The challenge of treating obesity: the endocannabinoid system as a potential target.

Abstract

“Obesity and cardiometabolic risk, or the metabolic syndrome, continue to be major public health concerns. To date, treatment with lifestyle and pharmacotherapy interventions has resulted in limited efficacy in reversing the upward trend in this present-day health crisis. Research reveals that a modest 5% to 10% weight loss results in substantial improvement in health. While obtaining modest weight loss is often achievable, maintaining lost weight is challenging. Research has recently improved our understanding of several endogenous pathways that influence body weight regulation and disease risk. The endocannabinoid system has been found to regulate appetite and energy expenditure, as well as lipid and glucose metabolism. Interest in blocking stimulation of this pathway to aid weight loss and reduce cardiometabolic risk factor development is an area of interest and research. This article reviews the mechanisms by which the endocannabinoid system is believed to influence body weight regulation and cardiometabolic risk factors, as well as the results of clinical trials investigating the safety and efficacy of a selective cannabinoid-1 receptor antagonist (rimonabant). Clinical trials investigating rimonabant treatment resulted in substantial reductions in body weight and markers for cardiometabolic risk in study participants. However, increases in adverse events were reported in the drug-treated group. Data regarding long-term benefit and adverse events from rimonabant treatment are being collected in several ongoing clinical trials. Rimonabant is currently available in 42 countries, but has not received United States Food and Drug Administration approval. Food and nutrition professionals play a pivotal role in tackling the current obesity crisis; it is essential that they understand the many physiological mechanisms regulating body weight. Emerging research data reveals pathways that influence appetite and energy metabolism, and this knowledge may form the foundation for new clinical treatment options for obese individuals.”

http://www.ncbi.nlm.nih.gov/pubmed/18442506

The endocannabinoid system: its roles in energy balance and potential as a target for obesity treatment.

Abstract

“Obesity and cardiometabolic risk continue to be major public health concerns. A better understanding of the physiopathological mechanisms leading to obesity may help to identify novel therapeutic targets. The endocannabinoid system discovered in the early 1990s is believed to influence body weight regulation and cardiometabolic risk factors. This article aims to review the literature on the endocannabinoid system including the biological roles of its major components, namely, the cannabinoid receptors, their endogenous ligands the endocannabinoids and the ligand-metabolising enzymes. The review also discusses evidence that the endocannabinoid system constitutes a new physiological pathway occurring in the central nervous system and peripheral tissues that has a key role in the control of food intake and energy expenditure, insulin sensitivity, as well as glucose and lipid metabolism. Based on the important finding that there is a close association between obesity and the hyperactivity of the endocannabinoid system, interest in blocking stimulation of this pathway to aid weight loss and reduce cardiometabolic risk factor development has become an important area of research. Among the pharmacological strategies proposed, the antagonism of the cannabinoid receptors has been particularly investigated and several clinical trials have been conducted. One challenging pharmacological task will be to target the endocannabinoid system in a more selective, and hence, safe way. As the management of obesity also requires lifestyle modifications in terms of healthy eating and physical activity, the targeting of the endocannabinoid system may represent a novel approach for a multifactorial therapeutic strategy.”

http://www.ncbi.nlm.nih.gov/pubmed/20541029

Targeted modulators of the endogenous cannabinoid system: future medications to treat addiction disorders and obesity.

Abstract

“The endogenous endocannabinoid system encompasses a family of natural signaling lipids (“endocannabinoids”) functionally related to (9)-tetrahydrocannabinol, the psychoactive ingredient of marijuana (cannabis), along with proteins that modulate the endocannabinoids, including enzymes, transporters, and receptors. The endocannabinoid system’s ubiquitous regulatory actions in health and disease underscore its importance to mammalian (patho)physiology and suggest discrete targets through which it may be modulated for therapeutic gain. Medications based on the endocannabinoid system are an important focus of contemporary translational research, particularly with respect to substance abuse and obesity, two prevalent disorders with a pathogenic component of endocannabinoid system hyperactivity. Pressing health care needs have made the rational design of targeted CB1 cannabinoid-receptor modulators a promising route to future medications with significant therapeutic impact against psychobehavioral and metabolic disturbances having a reward-supported appetitive component.”

http://www.ncbi.nlm.nih.gov/pubmed/17915075

The endocannabinoid system as a target for the treatment of visceral obesity and metabolic syndrome.

