CBD Effects on TRPV1 Signaling Pathways in Cultured DRG Neurons

 “Cannabidiol (CBD) is reported to produce pain relief, but the clinically relevant cellular and molecular mechanisms remain uncertain.

The TRPV1 receptor integrates noxious stimuli and plays a key role in pain signaling. Hence, we conducted in vitro studies, to elucidate the efficacy and mechanisms of CBD for inhibiting neuronal hypersensitivity in cultured rat sensory neurons, following activation of TRPV1.

Results: DRG neurons treated with 10 and 50 µMol/L CBD showed calcium influx, but not at lower doses. Neurons treated with capsaicin demonstrated robust calcium influx, which was dose-dependently reduced in the presence of low dose CBD (IC50 = 100 nMol/L). The inhibition or desensitization by CBD was reversed in the presence of forskolin and cyclosporin. Forskolin-stimulated cAMP levels were significantly reduced in CBD treated neurons.

Conclusion: CBD at low doses corresponding to plasma concentrations observed physiologically inhibits or desensitizes neuronal TRPV1 signalling by inhibiting the adenylyl cyclase – cAMP pathway, which is essential for maintaining TRPV1 phosphorylation and sensitization. CBD also facilitated calcineurin-mediated TRPV1 inhibition. These mechanisms may underlie nociceptor desensitization and the therapeutic effect of CBD in animal models and patients with acute and chronic pain.”

https://pubmed.ncbi.nlm.nih.gov/32982390/

https://www.dovepress.com/cbd-effects-on-trpv1-signaling-pathways-in-cultured-drg-neurons-peer-reviewed-article-JPR

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Anticonvulsive Properties of Cannabidiol in a Model of Generalized Seizure Are Transient Receptor Potential Vanilloid 1 Dependent

View details for Cannabis and Cannabinoid Research cover image“Highly purified cannabidiol (CBD) (approved as Epidiolex® in the United States) has demonstrated efficacy with an acceptable safety profile in patients with Lennox-Gastaut or Dravet syndrome in four randomized controlled trials. CBD possesses affinity for many target classes with functional effects relevant to the pathophysiology of many disease types, including epilepsy.

Although the mechanism of action of CBD underlying the reduction of seizures in humans is unknown, transient receptor potential vanilloid 1 (TRPV1) represents a plausible target because (1) CBD activates and then desensitizes TRPV1, (2) TRPV1 is overexpressed in models of temporal lobe epilepsy and patients with epilepsy, (3) and TRPV1 modulates neuronal excitability.

Methods: To investigate a potential role of TRPV1 in the anticonvulsive effects of CBD, the effect of CBD on seizure threshold was assessed using a mouse maximal electroshock threshold model of generalized seizure in TRPV1 knockout and wildtype mice. The dose dependence of the CBD effect was determined and compared with that of the positive comparator diazepam and vehicle.

Results: At 50 and 100 mg/kg, CBD significantly (p<0.0001) increased seizure threshold in wildtype mice compared with TRPV1 knockout and vehicle controls. This effect was observed only at 100 mg/kg in TRPV1 knockout mice compared with knockout vehicle mice, in which gene deletion partially attenuated the CBD-increased seizure threshold. The effect of high-dose CBD in wildtype mice was nevertheless significantly different from vehicle-treated TRPV1 knockout mice (p<0.0001). Bioanalysis confirmed that genotype-specific differential brain exposure to CBD was not responsible for the observed effect on seizure threshold.

Conclusion: These data strongly implicate TRPV1 in the potential mechanisms of action for the anticonvulsive effects of CBD. The partial inhibition of the anticonvulsive effect of high-dose CBD in TRPV1 knockout mice may indicate the involvement of targets other than TRPV1. Further characterization of TRPV1 in the anticonvulsive effect of CBD in validated models of seizure is warranted, as is pharmacological investigation of the molecular interaction between CBD and TRPV1.”

https://pubmed.ncbi.nlm.nih.gov/32656346/

https://www.liebertpub.com/doi/10.1089/can.2019.0028

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Exploiting cannabinoid and vanilloid mechanisms for epilepsy treatment.

“This review focuses on the possible roles of phytocannabinoids, synthetic cannabinoids, endocannabinoids, and “transient receptor potential cation channel, subfamily V, member 1” (TRPV1) channel blockers in epilepsy treatment.

The phytocannabinoids are compounds produced by the herb Cannabis sativa, from which Δ9-tetrahydrocannabinol (Δ9-THC) is the main active compound. The therapeutic applications of Δ9-THC are limited, whereas cannabidiol (CBD), another phytocannabinoid, induces antiepileptic effects in experimental animals and in patients with refractory epilepsies.

