Targeting the Endocannabinoid System for Neuroprotection: A 19F-NMR Study of a Selective FAAH Inhibitor Binding with an Anandamide Carrier Protein, HSA

Fatty acid amide hydrolase (FAAH), the enzyme involved in the inactivation of the endocannabinoid anandamide (AEA), is being considered as a therapeutic target for analgesia and neuroprotection. We have developed a brain permeable FAAH inhibitor, AM5206, which has served as a valuable pharmacological tool to explore neuroprotective effects of this class of compounds. In the present work, we characterized the interactions of AM5206 with a representative AEA carrier protein, human serum albumin (HSA), using 19F nuclear magnetic resonance (NMR) spectroscopy. Our data showed that as a drug carrier, albumin can significantly enhance the solubility of AM5206 in aqueous environment. Through a series of titration and competitive binding experiments, we also identified that AM5206 primarily binds to two distinct sites within HSA. Our results may provide insight into the mechanism of HSA-AM5206 interactions. The findings should also help in the development of suitable formulations of the lipophilic AM5206 and its congeners for their effective delivery to specific target sites in the brain

Probing the Carboxyester Side Chain in Controlled Deactivation (−)-Δ8-Tetrahydrocannabinols

We recently reported on a controlled deactivation/detoxification approach for obtaining cannabinoids with improved druggability. Our design incorporates a metabolically labile ester group at strategic positions within the THC structure. We have now synthesized a series of (−)-Δ8-THC analogues encompassing a carboxyester group within the 3-alkyl chain in an effort to explore this novel cannabinergic chemotype for CB receptor binding affinity, in vitro and in vivo potency and efficacy, as well as controlled deactivation by plasma esterases. We have also probed the chain’s polar characteristics with regard to fast onset and short duration of action. Our lead molecule, namely 2-[(6aR,10aR)-6a,7,10,10a-tetrahydro-1-hydroxy-6,6,9-trimethyl-6H-dibenzo[b,d]pyran-3-yl]-2-methyl-propanoic acid 3-cyano-propyl ester (AM7438), showed picomolar affinity for CB receptors and is deactivated by plasma esterases while the respective acid metabolite is inactive. In further in vitro and in vivo experiments, the compound was found to be a remarkably potent and efficacious CB1 receptor agonist with relatively fast onset/offset of action

Controlled-Deactivation CB1 Receptor Ligands as a Novel Strategy to Lower Intraocular Pressure

Nearly half a century has passed since the demonstration that cannabis and its chief psychoactive component Δ9-THC lowers intraocular pressure (IOP). Elevated IOP remains the chief hallmark and therapeutic target for glaucoma, a condition that places millions at risk of blindness. It is likely that Δ9-THC exerts much of its IOP-lowering effects via the activation of CB1 cannabinoid receptors. However, the initial promise of CB1 as a target for treating glaucoma has not thus far translated into a credible therapeutic strategy. We have recently shown that blocking monoacylglycerol lipase (MAGL), an enzyme that breaks the endocannabinoid 2-arachidonoyl glycerol (2-AG), substantially lowers IOP. Another strategy is to develop cannabinoid CB1 receptor agonists that are optimized for topical application to the eye. Recently we have reported on a controlled-deactivation approach where the “soft” drug concept of enzymatic deactivation was combined with a “depot effect” that is commonly observed with Δ9-THC and other lipophilic cannabinoids. This approach allowed us to develop novel cannabinoids with a predictable duration of action and is particularly attractive for the design of CB1 activators for ophthalmic use with limited or no psychoactive effects. We have tested a novel class of compounds using a combination of electrophysiology in autaptic hippocampal neurons, a well-characterized model of endogenous cannabinoid signaling, and measurements of IOP in a mouse model. We now report that AM7410 is a reasonably potent and efficacious agonist at CB1 in neurons and that it substantially (30%) lowers IOP for as long as 5 h after a single topical treatment. This effect is absent in CB1 knockout mice. Our results indicate that the direct targeting of CB1 receptors with controlled-deactivation ligands is a viable approach to lower IOP in a murine model and merits further study in other model systems

Blockade of CB1 or Activation of CB2 Cannabinoid Receptors Is Differentially Efficacious in the Treatment of the Early Pathological Events in Streptozotocin-Induced Diabetic Rats

