Study on Cardiac Aging Phenotypes of SHJH hr Mice

doi:10.12300/j.issn.1674-5817.2024.100

Abstract

Abstract:

Objective To investigate the spontaneous premature cardiac aging in SHJH ^hr mice. Methods A comparative study was conducted between SHJH ^hr mice (SHJH ^hr group) and wild-type ICR mice (WT group) at different ages (10 and 24 weeks). Cardiac function was analyzed using a small animal in vivo ultrasound imaging system. After euthanasia, organs were collected and weighed to assess the extent of cardiac atrophy. Cardiac pathological damage was observed using hematoxylin-eosin (HE) staining. Cardiac fibrosis was analyzed using Masson staining. Myocardial cell area was analyzed after wheat germ agglutinin (WGA) staining. The activities of oxidative damage indicators in myocardial tissue, including superoxide dismutase (SOD), glutathione peroxidase (GPX), and catalase (CAT), as well as the content of 8-hydroxy-2'-deoxyguanosine (8-OHdG), were measured using enzyme-linked immunosorbent assay. Real-time fluorescence quantitative PCR was used to measure the mRNA expression levels of factors associated with inflammation, fibrosis, and oxidative stress. Colorimetric assay was used to measure malondialdehyde (MDA) levels. Results Compared to WT group mice of the same age, 10-week-old mice in the SHJH ^hr group showed no significant differences in stroke volume (SV), ejection fraction (EF), fractional shortening (FS), or heart and lung weights. However, at 24 weeks of age, mice in the SHJH ^hr group had significantly lower SV, EF, and FS values compared to mice of the same age in the WT group (P<0.05), with no significant change in lung weight but a significant reduction in heart weight (P<0.05). Histological analysis of heart tissue from 24-week-old mice revealed no significant difference in cardiac fibrosis levels between SHJH ^hr and WT groups, but WGA staining showed a significant reduction in myocardial cell area in mice in the SHJH ^hr group (P<0.05). PCR analysis revealed a significant downregulation of mRNA levels of oxidative stress factors Sod2, Gpx1, and Cat genes (P<0.05). Biochemical assays indicated significantly reduced activities of oxidative damage-related enzymes SOD, GPX, and CAT in myocardial tissue (P<0.05), while the levels of oxidative damage markers 8-OHdG and MDA significantly increased (P<0.05). Conclusion Mice in the SHJH ^hr group exhibit premature cardiac aging, which may be associated with oxidative stress damage in myocardial tissue.

Key words: SHJH ^hr mice, Cardiac aging, Oxidative damage

CLC Number:

R-332

LIU Rongle,CHENG Hao,SHANG Fusheng,et al. Study on Cardiac Aging Phenotypes of SHJH ^hr Mice[J]. Laboratory Animal and Comparative Medicine, 2025, 45(1): 13-20. DOI: 10.12300/j.issn.1674-5817.2024.100.

Figures/Tables 5

Table 1 Primer sequences of target genes used for real-time fluorescent quantitative PCR

基因名称 Name of genes	引物序列 Sequence (5’→3’)
Sod2	CAGACCTGCCTTACGACTATGG; CTCGGTGGCGTTGAGATTGTT
Sod3	CCTTCTTGTTCTACGGCTTGC; TCGCCTATCTTCTCAACCAGG
Gpx1	CCACCGTGTATGCCTTCTCC; AGAGAGACGCGACATTCTCAAT
Cat	GGAGGCGGGAACCCAATAG; GTGTGCCATCTCGTCAGTGAA
Il1β	GCAACTGTTCCTGAACTCAACT; ATCTTTTGGGGTCCGTCAACT
Il6	CCAAGAGGTGAGTGCTTCCC; CTGTTGTTCAGACTCTCTCCCT
Tnf	CACGCTCTTCTGTCTACTGAACTTC; CTTGGTGGTTTGTGAGTGTGAGG
Ccl2	TAAAAACCTGGATCGGAACCAAA; GCATTAGCTTCAGATTTACGGGT
Tgfβ1	CCACCTGCAAGACCATCGAC; CTGGCGAGCCTTAGTTTGGAC
Col1α1	GCTCCTCTTAGGGGCCACT; ATTGGGGACCCTTAGGCCAT
Actα2	GTCCCAGACATCAGGGAGTAA; TCGGATACTTCAGCGTCAGGA
GAPDH	AGAAGGTGGTGAAGCAGGCATC; CGAAGGTGGAAGAGTGGGAGTTG

Figure 1 Cardiac ultrasound examination of SHJH hr mice cardiac function at different agesNote： A， Doppler ultrasound images； B to E， Intergroup comparison of cardiac function indicators： stroke volume （SV）， ejection fraction （EF）， fractional shortening （FS）， and the ratio of the early （E'） to late （A'） mitral inflow velocities （E'/A'）. Wild-type ICR mice without premature aging （WT group） were used as controls， n=6； *P<0.05.

Figure 2 Lung and heart weights of SHJH hr mice at different agesNote： A， Lung weight to tibia length ratio； B， Heart weight to tibia length ratio. Wild-type ICR mice without premature aging （WT group） were used as controls， n=6， *P<0.05.

Figure 3 Analysis of cardiac histopathology and related factor transcriptional levels in 24-week-old SHJH hr miceNote： A， Representative images of HE， Masson， and WGA staining； B， Statistical analysis of myocardial fibrosis levels shown by Masson staining； C， Analysis of the area occupied by WGA-positive cells in myocardial tissue as shown by WGA staining； D， Real-time fluorescent quantitative PCR （RFQ-PCR） measurement of mRNA expression levels of Il1β， Il6， Tnf， and Ccl2 in cardiomyocytes； E， RFQ-PCR measurement of mRNA expression levels of Tgfβ1， Col1α1， and Actα2 in cardiomyocytes. Wild-type ICR mice without premature aging （WT group） were used as controls， n=6. Compared with the WT group， *P <0.05.

Figure 4 Analysis of oxidative damage-related factors in cardiac tissue of 24-week-old SHJH hr miceNote： A， RT-PCR was used to measure the mRNA expression levels ofoxidative stress factors superoxide dismutase（Sod）2， Sod3， glutathione peroxidase（Gpx）1， and catalase（Cat）； B to D， ELISA was used to determine the activities of SOD， GPX， and CAT； E， ELISA was used to measure the expression level of 8-hydroxy-2'-deoxyguanosine （8-OHdG）； F， ELISA was used to assess the level of malondialdehyde （MDA）. Wild-type ICR mice without premature aging （WT group） were used as controls， n=6. Compared with the WT group， *P <0.05.

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