Inhibition of endocannabinoid catabolic enzymes elicits anxiolytic-like effects in the marble burying assay

“Cannabinoids have long been shown to have a range of potential therapeutic effects, including antiemetic actions, analgesia, and anxiolysis. These data indicate that elevation of AEA or 2-AG reduces marble burying behavior and suggest that their catabolic enzymes represent potential targets for the development of new classes of pharmacotherapeutics to treat anxiety-related disorders.

Marijuana is commonly smoked to reduce feelings of stress and anxiety… much interest has been generated by the discovery of the endogenous cannabinoid (i.e. endocannabinoid; eCB) system as a source of targets for the development of new therapeutic treatments of a range of ailments including anxiety and depression…”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3034086/

Acute stress increases circulating anandamide and other N-acylethanolamines in healthy humans.

“Stress plays an important role in psychiatric disorders, and preclinical evidence indicates that the central endocannabinoid system modulates endocrine and neuronal responses to stress. This study aimed to investigate the effect of acute stress on circulating concentrations of endocannabinoids (eCBs) in healthy humans…

 …stress increased serum concentrations of AEA and the other NAEs immediately after the stress period…These results indicate that stress increases circulating NAEs in healthy human volunteers.

This finding supports a protective role for eCBs in anxiety. Further research is needed to elucidate the function of these lipid mediators, and to determine the mechanisms that regulate their appearance in the circulation.”

http://www.ncbi.nlm.nih.gov/pubmed/22763622

Role in Anxiety Behavior of the Endocannabinoid System in the Prefrontal Cortex

“Increasing evidence that low doses of cannabinoid agonists reduce anxiety-like behaviors in mice and rats is being reported, thus suggesting an anxiolytic role for the endogenous cannabinoid signaling. In line with this hypothesis, pharmacological agents that enhance the endogenous cannabinoid signaling exert anxiolytic-like actions…

  These findings support an anxiolytic role for physiological increases in AEA in the PFC, whereas more marked increases or decreases of this endocannabinoid might lead to an anxiogenic response due to TRPV1 stimulation or the lack of CB1 activation, respectively.”

http://cercor.oxfordjournals.org/content/18/6/1292.long

Endocannabinoid system and mood disorders: Priming a target for new therapies.

“The endocannabinoid system (ECS), comprising two G protein-coupled receptors (the cannabinoid receptors 1 and 2 [CB1 and CB2] for marijuana’s psychoactive principle ∆(9)-tetrahydrocannabinol [∆(9)-THC]), their endogenous small lipid ligands (namely anandamide [AEA] and 2-arachidonoylglycerol [2-AG], also known as endocannabinoids), and the proteins for endocannabinoid biosynthesis and degradation, has been suggested as a pro-homeostatic and pleiotropic signaling system activated in a time- and tissue-specific way during physiopathological conditions. In the brain activation of this system modulates the release of excitatory and inhibitory neurotransmitters and of cytokines from glial cells. As such, the ECS is strongly involved in neuropsychiatric disorders, particularly in affective disturbances such as anxiety and depression. It has been proposed that synthetic molecules that inhibit endocannabinoid degradation can exploit the selectivity of endocannabinoid action, thus activating cannabinoid receptors only in those tissues where there is perturbed endocannabinoid turnover due to the disorder, and avoiding the potential side effects of direct CB1 and CB2 activation. However, the realization that endocannabinoids, and AEA in particular, also act at other molecular targets, and that these mediators can be deactivated by redundant pathways, has recently led to question the efficacy of such approach, thus opening the way to new multi-target therapeutic strategies, and to the use of non-psychotropic cannabinoids, such as cannabidiol (CBD), which act via several parallel mechanisms, including indirect interactions with the ECS. The state of the art of the possible therapeutic use of endocannabinoid deactivation inhibitors and phytocannabinoids in mood disorders is discussed in this review article.”

http://www.ncbi.nlm.nih.gov/pubmed/23261685

Endocannabinoid system: emerging role from neurodevelopment to neurodegeneration.

