Tag Archives: CB(1) and CB(2) receptors

Cannabinoid Receptors and the Endocannabinoid System: Signaling and Function in the Central Nervous System.

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“The biological effects of cannabinoids, the major constituents of the ancient medicinal plant Cannabis sativa (marijuana) are mediated by two members of the G-protein coupled receptor family, cannabinoid receptors 1 (CB1R) and 2. The CB1R is the prominent subtype in the central nervous system (CNS) and has drawn great attention as a potential therapeutic avenue in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Furthermore, cannabinoids also modulate signal transduction pathways and exert profound effects at peripheral sites. Although cannabinoids have therapeutic potential, their psychoactive effects have largely limited their use in clinical practice. In this review, we briefly summarized our knowledge of cannabinoids and the endocannabinoid system, focusing on the CB1R and the CNS, with emphasis on recent breakthroughs in the field. We aim to define several potential roles of cannabinoid receptors in the modulation of signaling pathways and in association with several pathophysiological conditions. We believe that the therapeutic significance of cannabinoids is masked by the adverse effects and here alternative strategies are discussed to take therapeutic advantage of cannabinoids.”

https://www.ncbi.nlm.nih.gov/pubmed/29533978

http://www.mdpi.com/1422-0067/19/3/833

Chronic treatment with URB597 ameliorates post-stress symptoms in a rat model of PTSD.

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Cover image volume 28, Issue 3

“Activating the endocannabinoid system has become a major focus in the search for novel therapeutics for anxiety and deficits in fear extinction, two defining features of PTSD. We examined whether chronic treatment with the fatty acid amide hydrolase (FAAH) inhibitor URB597 (0.2, 0.3, 0.4 mg/kg, i.p.) or the CB1/2 receptor agonist WIN55,212-2 (0.25, 0.5 mg/kg, i.p.) injected for 3 weeks to rats exposed to the shock and reminders model of PTSD would attenuate post-stress symptoms and affect basolateral amygdala (BLA) and CA1 CB1 receptors.

Exposure to shock and reminders enhanced acoustic startle response and impaired extinction. Rats exposed to shock and reminders and chronically treated with URB597 demonstrated normalized startle response and intact extinction kinetics. WIN55,212-2 only affected the startle response. The therapeutic effects of URB597 and WIN55,212-2 were found to be CB1 receptor dependent, as these effects were blocked when a low dose of the CB1 receptor antagonist AM251 (0.3 mg/kg, i.p. for 3 weeks) was co-administered. Moreover, URB597, but not WIN55,212-2, normalized the shock/reminders-induced upregulation in CB1 receptor levels in the BLA and CA1. One hour after the shock, N-arachidonoylethanolamine (AEA) was increased in the BLA and decreased in the CA1. Circulating 2-arachidonoylglycerol (2-AG) concentrations were decreased in shocked rats, with no significant effect in the BLA or CA1. FAAH activity was increased in the CA1 of shocked rats.

Chronic cannabinoid treatment with URB597 can ameliorate PTSD-like symptoms suggesting FAAH inhibitors as a potentially effective therapeutic strategy for the treatment of disorders associated with inefficient fear coping.”

https://www.ncbi.nlm.nih.gov/pubmed/29519609

http://www.europeanneuropsychopharmacology.com/article/S0924-977X(18)30045-2/fulltext

The anxiolytic effects of cannabidiol in chronically stressed mice are mediated by the endocannabinoid system: Role of neurogenesis and dendritic remodeling.

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“Repeated injections of cannabidiol (CBD), the major non-psychotomimetic compound present in the Cannabis sativa plant, attenuate the anxiogenic effects induced by Chronic Unpredictable Stress (CUS). The specific mechanisms remain to be fully understood but seem to involve adult hippocampal neurogenesis and recruitment of endocannabinoids.

