Scientists map how cannabis drugs trigger different cellular pathways
Researchers systematically measured how cannabis-like compounds activate distinct signaling routes in cells, finding some trigger multiple pathways simultaneously while others target specific routes. The discovery could unlock safer cannabis-derived treatments with fewer side effects, a major bottleneck for pharmaceutical development in this emerging drug class.
Originaltitel: Functional selectivity of cannabinoids at CB1 receptors: Comprehensive analysis of G proteins, β-arrestin and cAMP signalling dynamics in HEK293T cells
Therapeutic targeting of CB 1 has been limited by adverse effects of orthosteric ligands. Allosteric modulation and biased signalling have been proposed to achieve pathway-selective control, but the receptor’s complex coupling complicates interpretation of ligand actions. In this study, we systematically compared orthosteric and allosteric CB 1 ligands in transfected HEK293T cells by measuring G-protein coupling and downstream cAMP regulation in real time using NanoBiT and GloSensor assays. Orthosteric agonists CP 55,940 and methanandamide activated both G i and G s with weak and transient β-arrestin2 recruitment, producing potent inhibition of forskolin-stimulated cAMP and modest increases in basal levels. The inverse agonist AM251 reduced basal G i coupling and increased basal cAMP, consistent with inverse agonism at constitutively active CB 1 receptors. Under forskolin stimulation, AM251 attenuated agonist-induced inhibition of cAMP and produced concentration-dependent modulation of forskolin-stimulated responses. AM4113 marginally reduced G-protein coupling and increased basal, while modestly reducing forskolin-stimulated cAMP, consistent with very low inverse efficacy. Among allosteric ligands, the positive allosteric modulator GAT229 increased G i coupling and, with orthosteric agonists, further enhanced G i and G s signalling, elevating basal cAMP, without affecting β-arrestin2. The negative allosteric modulators PSNCBAM-1 and ORG27569 each reduced G i - and G s -coupling, elevated basal cAMP, and attenuated agonist-induced inhibition of forskolin-stimulated cAMP. Cannabidiol showed no intrinsic activity at CB 1 and marginally reduced orthosteric G-protein signalling, consistent with indirect interaction with the receptor. In summary, this study shows that orthosteric and allosteric CB 1 ligands differ in G-protein coupling and cAMP regulation, clarifying key aspects of cannabinoid receptor signalling.