Tag Archives: agonists

The endocannabinoid system in advanced liver cirrhosis: pathophysiological implication and future perspectives.

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“Endogenous cannabinoids (EC) are ubiquitous lipid signalling molecules providing different central and peripheral effects that are mediated mostly by the specific receptors CB1 and CB2. The EC system is highly upregulated during chronic liver disease and consistent experimental and clinical findings indicate that it plays a role in the pathogenesis of liver fibrosis and fatty liver disease associated with obesity, alcohol abuse and hepatitis C.

Furthermore, a considerable number of studies have shown that EC and their receptors contribute to the pathogenesis of the cardio-circulatory disturbances occurring in advanced cirrhosis, such as portal hypertension, hyperdynamic circulatory syndrome and cirrhotic cardiomyopathy.

More recently, the EC system has been implicated in the development of ascites, hepatic encephalopathy and the inflammatory response related to bacterial infection. Rimonabant, a selective CB1 antagonist, was the first drug acting on the EC system approved for the treatment of obesity. Unfortunately, it has been withdrawn from the market because of its neuropsychiatric side effects.

Compounds able to target selectively the peripheral CB1 receptors are under evaluation.

In addition, molecules stimulating CB2 receptor or modulating the activity of enzymes implicated in EC metabolism are promising areas of pharmacological research.

Liver cirrhosis and the related complications represent an important target for the clinical application of these compounds.”

http://www.ncbi.nlm.nih.gov/pubmed/23890208

Therapeutic Utility of Cannabinoid Receptor Type 2 (CB2) Selective Agonists.

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“The cannabinoid receptor type 2 (CB2), is a class A GPCR that was cloned in 1993 while looking for an alternate receptor that could explain the pharmacological properties of 9- tetrahydrocannabinol. CB2 was identified among cDNAs based on its similarity in amino-acid sequence to the CB1 receptor and helped provide an explanation for the established effects of cannabinoids on the immune system.

In addition to the immune system, CB2 has widespread tissue expression and has been found in brain, PNS and GI tract. Several “mixed” cannabinoid agonists are currently in clinical use primarily for controlling pain and it is believed that selective CB2 agonism may afford a superior analgesic agent devoid of the centrally mediated CB1 effects.

Thus, selective CB2 receptor agonists represent high value putative therapeutics for treating pain and other disease states. In this perspective, we seek to provide a concise update of progress in the field.”

http://www.ncbi.nlm.nih.gov/pubmed/23865723

CB1 agonists, locally applied to the cortico-thalamic circuit of rats with genetic absence epilepsy, reduce epileptic manifestations.

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“Drugs that modulate the endocannabinoid system and endocannabinoids typically play an anticonvulsant role although some proconvulsant effects have been reported both in humans and animal models.

 This study aims to characterize the role of cannabinoids in specific areas of the cortico-thalamic network involved in oscillations that underlie seizures in a genetic animal model of absence epilepsy, the WAG/Rij rat.

These results, together with previous reports, support therapeutic potential for endocannabinoid system modulators in absence epilepsy and highlight that attenuated endocannabinergic function may contribute to the generation and maintenance of seizures. Furthermore, the entire cortico-thalamic network responds to cannabinoid treatment, indicating that in all areas considered, CB receptor activation inhibits the pathological synchronization that subserves absence seizures.

 In conclusion, our result might be useful for the identification of future drug therapies in absence epilepsy.”

http://www.ncbi.nlm.nih.gov/pubmed/23860329

The Cannabinoid Receptor Agonist THC Attenuates Weight Loss in a Rodent Model of Activity-Based Anorexia

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“Anorexia nervosa (AN) is characterized by anhedonia whereby patients experience little pleasure or reward in many aspects of their lives. Reward pathways and the endocannabionid system have been implicated in the mediation of food intake. The potential to exploit these systems to reverse weight loss is investigated in a rodent model of activity-based anorexia (ABA).

Given the powerful role of the endocannabionid system in stimulating reward processes and the apparent poor development of these processes in AN, it is important to test the hypothesis that exogenous administration of cannabinoid type 1 (CB1) receptor agonists can reverse the anorexia displayed in a rodent ABA model…

Importantly, the data presented here show for the first time the efficacy of THC  in retarding the progression of ABA…

In conclusion, these data establish for the first time the effectiveness of THC in rescuing animals from profound body weight loss associated with the development of ABA, independent of physical activity, which is enhanced if allowed access to highly palatable foods.

These results from the animal-based model of AN highlight the potential of cannabinoids and of the endocannabinoid system in the treatment of human anorexia.”

