High mobility group box 1 (
HMGB1) protein serves an important role in
myocardial ischemia/reperfusion (I/R) injury.
MicroRNAs (
miRNAs) are a group of small non‑coding RNAs that regulate numerous signaling pathways involved in myocardial I/R injury. The present study aimed to investigate whether miR‑451 protects against cardiomyocyte
anoxia/reoxygenation (A/R) injury by attenuating
HMGB1 expression. Neonatal rat ventricular cardiomyocytes were prepared and then subjected to A/R injury. The effect of upregulation or downregulation of miR‑451 on cell viability, apoptosis,
superoxide dismutase (SOD) activity, and the expression of cleaved‑caspase‑3 and
HMGB1 were measured accordingly. A
luciferase assay was performed to further confirm whether miR‑451 can directly recognize the 3'‑untranslated region of
HMGB1 in HEK293 cells. The expression of miR‑451 was significantly decreased in the cardiomyocytes during A/R, and upregulation of miR‑451 led to increased miR‑451 expression (P<0.05). Upregulation of miR‑451 significantly attenuated the loss of cardiomyocyte viability (P<0.05) and increased the intracellular levels of SOD during A/R (P<0.05). Furthermore, upregulation of miR‑451 significantly decreased the apoptosis of cardiomyocytes during A/R (P<0.05). The
HMGB1 mRNA and
protein expression levels were significantly downregulated in the Ad‑miR‑451 group compared with those in the A/R group (P<0.05). In addition, upregulation of miR‑451 reduced its translocation from the nucleus to the cytoplasm. The
luciferase assay confirmed that
HMGB1 mRNA is a direct target of miR‑451 in cardiomyocytes. In conclusion, the present study suggested that upregulation of miR‑451 could protect against A/R‑induced cardiomyocyte injury by inhibiting
HMGB1 expression.