The metabolic evidence of synergistic interaction between DAMGO and DPDPE on undifferentiated SH-SY5Y cells.

Recent studies have demonstrated the analgesic synergy between mu- and delta-opioid receptor, but evidence obtained at the cellular level is scanty. This work was designed to find the evidence of synergy between the actions of D-Ala2-Mephe4-glyol5 enkephalin (DAMGO) and D-Phe2, D-Phe5 enkephalin (DPDPE) on undifferentiated SH-SY5Y cells. Microphysiometer was used to detect the functional activity of cells by measuring the real-time extracellular acidification rate (ECAR). The results demonstrate the unequivocal synergy between DAMGO and DPDPE at least within certain ratios. In addition, combined administration of the two drugs in the synergistic ratios attenuates receptor desensitization. These data indicate that DAMGO and DPDPE have a synergistic effect at cellular level.