To investigate the effects of abatacept (ABT)-mediated micro ribonucleic acid-16-5p (miR-16-5p) in rats with acute myocardial infarction (AMI) based on the neurogenic locus notch homolog protein 1 (Notch1)/hypoxia inducible factor 1α (HIF-1α) signaling pathway.

AMI rat model was established using the left anterior descending coronary artery ligation method. A total of 50 rats were randomly divided into the sham-operation group (thoracotomy without ligation), model group, experimental group (5 mg·kg^-1 ABT), Ad-scramble group (tail vein injection of adenovirus-coated NC-mimic) and Ad-miR-16-5p group (tail vein injection of adenovirus-coated miR-16-5p mimic), with 10 rats in each group. Cardiac function indicators in each group were detected by echocardiography. Fluorescence in situ hybridization was used to detect miR-16-5p relative expression levels in rat myocardial tissue. Enzyme-linked immunosorbent assay was used to detect serum lactate dehydrogenase and creatine phosphohykinase levels, as well as inflammatory factor and oxidative stress factor levels in myocardial tissue. Immunofluorescence was used to detect Notch1 and HIF-1α protein expression in rat myocardial tissue.

The left ventricular ejection fractions (EF) in the sham-operation group, model group and experimental group were (64.72±6.15)%, (42.70±5.26)% and (59.51±6.61)%, respectively; the relative fluorescence intensities of miR-16-5p were 1.00±0.11, 2.53±0.33 and 1.37±0.19, respectively; the lactate dehydrogenase (LDH) levels in the sham-operation group, model group, experimental group, Ad-scramble group and Ad-miR-16-5p group were (154.64±27.48), (347.14±48.67), (173.42±28.45), (179.75±29.83) and (336.47±41.35) IU·L^-1, respectively; the creatine phosphohykinase (CPK) levels were (161.37±29.14), (425.43±52.34), (201.67±31.23), (197.74±30.48) and (413.46±49.78) IU·L^-1, respectively; the interleukin-1β (IL-1β) levels in myocardial tissue were (35.48±6.93), (129.64±19.51), (52.52±8.48), (51.62±7.32) and (118.42±19.51) pg·mg^-1 prot, respectively; the superoxide dismutase levels in myocardial tissue were (83.45±13.42), (34.54±5.61), (76.63±15.63), (75.87±14.23) and (41.75±5.92) U·mg^-1 prot, respectively; the relative fluorescence intensities of Notch1 were 1.00±0.16, 1.86±0.22, 1.36±0.19, 1.29±0.25 and 1.71±0.28, respectively; the relative fluorescence intensities of HIF-1α were 1.00±0.13, 2.41±0.37, 1.64±0.24, 1.57±0.29 and 2.10±0.38, respectively; the above indicators showed statistically significant differences between the sham-operation group and the model group, between the model group and the experimental group, and between the Ad-scramble group and the Ad-miR-16-5p group (P<0.01, P<0.001).

ABT may protect cardiac function in AMI rats, improve myocardial tissue pathological damage and fibrosis, and reduce oxidative stress and inflammatory responses by mediating miR-16-5p expression to regulate the Notch1/HIF-1α signaling pathway.