Category Archives: Obesity

Cannabinoid receptor antagonists: pharmacological opportunities, clinical experience, and translational prognosis.

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Abstract

“The endogenous cannabinoid (CB) (endocannabinoid) signaling system is involved in a variety of (patho)physiological processes, primarily by virtue of natural, arachidonic acid-derived lipids (endocannabinoids) that activate G protein-coupled CB1 and CB2 receptors. A hyperactive endocannabinoid system appears to contribute to the etiology of several disease states that constitute significant global threats to human health. Consequently, mounting interest surrounds the design and profiling of receptor-targeted CB antagonists as pharmacotherapeutics that attenuate endocannabinoid transmission for salutary gain. Experimental and clinical evidence supports the therapeutic potential of CB1 receptor antagonists to treat overweight/obesity, obesity-related cardiometabolic disorders, and substance abuse. Laboratory data suggest that CB2 receptor antagonists might be effective immunomodulatory and, perhaps, anti-inflammatory drugs. One CB1 receptor antagonist/inverse agonist, rimonabant, has emerged as the first-in-class drug approved outside the United States for weight control. Select follow-on agents (taranabant, otenabant, surinabant, rosonabant, SLV-319, AVE1625, V24343) have also been studied in the clinic. However, rimonabant’s market withdrawal in the European Union and suspension of rimonabant’s, taranabant’s, and otenabant’s ongoing development programs have highlighted some adverse clinical side effects (especially nausea and psychiatric disturbances) of CB1 receptor antagonists/inverse agonists. Novel CB1 receptor ligands that are peripherally directed and/or exhibit neutral antagonism (the latter not affecting constitutive CB1 receptor signaling) may optimize the benefits of CB1 receptor antagonists while minimizing any risk. Indeed, CB1 receptor-neutral antagonists appear from preclinical data to offer efficacy comparable to or better than that of prototype CB1 receptor antagonists/inverse agonists, with less propensity to induce nausea. Continued pharmacological profiling, as the prelude to first-in-man testing of CB1 receptor antagonists with unique modes of targeting/pharmacological action, represents an exciting translational frontier in the critical path to CB receptor blockers as medicines.”

http://www.ncbi.nlm.nih.gov/pubmed/19249987

Neutral antagonism at the cannabinoid 1 receptor: a safer treatment for obesity.

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Abstract

“Obesity is a global problem with often strong neurobiological underpinnings. The cannabinoid 1 receptor (CB1R) was put forward as a promising drug target for antiobesity medication. However, the first marketed CB1R antagonist/inverse agonist rimonabant was discontinued, as its use was occasionally associated with negative affect and suicidality. In artificial cell systems, CB1Rs can become constitutively active in the absence of ligands. Here, we show that such constitutive CB1R activity also regulates GABAergic and glutamatergic neurotransmission in the ventral tegmental area and basolateral amygdala, regions which regulate motivation and emotions. We show that CB1R inverse agonists like rimonabant suppress the constitutive CB1R activity in such regions, and cause anxiety and reduced motivation for reward. The neutral CB1R antagonist NESS0327 does not suppress constitutive activity and lacks these negative effects. Importantly, however, both rimonabant and NESS0327 equally reduce weight gain and food intake. Together, these findings suggest that neutral CB1R antagonists can treat obesity efficiently and more safely than inverse agonists.”

http://www.ncbi.nlm.nih.gov/pubmed/23070073

Cannabinoid 1 G protein-coupled receptor (periphero-)neutral antagonists: emerging therapeutics for treating obesity-driven metabolic disease and reducing cardiovascular risk.

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Abstract

“Introduction: Obesity and related cardiometabolic derangements are spiraling global health problems urgently in need of safe, effective and durable pharmacotherapy. Areas covered: As an orexigenic and anabolic biosignaling network, the endocannabinoid system interacts with other information-transducing pathways to help ensure metabolic homeostasis. Hyperphagia stimulates reinforcing neuronal circuits favoring energy intake and conservation, inviting overweight/obesity and cardiometabolic risk factors (‘metabolic syndrome’). Associated increases in cannabinoid 1 G protein-coupled receptor (CB1R) activity/expression further exacerbate food consumption and the metabolic shift toward fat production and accumulation. The role of CB1R activity in hyperphagia and weight gain spurred the development of rimonabant (SR141716; Acomplia), the first-in-class CB1R antagonist/inverse agonist weight-loss drug. Rimonabant and similar CB1R inverse agonists also exert pleiotropic actions in addition to weight-loss effects that help correct obesity-related metabolic derangements and reduce cardiovascular risk in humans. The medicinal utility of these agents was crippled by clinically significant central and peripheral adverse effects that appear to reflect CB1R inverse agonists as a class. Consequently, increased attention is being given to CB1R neutral antagonists, CB1R blockers with intrinsically weak, if any, functional potency to elicit the negative-efficacy responses associated with inverse agonists. Laboratory studies demonstrate that CB1R neutral antagonists – whether readily accessible to the central nervous system or not (i.e., ‘periphero-neutral’ antagonists) – retain the salient therapeutic effects of CB1R inverse agonists on hyperphagia, weight-gain, and obesity-driven metabolic abnormalities with the distinct advantage of being associated with significantly less preclinical adverse events than are conventional CB1R inverse agonists such as rimonabant. Expert opinion: CB1R (periphero-)neutral antagonists merit continued analysis of their molecular pharmacology and evaluation of their therapeutic significance and translational potential as new-generation medicines for obesity-related derangements, including nonalcoholic fatty liver disease and type 2 diabetes, if not obesity itself.”

