The synthetic cannabinoids ADB-FUBINACA and THJ-2201 decrease mitochondrial activity and ATP levels during neurodifferentiation of NG108-15 cells
Synthetic cannabinoids (SCs) comprise a group of new psychoactive substances with stronger affinity to cannabinoid receptors than tetrahydrocannabinol (Δ9-THC), the main psychoactive component of cannabis. We have shown that SCs THJ-2201 and ADB-FUBINACA enhanced neurodifferentiation of NG108-15 neuroblastoma x glioma cells via CB1 receptor (CB1R) activation. Given the key role played by mitochondria during neurogenesis, we herein aimed to evaluate the effects of these two SCs on mitochondrial function during neurodifferentiation.
Neurodifferentiation of NG108-15 cells was induced in serum-starved (1% fetal bovine serum) cell culture medium supplemented with 10µM forskolin and 30µM retinoic acid. Mitochondrial membrane potential (MMP, assessed by TMRE labelling) and intracellular ATP levels (luciferase-based luminescence assay) were evaluated 24h and 72h following SCs addition at biologically-relevant concentrations (1pM-1µM). A 20-min pre-incubation with 500nM SR141716A (cell-permeable) or 5μM hemopressin (cell-impermeable) CB1R antagonists tested the involvement of membrane and intracellular CB1Rs.
Both tested SCs decreased intracellular ATP levels around 1.2-1.5-fold following a 24h exposure, but not after 72h. THJ-2201-mediated effects were blocked by SR141716A but not by hemopressin, suggesting the involvement of intracellular receptors, like mitochondrial CB1R in this process. The ADB-FUBINACA-induced decrease in intracellular ATP levels was prevented by pre-incubation with both SR141716A and hemopressin, indicating the involvement of plasma membrane-located CB1R, but not discarding a contribution by intracellular receptors. Both SCs reduced MMP around 1.2-1.3-fold at all concentrations tested, but only after 72h. This decrease was not blocked by CB1R antagonists, indicating that SC-induced MMP regulation was CB1R activation-independent.
Overall, THJ-2201 and ADB-FUBINACA disrupted mitochondrial activity during neurodifferentiation of NG108-15 cells. Different mechanisms seem to underlie this effect, as only the modulation of energy supply was dependent on CB1R activation, and for THJ-2201, this effect only depended on intracellular CB1R activation. Further research is required to understand the association of SC-mediated mitochondrial function disruption with enhanced neurodifferentiation.