Cannabinoid Ligand-Mediated Glycogen Depletion in Astrocytes Is Associated With Increased Intracellular Calcium, Energy Metabolism, and Membrane Dynamics

Abstract

Astrocytes orchestrate brain energy metabolism and respond to endocannabinoids via cannabinoid receptor type 1 (CB1R), whereas the contribution of CB2R remains uncertain. We combined live-cell Förster resonance energy transfer sensors for D-glucose and L-lactate, intracellular Ca2+ imaging, glycogen assays, and whole-cell patch-clamp capacitance measurements to define how cannabinoid ligands shape astrocyte physiology in primary rat cultures. The CB1-selective agonist ACEA triggered rapid, transient elevations in [Ca2+]ᵢ and metabolic readouts, whereas the CB2-biased ligands AM1241 and Gp1a produced sustained metabolic effects, including prolonged increases in intracellular D-glucose and L-lactate. AM1241 additionally evoked glycogen depletion. Ligand applications also increased membrane capacitance, consistent with enhanced exocytotic activity and altered membrane dynamics. CB1 immunoreactivity predominated over a weak CB2-like signal, and RT-qPCR detected Cnr1 but not Cnr2 transcripts under our conditions. Accordingly, we interpret AM1241/Gp1a actions as ligand-evoked effects that are predominantly CB1-linked (and/or off-target at the concentrations used). Together, these results show that cannabinoid ligands robustly remodel astrocytic energy metabolism and membrane behavior chiefly through CB1-associated pathways, highlighting a functional axis between cannabinoid signaling, Ca2+ mobilization, glycogen remodeling, and exocytosis in astrocytes. (Figure presented.).