Category Archives: Endocannabinoid System

Type-2 Cannabinoid Receptors in Neurodegeneration.

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“Based on its wide expression in immune cells, type 2 cannabinoid (CB2) receptors were traditionally thought to act as “peripheral receptors” with an almost exclusively immunomodulatory function. However, their recent identification in mammalian brain areas, as well as in distinct neuronal cells, has opened the way to a re-consideration of CB2 signaling in the context of brain pathophysiology, synaptic plasticity and neuroprotection. To date, accumulated evidence from several independent preclinical studies has offered new perspectives on the possible involvement of CB2signaling in brain and spinal cord traumatic injury, as well as in the most relevant neurodegenerative disorders like Alzheimer’s disease, Parkinson’s disease and Huntington’s chorea. Here, we will review available information on CB2 in these disease conditions, along with data that support also its therapeutic potential to treat them.”

http://www.ncbi.nlm.nih.gov/pubmed/27450295

Discovery of novel Tetrahydrobenzo[b]thiophene and pyrrole based scaffolds as potent and selective CB2 receptor ligands: The structural elements controlling binding affinity, selectivity and functionality.

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“CB2-based therapeutics show strong potential in the treatment of diverse diseases such as inflammation, multiple sclerosis, pain, immune-related disorders, osteoporosis and cancer, without eliciting the typical neurobehavioral side effects of CB1 ligands.

For this reason, research activities are currently directed towards the development of CB2 selective ligands. Herein, the synthesis of novel heterocyclic-based CB2 selective compounds is reported.

The present findings thus pave the way to the design and optimization of heterocyclic-based scaffolds with lipophilic carboxamide and/or retroamide substituent that can be exploited as potential CB2 receptor activity modulators.”

http://www.ncbi.nlm.nih.gov/pubmed/27448919

Allosteric modulation of heterodimeric G-protein-coupled receptors.

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“G-protein-coupled receptors (GPCRs) are, and will probably remain, the most tractable class of targets for the development of small-molecule therapeutic medicines.

Currently, all approved GPCR-directed medicines are agonists or antagonists at orthosteric binding sites – except for the calcimimetic cinacalcet, which is a positive allosteric modulator of Ca(2+)-sensing receptors, and maraviroc, an allosteric inhibitor of CC-chemokine receptor (CCR) 5.

It is now widely accepted that GPCRs exist and might function as dimers, and there is growing evidence for the physiological presence and relevance of GPCR heterodimers.

Molecules that can regulate a GPCR within a heterodimer, through allosteric effects between the two protomers of the dimer or between a protomer or protomers and the associated G protein, offer the potential to function in a highly selective and tissue-specific way.

Despite the conceptual attraction of such allosteric regulators of GPCR heterodimers as drugs, they cannot be identified by screening approaches that routinely use a ‘one GPCR target at a time’ strategy.

In our opinion, this will require the development of new approaches for screening and a return to the use of physiologically relevant cell systems at an early stage in compound identification.”

http://www.ncbi.nlm.nih.gov/pubmed/18022255

Allosteric modulation of the cannabinoid CB1 receptor.

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“We investigated the pharmacology of three novel compounds, Org 27569 (5-chloro-3-ethyl-1H-indole-2-carboxylic acid [2-(4-piperidin-1-yl-phenyl)-ethyl]-amide), Org 27759 (3-ethyl-5-fluoro-1H-indole-2-carboxylic acid [2-94-dimethylamino-phenyl)-ethyl]-amide), and Org 29647 (5-chloro-3-ethyl-1H-indole-2-carboxylic acid (1-benzyl-pyrrolidin-3-yl)-amide, 2-enedioic acid salt), at the cannabinoid CB1 receptor.

These data suggest that the Org compounds bind allosterically to the CB1 receptor and elicit a conformational change that increases agonist affinity for the orthosteric binding site.

The data presented clearly demonstrate, for the first time, that the cannabinoid CB1 receptor contains an allosteric binding site that can be recognized by synthetic small molecule ligands.”

http://www.ncbi.nlm.nih.gov/pubmed/16113085

Cannabidiol is an allosteric modulator at mu- and delta-opioid receptors.

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“The mechanism of action of cannabidiol, one of the major constituents of cannabis, is not well understood but a noncompetitive interaction with mu opioid receptors has been suggested on the basis of saturation binding experiments.

The aim of the present study was to examine whether cannabidiol is an allosteric modulator at this receptor, using kinetic binding studies, which are particularly sensitive for the measurement of allosteric interactions at G protein-coupled receptors.

In addition, we studied whether such a mechanism also extends to the delta opioid receptor. For comparison, (-)-Delta9-tetrahydrocannabinol (THC; another major constituent of cannabis) and rimonabant (a cannabinoid CB1 receptor antagonist) were studied.

