Eight-week-old male C57BL/6J wildtype (WT) mice were purchased from the laboratory animal center of the Xi’an Jiaotong University (Xi’an, China). The Fndc5+/- mice (C57BL/6N-Fndc5em1Cya, S-KO-09897), which were conventional knockout by CRISPR-Cas9, were purchased from Cyagen Biosciences Inc. (Guangzhou, China) and were used to generate the homozygous target mice. The sequence of primers for screening homozygous mice is as follows: F1: 5′-CTGTCTCCAATGTTCCACT TGTCTG-3′; R1: 5′-CTTGCCTTTGTTCTTTGAGGCCATC-3′; R2: 5′-GCTTGAACCAAGGCGAGAGCTAGT-3′. All animals were housed in the Institute of Sports Biology, Shaanxi Normal University (temperature: 23–25 °C and humidity: 40–60%), with four to five animals per cage, who resided under a 12 h light/12 h dark cycle and received ad libitum access to water and standard rodent chow. All experimental protocols were approved by the Ethics Committee of Shaanxi Normal University.
WT and Fndc5-/- mice were used to establish the MI model by ligation of the left anterior descending coronary artery at the position approximately 2 mm under the junction of the pulmonary conus and left atrial appendage. Surviving WT mice were randomly divided into the sham-operated group (S), MI group, and MI with AE group (ME), n = 6; the surviving Fndc5-/- mice were also divided into the S group (KS), MI group (KMI), and ME group (KME), n = 3.
Mice in ME and KME groups were subjected to six weeks of treadmill AE from the second week after surgery. The exercise training protocol was based on a previous study [64 (link)] and adjusted according to the state of the exercised mice. During the first five days, mice were subjected to adaptive training, in which the speed and duration were gradually increased from 5 m/min for 10 min to 10 m/min for 50 min. The formal training speed was 10 m/min for 60 min per day, five days per week, for six weeks, corresponding to a moderate intensity exercise, and the maximum oxygen uptake was about 65–70% [65 (link),66 (link)]. No mice died during the process.
WT and Fndc5-/- mice were used to establish the MI model by ligation of the left anterior descending coronary artery at the position approximately 2 mm under the junction of the pulmonary conus and left atrial appendage. Surviving WT mice were randomly divided into the sham-operated group (S), MI group, and MI with AE group (ME), n = 6; the surviving Fndc5-/- mice were also divided into the S group (KS), MI group (KMI), and ME group (KME), n = 3.
Mice in ME and KME groups were subjected to six weeks of treadmill AE from the second week after surgery. The exercise training protocol was based on a previous study [64 (link)] and adjusted according to the state of the exercised mice. During the first five days, mice were subjected to adaptive training, in which the speed and duration were gradually increased from 5 m/min for 10 min to 10 m/min for 50 min. The formal training speed was 10 m/min for 60 min per day, five days per week, for six weeks, corresponding to a moderate intensity exercise, and the maximum oxygen uptake was about 65–70% [65 (link),66 (link)]. No mice died during the process.
Free full text: Click here
