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Association between myocardial cell apoptosis and calpain-1/caspase-3 expression in rats with hypoxic-ischemic brain
Hong Zhao1, Mei Xu1, Guilan Chu1
1Department of Pediatrics, Tianjin Medical University General Hospital, Tianjin 300052, P.R. China.
Insights
Hypoxic-ischemic brain damage (HIBD) in rats increases myocardial cell apoptosis. This study links increased apoptosis to elevated calpain-1 and caspase-3 expression, suggesting their role in HIBD-related heart damage.
Area of Science:
- Cardiovascular Science
- Neuroscience
- Cellular Biology
Background:
- Hypoxic-ischemic brain damage (HIBD) can lead to secondary organ damage.
- Myocardial cell apoptosis is a critical factor in cardiac dysfunction following HIBD.
Purpose of the Study:
- To investigate the association between myocardial cell apoptosis and the expression of calpain-1 and caspase-3 in a rat model of HIBD.
- To analyze the correlation between these molecular markers and the extent of myocardial apoptosis.
Main Methods:
- Utilized a rat model of HIBD, with groups sacrificed at various time points post-injury.
- Assessed myocardial apoptosis using the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNL) assay.
- Quantified calpain-1 and caspase-3 expression at both mRNA (RT-PCR) and protein (Western blot) levels.
Main Results:
- Apoptotic myocardial cells significantly increased in HIBD rats, peaking on day 3.
- Both calpain-1 and caspase-3 mRNA levels elevated early post-HIBD, with peak expression observed on day 2.
- Calpain-1 protein expression increased from 2 hours post-HIBD, peaking on day 3.
- Strong positive linear correlations were found between calpain-1/caspase-3 expression and the apoptosis index (AI).
Conclusions:
- Increased myocardial cell apoptosis in HIBD rats is positively correlated with elevated calpain-1 and caspase-3 expression.
- Calpain-1 and caspase-3 may play a significant role in the pathogenesis of myocardial damage following HIBD.
Abstract:
The present study aimed to investigate the association between myocardial cell apoptosis and calpain-1/caspase-3 expression in a rat model of hypoxic-ischemic brain damage (HIBD). A total of 64 newborn rats were divided into control (n=8; sacrificed on day 7) and HIBD groups (n=56). HIBD group rats were sacrificed 2, 12 or 24 h, or 2, 3, 5 or 7 days following HIBD (n=8/group). A terminal deoxynucleotidyl transferase dUTP nick-end labeling assay was performed to detect myocardial apoptotic cells and calculate the apoptosis index (AI), reverse transcription-polymerase chain reaction was performed to detect myocardial calpain-1/caspase-3 mRNA expression levels and a western blot analysis was conducted to detect calpain‑1 protein expression levels. The correlations between calpain‑1 and caspase‑3 expression levels and AI were analyzed. The results demonstrated that apoptotic myocardial cells in the HIBD groups were markedly increased compared with the control group, with AI peaking in the day 3 group. Caspase‑3 and calpain‑1 mRNA expression levels were increased from 2 and 12 h following HIBD, respectively, with the most elevated levels in the day 2 group. Compared with the control group, calpain‑1 protein expression levels were increased from 2 h, with the greatest expression levels in the day 3 group (P<0.05). Calpain‑1 mRNA and protein (76/80 kDa) expression levels demonstrated positive linear correlations with AI (r=0.786, P=0.001; and r=0.853, P=0.001, respectively) Caspase-3 mRNA expression levels were positively correlated with AI (r=0.894; P=0.001). In conclusion, the present study demonstrated that in rats with HIBD, there is a positive correlation between increased apoptosis of myocardial cells and expression levels of calpain-1 and caspase-3.