Here we investigated for the first time if the behavioral and pro-neurogenic effects of CBD administered concomitant the CUS procedure (14 days) are mediated by CB1, CB2 or 5HT1A receptors, as well as CBD effects on dendritic remodeling and on intracellular/synaptic signaling (fatty acid amide hydrolase – FAAH, Akt, GSK3β and the synaptic proteins Synapsin Ia/b, mGluR1 and PSD95).

After 14 days, CBD injections (30 mg/kg) induced anxiolytic responses in stressed animals in the elevated plus-maze and novelty suppressed feeding tests, that were blocked by pre-treatment with a CB1 (AM251, 0.3 mg/kg) or CB2 (AM630, 0.3 mg/kg), but not by a 5HT1A (WAY100635, 0.05 mg/kg) receptor antagonist. Golgi staining and immunofluorescence revealed that these effects were associated with an increase in hippocampal neurogenesis and spine density in the dentate gyrus of the hippocampus. AM251 and AM630 abolished the effects of CBD on spines density. However, AM630 was more effective in attenuating the pro-neurogenic effects of CBD. CBD decreased FAAH and increased p-GSK3β expression in stressed animals, which was also attenuated by AM630.

These results indicate that CBD prevents the behavioral effects caused by CUS probably due to a facilitation of endocannabinoid neurotransmission and consequent CB1/CB2receptors activation, which could recruit intracellular/synaptic proteins involved in neurogenesis and dendritic remodeling.”

https://www.ncbi.nlm.nih.gov/pubmed/29510186

https://www.sciencedirect.com/science/article/pii/S0028390818301023

Toxicity, Cannabinoids.

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Cover of StatPearls

“Cannabinoids are a collective group of compounds that act on cannabinoid receptors. They include plant-derived phytocannabinoids, synthetic cannabinoids, and endogenously-derived endocannabinoids. The primary source of cannabinoid toxicity is from plant-derived cannabinoids and synthetic cannabinoids. These agents act as cannabinoid receptor agonists. More than 60 naturally occurring cannabinoids are found in the Sativa and Indica species of Cannabis, with delta-9 tetrahydrocannabinol (THC) being the main psychoactive compound. Other naturally occurring cannabinoids include cannabidiol and cannabinol. Marijuana is the most common colloquial name for crushed, dried leaves and flowers of the Cannabis plant. In recent years, there have been many reports of marijuana toxicity, primarily in the pediatric population, as medical and recreational marijuana has been legalized. The terms phytocannabinoids, marijuana and cannabis are used interchangeably. Synthetic cannabinoids were created for therapeutic and research purposes; however, despite legal efforts to limit their availability, synthetic cannabinoids have become an increasingly common drug of abuse, sold under various street names such as K2, Spice, and Black Mamba. Synthetic cannabinoids are associated with much more morbidity and mortality than the phytocannabinoids. Prescription preparations for medical usage include dronabinol, or pure THC, nabilone, a synthetic cannabinoid, and cannabidiol (CBD). Pharmaceutical use of cannabinoids is an ongoing field of research.”

https://www.ncbi.nlm.nih.gov/pubmed/29489164

https://www.ncbi.nlm.nih.gov/books/NBK482175/

Innovative Therapeutic Potential of Cannabinoid Receptors as Targets in Alzheimer’s disease and Less Well-Known Diseases.

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“The discovery of cannabinoid receptors at the beginning of the 1990s, CB1 being cloned in 1990 and CB2 cloned in 1993, and the availability of selective and potent cannabimimetics could only be justified by the existence of endogenous ligands that are capable of binding to them. Thus, the characterisation and cloning of the first cannabinoid receptor (CB1) led to the isolation and characterisation of the first endocannabinoid, arachidonoylethanolamide (AEA), two years later and the subsequent identification of a family of lipid transmitters known as the fatty acid ester 2-arachidonoylglycerol (2-AG). The endogenous cannabinoid system is a complex signalling system that comprises transmembrane endocannabinoid receptors, their endogenous ligands (the endocannabinoids), the specific uptake mechanisms and the enzymatic systems related to their biosynthesis and degradation. The endocannabinoid system has been implicated in a wide diversity of biological processes, in both the central and peripheral nervous systems, including memory, learning, neuronal development, stress and emotions, food intake, energy regulation, peripheral metabolism, and the regulation of hormonal balance through the endocrine system. In this context, this article will review the current knowledge of the therapeutic potential of cannabinoid receptor as a target in Alzheimer’s disease and other less well-known diseases that include, among others, multiple sclerosis, bone metabolism, and Fragile X syndrome. The therapeutic applications will be addressed through the study of cannabinoid agonists acting as single drugs and multi-target drugs highlighting the CB2 receptor agonist.”

