Tag Archives: agonists

Cannabinoids.

Posted on by

“Since the discovery of an endogenous cannabinoid system, research into the pharmacology and therapeutic potential of cannabinoids has steadily increased. Two subtypes of G-protein coupled cannabinoid receptors, CB(1) and CB(1), have been cloned and several putative endogenous ligands (endocannabinoids) have been detected during the past 15 years. The main endocannabinoids are arachidonoyl ethanolamide (anandamide) and 2-arachidonoyl glycerol (2-AG), derivatives of arachidonic acid, that are produced “on demand” by cleavage of membrane lipid precursors.

 Besides phytocannabinoids of the cannabis plant, modulators of the cannabinoid system comprise synthetic agonists and antagonists at the CB receptors and inhibitors of endocannabinoid degradation. Cannabinoid receptors are distributed in the central nervous system and many peripheral tissues, including immune system, reproductive and gastrointestinal tracts, sympathetic ganglia, endocrine glands, arteries, lung and heart. There is evidence for some non-receptor dependent mechanisms of cannabinoids and for endocannabinoid effects mediated by vanilloid receptors.

Properties of CB receptor agonists that are of therapeutic interest include analgesia, muscle relaxation, immunosuppression, anti-inflammation, antiallergic effects, improvement of mood, stimulation of appetite, antiemesis, lowering of intraocular pressure, bronchodilation, neuroprotection and antineoplastic effects. The current main focus of clinical research is their efficacy in chronic pain and neurological disorders. CB receptor antagonists are under investigation for medical use in obesity and nicotine addiction. Additional potential was proposed for the treatment of alcohol and heroine dependency, schizophrenia, conditions with lowered blood pressure, Parkinson’s disease and memory impairment in Alzheimer’s disease.”

http://www.ncbi.nlm.nih.gov/pubmed/16266285

Anti-inflammatory cannabinoids in diet: Towards a better understanding of CB(2) receptor action?

Posted on by

“The endocannabinoid system is an ancient lipid signaling network which in mammals modulates neuronal functions, inflammatory processes, and is involved in the aetiology of certain human lifestyle diseases, such as Crohn’s disease, atherosclerosis and osteoarthritis.

The system is able to downregulate stress-related signals that lead to chronic inflammation and certain types of pain, but it is also involved in causing inflammation-associated symptoms, depending on the physiological context.

The cannabinoid type-2 (CB2) receptor, which unlike the CB1 receptor does not induce central side effects, has been shown to be a promising therapeutic target. While CB1 receptor antagonists/inverse agonists are of therapeutic value, also CB2 receptor ligands including agonists are of pharmacological interest.

 Although the endocannabinoid system is known to be involved in the regulation of energy homoeostasis and metabolism (mainly via CB1 receptors) there was hitherto no direct link between food intake and cannabinoid receptor activation. Our recent finding that beta-caryophyllene, a ubiquitous lipohilic plant natural product, selectively binds to the CB2 receptor and acts as a full agonist is unexpected…

In the case of the dietary natural product beta-caryophyllene, a full CB2 receptor-selective agonist in vitro, potent anti-inflammatory cannabimimetic effects are observed. Intriguingly, the lowest oral dose tested (5 mg/Kg) of this widespread and apparently non-toxic compound, which is also an FDA-approve food additive, was the most effective. Maybe this strengthens the hypothesis that beta-caryophyllene is indeed a dietary cannabinoid, thus inferring that by eating this compound the endocannabinoid system may be modulated in a beneficial way…”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2633791/

The endocannabinoid system in inflammatory bowel diseases: from pathophysiology to therapeutic opportunity.

Posted on by

“Crohn’s disease and ulcerative colitis are two major forms of inflammatory bowel diseases (IBD), which are chronic inflammatory disorders of the gastrointestinal tract. These pathologies are currently under investigation to both unravel their etiology and find novel treatments.

Anandamide and 2-arachidonoylglycerol are endogenous bioactive lipids that bind to and activate the cannabinoid receptors, and together with the enzymes responsible for their biosynthesis and degradation [fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL)] constitute the endocannabinoid system (ECS).

The ECS is implicated in gut homeostasis, modulating gastrointestinal motility, visceral sensation, and inflammation, as well as being recently implicated in IBD pathogenesis.