“The endocannabinoid system, including endogenous ligands (‘endocannabinoids’ ECs), their receptors, synthesizing and degrading enzymes, as well as transporter molecules, has been detected from the earliest stages of embryonic development and throughout pre- and postnatal development. ECs are bioactive lipids, which comprise amides, esters and ethers of long chain polyunsaturated fatty acids. Anandamide (N-arachidonoylethanolamine; AEA) and 2-arachidonoylglycerol (2-AG) are the best studied ECs, and act as agonists of cannabinoid receptors.

Thus, AEA and 2-AG mimic several pharmacological effects of the exogenous cannabinoid delta9-tetrahydrocannabinol (Delta(9)-THC), the psychoactive principle of cannabis sativa preparations like hashish and marijuana. Recently, however, several lines of evidence have suggested that the EC system may play an important role in early neuronal development as well as a widespread role in neurodegeneration disorders. Many of the effects of cannabinoids and ECs are mediated by two G protein-coupled receptors (GPCRs), CB1 and CB2, although additional receptors may be implicated. Both CB1 and CB2 couple primarily to inhibitory G proteins and are subject to the same pharmacological influences as other GPCRs. This new system is briefly presented in this review, in order to put in a better perspective the role of the EC pathway from neurodevelopment to neurodegenerative disorders, like Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and multiple sclerosis.

In addition, the potential exploitation of antagonists of CB1 receptors, or of inhibitors of EC metabolism, as next-generation therapeutics is discussed.”

http://www.ncbi.nlm.nih.gov/pubmed/19356123

The endocannabinoid, anandamide, augments Notch-1 signaling in cultured cortical neurons exposed to amyloid-β and in the cortex of aged rats.

“Aberrant Notch signaling has recently emerged as a possible mechanism for the altered neurogenesis, cognitive impairment, and learning and memory deficits associated with Alzheimer disease (AD). Recently, targeting the endocannabinoid system in models of AD has emerged as a potential approach to slow the progression of the disease process. Although studies have identified neuroprotective roles for endocannabinoids, there is a paucity of information on modulation of the pro-survival Notch pathway by endocannabinoids. In this study the influence of the endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol, on the Notch-1 pathway and on its endogenous regulators were investigated in an in vitro model of AD. We report that AEA up-regulates Notch-1 signaling in cultured neurons… In summary, AEA has the proclivity to enhance Notch-1 signaling in an in vitro model of AD, which may have relevance for restoring neurogenesis and cognition in AD.”

http://www.ncbi.nlm.nih.gov/pubmed/22891244

Endocannabinoids accumulate in spinal cord of SOD1 G93A transgenic mice.

Abstract

“Approximately 2% of amyotrophic lateral sclerosis (ALS) cases are caused by mutations in the super oxide dismutase 1 (SOD1) gene and transgenic mice for these mutations recapitulate many features of this devastating neurodegenerative disease. Here we show that the amount of anandamide (AEA) and 2-arachidonoylglycerol (2-AG), two endocannabinoids that have neuroprotective properties, increase in spinal cord of SOD1(G93A) transgenic mice. This increase occurs in the lumbar section of spinal cords, the first section to undergo neurodegeneration, and is significant before overt motor impairment. Our results show that chronic neurodegeneration induced by a genetic mutation increases endocannabinoid production possibly as part of an endogenous defense mechanism.”

http://www.ncbi.nlm.nih.gov/pubmed/15189359

Increasing 2-arachidonoyl glycerol signaling in the periphery attenuates mechanical hyperalgesia in a model of bone cancer pain

“Metastatic and primary bone cancers are usually accompanied by severe pain that is difficult to manage. In light of the adverse side effects of opioids, manipulation of the endocannabinoid system may provide an effective alternative for the treatment of cancer pain…

These data extend our previous findings with anandamide in the same model and suggest that the peripheral endocannabinoid system is a promising target for the management of cancer pain.

