Combined Effect of Ethanol and Acetaminophen on the Central Nervous System of Daphnia magna

The combined consumption of acetaminophen (APAP) and ethanol (EtOH) has been an issue with clinical implications. Previous findings regarding the simultaneous consumption of APAP and EtOH have reported harmful effects on the liver and stomach; however, little is known about the effects on the central nervous system (CNS). We hypothesized that EtOH and APAP will have a synergistic effect on the CNS of Daphnia magna (D. magna), causing a pronounced decrease in heart rate at a toxic dose of EtOH. To better understand the effects of the combined consumption of EtOH and APAP on the CNS, the heart rates of D. magna were measured under a dissection microscope after exposure to EtOH, APAP, or a combined EtOH-APAP solution. Interestingly, the average heart rates of D. magna exposed to the EtOH-APAP solution and D. magna exposed only to APAP were approximately the same. Although our results did not support our original hypothesis, the data demonstrated that APAP exerted a dominant effect over EtOH. APAP and EtOH are known to have inhibitory effects on the CNS. Therefore, these findings suggest that APAP and EtOH may compete against each other on similar pathways to be the substance that exerts an inhibitory effect in the CNS.