Related Experiment Video
Updated: Jul 9, 2025
14:25
Synthesis of a Deuterated Standard for the Quantification of 2-Arachidonoylglycerol in Caenorhabditis elegans
Published on: September 21, 2019
7.3K
Pharmacological Characterization of the Endocannabinoid Sensor GRABeCB2.0
Simar Singh1,2,3, Dennis Sarroza1, Anthony English1,2,3
1Department of Pharmacology, Pain, and Emotion, School of Medicine, University of Washington, Seattle, Washington, USA.
Cannabis and Cannabinoid Research
|December 8, 2023
Summary
The genetically encoded sensor GRABeCB2.0 responds to endocannabinoids (eCBs) and phytocannabinoids, with its pharmacological profile now characterized. This study clarifies how GRABeCB2.0 signals changes in eCB levels, enhancing its utility in cannabinoid research.
Area of Science:
- Neuroscience
- Pharmacology
- Biochemistry
Background:
- Endocannabinoids (eCBs), 2-arachidonoylglycerol (2-AG) and arachidonoyl ethanolamine (AEA), are key signaling molecules with distinct pharmacological profiles.
- The genetically encoded sensor GRABeCB2.0 enables real-time detection of eCB levels but its response to analogues and phytocannabinoids is uncharacterized.
- Understanding GRABeCB2.0 activation is crucial for interpreting its utility in preclinical and in vivo pharmacology studies, particularly for phytocannabinoid action.
Purpose of the Study:
- To characterize the activation profile of the GRABeCB2.0 sensor by endogenous eCBs, eCB analogues, and phytocannabinoids.
- To determine the potencies of various ligands at GRABeCB2.0 and compare them to their known potencies at cannabinoid receptors (CB1R).
- To assess the potential of GRABeCB2.0 to reflect the allosteric modulatory properties of compounds like cannabidiol (CBD).
Main Methods:
- GRABeCB2.0 was expressed in HEK293 cells for functional characterization.
- Live-cell confocal microscopy and high-throughput fluorescent signal measurements were employed.
- Dose-response curves were generated for various eCBs, analogues, phytocannabinoids, and CB1R ligands.
Main Results:
- 2-AG and SR141716 (SR1) modulated GRABeCB2.0 signal with potencies mirroring their CB1R activity (EC50=85 nM and IC50=3.3 nM, respectively).
- AEA, eCB analogues (2-linoleoylglycerol, 2-oleoylglycerol), Δ9-THC, Δ8-THC, and CP55,940 (CP) increased the GRABeCB2.0 signal, but with lower potencies than at CB1R.
- Cannabidiol (CBD) inhibited 2-AG-stimulated GRABeCB2.0 responses (IC50=9.7 nM) without affecting basal signal, suggesting retained negative allosteric modulator (NAM) properties.
Conclusions:
- GRABeCB2.0 activation by 2-AG and SR1 accurately reflects their CB1R potencies.
- The sensor exhibits altered potency for AEA, eCB analogues, THC, and CP compared to CB1R, necessitating careful interpretation.
- GRABeCB2.0 retains CBD's negative allosteric modulator property at CB1R, offering a valuable tool for studying cannabinoid pharmacology.
More Related Videos
Related Concept Videos
01:30Spare Receptors
3.6K
Some receptors remain unoccupied even when an agonist produces a maximal response. Such empty ones are called spare receptors. In presence of spare receptors the maximum effect of an agonist drug is achieved with fewer than 100% of the receptors being occupied. To determine the presence of spare receptors, scientists often compare the concentration of the drug needed to produce 50% of the maximum effect (EC50) with the concentration of the drug needed to occupy 50% of the receptors (Kd). If the...
3.6K
01:30Transducer Mechanism: G Protein–Coupled Receptors
2.0K
G Protein–Coupled Receptors (GPCRs) are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to various stimuli. GPCRs regulate critical physiological pathways and are excellent drug targets for treating diseases such as diabetes, cancer, obesity, depression, or Alzheimer's. Nearly 35% of approved drugs implement their therapeutic effects by selectively interacting with specific GPCRs.
GPCRs are also called heptahelical,...
GPCRs are also called heptahelical,...
2.0K
01:15G Protein-coupled Receptors
12.1K
G Protein-Coupled Receptors or GPCRs are membrane-bound receptors that transiently associate with heterotrimeric G proteins and induce an appropriate response to sensory stimuli such as light, odors, hormones, cytokines, or neurotransmitters.
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
GPCRs are also called heptahelical, 7TM, or serpentine receptors, and consist of seven (H1-H7) transmembrane alpha-helices that span the bilayer to form a cylindrical core. The transmembrane helices are connected by three extracellular loops and three...
12.1K
01:12GPCR Desensitization
6.1K
G protein-coupled receptor (GPCR) signaling plays a crucial role in cell functioning. GPCR desensitization is an equally essential process. It allows cells to respond to changing environments and regain sensitivity to new stimuli while preventing unnecessary stimulation when no longer needed. Prolonged exposure to stimuli leads to GPCR desensitization. It involves blocking the receptors from binding and activating additional G proteins. This inhibits activation of downstream effectors, thereby...
6.1K
01:09GPCRs Regulate Adenylyl Cylase Activity
5.6K
Some GPCRs transmit signals through adenylyl cyclase (AC), a transmembrane enzyme. AC helps synthesize second messenger cyclic adenosine monophosphate (cAMP). AC catalyzes cyclization reaction and converts ATP to cAMP by releasing a pyrophosphate. The pyrophosphate is further hydrolyzed to phosphate by the enzyme pyrophosphatase, which drives cAMP synthesis to completion. However, cAMP is rapidly degraded to 5′ AMP by the enzymes phosphodiesterase (PDE), preventing overstimulation of...
5.6K
01:22Opioid Receptors: Overview
891
Opioid receptors, including the mu (μ, MOR), delta (δ, DOR), and kappa (κ, KOR) types, belong to the rhodopsin family of G protein-coupled receptors. These receptors are located throughout the central and peripheral nervous systems and in non-neuronal tissues such as macrophages and astrocytes. Opioid receptor ligands can be categorized into agonists or antagonists. Highly selective agonists include [d-Ala2, MePhe4, Gly(ol)5]-enkephalin or DAMGO for MOR, [D-Pen2,...
891