Objective: To investigate the effects of lycopene on primary cultured neonatal mouse cardiomyocytes with hypoxia/reoxgenation (H/R) injury and explore related mechanism.
Methods: Primary cultured neonatal mouse cardiomyocytes were randomly divided to control group (control); lycopene group (5 μmol/L, lyc); H/R group (4 hours hypoxia followed by 6 hours reoxgenation); lycopene+ H/R group (lyc+ H/R, the cardiomyocytes were incubated with 5 μmol/L lycopene for 4 hours before H/R treatment). The cell viability of cardiomyocytes was assessed by CCK-8 assay. The apoptotic rate of cardiomyocytes was evaluated by flow cytometry using AnnexinV-PI double staining. Western blot was used to determine the GRP78, CHOP, Bax and Bcl-2 protein expression in cardiomyocytes. The mRNA expressions of ATF6、eIF2α and sXbp-1 were detected by real-time PCR. The fluorescence intensity for reactive oxygen species (ROS) in cardiomyocytes was measured with Olympus fluorescence microscope.
Results: Compared to control group, the cell viability of cardiomyocytes was significantly reduced ((64.28±6.12)% vs. (100.00±4.98)%, P<0.01), the apoptotic rate ((24.42±1.76)% vs. (5.16±1.31)%, P<0.01) and ratio of Bax/Bcl-2 (2.33±0.20 vs. 1.00±0.09, P<0.01) significantly increased, the ATF6, eIF2α and sXbp-1 mRNA expression, the CHOP and GRP78 protein expression (1.98±0.15 vs. 1.00±0.12, 2.09±0.11 vs. 1.00±0.09) as well as fluorescence intensity for ROS ((262.13±22.03)% vs. (100.00±12.35)%) were markedly increased in H/R group (all P<0.01). Compared to the H/R group, pretreatment with lycopene markedly improved the cell viability of cardiomyocytes ((81.75±6.85)%, P<0.01), significantly decreased the apoptotic rate ((17.24±2.02)%, P<0.01) and ratio of Bax/Bcl-2(1.64±0.13, P<0.01), significantly down-regulated the mRNA expression levels of ATF6, eIF2α and sXbp-1, and the protein expression levels of CHOP (1.54±0.12) and GRP78 (1.53±0.12), significantly reduced the fluorescence intensity for ROS ((171.18±19.09)%, all P<0.01).
Conclusions: Lycopene could attenuate hypoxia/reoxygenation-injury in primary cultured neonatal mouse cardiomyocytes, possibly through inhibiting the ER stress and alleviating the ER stress-induced apoptosis.