https://www.ncbi.nlm.nih.gov/pubmed/29484980

http://www.eurekaselect.com/160083/article

Cannabidiol inhibits pathogenic T cells, decreases spinal microglial activation and ameliorates multiple sclerosis-like disease in C57BL/6 mice.

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British Journal of Pharmacology

“Cannabis extracts and several cannabinoids have been shown to exert broad anti-inflammatory activities in experimental models of inflammatory CNS degenerative diseases.

Clinical use of many cannabinoids is limited by their psychotropic effects. However, phytocannabinoids like cannabidiol (CBD), devoid of psychoactive activity, are, potentially, safe and effective alternatives for alleviating neuroinflammation and neurodegeneration.

Treatment with CBD during disease onset ameliorated the severity of the clinical signs of EAE.

CBD, a non-psychoactive cannabinoid, ameliorates clinical signs of EAE in mice, immunized against MOG. Suppression of microglial activity and T-cell proliferation by CBD appeared to contribute to these beneficial effects.”

https://www.ncbi.nlm.nih.gov/pubmed/21449980

“In summary, we have shown that CBD administered to MOG-immunized C57BL/6 mice, at the onset of EAE disease, reduced the severity of the clinical signs of EAE. CBD treatment was accompanied by diminished axonal loss and inflammation (infiltration of T cells and microglial activation). Moreover, CBD prevented proliferation of myelin-specific T cells in vitro. These observations suggest that CBD may have potential for alleviating MS-like pathology.” http://onlinelibrary.wiley.com/doi/10.1111/j.1476-5381.2011.01379.x/full

“Study Shows Cannabidiol (CBD) Improves MS-Like Symptoms”  http://www.prohealth.com/library/showarticle.cfm?libid=31211

Sex differences in antinociceptive response to Δ-9-tetrahydrocannabinol and CP 55,940 in the mouse formalin test.

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“Cannabinoids have shown promise for the treatment of intractable pain states and may represent an alternative pharmacotherapy for pain management.

A growing body of clinical evidence suggests a role for sex in pain perception and in cannabinoid response.

We examined cannabinoid sensitivity and tolerance in male and female mice expressing a desensitization-resistant form (S426A/S430A) of the cannabinoid type 1 receptor (CB1R).

Mice were assessed for acute and inflammatory nociceptive behaviors in the formalin test following pretreatment with either vehicle or mixed CB1R/CB2R agonists, Δ-9-tetrahydrocannabinol ([INCREMENT]-THC) (1-6 mg/kg) or CP 55,940 (0.06-0.2 mg/kg). Tolerance to the effects of 6 mg/kg [INCREMENT]-THC or 0.1 mg/kg CP 55,940 was examined by the formalin test following chronic daily dosing.

Female mice showed decreased sensitivity to the effects of [INCREMENT]-THC and CP 55,940 compared with male mice. The S426A/S430A mutation increased the attenuation of nociceptive behaviors for both agonists in both sexes. Female mice displayed delayed tolerance to [INCREMENT]-THC compared with male mice, whereas the S426A/S430A mutation conferred a delay in tolerance to [INCREMENT]-THC in both sexes. Male S426A/S430A mutant mice also display resistance to tolerance to CP 55,940 compared with wild-type controls.

