Allosteric Modulation: An Alternate Approach Targeting the Cannabinoid CB1 Receptor.

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“The cannabinoid CB1 receptor is a G protein coupled receptor and plays an important role in many biological processes and physiological functions.

A variety of CB1 receptor agonists and antagonists, including endocannabinoids, phytocannabinoids, and synthetic cannabinoids, have been discovered or developed over the past 20 years.

In 2005, it was discovered that the CB1 receptor contains allosteric site(s) that can be recognized by small molecules or allosteric modulators.

A number of CB1 receptor allosteric modulators, both positive and negative, have since been reported and importantly, they display pharmacological characteristics that are distinct from those of orthosteric agonists and antagonists.

Given the psychoactive effects commonly associated with CB1 receptor agonists and antagonists/inverse agonists, allosteric modulation may offer an alternate approach to attain potential therapeutic benefits while avoiding inherent side effects of orthosteric ligands.

This review details the complex pharmacological profiles of these allosteric modulators, their structure-activity relationships, and efforts in elucidating binding modes and mechanisms of actions of reported CB1 allosteric modulators.

The ultimate development of CB1 receptor allosteric ligands could potentially lead to improved therapies for CB1-mediated neurological disorders.”

https://www.ncbi.nlm.nih.gov/pubmed/27879006

Central Aspects of Nausea and Vomiting in GI Disorders.

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“Nausea and vomiting result from continuous interactions among gastrointestinal, central nervous system, and autonomic nervous system. Despite being closely associated, central pathways of nausea and vomiting appear to be at least partly different and nausea is no longer considered only a penultimate step of vomiting. Although our understanding of central pathways of nausea has improved over the last one decade, it is still very basic.

Afferent pathways from gastrointestinal tract via vagus, vestibular system, and chemoreceptor trigger zone project to nucleus tractus solitarius which, in turn, relays the signal to central pattern generator initiating multiple downstream pathways. This central nausea pathway appears to be under constant modulation by autonomic nervous system and cerebral cortex.

There is also some evidence that central pathway of chronic nausea is different from that of acute nausea and closely resembles that of neuropathic pain. This improved understanding has modified the way we can approach the treatment of acute and chronic nausea.

While conventional therapies such as antiemetics (antiserotoninergic, antihistaminic, antidopaminergic) and prokinetics are commonly used to manage acute nausea, they are not as effective in improving chronic nausea.

Recently, neuromodulators such as tricyclic antidepressants, gabapentin, olanzapine, benzodiazepines, and cannabinoids have been shown to have antinausea effect.

There is a need to study the utility of these drugs in managing chronic functional nausea. Improving our understanding of central and peripheral circuitry of nausea will allow us to better utilize the currently available drugs and develop new therapeutic options.”

https://www.ncbi.nlm.nih.gov/pubmed/27734216

From Phytocannabinoids to Cannabinoid Receptors and Endocannabinoids: Pleiotropic Physiological and Pathological Roles Through Complex Pharmacology.

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“Apart from having been used and misused for at least four millennia for, among others, recreational and medicinal purposes, the cannabis plant and its most peculiar chemical components, the plant cannabinoids (phytocannabinoids), have the merit to have led humanity to discover one of the most intriguing and pleiotropic endogenous signaling systems, the endocannabinoid system (ECS).

This review article aims to describe and critically discuss, in the most comprehensive possible manner, the multifaceted aspects of 1) the pharmacology and potential impact on mammalian physiology of all major phytocannabinoids, and not only of the most famous one Δ9-tetrahydrocannabinol, and 2) the adaptive pro-homeostatic physiological, or maladaptive pathological, roles of the ECS in mammalian cells, tissues, and organs.

In doing so, we have respected the chronological order of the milestones of the millennial route from medicinal/recreational cannabis to the ECS and beyond, as it is now clear that some of the early steps in this long path, which were originally neglected, are becoming important again. The emerging picture is rather complex, but still supports the belief that more important discoveries on human physiology, and new therapies, might come in the future from new knowledge in this field.”

http://www.ncbi.nlm.nih.gov/pubmed/27630175

Evaluation of Two Commercially Available Cannabidiol Formulations for Use in Electronic Cigarettes.

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“Since 24 states and the District of Columbia have legalized marijuana in some form, suppliers of legal marijuana have developed Cannabis sativa products for use in electronic cigarettes (e-cigarettes).

Personal battery powered vaporizers, or e-cigarettes, were developed to deliver a nicotine vapor such that smokers could simulate smoking tobacco without the inherent pathology of inhaled tobacco smoke. The liquid formulations used in these devices are comprised of an active ingredient such as nicotine mixed with vegetable glycerin (VG) and/or propylene glycol (PG) and flavorings.

A significant active ingredient of C. sativa, cannabidiol (CBD), has been purported to have anti-convulsant, anti-nociceptive, and anti-psychotic properties. These properties have potential medical therapies such as intervention of addictive behaviors, treatments for epilepsy, management of pain for cancer patients, and treatments for schizophrenia.

However, CBD extracted from C. sativa remains a DEA Schedule I drug since it has not been approved by the FDA for medical purposes.

Two commercially available e-cigarette liquid formulations reported to contain 3.3 mg/mL of CBD as the active ingredient were evaluated. These products are not regulated by the FDA in manufacturing or in labeling of the products and were found to contain 6.5 and 7.6 mg/mL of CBD in VG and PG with a variety of flavoring agents. Presently, while labeled as to content, the quality control of manufacturers and the relative safety of these products is uncertain.”

http://www.ncbi.nlm.nih.gov/pubmed/27621706

Targeting the endocannabinoid system: future therapeutic strategies.