Numerous subsequent studies investigating the effects of cannabinoid agonists and endocannabinoid degradation inhibitors in rodent models of IBD have identified a potential therapeutic role for the ECS.”

http://www.ncbi.nlm.nih.gov/pubmed/22917662

The Cannabinoid 1 Receptor (CNR1) 1359 G/A Polymorphism Modulates Susceptibility to Ulcerative Colitis and the Phenotype in Crohn’s Disease

Posted on by

“Anecdotal reports suggest that marijuana- or tetrahydrocannabinol-containing products may be effective in alleviating symptoms in patients with ulcerative colitis (UC) and Crohn’s disease (CD). This is supported by recent studies of our group and others suggesting that pharmacological activation of the cannabinoid 1 (CB1) receptor with selective receptor agonists decreases the inflammatory response in various murine models of colonic inflammation…

Recent evidence suggests a crucial role of the endocannabinoid system, including the cannabinoid 1 receptor (CNR1), in intestinal inflammation. We therefore investigated the influence of the CNR1 1359 G/A (p.Thr453Thr; rs1049353) single nucleotide polymorphism (SNP) on disease susceptibility and phenotype in patients with ulcerative colitis (UC) and Crohn’s disease (CD)…

Conclusion

The CNR1 p.Thr453Thr polymorphism appears to modulate UC susceptibility and the CD phenotype. The endocannabinoid system may influence the manifestation of inflammatory bowel diseases, suggesting endocannabinoids as potential target for future therapies.

…our findings provide further evidence that endocannabinoids modulate intestinal inflammation, suggesting that this system could act as a target for future therapeutic interventions.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2829088/

The endocannabinoid system in the physiology and pathophysiology of the gastrointestinal tract.

Posted on by

“Numerous investigations have recently demonstrated the important roles of the endocannabinoid system in the gastrointestinal (GI) tract under physiological and pathophysiological conditions.

 In the GI tract, cannabinoid type 1 (CB1) receptors are present in neurons of the enteric nervous system and in sensory terminals of vagal and spinal neurons, while cannabinoid type 2 receptors are located in immune cells. Activation of CB1 receptors was shown to modulate several functions in the GI tract, including gastric secretion, gastric emptying and intestinal motility.

Under pathophysiological conditions induced experimentally in rodents, the endocannabinoid system conveys protection to the GI tract (e.g. from inflammation and abnormally high gastric and enteric secretions).

Such protective activities are largely in agreement with anecdotal reports from folk medicine on the use of Cannabis sativa extracts by subjects suffering from various GI disorders.

 Thus, the endocannabinoid system may serve as a potentially promising therapeutic target against different GI disorders, including frankly inflammatory bowel diseases (e.g. Crohn’s disease), functional bowel diseases (e.g. irritable bowel syndrome) and secretion- and motility-related disorders.

As stimulation of this modulatory system by CB1 receptor agonists can lead to unwanted psychotropic side effects, an alternative and promising avenue for therapeutic applications resides in the treatment with CB1 receptor agonists that are unable to cross the blood-brain barrier, or with compounds that inhibit the degradation of endogenous ligands (endocannabinoids) of CB1 receptors, hence prolonging the activity of the endocannabinoid system.”

http://www.ncbi.nlm.nih.gov/pubmed/16133420

Cannabinoid Receptor 2-Mediated Attenuation of CXCR4-Tropic HIV Infection in Primary CD4+ T Cells

Posted on by

“Agents that activate cannabinoid receptor pathways have been tested as treatments for cachexia, nausea or neuropathic pain in HIV-1/AIDS patients… Cannabinoid agonists activate the CB1R and CB2R cannabinoid receptors…

Cannabinoid agonists are currently under investigation for the treatment of AIDS-associated cachexia, nausea, and neuropathic pain. One such drug, dronabinol (Δ9-THC; Marinol®), has won Food and Drug Administration (FDA) approval for treatment of HIV-associated anorexia. Additionally, the prescription of smoked or ingested cannabis (marijuana) for treatment of AIDS-related symptoms has been approved…. Despite the use of cannabinoids by HIV/AIDS patients, few studies have investigated the impact of such drugs in regard to viral pathogenesis or immune regulation…

….Indeed, both smoked marijuana and dronabinol were reported to increase total CD4+ T cell number and naïve T cell number over a 21-day period. A decrease in viral load was also observed in these patients. Similarly, in SIV infected rhesus macaques, Δ9-THC exposure reduced viral load and CD4+ T cell depletion, significantly increasing animal survival over an 11 month period.

. Our findings suggest that CB2R activation in CD4+ T cells can inhibit actin reorganization and impair productive infection following cell-free or cell-associated viral acquisition of CXCR4-tropic HIV-1 in resting cells.