Full text: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096804/

CB1 Cannabinoid Receptor Agonist Prevents NGF-Induced Sensitization of TRPV1 in Sensory Neurons.

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“The transient receptor potential vanilloid type 1 channel (TRPV1) and nerve growth factor (NGF) are important mediators of inflammatory pain…

Cannabinoids, by activating CB1 G protein-coupled receptors, produce analgesia in a variety of pain models, though the exact mechanisms are not known. We tested the hypothesis that activation of the CB1 receptor by cannabinoids attenuates NGF-induced TRPV1 sensitization….

These results support the hypothesis that cannabinoids, acting through CB1 receptors, may produce analgesia in part by preventing NGF-induced sensitization of TRPV1 in afferent nociceptor nerve endings.”

http://www.ncbi.nlm.nih.gov/pubmed/23850608

The role of CB1 in immune modulation by cannabinoids.

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“There is clear evidence that CB(2), historically referred to as the peripheral cannabinoid receptor, mediates many of the immune modulatory effects of cannabinoids.

 However, cannabinoid receptors cannot be classified simply as central or peripheral since CB(2) has been shown to play a role in the central nervous system (CNS) and CB(1) mediates many immune system effects. Although Cnr1 mRNA and CB(1) protein expression is lower than Cnr2 mRNA or CB(2) protein expression in cells of the immune system, several studies have shown direct modulation of immune function via CB(1) by endogenous and exogenous cannabinoids in T cells, innate cells, and to a lesser extent, B cells.

In addition, indirect, but CB(1)-dependent, mechanisms of immune modulation exist. In fact, the mechanism by which cannabinoids attenuate neuroinflammation via CB(1) is likely a combination of immune suppression and neuroprotection.

 Although many studies demonstrate that agonists for CB(1) are immune suppressive and anti-inflammatory, CB(1) antagonists also exhibit anti-inflammatory properties. Overall, the data demonstrate that many of the immune modulatory effects of cannabinoids are mediated via CB(1).”

http://www.ncbi.nlm.nih.gov/pubmed/23261520

Researchers Have Discovered Synthetic Agents Used To Treat HIV Inflammation – Medical News Today

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“HIV can cause serious inflammation, regardless of drug therapy, as it develops slowly in immune cells called macrophages. However, new research conducted at the Temple University School of Medicine’s Department of Pathology and Laboratory Medicine and Center for Substance Abuse Research (CSAR) has just found that there are synthetic agents with anti-inflammatory properties, related to the active ingredient in cannabis, THC (tetrahydrocannabinol) which could limit and treat the chronic inflammation.

These findings suggest that CB2 agonists could be used along with antiretroviral drugs which could lead to a new form of therapy for HIV/AIDS.

It also suggests that the human immune system itself could be used to fight off the HIV infection.

According to Persidsky: “Our study suggests that the body’s own natural defenses can be made more powerful to fight some of the worst symptoms of HIV.”

Stimulating CB2 receptors could also be applied for treating other infections.”

More: http://www.medicalnewstoday.com/articles/260152.php

TEMPLE SCIENTISTS WEAKEN HIV INFECTION IN IMMUNE CELLS USING SYNTHETIC AGENTS RELATED TO ACTIVE INGREDIENT IN MARIJUANA

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“HIV, the virus that causes AIDS, is notorious for hiding within certain types of cells, where it reproduces at a slowed rate and eventually gives rise to chronic inflammation, despite drug therapy. But researchers at Temple University School of Medicine’s Department of Pathology and Laboratory Medicine and Center for Substance Abuse Research (CSAR) recently discovered that synthetic anti-inflammatory substances distantly related to the active ingredient of marijuana may be able to take the punch out of HIV while inside one of its major hideouts – immune cells known as macrophages. 

The breakthrough comes at a crucial time in the HIV/AIDS pandemic…

To better understand the connection between inflammation and neurocognitive conditions linked to long-term exposure to HIV, Ramirez and colleagues looked specifically at the CB2 receptor, a protein located on the surface of macrophages. CB2 is a binding site for substances called cannabinoids, the primary active compounds of cannabis (marijuana), and it may play a role in blocking inflammation in the CNS. Unlike its counterpart, the CB1 receptor, which is found primarily on neurons in the brain, CB2 does not mediate the psychoactive effects for which cannabis is popularly known.

Ramirez explained that there has been much pharmacological interest in developing agents that selectively target CB2. Ideally, these compounds would help limit chronic inflammatory responses and would not bind to CB1. The most promising compounds are those derived from THC (tetrahydrocannabinol), the main active substance in cannabis. 

