Journal
JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY
Volume 49, Issue 2, Pages 234-244Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.yjmcc.2010.03.007
Keywords
Vagus Nerve; Myocardial Ischemia; Tumor necrosis factor-alpha; TNF receptors; Apoptosis
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Funding
- Ministry of Health, Labor, and Welfare of Japan [H14-NANO-002, H16-NANO-005]
- Ministry of Education, Science, Sports, and Culture of Japan [15300165, 17790892]
- Grants-in-Aid for Scientific Research [17790892, 15300165] Funding Source: KAKEN
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Vagal nerve stimulation (VS) has been reported to improve the survival after both acute and chronic myocardial infarction through the release of neurotransmitter ACh. However, the precise mechanism behind its beneficial effect is still unknown. In this study, we demonstrate the upregulation of tumor necrosis factor-alpha (TNF-alpha) and its cell survival TNF receptor-2 (TNFR2) as the mechanism behind VS induced myocardial protection. We investigated the effects of efferent VS on myocardial ischemic injury with in vivo and in vitro mouse models. In in vivo hearts VS significantly increased the expression of TNF-alpha both at the messenger and protein level after 3-hours of myocardial ischemia. In the in vitro studies ACh treatment before hypoxia, induced a significant upregulation of TNF-alpha compared to the untreated cardiomyocytes. Immunofluorescence analysis confirmed the synthesis of TNF-alpha by cardiomyocytes both in vivo and in vitro. VS also significantly reduced the myocardial infarct size (23.9 +/- 5.7% vs. 56 +/- 1.9%) and activated the cell survival Akt cascade system. Further, ACh upregulated the cell survival TNFR2 expression, while downregulating the cell destructive TNF receptor 1 (TNFR1) expression. These results were confirmed using the TNF receptors deficient mice, where the VS mediated protection was lost both in vivo and in vitro in TNFR2 (TNFR2(-/-)) and TNF receptors double knock out (TNFR1(-/-)2(-/-)) mice. VS and ACh protects the heart against acute ischemia or hypoxic injury by differentially regulating the TNF receptor subtypes. (C) 2010 Elsevier Ltd. All rights reserved.
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