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Updated: Oct 17, 2026
Myocardial Infarction in Neonatal Mice, A Model of Cardiac Regeneration
Published on: May 24, 2016
Tumor necrosis factor-alpha induces apoptosis via inducible nitric oxide synthase in neonatal mouse cardiomyocytes
Objective:
It has been demonstrated that tumor necrosis factor-alpha (TNF alpha) induces apoptosis in cardiac myocytes. However, its mechanism of action is still not well understood. In the present study, we hypothesized that TNF alpha induces myocardial apoptosis by induction of inducible nitric oxide synthase (iNOS).
Methods:
Neonatal cardiac myocytes were isolated from iNOS (-/-) mutant and C57BL6 wild type mice. Cells were cultured for 3 days before treatment with an NO donor or TNF alpha. Following treatment with S-nitroso-N-acetyl-penicillamine (SNAP) or TNF-alpha, cells were tested for apoptosis by terminal deoxynucleotidyl transfer-mediated end labeling (TUNEL) staining and cell death detection ELISA. NO production was measured by nitrite concentration in the culture medium. Cardiomyocyte expression of iNOS and TNF type 1 receptor (TNFR1) mRNA was determined by reverse transcriptase-polymerase chain reaction (RT-PCR).
Results:
SNAP (0.01-100 microM) induced apoptosis of cardiac myocytes in a concentration-dependent manner in the wild type mice (n = 5, P < 0.01). TNFR1 mRNA was expressed in neonatal cardiomyocytes from both wild type and iNOS (-/-) mutant mice. TNF alpha induced a concentration-dependent increase in iNOS mRNA expression and nitrite production as well as significant apoptosis of cardiomyocytes in the wild type mice (n = 4, P < 0.01). However, without iNOS expression, the apoptotic effects of TNF-alpha were significantly attenuated in cardiomyocytes from iNOS (-/-) mutant mice (n = 4, P < 0.05).
Conclusion:
TNF alpha induces apoptosis via iNOS expression and NO production in neonatal mouse cardiomyocytes.
Insights
Tumor necrosis factor-alpha (TNF alpha) triggers heart cell death by increasing inducible nitric oxide synthase (iNOS) and nitric oxide (NO) production. This mechanism explains how TNF alpha causes myocardial apoptosis in neonatal mouse cardiomyocytes.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Cell Death Mechanisms
Background:
- Tumor necrosis factor-alpha (TNF alpha) is known to induce apoptosis in cardiac myocytes.
- The precise molecular mechanisms underlying TNF alpha-induced myocardial apoptosis remain incompletely understood.
- This study investigates the role of inducible nitric oxide synthase (iNOS) in mediating TNF alpha's apoptotic effects on heart cells.
Purpose of the Study:
- To elucidate the mechanism by which TNF alpha induces apoptosis in cardiac myocytes.
- To test the hypothesis that TNF alpha induces myocardial apoptosis through the upregulation of inducible nitric oxide synthase (iNOS).
Main Methods:
- Primary neonatal mouse cardiomyocytes were isolated from wild type and iNOS knockout mice.
- Cells were treated with nitric oxide (NO) donor (SNAP) or TNF alpha.
- Apoptosis was assessed using TUNEL staining and ELISA; NO production was measured by nitrite levels; gene expression of iNOS and TNF receptor 1 (TNFR1) was analyzed via RT-PCR.
Main Results:
- SNAP and TNF alpha induced concentration-dependent apoptosis in wild type cardiomyocytes.
- TNF alpha treatment increased iNOS mRNA expression and nitrite production in wild type cells.
- The apoptotic effect of TNF alpha was significantly reduced in cardiomyocytes lacking iNOS expression.
Conclusions:
- TNF alpha induces apoptosis in neonatal mouse cardiomyocytes.
- This apoptotic process is mediated by the induction of iNOS expression and subsequent nitric oxide production.
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