The preparation of 5′-iodo-125I-Δ8-THC; a radioligand for the radioimmunoassay of cannabinoids

Chemical Tools for Studying Lipid-Binding Class A G Protein-Coupled Receptors

Cannabinoid, free fatty acid, lysophosphatidic acid, sphingosine 1-phosphate, prostanoid, leukotriene, bile acid, and platelet-activating factor receptor families are class A G protein-coupled receptors with endogenous lipid ligands. Pharmacological tools are crucial for studying these receptors and addressing the many unanswered questions surrounding expression of these receptors in normal and diseased tissues. An inherent challenge for developing tools for these lipid receptors is balancing the often lipophilic requirements of the receptor-binding pharmacophore with favorable physicochemical properties to optimize highly specific binding. In this study, we review the radioligands, fluorescent ligands, covalent ligands, and antibodies that have been used to study these lipid-binding receptors. For each tool type, the characteristics and design rationale along with in vitro and in vivo applications are detailed.

The role of halogen substitution in classical cannabinoids: a CB1 pharmacophore model

The presence of halogens within the classical cannabinoid structure leads to large variations in the compounds' potencies and affinities for the CB1 receptors. To explore the structure activity relationships within this class of analogs we have used a series of halogen-substituted (-)-Delta8-tetrahydrocannabinol analogs and compared their affinities for the CB1 cannabinoid receptor. Our results indicate that halogen substitution at the end-carbon of the side chain leads to an enhancement in affinity with the bulkier halogens (Br, I) producing the largest effects. Conversely, 2-iodo substitution on the phenolic ring leads to a 2-fold reduction in affinity while iodo-substitution in the C1'-position of the side chain lowers the compound's affinity for CB1 by more than 8-fold. The pharmacophoric requirements resulting from halogen-substitution are explored using computer modeling methods.

Effect of acute marijuana on cardiovascular function and central nervous system pharmacokinetics of [(15)O]water: effect in occasional and chronic users

The objective of this study was to evaluate the effect of the acute administration of marijuana (MJ) on cardiovascular (CV) function and CNS pharmacokinetics (PK) of [(15)O]water in occasional (O) versus chronic (C) MJ users. Each subject received four injections of [(15)O]water (one prior and three postsmoking) on two occasions in which they received active or placebo MJ. For each injection, measures of CV function and CNS PK [(15)O]water were made. Postsmoking, MJ influenced all measured CV and [(15)O]water PK parameters. C users reported significantly lower "highness" and smaller heart rate (HR) changes, which resulted in reduced rate pressure product (RPP) changes compared to O users, even though Delta(9)-tetrahydrocannabinol levels were higher, whereas changes in blood pressure (BP), arrival time, and [(15)O]water concentration were not significantly different between the groups. Significant CV changes resulted in changes in the whole-body distribution of cardiac output rather than changes in cerebral blood flow. Chronic MJ use produces tolerance to the HR increases induced by acute MJ smoking compared to changes observed in occasional users, without changing the effects on BP and [(15)O]water PK.