Electroacupuncture alleviates acute myocardial ischemic injury in mice by regulating the β ₁ adrenergic receptor and post-receptor protein kinase A signaling pathway

Figure 1.. (a) Flow diagram of the study. (b) Location of traditional acupuncture points HT7 (Shenmen), HT5 (Tongli), LU9 (Taiyuan) and LU8 (Jingqu) in humans and mice. (c, d) Time chart and protocols of experiments 1 and 2.

Figure 2.. Cardiac function and β1 adrenergic receptor (β1-AR) expression levels in myocardial tissue after electroacupuncture (EA) at HT7-HT5 (EA1) and LU9-LU8 (EA2) in a mouse model of myocardial ischemia (MI). (a) Representative electrocardiogram (ECG) of mice in each group. (b) Quantitative analysis of ST segment displacement (n = 8 per group). (c, d) Serum levels of MB isoenzyme of creatine kinase (CK-MB) and lactate dehydrogenase (LDH; n = 8 per group). (e) Representative images of triphenyltetrazolium chloride (TTC) staining. (f) Infarction area (n = 5 per group). (g) Representative Western blot images of β1-AR. (h) Quantification of β1-AR expression levels (n = 3 per group). (i) mRNA level of β1-AR in myocardial tissue measured by RT-qPCR (n = 3 per group). Data are mean ± SD. (j–l) Correlation analysis of β1-AR with ST segment displacement, CK-MB and LDH. *p < 0.05, **p < 0.01.

Figure 3.. Effect of electroacupuncture (EA) on myocardial ischemia injury in mice. (a) Representative electrocardiogram (ECG) of mice in each group. (b) Quantitative analysis of ST segment displacement (n = 12 per group). (c, d) Serum MB isoenzyme of creatine kinase (CK-MB) and lactate dehydrogenase (LDH; n = 12 per group). (e) Representative images of infarction area by 2,3,5-triphenyltetrazolium (TTC) staining. (f) Quantitative analysis of infarction area (n = 5 per group). (g) Histological observation after hematoxylin and eosin (H&E) staining. (h) Cardiomyocyte apoptosis after terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in each group. (i) Quantitative analysis of apoptosis (n = 4 per group). (j) Representative Western blot images of cleaved caspase-3. (k) Quantification of cleaved caspase-3 protein expression levels (n = 3 per group). Scale bar: 100 and 20 µm. Data are mean ± SD. *p < 0.05, **p < 0.01.

Figure 4.. Effects of electroacupuncture (EA) on the level of norepinephrine (NE), post-receptor protein kinase A (PKA) signaling pathway and expression levels of L-type voltage-gated calcium channel α1 C (Cav1.2), serine phosphorylated 16-phospholamban (p-PLBs16) and sarcoplasmic reticulum (SR) Ca2+-adenosine triphosphate (ATP)ase 2a (SERCA2a) in myocardial tissues in vivo. (a) NE levels in myocardial tissue (n = 3 per group). (b) Representative Western blot images of stimulatory G protein (Gs), phosphorylated PKA (p-PKA), Cav1.2, p-PLBs16 and SERCA2a. (c–g) Quantification of Gs, p-PKA, Cav1.2 p-PLBs16 and SERCA2a protein expression levels (n = 3 per group). (h, i) Levels of adenylate cyclase (AC) and cyclic adenosine monophosphate (cAMP) in myocardial tissue (n = 3 per group). Data are mean ± SD. *p < 0.05, **p < 0.01.

Figure 5.. Schematic representation of the cardiac β1 adrenergic receptor (β1-AR) and post-receptor protein kinase A (PKA) signaling pathway regulated by electroacupuncture (EA). MI: myocardial ischemia; LAD: left anterior descending coronary artery; NE: norepinephrine; Gs: stimulatory G protein; AC: adenylate cyclase; cAMP: cyclic adenosine monophosphate; Cav1.2: L-type voltage-gated calcium channel α1 C; p-PLBs16: serine phosphate 16-phospholamban; SERCA2a: sarcoplasmic reticulum Ca2+-adenosine triphosphate (ATP)ase 2a.