Synthetic CB1 agonists induce mixed effects, which hamper their therapeutic applications. A more promising strategy focuses on compounds that increase the brain levels of anandamide, an endocannabinoid produced on-demand to counteract hyperexcitability. Thus, anandamide hydrolysis inhibitors might represent a future class of antiepileptic drugs. Finally, compounds that block the TRPV1 (“vanilloid”) channel, a possible anandamide target in the brain, have also been investigated.

In conclusion, the therapeutic use of phytocannabinoids (CBD) is already in practice, although its mechanisms of action remain unclear. Endocannabinoid and TRPV1 mechanisms warrant further basic studies to support their potential clinical applications.”

https://www.ncbi.nlm.nih.gov/pubmed/31839498

“Cannabidiol is in clinical use for refractory epilepsies.”

https://www.epilepsybehavior.com/article/S1525-5050(19)30373-7/fulltext

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Myrcene and terpene regulation of TRPV1.

Publication Cover“Nociceptive Transient Receptor Potential channels such as TRPV1 are targets for treating pain. Both antagonism and agonism of TRP channels can promote analgesia, through inactivation and chronic desensitization.

Since plant-derived mixtures of cannabinoids and the Cannabis component myrcene have been suggested as pain therapeutics, we screened terpenes found in Cannabis for activity at TRPV1.

These data establish TRPV1 as a target of Myrcene and suggest the therapeutic potential of analgesic formulations containing Myrcene.”

https://www.ncbi.nlm.nih.gov/pubmed/31446830

https://www.tandfonline.com/doi/full/10.1080/19336950.2019.1654347

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Role of the endocannabinoid and endovanilloid systems in an animal model of schizophrenia-related emotional processing/cognitive deficit.

Neuropharmacology

“Studies suggest that the endocannabinoid and endovanilloid systems are implicated in the pathophysiology of schizophrenia.

The Spontaneously Hypertensive Rats (SHR) strain displays impaired contextual fear conditioning (CFC) attenuated by antipsychotic drugs and worsened by pro-psychotic manipulations. Therefore, SHR strain is used to study emotional processing/associative learning impairments associated with schizophrenia and effects of potential antipsychotic drugs.

Here, we evaluated the expression of CB1 and TRPV1 receptors in some brain regions related to the pathophysiology of schizophrenia. We also assessed the effects of drugs that act on the endocannabinoid/endovanilloid systems on the CFC task in SHRs and control animals (Wistar rats – WRs).

These results reinforce the involvement of the endocannabinoid/endovanilloid systems in the SHRs CFC deficit and point to these systems as targets to treat the emotional processing/cognitive symptoms of schizophrenia.”

https://www.ncbi.nlm.nih.gov/pubmed/31103618

https://www.sciencedirect.com/science/article/pii/S0028390819301649?via%3Dihub

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Diverse TRPV1 responses to cannabinoids.

 Publication Cover“Cannabinoid compounds are potential analgesics. Users of medicinal Cannabis report efficacy for pain control, clinical studies show that cannabis can be effective and opioid sparing in chronic pain, and some constituent cannabinoids have been shown to target nociceptive ion channels. Here, we explore and compare a suite of cannabinoids for their impact upon the physiology of TRPV1. The cannabinoids tested evoke differential responses in terms of kinetics of activation and inactivation. Cannabinoid activation of TRPV1 displays significant dependence on internal and external calcium levels. Cannabinoid activation of TRPV1 does not appear to induce the highly permeant, pore-dilated channel state seen with Capsaicin, even at high current amplitudes. Finally, we analyzed cannabinoid responses at nocioceptive channels other than TRPV1 (TRPV2, TRPM8 and TRPA1), and report that cannabinoids differentially activate these channels. On the basis of response activation and kinetics, state-selectivity and receptor selectivity, it may be possible to rationally design approaches to pain using single or multiple cannabinoids.”

https://www.ncbi.nlm.nih.gov/pubmed/31096838

https://www.tandfonline.com/doi/full/10.1080/19336950.2019.1619436

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The Endocannabinoid/Endovanilloid System in Bone: From Osteoporosis to Osteosarcoma.

ijms-logo

“Bone is a dynamic tissue, whose homeostasis is maintained by a fine balance between osteoclast (OC) and osteoblast (OB) activity. The endocannabinoid/endovanilloid (EC/EV) system’s receptors are the cannabinoid receptor type 1 (CB1), the cannabinoid receptor type 2 (CB2), and the transient receptor potential cation channel subfamily V member 1 (TRPV1). Their stimulation modulates bone formation and bone resorption. Bone diseases are very common worldwide. Osteoporosis is the principal cause of bone loss and it can be caused by several factors such as postmenopausal estrogen decrease, glucocorticoid (GC) treatments, iron overload, and chemotherapies. Studies have demonstrated that CB1 and TRPV1 stimulation exerts osteoclastogenic effects, whereas CB2 stimulation has an anti-osteoclastogenic role. Moreover, the EC/EV system has been demonstrated to have a role in cancer, favoring apoptosis and inhibiting cell proliferation. In particular, in bone cancer, the modulation of the EC/EV system not only reduces cell growth and enhances apoptosis but it also reduces cell invasion and bone pain in mouse models. Therefore, EC/EV receptors may be a useful pharmacological target in the prevention and treatment of bone diseases. More studies to better investigate the biochemical mechanisms underlining the EC/EV system effects in bone are needed, but the synthesis of hybrid molecules, targeting these receptors and capable of oppositely regulating bone homeostasis, seems to be a promising and encouraging prospective in bone disease management.”

