Involvement of Mu Opioid Receptor Signaling in the Protective Effect of Opioid against 6-Hydroxydopamine-Induced SH-SY5Y Human Neuroblastoma Cells Apoptosis

introduction: the neuroprotective role of opioid morphine against 6-hydroxydopamineinducedcell death has been demonstrated. however, the exact mechanism(s) underlying suchneuroprotection, especially the role of subtype receptors, has not yet been fully clarified. methods: here, we investigated the effects of different opioid agonists on 6-ohda-inducedneurotoxicity in human neuroblastoma sh-sy5y cell line as an in vitro model of parkinson’sdisease. cell damage was induced by 150 μm 6-ohda and the cells viability was examined bymtt assay. intracellular calcium, reactive oxygen species and mitochondrial membrane potentialwere assessed by fluorescence spectrophotometry method. immunoblot technique was used toevaluate cytochrome-c and activated caspase-3 as biochemical markers of apoptosis induction. results: the data showed that 6-ohda caused significant cell damage, loss of mitochondrialmembrane potential and increase in intracellular reactive oxygen species and calcium levelsas well as activated caspase-3 and cytochrome-c release. incubation of sh-sy5y cells withμ-opioid agonists, morphine and damgo, but not with δ-opioid agonist, dadle, elicitedprotective effect and reduced biochemical markers of cell damage and death. discussion: the results suggest that μ-opioid receptors signaling participate in the opioidneuroprotective effects against 6-ohda-induced neurotoxicity.