Potential Effects of Selected Synthetic Cannabinoids on Neuronal Senescence: Impact on Proliferation and Beta-Galactosidase Activity in SH-SY5Y Cells

Synthetic cannabinoids (SC) display a pharmacological mechanism similar to that of Δ9-tetrahydrocannabinol (THC), the key active principle of cannabis. SC are full agonists with higher potency at the CB1 and CB2 receptors, contrasting with THC's partial agonism. Cannabis use precipitates certain aspects of senescence/ageing, so it is plausible that SC act alike. Thus, for the present study the impact of SC exposure on in vitro neuronal cells proliferation and beta-galactosidase activity (a marker of senescence) was determined, to investigate their putative pro-senescence effects. Human neuroblastoma SH-SY5Y cells were exposed to 1µM, 1nM and 1pM AMB-FUBINACA and ADB-FUBINACA for 24, 48, 72 and 96h, after which the sulforhodamine B assay (an indirect measure of cell proliferation) was conducted. To determine CB1R and CB2R involvement, the assays were repeated after cells’ pre-incubation for 20 min in the presence of the selective antagonists, SR141716A and SR144528, respectively, at 0.5µM. Beta-galactosidase activity was measured in cells exposed to 1µM and 1nM AMB-FUBINACA for 22 passages (P24-46, 68 days), using the Enzo Life Sciences Cellular Secescence Activity Assay kit. At 96h, SH-SY5Y proliferation was increased after exposure to test concentrations of both SC (p<0.05); the use of CB1 antagonist reverted proliferation for AMB-FUBINACA, while CB2 antagonist reversed effects for both SC (p<0.05). Preliminary results show increased beta-galactosidase activity at passage 46 in SC-treated cells (p<0.05). These results show a possible influence of SC on senescence-associated markers, proving the need to test additional neuronal ageing markers.