“This unit describes the use of cannabinoid radioligands in competitive binding assays for determining affinity parameters (IC50 , Ki ) of unlabeled compounds at transfected CB1 and CB2 receptors expressed in cell lines.”
Category Archives: Endocannabinoid System
The endocannabinoid system controls food intake via olfactory processes.
“Hunger arouses sensory perception, eventually leading to an increase in food intake, but the underlying mechanisms remain poorly understood. We found that cannabinoid type-1 (CB1) receptors promote food intake in fasted mice by increasing odor detection.
CB1 receptors were abundantly expressed on axon terminals of centrifugal cortical glutamatergic neurons that project to inhibitory granule cells of the main olfactory bulb (MOB).
Local pharmacological and genetic manipulations revealed that endocannabinoids and exogenous cannabinoids increased odor detection and food intake in fasted mice by decreasing excitatory drive from olfactory cortex areas to the MOB.
Consistently, cannabinoid agonists dampened in vivo optogenetically stimulated excitatory transmission in the same circuit.
Our data indicate that cortical feedback projections to the MOB crucially regulate food intake via CB1 receptor signaling, linking the feeling of hunger to stronger odor processing.Thus, CB1 receptor-dependent control of cortical feedback projections in olfactory circuits couples internal states to perception and behavior.”
Altered Expression of the CB1 Cannabinoid Receptor in the Triple Transgenic Mouse Model of Alzheimer’s Disease.
“The endocannabinoid system has gained much attention as a new potential pharmacotherapeutic target in various neurodegenerative diseases, including Alzheimer’s disease (AD).
…The altered CB1 levels appear, rather, to be age-and/or pathology-dependent, indicating an involvement of the endocannabinoid system in AD pathology and supporting the ECS as a potential novel therapeutic target for treatment of AD.”
Involvement of the endocannabinoid system in osteoarthritis pain.
“Increasing evidence from preclinical studies supports the interest of the endocannabinoid system as an emerging therapeutic target for osteoarthritis pain.
Indeed, pharmacological studies have shown the anti-nociceptive effects of cannabinoids in different rodent models of osteoarthritis, and compelling evidence suggests an active participation of the endocannabinoid system in the pathophysiology of this disease.
The ubiquitous distribution of cannabinoid receptors, together with the physiological role of the endocannabinoid system in the regulation of pain, inflammation and even joint function further support the therapeutic interest of cannabinoids for osteoarthritis.
…review summarizes the promising results that have been recently obtained in support of the therapeutic value of cannabinoids for osteoarthritis management.”
No more pain upon Gq -protein-coupled receptor activation: role of endocannabinoids.
“Marijuana has been used to relieve pain for centuries. The analgesic mechanism of its constituents, the cannabinoids, was only revealed after the discovery of cannabinoid receptors (CB1 and CB2 ) two decades ago.
The subsequent identification of the endocannabinoids, anandamide and 2-arachidonoylglycerol (2-AG), and their biosynthetic and degradation enzymes discloses the therapeutic potential of compounds targeting the endocannabinoid system for pain control.
Inhibitors of the anandamide and 2-AG degradation enzymes, fatty acid amide hydrolase and monoacylglycerol lipase, respectively, may be superior to direct cannabinoid receptor ligands as endocannabinoids are synthesized on demand and rapidly degraded, focusing action at generating sites.
Recently, a promising strategy for pain relief was revealed in the periaqueductal gray (PAG). It is initiated by Gq -protein-coupled receptor (Gq PCR) activation of the phospholipase C-diacylglycerol lipase enzymatic cascade, generating 2-AG that produces inhibition of GABAergic transmission (disinhibition) in the PAG, thereby leading to analgesia.
Here, we introduce the antinociceptive properties of exogenous cannabinoids and endocannabinoids, involving their biosynthesis and degradation processes, particularly in the PAG. We also review recent studies disclosing the Gq PCR-phospholipase C-diacylglycerol lipase-2-AG retrograde disinhibition mechanism in the PAG, induced by activating several Gq PCRs, including metabotropic glutamatergic (type 5 metabotropic glutamate receptor), muscarinic acetylcholine (M1/M3), and orexin 1 receptors.
