Pannexin channel 1, P2×7 receptors, and Dimethyl Sulfoxide mediate pain responses in zebrafish.

The zebrafish has been considered an ideal model for studies of complex behaviors since its behavioral repertoire is well described. Therefore, this study evaluated the perceived pain through behavioral changes in zebrafish larvae. Here we investigated the Acetic Acid (AA) effects on zebrafish larvae exposed in a short-time period (60 s) and the preventive effect from routinely used compounds, Dimethyl Sulfoxide (DMSO), Ethanol (EtOH), Ibuprofen (IBP), and Paracetamol (PAR). In addition, the effect of P2×7 antagonist, A740003, and pannexin channel 1 (PANX-1) inhibitor Probenecid (PROB) on AA-induced behavioral changes were evaluated. AA impaired the distance covered, acceleration, movement, and latency to the first entry in the center from 5 dpf exposed larvae. At 0.050% AA, PAR prevented alterations from the distance covered, acceleration, and movement. Surprisingly, 0.3% DMSO prevented behavioral changes induced by AA. However, the effects from 0.2% DMSO were not prominent. We used 0.2% DMSO as a PROB diluent. PROB prevented the changes in distance and movement observed at both AA concentrations (0.0025% and 0.05%) tested. Since EtOH had no analgesic properties, we used it as an A740003 vehicle to observe the analgesic effects of this compound. As noted, A740003 did not prevent the behavioral changes in the AA-induced pain model. In contrast, 0.2% DMSO and PROB prevented AA-induced behavioral changes. These data enforce that zebrafish could be used in translational studies since this species has behavioral responses related to pain in the early stages of development and responses to analgesics similar to observed in mammals.