The phytocannabinoid, Δ(9) -tetrahydrocannabivarin, can act through 5-HT1 A receptors to produce antipsychotic effects

Funded by: •GW Pharmaceuticals Acknowledgements: The authors wish to thank Mrs Lesley Stevenson for technical support and Dr John Raymond, Dr Keith Parker and Dr Ethan Russo for providing human 5-HT1A CHO cells. This research was supported by a grant from GW Pharmaceuticals to M. G. C. and R. G. P.Peer reviewedPostprin

Role of endocannabinoids in regulating drug dependence

This review will discuss the latest knowledge of how the endocannabinoid system might be involved in treating addiction to the most common illicit drugs. Experimental models are providing increasing evidence for the pharmacological management of endocannabinoid signaling not only to block the direct reinforcing effects of cannabis, opioids, nicotine and ethanol, but also for preventing relapse to the various drugs of abuse, including opioids, cocaine, nicotine, alcohol and metamphetamine. Preclinical and clinical studies suggest that the endocannabinoid system can be manipulated by the CBI receptor antagonist SR141716A, that might constitute a new generation of compounds for treating addiction across different classes of abused drugs

Release of anandamide from blood cells

Background: Endogenous ligands of cannabinoid receptors ( endocannabinoids), in particular anandamide ( arachidonylethanolamide), have been recognized as being of crucial importance in a variety of physiological functions. Plasma concentrations of anandamide have been measured in a number of investigations; however, discrepant data on "normal'' anandamide plasma concentrations were reported. Since this might be caused by pre-analytical variables, we investigated the impact of different sample handling conditions on measured plasma anandamide concentrations. Methods: Blood samples were taken from healthy volunteers in EDTA- or heparin-containing tubes; whole blood samples were kept at +4 degrees C, room temperature, or 37 degrees C, respectively, for up to 120 min before obtaining plasma by centrifugation. Plasma anandamide concentrations were measured by an isotope-dilution liquid chromatography tandem mass spectrometry ( LC-MS/MS) method. Results: A marked time- and temperature-dependent increase in plasma anandamide concentrations ex vivo was observed in both EDTA- and heparin-containing tubes. Mean anandamide concentrations approximately doubled when EDTA samples were kept at 4 degrees C for 60 min before centrifugation {[}immediately centrifuged, 1.3 mg/L ( SD 0.3 mg/L); 2.8 mg/L ( SD 0.5 mg/L) after storage for 60 min; n=12). After storage of heparinized whole-blood samples for 120 min at 37 degrees C, a mean plasma anandamide concentration of 11.9 mg/L ( SD 1.8 mg/L) was found. In cell-free plasma, no increase in anandamide concentrations was found. Conclusion: Anandamide is released from blood cells ex vivo at a very high rate; therefore, strictly standardized pre-analytical protocols have to be applied for plasma anandamide determination

A molecular basis of analgesic tolerance to cannabinoids

Clinical usage of cannabinoids in chronic pain states is limited by their central side effects and the pharmacodynamic tolerance that sets in after repeated dosage. Analgesic tolerance to cannabinoids in vivo could be caused by agonist-induced downregulation and intracellular trafficking of cannabinoid receptors, but little is known about the molecular mechanisms involved. We show here that the type 1 cannabinoid receptor (CB1) interacts physically with G-protein-associated sorting protein 1 (GASP1), a protein that sorts receptors in lysosomal compartments destined for degradation. CB1 - GASP1 interaction was observed to be required for agonist-induced downregulation of CB1 in spinal neurons ex vivo as well as in vivo. Importantly, uncoupling CB1 from GASP1 in mice in vivo abrogated tolerance toward cannabinoid-induced analgesia. These results suggest that GASP1 is a key regulator of the fate of CB1 after agonist exposure in the nervous system and critically determines analgesic tolerance to cannabinoids

Adult Cellular Neuroadaptations Induced by Adolescent THC Exposure in Female Rats Are Rescued by Enhancing Anandamide Signaling

BackgroundIn rodent models, chronic exposure to cannabis' psychoactive ingredient, Δ9-tetrahydrocannabinol, during adolescence leads to abnormal behavior in adulthood. In female rats, this maladaptive behavior is characterized by endophenotypes for depressive-like and psychotic-like disorders as well as cognitive deficits. We recently reported that most depressive-like behaviors triggered by adolescent Δ9-tetrahydrocannabinol exposure can be rescued by manipulating endocannabinoid signaling in adulthood with the anandamide-inactivating enzyme FAAH inhibitor, URB597. However, the molecular mechanisms underlying URB597's antidepressant-like properties remain to be established.MethodsHere we examined the impact of adult URB597 treatment on the cellular and functional neuroadaptations that occurred in the prefrontal cortex and dentate gyrus of the hippocampus upon Δ9-tetrahydrocannabinol during adolescence through biochemical, morphofunctional, and electrophysiological studies.ResultsWe found that the positive action of URB597 is associated with the rescue of Δ9-tetrahydrocannabinol-induced deficits in endocannabinoid-mediated signaling and synaptic plasticity in the prefrontal cortex and the recovery of functional neurogenesis in the dentate gyrus of the hippocampus. Moreover, the rescue property of URB597 on depressive-like behavior requires the activity of the CB1 cannabinoid receptor.ConclusionsBy providing novel insights into the cellular and molecular mechanisms of URB597 at defined cortical and hippocampal circuits, our results highlight that positive modulation of endocannabinoid-signaling could be a strategy for treating mood alterations secondary to adolescent cannabis use

Repeated cocaine exposure and prolonged withdrawal induce spatial memory impairment and dysregulate the glutamatergic synapse composition in the dorsal hippocampus of male rats

Adolescents are particularly susceptible to various forms of gratification, among which psychostimulants. During adolescence the hippocampus, a brain area relevant to spatial memory domain, undergoes maturational processes, such as structural and molecular reorganization of the excitatory synapses. Our goal was to reveal putatively enduring spatial memory deficits and molecular correlates in male rats exposed to repeated cocaine after a period of withdrawal. Towards this goal, adolescent Sprague-Dawley male rats were exposed to chronic cocaine treatment (5 mg/kg/day, subcutaneously) for 15 days and, after 2 weeks of withdrawal, were subjected to spatial order object recognition (SOOR) test, a memory task based on the rat's ability to recognize objects displacement. Next, we investigated subcellular specific expression of markers of the glutamate synapse in the dorsal hippocampus. Our findings show that withdrawal from repeated cocaine exposure during adolescence is associated with spatial memory impairment. Such deficit was correlated to a reduced expression and retention of NMDA receptor subunits, GluN1, GluN2A and GluN2B, at both synaptic and extra-synaptic sites, an effect indicative of impaired NMDA receptor trafficking. Analysis of endocytosis markers (Rab family of monomeric GTPase) revealed that cocaine-withdrawn rats favor the degradative pathway (Rab7-Rab9) over the recycling pathway (Rab11). In contrast, saline-treated rats primarily activate the recycling pathway. Our findings, mislocalization of glutamatergic receptors together with sorting of NMDA receptor towards degradation, rather than recycling, may contribute to the understanding of the mechanisms underlying the spatial memory deficits in male rats with an adolescent history of cocaine