https://www.ncbi.nlm.nih.gov/pubmed/31003519

https://www.mdpi.com/1422-0067/20/8/1919

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Anticonvulsant effect of cannabidiol in the pentylenetetrazole model: Pharmacological mechanisms, electroencephalographic profile, and brain cytokine levels.

“Cannabidiol (CBD), the main nonpsychotomimetic compound from Cannabis sativa, inhibits experimental seizures in animal models and alleviates certain types of intractable epilepsies in patients.

Here we tested the hypothesis that CBD anticonvulsant mechanisms are prevented by cannabinoid (CB1 and CB2) and vanilloid (TRPV1) receptor blockers. We also investigated its effects on electroencephalographic (EEG) activity and hippocampal cytokines in the pentylenetetrazole (PTZ) model.

Pretreatment with CBD (60mg/kg) attenuated seizures induced by intraperitoneal, subcutaneous, and intravenous PTZ administration in mice. The effects were reversed by CB1, CB2, and TRPV1 selective antagonists (AM251, AM630, and SB366791, respectively). Additionally, CBD delayed seizure sensitization resulting from repeated PTZ administration (kindling). This cannabinoid also prevented PTZ-induced EEG activity and interleukin-6 increase in prefrontal cortex.

In conclusion, the robust anticonvulsant effects of CBD may result from multiple pharmacological mechanisms, including facilitation of endocannabinoid signaling and TRPV1 mechanisms. These findings advance our understanding on CBD inhibition of seizures, EEG activity, and cytokine actions, with potential implications for the development of new treatments for certain epileptic syndromes.”

https://www.ncbi.nlm.nih.gov/pubmed/28821005

http://www.epilepsybehavior.com/article/S1525-5050(17)30322-0/fulltext

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Endocannabinoid analogues exacerbate marble-burying behavior in mice via TRPV1 receptor.

“Activation of cannabinoid CB(1) receptor is shown to inhibit marble-burying behavior (MBB), a behavioral model for assessing obsessive-compulsive disorder (OCD).

Anandamide, an endogenous agonist at CB(1) receptor also activates the transient receptor potential vanilloid type 1 (TRPV1) channels but at a higher concentration.

Furthermore, anandamide-mediated TRPV1 effects are opposite to that of the CB(1) receptor. Therefore, the present study was carried out to investigate the influence of low and high doses of anandamide on MBB in CB(1) and TRPV1 antagonist pre-treated mice.

Thus, the study indicates the biphasic influence of anandamide on MBB, and chronic administration of capsazepine either alone or with URB597 might be an effective tool in the treatment of OCD.”

http://www.ncbi.nlm.nih.gov/pubmed/22248639

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Cannabinoid-based drugs targeting CB1 and TRPV1, the sympathetic nervous system, and arthritis.

“Chronic inflammation in rheumatoid arthritis (RA) is accompanied by activation of the sympathetic nervous system, which can support the immune system to perpetuate inflammation. Several animal models of arthritis already demonstrated a profound influence of adrenergic signaling on the course of RA.

Peripheral norepinephrine release from sympathetic terminals is controlled by cannabinoid receptor type 1 (CB1), which is activated by two major endocannabinoids (ECs), arachidonylethanolamine (anandamide) and 2-arachidonylglycerol.

These ECs also modulate function of transient receptor potential channels (TRPs) located on sensory nerve fibers, which are abundant in arthritic synovial tissue. TRPs not only induce the sensation of pain but also support inflammation via secretion of pro-inflammatory neuropeptides.

In addition, many cell types in synovial tissue express CB1 and TRPs.

In this review, we focus on CB1 and transient receptor potential vanilloid 1 (TRPV1)-mediated effects on RA since most anti-inflammatory mechanisms induced by cannabinoids are attributed to cannabinoid receptor type 2 (CB2) activation.

We demonstrate how CB1 agonism or antagonism can modulate arthritic disease.

The concept of functional antagonism with continuous CB1 activation is discussed.

Since fatty acid amide hydrolase (FAAH) is a major EC-degrading enzyme, the therapeutic possibility of FAAH inhibition is studied.

Finally, the therapeutic potential of ECs is examined since they interact with cannabinoid receptors and TRPs but do not produce central side effects.”

http://www.ncbi.nlm.nih.gov/pubmed/26343051

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