Disinhibition mediated by type 5 metabotropic glutamate receptor can be initiated by glutamate transporter inhibitors or indirectly by substance P, neurotensin, cholecystokinin and capsaicin. Finally, the putative role of 2-AG generated after activating the above neurotransmitter receptors in stress-induced analgesia is discussed.”
Anandamide in primary sensory neurons: too much of a good thing?
“The quest for possible targets for the development of novel analgesics has identified the activation of the cannabinoid type 1 (CB1) receptor outside the CNS as a potential means of providing relief from persistent pain, which currently constitutes an unmet medical need.
Increasing tissue levels of the CB1 receptor endogenous ligand N-arachidonoylethanolamine (anandamide), by inhibiting anandamide degradation through blocking the anandamide-hydrolysing enzyme fatty acid amide hydrolase, has been suggested to be used to activate the CB1 receptor.
However, recent clinical trials revealed that this approach does not deliver the expected relief from pain. Here, we discuss one of the possible reasons, the activation of the transient receptor potential vanilloid type 1 ion channel (TRPV1) on nociceptive primary sensory neurons (PSNs) by anandamide, which may compromise the beneficial effects of increased tissue levels of anandamide.
We conclude that better design such as concomitant blocking of anandamide hydrolysis and anandamide uptake into PSNs, to inhibit TRPV1 activation, could overcome these problems.”
Endocannabinoids and neuropathic pain: focus on neuron-glia and endocannabinoid-neurotrophin interactions.
“Although originally described as a signalling system encompassing the cannabinoid CB1 and CB2 receptors, their endogenous agonists (the endocannabinoids), and metabolic enzymes regulating the levels of such agonists, the endocannabinoid system is now viewed as being more complex, and including metabolically related endocannabinoid-like mediators and their molecular targets as well.
The function and dysfunction of this complex signalling system in the molecular and cellular mechanisms of pain transduction and control has been widely studied over the last two decades.
In this review article, we describe some of the latest advances in our knowledge on the role of the endocannabinoid system, in its most recent and wider conception, in pain pathways, by focusing on: (1) neuron-glia interactions; and (2) emerging data on endocannabinoid cross-talk with neurotrophins, such as nerve growth factor and brain-derived neurotrophic factor.”
Neurotrophins, endocannabinoids and thermo-transient receptor potential: a threesome in pain signalling.
“Although pain is multifactorial at cellular and molecular levels, it is widely accepted that neurotrophin (TrkA, p75NTR, Ret and GFRs), cannabinoid (CB1 and CB2), and thermo-transient receptor potential (TRPs; TRPV1, TRPA1 and TRPM8) receptors play a pivotal role.
…the available information confirms that pharmacological modulation of this signalling triad is a highly valuable therapeutic strategy for effectively treating pain syndromes.”
Basolateral amygdala CB1 cannabinoid receptors mediate nicotine-induced place preference.
“In the present study, the effects of bilateral microinjections of cannabinoid CB1 receptor agonist and antagonist into the basolateral amygdala (intra-BLA) on nicotine-induced place preference were examined in rats.
Taken together, these findings support the possible role of endogenous cannabinoid system of the BLA in the acquisition and the expression of nicotine-induced place preference. Furthermore, it seems that there is a functional interaction between the BLA cannabinoid receptors and nicotine in producing the rewarding effects.”
Regulatory role of the Cannabinoid-2 receptor in stress-induced neuroinflammation in mice.
“Stress-exposure produces excitoxicity and neuroinflammation, contributing to the cellular damage observed in stress-related neuropathologies. The endocannabinoid system is present in stress-responsive neural circuits and it is emerging as a homeostatic system. The aim of this study was to elucidate the possible regulatory role of cannabinoid-2 receptor in stress-induced excitotoxicity and neuroinflammation.
CONCLUSIONS AND IMPLICATIONS:
These results suggest that pharmacological manipulation of CB2 receptor is a potential therapeutic strategy for the treatment of stress-related pathologies with a neuroinflammatory component, such as depression.”