The scientists landed on their discovery by conducting a series of experiments in a well-established, non-clinical HIV macrophage cell model. They began by treating the HIV-infected cells with one of three different synthetic CB2-activating compounds. The cells were then sampled periodically to measure the activity of an enzyme called reverse transcriptase, which is essential for HIV replication. After seven days, the team found that all three compounds had successfully attenuated HIV replication. The experiments and findings are detailed in the May issue of the Journal of Leukocyte Biology. 

The results suggest that selective CB2 agonists could potentially be used in tandem with existing antiretroviral drugs, opening the door to the generation of new drug therapies for HIV/AIDS. The data also support the idea that the human immune system could be leveraged to fight HIV infection. 

“Our study suggests that the body’s own natural defenses can be made more powerful to fight some of the worst symptoms of HIV,” Persidsky explained. He also noted that stimulating CB2 receptors in white blood cells could produce similar benefits against other viral infections.”

More: http://www.temple.edu/medicine/hiv_immune_cells.htm

Synthetic Compounds From Marijuana Appear to Fight HIV

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“Synthetic anti-inflammatory compounds derived from the active ingredient of marijuana appear to show potential as anti-HIV agents, Wired.co.uk reports. Publishing their findings in the Journal of Leukocyte Biology, researchers from Temple University School of Medicine’s Department of Pathology and Laboratory Medicine and Center for Substance Abuse Research (CSAR) studied synthetic derivations of THC, or tetrahydrocannabinol, a key chemical compound in marijuana, in cultures of HIV-infected cells.

Cannabinoids, which are the primary active compounds in marijuana, bind to proteins called CB2 receptors on the surface of macrophage immune cells. The CB2 site may play a role in reducing inflammation in the central nervous system, which is a major concern for people living with HIV, even those whose virus is fully suppressed thanks to antiretrovirals (ARVs). It is the CB1 receptors, mostly found in neurons in the brain, however, that cause marijuana’s psychoactive effects. So synthetic THC that has been developed to bind only to CB2 receptors should not make people stoned.

It is believed that macrophage cells, which are found throughout the body, are a major component of the HIV reservoir and are probably the first cells infected after sexual transmission of the virus.

Using a non-clinical cell model, the investigators treated HIV-infected macrophages with one of three different synthetic compounds that bind to CB2. By periodically measuring the activity of the enzyme reverse transcriptase, which HIV needs to replicate itself, the investigators concluded after a seven-day period that all three compounds fought HIV replication.

The findings suggest that these “CB2 agonists” could be a potential addition to ARV therapy, and also that the human immune system could be prompted to fight the virus using similar mechanisms.”

http://www.aidsmeds.com/articles/pot_CB2_1667_23905.shtml

Marijuana and its CD4 Receptors: A New HIV Treatment Strategy?

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“Drugs that target one of the two cellular receptors stimulated by the active ingredient in marijuana may prove to be effective at blocking a form of HIV that has been linked to faster disease progression during late stages of the infection.

Though the PLoS One research report highlighting these findings—published March 20 by a team of scientists at Mt. Sinai School of Medicine in New York—stops short of concluding that marijuana is one of nature’s best antiretrovirals, the authors suggest that further study of cannabinoids is needed to ultimately discover drugs with both antiviral and symptom-reducing properties.

Marijuana—purchased legally or illegally and either smoked or ingested—along with its synthetic counterpart Marinol (dronabinol) are used by many people living with HIV to manage various symptoms of illness, including pain, depression and weight loss.

The numerous effects of marijuana are the result of chemical interactions between the drug’s active ingredient, tetrahydrocannabinol (THC), and two receptors on a variety of cells in the body: cannabinoid receptor 1 (CR1) and cannabinoid receptor 2 (CR2)…

Using a cannabinoid receptor agonist—a THC-like compound—her team found that activation of CR2 inhibited CXCR4-tropic HIV infection. It did this, not by altering the number of CXCR4 receptors on CD4 cells—this is a therapeutic approach being explored by others—but rather by blocking the receptor’s “signaling process” and interaction with HIV. 

According to the PLoS One report, activation of CR2 blocked the ability of CXCR4-tropic virus to infect other cells by 30 to 60 percent. “This inhibition is pronounced in resting cells,” the researchers explain, “which are a target of CXCR4-tropic HIV.”

“Developing a drug that triggers only [CR2] as an adjunctive treatment to standard antiviral medication may help alleviate the symptoms of late-stage AIDS and prevent the virus from spreading,” said Dr. Costantino in an accompanying news announcement.”

More: http://www.aidsmeds.com/articles/hiv_marijuana_cannabinoids_1667_22119.shtml#.Ub8Pcix9Dhs.twitter