Protein Kinase C mediates the effects of δ-opioid receptor stimulation on survival and apoptosis in neonatal cardiomyocytes cultured in serum-deprived condition

The aims of the present study were to determine whether Delta opioid receptor (δ-OR) stimulation improved the survival of cardiomyocytes cultured in serum-deprived conditions, which impaired their growth. [D-Ala2, D-Leu5]-enkephalin (DADLE), a selective δ-OR agonist, at a concentration range of 0.1 μmol/L to 10 μmol/L for 48 h increased the viability of the cardiomyocyte under serum deprivation conditions. DADLE (0.1 μmol/L) also decreased the early cell apoptosis rate and the expression of Caspase-3. The effects of 0.1 μmol/L DADLE were abolished by 10 μmol · L–1 naltrindole, a selective δ&OR antagonist, or by blockade of protein kinase C (PKC) with its blockers, 10 μmol · L–1 GF109203X or 1 μmol/L staurosporine. Furthermore, 0.1 μmol · L–1 DADLE increased the expression of PKC, an effect abrogated by 10 μmol · L–1 naltrindole. The observations indicate that δ-OR stimulation improves the viability and reduces the apoptosis via PKC pathway in neonatal cardiomyocytes cultured in serum deprived conditions.