Effect Of Opioid Drugs On NMDA Receptor Current In Rat Spinal Cord Dorsal Horn Neurons

Objective To investigate the effect of remifentanil, fentanyl, ketamineand naloxone on N-Methyl-D-aspartate evoked current in rat spinal corddorsal horn neurons by whole-cell patch. Explore the functional changes ofNMDA receptor on rat spinal cord dorsal horn neurons in acute opioidtolerance.Methods Recorded NMDA evoked currents by whole-cell patch.Randomly divided the primary E14SD rat spinal cord dorsal hornneurons(DH Cells) into remifentanil group(group R, n=10)， fentanylgroup(group F, n=10) and control1group(group C1, n=10). Added4nMremifentanil(group R) and added10μM fentanyl(group F) for60min,thenwash out the drugs. Recorded NMDA evoked currents immediately afteradministration (T0),15min (T1),30min (T2),45min (T3),60min (T4),eluted after15min (T5),30min (T6). Reselected the rat spinal cord dorsalhorn neurons and randomly divided them into ketamine group(group K,n=10), naloxone group(group N, n=10) and control2group(group C2, n=6).Added4nM remifentanil to each of the3group above, wash out theremifentanil60minutes later, added100nm naloxone(group N) and added 100μm ketamine(group K), recorded NMDA evoked currents after15minand30min.Result There was no significant difference in NMDA evoked peakcurrent at each time point between group F and C1. Compared to C1,groups R presented no significant difference in NMDA evoked peakcurrent at T0and T1，but could cause significant increases in NMDAevoked currents at T2~T6. Compared to T0, groups R presented significantincreases in NMDA evoked currents at T3~T6; Compared to T5, groups Rpresented significant decreases in NMDA evoked currents at T2~T4, T6.Compared to C2, Group K and Group N both inhibited the enhancement ofNMDA evoked current at each time point.Conclusion （1） Remifentanil can increase NMDA receptor functionin rat spinal cord dorsal horn neurons, and the peck effect is reached afterwashout, but fentanyl dose not have the effect.（2）Ketamine and naloxone can decrease NMDA receptor function inrat spinal cord dorsal horn neurons.