http://www.ncbi.nlm.nih.gov/pubmed/22646861

Cannabinoid-1 receptor (CB1R) blockers as medicines: beyond obesity and cardiometabolic disorders to substance abuse/drug addiction with CB1R neutral antagonists.

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Abstract

“INTRODUCTION:

Addiction to chemical substances with abuse potential presents medical needs largely unsolved by extant therapeutic strategies. Signal transmission through the cannabinoid-1 receptor (CB1R) in the central nervous system (CNS) modulates neurotransmitters/neuronal pathways contributing to the rewarding properties and hedonic effects of certain nondrug stimuli (e.g., food) and many prototypical addictive drugs, promoting excessive intake and its pathological consequences. Typical CB1R antagonists/inverse agonists reduce the rewarding effects and normalize behavioral phenotypes associated with food and abused drugs, but carry an unacceptable adverse-event profile that may reflect, at least partly, their intrinsic ability to alter basal homeostatic CB1R signaling in the CNS and elicit a negative efficacy response. Alternatively, peripherally biased CB1R inverse agonists with limited CNS permeability and putative CB1R neutral antagonists expressing modest (if any) inverse-agonist efficacy are garnering attention for treating obesity and related cardiometabolic complications with a potentially enhanced benefit-to-risk profile.

AREAS COVERED:

This mini-review calls attention to the proposition that CB1R neutral antagonists offer attractive opportunities for pharmacotherapeutic exploitation in the substance abuse/drug addiction space, whereas the restricted CNS accessibility of peripherally biased CB1R inverse agonists circumscribes their therapeutic utility for this indication.

EXPERT OPINION:

The unique preclinical pharmacology, efficacy profiles, and reduced adverse-event risk of CB1R neutral antagonists make them worthy of translational study for their potential therapeutic application beyond obesity/cardiometabolic disease to include substance-abuse/drug-addiction disorders.”

http://www.ncbi.nlm.nih.gov/pubmed/22335400

Peripheral CB1 cannabinoid receptor blockade improves cardiometabolic risk in mouse models of obesity

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Abstract

“Obesity and its metabolic consequences are a major public health concern worldwide. Obesity is associated with overactivity of the endocannabinoid system, which is involved in the regulation of appetite, lipogenesis, and insulin resistance. Cannabinoid-1 receptor (CB1R) antagonists reduce body weight and improve cardiometabolic abnormalities in experimental and human obesity, but their therapeutic potential is limited by neuropsychiatric side effects. Here we have demonstrated that a CB1R neutral antagonist largely restricted to the periphery does not affect behavioral responses mediated by CB1R in the brains of mice with genetic or diet-induced obesity, but it does cause weight-independent improvements in glucose homeostasis, fatty liver, and plasma lipid profile. These effects were due to blockade of CB1R in peripheral tissues, including the liver, as verified through the use of CB1R-deficient mice with or without transgenic expression of CB1R in the liver. These results suggest that targeting peripheral CB1R has therapeutic potential for alleviating cardiometabolic risk in obese patients.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2912197/

The Central Cannabinoid CB1 Receptor Is Required for Diet-Induced Obesity and Rimonabant’s Antiobesity Effects in Mice

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Abstract

“Cannabinoid receptor CB1 is expressed abundantly in the brain and presumably in the peripheral tissues responsible for energy metabolism. It is unclear if the antiobesity effects of rimonabant, a CB1 antagonist, are mediated through the central or the peripheral CB1 receptors. To address this question, we generated transgenic mice with central nervous system (CNS)-specific knockdown (KD) of CB1, by expressing an artificial microRNA (AMIR) under the control of the neuronal Thy1.2 promoter. In the mutant mice, CB1 expression was reduced in the brain and spinal cord, whereas no change was observed in the superior cervical ganglia (SCG), sympathetic trunk, enteric nervous system, and pancreatic ganglia. In contrast to the neuronal tissues, CB1 was undetectable in the brown adipose tissue (BAT) or the liver. Consistent with the selective loss of central CB1, agonist-induced hypothermia was attenuated in the mutant mice, but the agonist-induced delay of gastrointestinal transit (GIT), a primarily peripheral nervous system-mediated effect, was not. Compared to wild-type (WT) littermates, the mutant mice displayed reduced body weight (BW), adiposity, and feeding efficiency, and when fed a high-fat diet (HFD), showed decreased plasma insulin, leptin, cholesterol, and triglyceride levels, and elevated adiponectin levels. Furthermore, the therapeutic effects of rimonabant on food intake (FI), BW, and serum parameters were markedly reduced and correlated with the degree of CB1 KD. Thus, KD of CB1 in the CNS recapitulates the metabolic phenotype of CB1 knockout (KO) mice and diminishes rimonabant’s efficacy, indicating that blockade of central CB1 is required for rimonabant’s antiobesity actions.”

http://www.nature.com/oby/journal/v19/n10/full/oby2011250a.html

Marijuana smokers are thinner, less likely to be obese than non-smokers, according to new study

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“Stoners may spend a lot of time on the couch and craving White Castle, but they apparently don’t let their bodies go to pot.