Oxidative stress, neurodegeneration, neuroinflammation, and vascular leakage are believed to play a key role in the early stage of diabetic retinopathy (ESDR). The aim of this study was to investigate the blockade of cannabinoid receptor 1 (CB1R) and activation of cannabinoid receptor 2 (CB2R) as putative therapeutics for the treatment of the early toxic events in DR. Diabetic rats [streptozotocin (STZ)-induced] were treated topically (20 μL, 10 mg/mL), once daily for fourteen days (early stage DR model), with SR141716 (CB1R antagonist), AM1710 (CB2R agonist), and the dual treatment SR141716/AM1710. Immunohistochemical-histological, ELISA, and Evans-Blue analyses were performed to assess the neuroprotective and vasculoprotective properties of the pharmacological treatments on diabetes-induced retinal toxicity. Activation of CB2R or blockade of CB1R, as well as the dual treatment, attenuated the nitrative stress induced by diabetes. Both single treatments protected neural elements (e.g., RGC axons) and reduced vascular leakage. AM1710 alone reversed all toxic insults. These findings provide new knowledge regarding the differential efficacies of the cannabinoids, when administered topically, in the treatment of ESDR. Cannabinoid neuroprotection of the diabetic retina in ESDR may prove therapeutic in delaying the development of the advanced stage of the disease

Blockade of CB1 or Activation of CB2 Cannabinoid Receptors Is Differentially Efficacious in the Treatment of the Early Pathological Events in Streptozotocin-Induced Diabetic Rats

Oxidative stress, neurodegeneration, neuroinflammation, and vascular leakage are believed to play a key role in the early stage of diabetic retinopathy (ESDR). The aim of this study was to investigate the blockade of cannabinoid receptor 1 (CB1R) and activation of cannabinoid receptor 2 (CB2R) as putative therapeutics for the treatment of the early toxic events in DR. Diabetic rats [streptozotocin (STZ)-induced] were treated topically (20 μL, 10 mg/mL), once daily for fourteen days (early stage DR model), with SR141716 (CB1R antagonist), AM1710 (CB2R agonist), and the dual treatment SR141716/AM1710. Immunohistochemical-histological, ELISA, and Evans-Blue analyses were performed to assess the neuroprotective and vasculoprotective properties of the pharmacological treatments on diabetes-induced retinal toxicity. Activation of CB2R or blockade of CB1R, as well as the dual treatment, attenuated the nitrative stress induced by diabetes. Both single treatments protected neural elements (e.g., RGC axons) and reduced vascular leakage. AM1710 alone reversed all toxic insults. These findings provide new knowledge regarding the differential efficacies of the cannabinoids, when administered topically, in the treatment of ESDR. Cannabinoid neuroprotection of the diabetic retina in ESDR may prove therapeutic in delaying the development of the advanced stage of the disease

Endocannabinoid Metabolome Characterization of Milk from Guatemalan Women Living in the Western Highlands

BACKGROUND: Recognized as the gold-standard ideal fare, human milk has a unique composition that meets infants\u27 needs throughout development. Endocannabinoids and endocannabinoid-like compounds [endocannabinoid metabolome (ECM)] are endogenous lipid mediators derived from long-chain polyunsaturated fatty acids. Based on animal models, it has been proposed that endocannabinoid arachidonoyl glycerol (AG) plays a role in establishing the suckling response during lactation. In addition, endocannabinoid ethanolamides have been shown to stimulate food intake. The mechanisms of action and the role of the ECM in human milk are not fully understood. OBJECTIVES: The present study aimed to characterize and quantify the ECM in human milk samples from an underserved population in Guatemala. METHODS: Human milk samples were collected from lactating women ( = 26) for ECM characterization and quantification. Samples were taken at 3 different time points between 4 and 6 mo of lactation during maternal fasting. Human milk samples were analyzed by liquid chromatography-mass spectrometry. Identified members of the ECM were: arachidonoyl ethanolamide, palmitoyl ethanolamide (PEA), oleoyl ethanolamide, docosahexaenoyl ethanolamide, eicoapentaenoyl ethanolamide, eicosenoyl ethanolamide, AG, palmitoyl glycerol, oleoyl glycerol, docosahexaenoyl glycerol, eicosapentaenoyl glycerol, eicosenoyl glycerol, arachidonic acid (ARA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA). RESULTS: Overall, concentrations in the ethanolamide group were lower than the glycerols. A time effect was observed for ARA, DHA, EPA, and PEA across the 3 time points ( ≤ 0.05). CONCLUSIONS: Our study identified the ECM in mature human milk and provides the first report for a population with health disparities within a developing country. The few studies available have been conducted in developed countries. Hypotheses for future studies can be developed based on this study\u27s data to help elucidate specific roles for members of the ECM and how this biological system modulates infant health and development

<i>C</i>1′-Azacycloalkyl Hexahydrocannabinols

We report the design, synthesis, and biological evaluation of a novel class of cannabinergic ligands, namely <i>C</i>1′-azacycloalkyl hexahydrocannabinols. Our synthetic approaches utilize an advanced common chiral intermediate triflate from which all analogues could be derived. Key synthetic steps involve microwave-assisted Liebeskind–Srogl C–C cross-coupling and palladium-catalyzed decarboxylative coupling reactions. The <i>C</i>1′-<i>N</i>-methylazetidinyl and <i>C</i>1′-<i>N</i>-methylpyrrolidinyl analogues were found to be high affinity ligands for the CB1 and CB2 cannabinoid receptors