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“The endocannabinoid system (ECS) is involved in many physiological regulation pathways in the human body, which makes this system the target of many drugs and therapies. In this review, we highlight the latest studies regarding the role of the ECS and the drugs that target it, with a particular focus on the basis for the discovery of new cannabinoid-based drugs. In addition, we propose some key steps, such as the creation of a cannabinoid-receptor interaction matrix (CRIM) and the use of metabolomics, towards the development of improved and more specific drugs for each relevant disease.”

http://www.ncbi.nlm.nih.gov/pubmed/27554802

Expression of Cannabinoid Receptors in Human Osteoarthritic Cartilage: Implications for Future Therapies

“Cannabinoids have shown to reduce joint damage in animal models of arthritis and reduce matrix metalloproteinase expression in primary human osteoarthritic (OA) chondrocytes.

Chondrocytes from OA joints were shown to express a wide range of cannabinoid receptors even in degenerate tissues, demonstrating that these cells could respond to cannabinoids.

Cannabinoids designed to bind to receptors inhibiting the catabolic and pain pathways within the arthritic joint, while avoiding psychoactive effects, could provide potential arthritis therapies.

Cannabinoids were originally derived from the cannabis plant, Cannabis sativa, which has been used medicinally and recreationally for many years because of its anti-inflammatory, analgesic, and psychoactive properties.”

http://online.liebertpub.com/doi/full/10.1089/can.2015.0001

Blockade of Cannabinoid CB1 receptor attenuates the acquisition of morphine-induced conditioned place preference along with a downregulation of ERK, CREB phosphorylation, and BDNF expression in the nucleus accumbens and hippocampus.

“Cannabinoid CB1 receptor (CB1R) is highly expressed in the mesocorticolimbic system and associated with drug craving and relapse.

Clinical trials suggest that CB1R antagonists may represent new therapies for drug addiction.

Collectively, these findings demonstrate that 1) Repeated morphine with context exposures but not merely the pharmacological effects of morphine increased CB1R expression both in the NAc and hippocampus. 2) CB1R antagonist mediated blockade of ERK-CREB-BDNF signaling activation in the NAc and hippocampus may be an important mechanism underlying the attenuation of morphine CPP.”

http://www.ncbi.nlm.nih.gov/pubmed/27461790

Assay of CB1 Receptor Binding.

“Type-1 cannabinoid receptor (CB1), one of the main targets of endocannabinoids, plays a key role in several pathophysiological conditions that affect both central nervous system and peripheral tissues. Today, its biochemical identification and pharmacological characterization, as well as the screening of thousands of novel ligands that might be useful for developing CB1-based therapies, are the subject of intense research. Among available techniques that allow the analysis of CB1 binding activity, radioligand-based assays represent one of the best, fast, and reliable methods.Here, we describe radioligand binding methods standardized in our laboratory to assess CB1 binding in both tissues and cultured cells. We also report a high-throughput radioligand binding assay that allows to evaluate efficacy and potency of different compounds, which might represent the basis for the development of new drugs that target CB1 receptor-dependent human diseases.”

http://www.ncbi.nlm.nih.gov/pubmed/27245890

Natural Phytochemicals in the Treatment and Prevention of Dementia: An Overview.

“The word dementia describes a class of heterogeneous diseases which etiopathogenetic mechanisms are not well understood. There are different types of dementia, among which, Alzheimer’s disease (AD), vascular dementia (VaD), dementia with Lewy bodies (DLB) and frontotemporal dementia (FTD) are the more common.

Currently approved pharmacological treatments for most forms of dementia seem to act only on symptoms without having profound disease-modifying effects. Thus, alternative strategies capable of preventing the progressive loss of specific neuronal populations are urgently required.

In particular, the attention of researchers has been focused on phytochemical compounds that have shown antioxidative, anti-amyloidogenic, anti-inflammatory and anti-apoptotic properties and that could represent important resources in the discovery of drug candidates against dementia.

In this review, we summarize the neuroprotective effects of the main phytochemicals belonging to the polyphenol, isothiocyanate, alkaloid and cannabinoid families in the prevention and treatment of the most common kinds of dementia.

We believe that natural phytochemicals may represent a promising sources of alternative medicine, at least in association with therapies approved to date for dementia.”

http://www.ncbi.nlm.nih.gov/pubmed/27110749

The multiplicity of action of cannabinoids: implications for treating neurodegeneration.

“The cannabinoid (CB) system is widespread in the central nervous system and is crucial for controlling a range of neurophysiological processes such as pain, appetite, and cognition. The endogenous CB molecules, anandamide, and 2-arachidonoyl glycerol, interact with the G-protein coupled CB receptors, CB(1) and CB(2).

These receptors are also targets for the phytocannabinoids isolated from the cannabis plant and synthetic CB receptor ligands.

The CB system is emerging as a key regulator of neuronal cell fate and is capable of conferring neuroprotection by the direct engagement of prosurvival pathways and the control of neurogenesis.

Many neurological conditions feature a neurodegenerative component that is associated with excitotoxicity, oxidative stress, and neuroinflammation, and certain CB molecules have been demonstrated to inhibit these events to halt the progression of neurodegeneration.

Such properties are attractive in the development of new strategies to treat neurodegenerative conditions of diverse etiology, such as Alzheimer’s disease, multiple sclerosis, and cerebral ischemia.

This article will discuss the experimental and clinical evidence supporting a potential role for CB-based therapies in the treatment of certain neurological diseases that feature a neurodegenerative component.”

http://www.ncbi.nlm.nih.gov/pubmed/20875047