This study demonstrates sex and genotype differences in response for two different cannabinoid agonists. The results underscore the importance of including both male and female mice in preclinical studies of pain and cannabinoid pharmacology.”

https://www.ncbi.nlm.nih.gov/pubmed/29461336

https://insights.ovid.com/crossref?an=00001756-900000000-98413

Cannabinoids prevent depressive-like symptoms and alterations in BDNF expression in a rat model of PTSD.

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“Posttraumatic stress disorder (PTSD) is a debilitating condition highly comorbid with depression. The endocannabinoid (eCB) system and brain-derived neurotrophic factor (BDNF) are suggestively involved in both disorders.

We examined whether cannabinoids can prevent the long-term depressive-like symptoms induced by exposure to the shock and situational reminders (SRs) model of PTSD. The CB1/2 receptor agonist WIN55,212-2 (0.5 mg/kg; i.p.), the fatty acid hydrolase (FAAH) inhibitor URB597 (0.3 mg/kg, i.p.) or vehicle were administered 2 h after severe shock.

Cannabinoids prevented the shock/SRs-induced alterations in social recognition memory, locomotion, passive coping, anxiety-like behavior, anhedonia, fear retrieval, fear extinction and startle response as well as the decrease in BDNF levels in the hippocampus and prefrontal cortex (PFC). Furthermore, significant correlations were found between depressive-like behaviors and BDNF levels in the brain.

The findings suggest that cannabinoids may prevent both depressive- and PTSD-like symptoms following exposure to severe stress and that alterations in BDNF levels in the brains’ fear circuit are involved in these effects.”

https://www.ncbi.nlm.nih.gov/pubmed/29458190

https://www.sciencedirect.com/science/article/pii/S027858461731000X

The Cannabinoids Δ8THC, CBD, and HU-308 Act via Distinct Receptors to Reduce Corneal Pain and Inflammation

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Mary Ann Liebert, Inc. publishers

“Corneal injury can result in dysfunction of corneal nociceptive signaling and corneal sensitization.

Activation of the endocannabinoid system has been reported to be analgesic and anti-inflammatory.

The purpose of this research was to investigate the antinociceptive and anti-inflammatory effects of cannabinoids with reported actions at cannabinoid 1 (CB1R) and cannabinoid 2 (CB2R) receptors and/or noncannabinoid receptors in an experimental model of corneal hyperalgesia.

Topical cannabinoids reduce corneal hyperalgesia and inflammation.

The antinociceptive and anti-inflammatory effects of Δ8THC are mediated primarily via CB1R, whereas that of the cannabinoids CBD and HU-308, involve activation of 5-HT1A receptors and CB2Rs, respectively.

Cannabinoids could be a novel clinical therapy for corneal pain and inflammation resulting from ocular surface injury.”

https://www.ncbi.nlm.nih.gov/pubmed/29450258

http://online.liebertpub.com/doi/abs/10.1089/can.2017.0041

Role of the endocannabinoid system in the formation and development of depression.

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“Two types of cannabinoid (CB) receptors have been described in the human body: CB1 and CB2 receptors. CB1 receptor distribution may be related to the cannabinoid functions of memory and cognition regulation as well as motor control.

In addition, the endocannabinoid system (ECS) related to CB1 receptors may be involved in human emotion regulation, especially depression occurrence. Indeed, CB1 receptors are all distributed in depression associated neuroanatomical structures and neural circuits.

Both animal experiments and clinical studies have demonstrated that impairment of the ECS pathway is present in depression models and patients, and application of both CB1 receptor agonists and anandamide (cannabinoid-like substance) degradation inhibitors produce similar biochemical and behavioral effects as antidepressants.

These findings provide a solid basis for understanding the ECS role in the formation and development of depression. Therefore, it can be inferred that the ECS may have an important function in both depression treatment and the effects of antidepressants.”

https://www.ncbi.nlm.nih.gov/pubmed/29441900