The present study shows that cannabidiol is an allosteric modulator at mu and delta opioid receptors. This property is shared by THC but not by rimonabant.”

http://www.ncbi.nlm.nih.gov/pubmed/16489449

Arachidonylcyclopropylamide increases microglial cell migration through cannabinoid CB2 and abnormal-cannabidiol-sensitive receptors.

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“Microglial cells, the macrophages of the brain, express low, yet detectable levels of cannabinoid CB(1) receptors, which are known to modulate cell migration.

To determine if cannabinoid CB(1) receptors expressed by microglial cells modulate their migration, we assessed whether arachidonylcyclopropylamide (ACPA, an agonist shown to selectively activate CB(1) receptors) affects the migration of BV-2 cells, a mouse microglial cell line.

Our results suggest that cannabinoid CB(2) receptors and abn-CBD receptors, rather than cannabinoid CB(1) receptors, regulate microglial cell migration, and that ACPA is a broad cannabinoid receptor agonist.”

http://www.ncbi.nlm.nih.gov/pubmed/12921861

Complex pharmacology of natural cannabinoids: evidence for partial agonist activity of delta9-tetrahydrocannabinol and antagonist activity of cannabidiol on rat brain cannabinoid receptors.

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“Delta9-tetrahydrocannabinol (delta9-THC), cannabinol and cannabidiol are three important natural cannabinoids from the Marijuana plant (Cannabis sativa).

Using [35S]GTP-gamma-S binding on rat cerebellar homogenate as an index of cannabinoid receptor activation we show that: delta9-THC does not induce the maximal effect obtained by classical cannabinoid receptor agonists such as CP55940.

Moreover at high concentration delta9-THC exhibits antagonist properties.

Cannabinol is a weak agonist on rat cerebellar cannabinoid receptors and cannabidiol behaves as an antagonist acting in the micromolar range.”

http://www.ncbi.nlm.nih.gov/pubmed/9667767

Enantiomeric cannabidiol derivatives: synthesis and binding to cannabinoid receptors.

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“(-)-Cannabidiol (CBD) is a major, non psychotropic constituent of cannabis.

It has been shown to cause numerous physiological effects of therapeutic importance.

We have reported that CBD derivatives in both enantiomeric series are of pharmaceutical interest. Here we describe the syntheses of the major CBD metabolites, (-)-7-hydroxy-CBD and (-)-CBD-7-oic acid and their dimethylheptyl (DMH) homologs, as well as of the corresponding compounds in the enantiomeric (+)-CBD series. The starting materials were the respective CBD enantiomers and their DMH homologs.

The binding of these compounds to the CB(1) and CB(2) cannabinoid receptors are compared.

Surprisingly, contrary to the compounds in the (-) series, which do not bind to the receptors, most of the derivatives in the (+) series bind to the CB(1) receptor in the low nanomole range. Some of these compounds also bind weakly to the CB(2) receptor.”

http://www.ncbi.nlm.nih.gov/pubmed/15750656

Cannabinoid receptors in microglia of the central nervous system: immune functional relevance.

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“Microglia, resident macrophages of the brain, function as immune effector and accessory cells. Paradoxically, they not only play a role in host defense and tissue repair but also have been implicated in a variety of neuropathological processes.

Microglia, in addition to exhibiting phenotypic markers for macrophages, express CB1 and CB2 cannabinoid receptors. Recent studies suggest the existence of a third, yet-to-be cloned, non-CB1, non-CB2 cannabinoid receptor.

These receptors appear to be functionally relevant within defined windows of microglial activation state and have been implicated as linked to cannabinoid modulation of chemokine and cytokine expression.

The recognition that microglia express cannabinoid receptors and that their activation results in modulation of select cellular activities suggests that they may be amenable to therapeutic manipulation for ablating untoward inflammatory responses in the central nervous system.”  http://www.ncbi.nlm.nih.gov/pubmed/16204639

http://www.jleukbio.org/content/78/6/1192.long

 

Role of CB1 and CB2 receptors in the inhibitory effects of cannabinoids on lipopolysaccharide-induced nitric oxide release in astrocyte cultures.

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“The purpose of this study was to investigate the role of the central cannabinoid receptor (CB(1)) in mediating the actions of the endogenous cannabinoid agonist anandamide and the synthetic cannabinoid CP-55940.

Activation of primary mouse astrocyte cultures by exposure to bacterial lipopolysaccharide (LPS) caused a marked (approximately tenfold) increase in nitric oxide (NO) release.

Coincubation with the cannabinoid agonists anandamide or CP-55940 markedly inhibited release of NO (-12% to -55%).

We also showed that endogenous or synthetic cannabinoids inhibit LPS-induced inducible NO synthase expression (mRNA and protein) in astrocyte cultures.

These results indicate that CB1 receptors may promote antiinflammatory responses in astrocytes.”

http://www.ncbi.nlm.nih.gov/pubmed/11891798