Abstract

“The endogenous cannabinoid system is a novel, remarkably elaborate physiological signaling system, comprising the recently identified endogenous cannabinoid ligands, their corresponding selective receptors, and the machinery of proteins and enzymes that is involved in their biosynthesis, release, transport, and degradation. This system extends widely in both the central nervous system (CNS) and the periphery and exhibits a variety of actions implicated in vital functions (e.g., behavioral, antinociceptive, neuroprotective, immunosuppressive, cardiovascular, and metabolic). Particular interest has been focused on the apparent participation of endocannabinoids in metabolic homeostasis by modulating the activity of CNS circuits that control food intake and energy expenditure, the neuroendocrine response of the stress system, and the metabolic functions of crucial peripheral tissues, such as the adipose tissue, the gastrointestinal tract, the liver, and the skeletal muscles. These effects are predominantly CB(1) receptor mediated and, thus, selective antagonists of this receptor subtype are being vigorously investigated as potential therapeutic agents for the treatment of various metabolic derangements (e.g., obesity, insulin resistance, dyslipidemia, and metabolic syndrome). The first selective CB(1) receptor antagonist, rimonabant, has already successfully completed phase III clinical trials as adjunctive obesity treatment, with significant improvements in several associated metabolic and cardiovascular risk factors that led to the recent approval of its clinical use by the Food and Drug Administration.”

http://www.ncbi.nlm.nih.gov/pubmed/17148745

Pharmacotherapeutic targeting of the endocannabinoid signaling system: drugs for obesity and the metabolic syndrome.

Abstract

“Endogenous signaling lipids (“endocannabinoids”) functionally related to Delta(9)-tetrahydrocannabinol, the psychoactive ingredient of marijuana (Cannabis), are important biomediators and metabolic regulators critical to mammalian (patho)physiology. The growing family of endocannabinoids, along with endocannabinoid biosynthetic and inactivating enzymes, transporters, and at least two membrane-bound, G-protein coupled receptors, comprise collectively the mammalian endocannabinoid signaling system. The ubiquitous and diverse regulatory actions of the endocannabinoid system in health and disease have supported the regulatory approval of natural products and synthetic agents as drugs that alter endocannabinoid-system activity. More recent data support the concept that the endocananbinoid system may be modulated for therapeutic gain at discrete pharmacological targets with safety and efficacy. Potential medications based on the endocannabinoid system have thus become a central focus of contemporary translational research for varied indications with important unmet medical needs. One such indication, obesity, is a global pandemic whose etiology has a pathogenic component of endocannabinoid-system hyperactivity and for which current pharmacological treatment is severely limited. Application of high-affinity, selective CB1 cannabinoid receptor ligands to attenuate endocannabinoid signaling represents a state-of-the-art approach for improving obesity pharmacotherapy. To this intent, several selective CB1 receptor antagonists with varied chemical structures are currently in advanced preclinical or clinical trials, and one (rimonabant) has been approved as a weight-management drug in some markets. Emerging preclinical data suggest that CB1 receptor neutral antagonists may represent breakthrough medications superior to antagonists/inverse agonists such as rimonabant for therapeutic attenuation of CB1 receptor transmission. Since obesity is a predisposing condition for the cluster of cardiovascular and metabolic derangements collectively known as the metabolic syndrome, effective endocannabinoid-modulatory anti-obesity therapeutics would also help redress other major health problems including type-2 diabetes, atherothrombosis, inflammation, and immune disorders. Pressing worldwide healthcare needs and increasing appreciation of endocannabinoid biology make the rational design and refinement of targeted CB1 receptor modulators a promising route to future medications with significant therapeutic impact against overweight, obesity, obesity-related cardiometabolic dysregulation, and, more generally, maladies having a reward-supported appetitive component.”

http://www.ncbi.nlm.nih.gov/pubmed/18155257