficult to study, particularly in the brain. This receptor is especially relevant in the context of neuroinflammation, so novel tools are needed to unveil its pathophysiological role(s).

METHODS:

We have generated a transgenic mouse model in which the expression of enhanced green fluorescent protein (EGFP) is under the control of the cnr2 gene promoter through the insertion of an Internal Ribosomal Entry Site followed by the EGFP coding region immediately 3′ of the cnr2 gene and crossed these mice with mice expressing five familial Alzheimer’s disease (AD) mutations (5xFAD).

RESULTS:

Expression of EGFP in control mice was below the level of detection in all regions of the central nervous system (CNS) that we examined. CB2R-dependent-EGFP expression was detected in the CNS of 3-month-old AD mice in areas of intense inflammation and amyloid deposition; expression was coincident with the appearance of plaques in the cortex, hippocampus, brain stem, and thalamus. The expression of EGFP increased as a function of plaque formation and subsequent microgliosis and was restricted to microglial cells located in close proximity to neuritic plaques. AD mice with CB2R deletion exhibited decreased neuritic plaques with no changes in IL1β expression.

CONCLUSIONS:

Using a novel reporter mouse line, we found no evidence for CB2R expression in the healthy CNS but clear up-regulation in the context of amyloid-triggered neuroinflammation. Data from CB2R null mice indicate that they play a complex role in the response to plaque formation.”

An overview of the cannabinoid type 2 receptor system and its therapeutic potential.

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“This narrative review summarizes recent insights into the role of the cannabinoid type 2 (CB2) receptor as potential therapeutic target in neuropathic pain and neurodegenerative conditions.

RECENT FINDINGS:

The cannabinoid system continues to receive attention as a therapeutic target. The CB2 receptor is primarily expressed on glial cells only when there is active inflammation and appears to be devoid of undesired psychotropic effects or addiction liability. The CB2 receptor has been shown to have potential as a therapeutic target in models of diseases with limited or no currently approved therapies, such as neuropathic pain and neurodegenerative conditions such as Alzheimer’s disease.

SUMMARY:

The functional involvement of CB2 receptor in neuropathic pain and other neuroinflammatory diseases highlights the potential therapeutic role of drugs acting at the CB2 receptor.”

https://www.ncbi.nlm.nih.gov/pubmed/29794855

https://insights.ovid.com/crossref?an=00001503-900000000-98981

Endocannabinoid system and pathophysiology of adipogenesis: current management of obesity.

“The endocannabinoids are now known as novel and important regulators of energy metabolism and homeostasis.

The endocrine functions of white adipose are chiefly involved in the control of whole-body metabolism, insulin sensitivity and food intake. Adipocytes produce hormones, such as leptin and adiponectin, that can improve insulin resistance or peptides, such as TNF-α, that elicit insulin resistance. Adipocytes express specific receptors, such as peroxisome proliferator-activated receptor (PPAR)-γ, which serve as adipocyte targets for insulin sensitizers such as thiazolidinediones.

Recently, endocannabinoids and related compounds were identified in human fat cells.

The endocannabinoid system consists primarily of two receptors, cannabinoid (CB)1 and CB2, their endogenous ligands termed endocannabinoids and the enzymes responsible for ligand biosynthesis and degradation.

The endocannabinoids 2-arachidonylglycerol and anandamide or N-arachidonoylethanolamine increase food intake and promote weight gain in animals. Rimonabant, a selective CB1 blocker, reduces food intake and body weight in animals and humans.”