Therefore, the clinical use of CB2R agonists in the treatment of AIDS symptoms may also exert beneficial adjunctive antiviral effects against CXCR4-tropic viruses in late stages of HIV-1 infection.

Further study of cannabinoids and other neuroendocrine regulators that selectively modulate immune function may result in the discovery of new anti-viral drugs that can also mitigate AIDS-associated symptoms.”

Full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3309010/

Attenuation of HIV-1 replication in macrophages by cannabinoid receptor 2 agonists.

Posted on by

“Previous studies showed that activation of the CB2 can attenuate inflammatory responses and affect HIV-1 infectivity in T cells and microglia. Here, we report that CB2 agonists can also act as immunomodulators on HIV-1-infected macrophages.

   We speculate that these findings indicate that prevention of viral entry is not a central mechanism for CB2-mediated suppression in viral replication.

However, CB2 may affect the HIV-1 replication machinery.

Results from a single-round infection with the pseudotyped virus revealed a marked decrease in HIV-1 LTR activation by the CB2 ligands.

Together, these results indicate that CB2 may offer a means to limit HIV-1 infection in macrophages.”

http://www.ncbi.nlm.nih.gov/pubmed/23463725

Functional role for cannabinoids in respiratory stability during sleep.

Posted on by

“Serotonin, acting in the peripheral nervous system, can exacerbate sleep-related apnea, and systemically administered serotonin antagonists reduce sleep-disordered respiration in rats and bulldogs. Because cannabinoid receptor agonists are known to inhibit the excitatory effects of serotonin on nodose ganglion cells, we examined the effects of endogenous (oleamide) and exogenous (delta9-tetrahydrocannabinol; delta9THC) cannabimimetic agents on sleep-related apnea…

Our data show that delta9THC and oleamide each stabilized respiration during all sleep stages… This observation suggests an important role for endocannabinoids in maintaining autonomic stability during sleep…

CONCLUSIONS:

This study demonstrates potent suppression of sleep-related apnea by both exogenous and endogenous cannabinoids. These findings are of relevance to the pathogenesis and pharmacological treatment of sleep-related breathing disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/12071539

Activation of Cannabinoid CB2 Receptor-Mediated AMPK/CREB Pathway Reduces Cerebral Ischemic Injury.

Posted on by

“The type 2 cannabinoid receptor (CB2R) was recently shown to mediate neuroprotection in ischemic injury. However, the role of CB2Rs in the central nervous system, especially neuronal and glial CB2Rs in the cortex, remains unclear. We, therefore, investigated anti-ischemic mechanisms of cortical CB2R activation in various ischemic models….

  Collectively, these data demonstrate that cortical CB2R activation by TC (trans-caryophyllene, a CB2R agonist,), ameliorates ischemic injury, potentially through modulation of AMPK/CREB signaling, and suggest that cortical CB2Rs might serve as a putative therapeutic target for cerebral ischemia.”

http://www.ncbi.nlm.nih.gov/pubmed/23414569

Role of cannabinoid and vanilloid receptors in invasion of human breast carcinoma cells.

Posted on by

“It is known that the diversified effects of cannabinoid on the fate of carcinoma cells are mediated predominantly through receptors. However, little is known about the effects of the individual activities of cannabinoid and noncannabinoid receptors. Here we investigate the role of cannabinoid receptor (CB) 1, CB2, and transient receptor potential vanilloid type 1 in cell proliferation and invasion patterns in the MDA-MB-231 cell line.

Our results showed that activation of CB1 and vanilloid receptors by methanandamide, a nonselective agonist, and arachidonyl-2′-choloroethylamide (ACEA) and N-oleoyldopamine, selective agonists, reduced invasion of MDA-MB-231 cells at pharmacological concentrations. Accordingly, CB1 activation resulted in decreased expression of matrix metalloproteinase (MMP) 2. On the other hand, administration of a CB2 agonist (CB65) increased cell invasion and expression of MMP2. The data obtained from MTT assay did not show any correlation between reduced invasion and cytotoxic effects of drugs. In addition, the level of vascular endothelial growth factor was significantly reduced in treatment with (R)-(+)-methanandamide, ACEA, CB65, and AM251 (a potent agonist for GPR55 and selective antagonist of CB1) compared with control. Elevated expression of cyclooxygenase-2 was observed in all of the MDA-MB-231 cells treated with agonists.

These results underline the influence of cannabinoid and vanilloid receptors on the invasiveness of MDA-MB-231 human breast carcinoma cells.”

http://www.ncbi.nlm.nih.gov/pubmed/23394450