The Influence of the Synthetic Cannabinoids AMB-FUBINACA, ADB-FUBINACA, AB-CHMINACA and THJ-2201 on In Vitro Viability and Senescence of SH-SY5Y Cells and Primary Rat Hippocampal Neurons

Synthetic Cannabinoids (SCs) are new psychoactive substances that display a similar effect to that of 9-tetrahydrocannabinol (THC), the main psychoactive principle of cannabis, by acting on the cannabinoid receptors 1 and 2. Unlike THC (a partial agonist of these receptors), SCs have demonstrated a more powerful agonism of these receptors. Recent research has shown that THC accelerates senescence/aging. It is therefore plausible that SCs also have the capacity to interfere with and aggravate cellular senescence, but, thus far, the SC effects on this biological process remains unexplored. This work aims to determine the effects of four SCs on cellular viability and proliferation, as a first approach to assess neuronal senescence.

Two distinct in vitro models were used, the neuroblastoma cell line SH-SY5Y and primary hippocampal neurons (PHN) isolated from Wistar rat embryos at E18-19. Cells were exposed to AMB-FUBINACA, ADB-FUBINACA, AB-CHMINACA and THJ-2201, at the biologically-relevant concentrations 1pM, 1nM and 1µM, for 24h, 48h, 72h and 96h. Cellular proliferation was evaluated in SH-SY5Y cells using the sulforhodamine B (SRB) assay and cellular viability of PHN was assessed using the MTT reduction assay. Preliminary results showed no significant differences in viability of PHN between the tested SCs and the solvent control (1002.38%), with the highest concentration of AMB-FUBINACA and AB-CHMINACA showing 81.036.69 and 82.717.21% viability (p<0.05), respectively. At 96h, cells exposed to AMB-FUBINACA and ADB-FUBINACA presented significant increases in proliferation rates at all concentrations (1µM, 1nM and 1pM, respectively: 1055%, 1152%, 1152% for AMB-FUBINACA; 977%, 1026%, 1067% for ADB-FUBINACA), compared to solvent control (821%) (p<0.05).

These results help to enlighten the effects of SC exposure over two different models of neuronal cells (primary neurons vs. cell line) and how they influence natural neuronal senescence (as greater proliferation rates may precipitate senescence). Further studies of specific senescence markers are the next step.