Taken together, the data demonstrate that peripheral 2-AG signaling may be a significant target to exploit for the management of cancer pain. In contrast to AEA, which inhibits nociception through CB1 receptors… Dual pharmacological modulation of peripheral AEA and 2-AG signaling that directly and indirectly affects DRG neurons may be a novel approach to reducing cancer pain without the side effects…”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3104059/

 

Cannabinoid type-1 receptor reduces pain and neurotoxicity produced by chemotherapy

 “Painful peripheral neuropathy is a dose-limiting complication of chemotherapy. Cisplatin produces a cumulative toxic effect on peripheral nerves…”

 

“Cannabinoid type-1 receptor reduces pain and neurotoxicity produced by chemotherapy”

 

“Clinically, the synthetic cannabinoid agonist nabilone reduces chemotherapy-induced pain”

 

“Like synthetic CB1R agonists, AEA attenuates hyperalgesia in models of neuropathic, inflammatory and tumor pain.”

 

“Collectively, these results suggest that pharmacological facilitation of AEA signaling is a promising strategy for attenuating cisplatin-associated sensory neuropathy.”

 

“Conclusion

We have shown that cisplatin produces hyperalgesia and toxicity to sensory neurons as indicated by neurochemical, morphological and functional measures. Increasing AEA signaling at CB1 receptors not only reduced the hyperalgesia but reduced the neurotoxicity of cisplatin as well. Although the mechanisms by which AEA reduce neurotoxicity remain to be resolved, the present studies underscore the dual utility in exploiting the endocannabinoid system for management of neuropathic pain produced by chemotherapy.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3366638/

Targeting CB2 receptors and the endocannabinoid system for the treatment of pain.

Abstract

“The endocannabinoid system consists of the cannabinoid (CB) receptors, CB(1) and CB(2), the endogenous ligands anandamide (AEA, arachidonoylethanolamide) and 2-arachidonoylglycerol (2-AG), and their synthetic and metabolic machinery. The use of cannabis has been described in classical and recent literature for the treatment of pain, but the potential for psychotropic effects as a result of the activation of central CB(1) receptors places a limitation upon its use. There are, however, a number of modern approaches being undertaken to circumvent this problem, and this review represents a concise summary of these approaches, with a particular emphasis upon CB(2) receptor agonists. Selective CB(2) agonists and peripherally restricted CB(1) or CB(1)/CB(2) dual agonists are being developed for the treatment of inflammatory and neuropathic pain, as they demonstrate efficacy in a range of pain models. CB(2) receptors were originally described as being restricted to cells of immune origin, but there is evidence for their expression in human primary sensory neurons, and increased levels of CB(2) receptors reported in human peripheral nerves have been seen after injury, particularly in painful neuromas. CB(2) receptor agonists produce antinociceptive effects in models of inflammatory and nociceptive pain, and in some cases these effects involve activation of the opioid system. In addition, CB receptor agonists enhance the effect of mu-opioid receptor agonists in a variety of models of analgesia, and combinations of cannabinoids and opioids may produce synergistic effects. Antinociceptive effects of compounds blocking the metabolism of anandamide have been reported, particularly in models of inflammatory pain. There is also evidence that such compounds increase the analgesic effect of non-steroidal anti-inflammatory drugs (NSAIDs), raising the possibility that a combination of suitable agents could, by reducing the NSAID dose needed, provide an efficacious treatment strategy, while minimizing the potential for NSAID-induced gastrointestinal and cardiovascular disturbances. Other potential “partners” for endocannabinoid modulatory agents include alpha(2)-adrenoceptor modulators, peroxisome proliferator-activated receptor alpha agonists and TRPV1 antagonists. An extension of the polypharmacological approach is to combine the desired pharmacological properties of the treatment within a single molecule. Hopefully, these approaches will yield novel analgesics that do not produce the psychotropic effects that limit the medicinal use of cannabis.”

http://www.ncbi.nlm.nih.gov/pubmed/19150370