People who smoke marijuana regularly are less likely to be obese than non-pot smokers, according to a new study by French researches.

“We found that cannabis users are less likely to be obese than non-users,” Dr. Yann Le Strat, French psychiatrist and co-author of a new study in the American Journal of Epidemiology told MSNBC. “We were so surprised, we thought we had [made] a mistake.”

Using data from two epidemiologic studies of U.S. adults, researchers found that between 22% to 25% of participants who didn’t smoke pot were obese.

But only between 14% and 17% of those people who admitted to taking a toke at least three times a week were overweight.

Le Strat said other factors, such as the stoners’ level of physical activity or diets, could have contributed to the results, but his team tried to rule out those factors.

The researches were also quick to point out that sucking on a bong isn’t the key to a tight tummy.

“The take-home message is certainly not ‘smoke cannabis, it will help you lose weight,'” Le Strat said. “The possibility that cannabis is associated with a lower risk of obesity remains an interesting hypothesis, but certainly does not counterbalance its negative effects on health and mental health.””

http://articles.nydailynews.com/2011-09-04/entertainment/30136983_1_cannabis-marijuana-smokers-smoke-pot

The Marijuana Diet: Study Says Pot Smokers Tend to be Skinnier (Really)

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“You know the stereotype: Marijuana user = Jonah Hill-looking dude who lives on his friend’s couch.

But if you look at the daily smokers around you, and we know you have daily smokers around you, this being the pot shop capital of the nation and all, what are you looking at?

You see skinny people.

For the first time, a study seems to back up the observation that stoners are actually lithe
Research published last week in the American Journal of Epidemiology (via our friends at SF Weekly) finds that weed smokers on average are more likely to have normal weight.

Parsing data, researchers found that 22 percent of nonsmokers were overweight while only 14 percent of bud aficionados were. Those ID’d as potheads had to smoke at least three times a week under the study.

What munchies? This might explain why pot-smoking women are often, well, smoking hot.

Interesting, because one of the arguments for legalizing medical marijuana is that it can be used to boost the appetites of AIDS sufferers and cancer patients who have trouble keeping weight on.

Still a valid use? Whatever works.

But we do know that the Marijuana Diet sounds way cooler than any eating plan South Beach Miami has ever produced.”

[@dennisjromero/djromero@laweekly.com]

http://blogs.laweekly.com/informer/2011/09/marijuana_skinny_fat_study.php

The future of weight loss: A ‘marijuana’ diet pill?

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“Limiting a brain compound that regulates metabolism allows genetically altered mice to stay skinny without exercising. Is a dream pill far behind?

If you find the prospect of staying thin while eating as much as you want appealing, scientists have news for you. New research from the University of California, Irvine — detailed in the March issue of Cell Metabolism — found that certain brain chemicals with characteristics similar to marijuana might help the body shed pounds without any exercise. A dream come true? Here’s a brief look at the promising discovery:

What chemical could have such power?
It’s an endocannabinoid compound called 2-AG. Endocannabinoids, as the name might suggest, share a similar molecular structure to the active ingredients in cannabis. Typically, high levels of 2-AG are found in the brains of mammals, and previous studies suggested that these compounds may make the body crave fat. Scientists think endocannabinoids play a key role in regulating the body’s metabolism, or the energy it makes from food.

How did scientists put the compound to the test?
Researchers genetically engineered brain cells in mice to exhibit low levels of 2-AG, on the theory that this would allow the rodents’ metabolic rates to “go crazy,” says Kristen Philipkoski at Gizmodo. And the hunch was right. These mice lived in a “hypermetabolic state,” burning fat calories far more efficiently than normal mice, study researcher Daniele Piomeli said in a statement. They were “resistant to obesity,” staying thin despite a high-fat diet without exercise. They even had normal blood pressure, and showed no increased risk of heart disease or diabetes. 

How could this discovery help humans?
“To produce the desired effects, we would need to create a drug that blocks 2-AG production in the brain,” says Piomeli, “something we’re not yet able to do.” 

So can we expect a miracle pill in the foreseeable future?
“Tweaking” human brain chemistry is no easy task, says Philipkoski. And preliminary estimates say it would take a decade and cost up to $2 billion to make the drug safe and effective enough for the FDA to to approve it. “So don’t cancel that gym membership just yet,” says Piomeli.”

http://news.yahoo.com/future-weight-loss-marijuana-diet-pill-071500947.html