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ERK1/2 MAPK signaling in hypothalamic paraventricular nucleus contributes to sympathetic excitation in rats with heart failure after myocardial infarction
Journal article   Open access   Peer reviewed

ERK1/2 MAPK signaling in hypothalamic paraventricular nucleus contributes to sympathetic excitation in rats with heart failure after myocardial infarction

Yang Yu, Shun-Guang Wei, Zhi-Hua Zhang, Robert M Weiss and Robert B Felder
American journal of physiology. Heart and circulatory physiology, Vol.310(6), pp.H732-H739
03/15/2016
DOI: 10.1152/ajpheart.00703.2015
PMCID: PMC4865063
PMID: 26801309
url
https://doi.org/10.1152/ajpheart.00703.2015View
Published (Version of record) Open Access

Abstract

Brain MAPK signaling pathways are activated in heart failure (HF) induced by myocardial infarction and contribute to augmented sympathetic nerve activity. We tested whether decreasing ERK1/2 (also known as p44/42 MAPK) signaling in the hypothalamic paraventricular nucleus (PVN), a forebrain source of presympathetic neurons, would reduce the upregulation of sympathoexcitatory mediators in the PVN and augmented sympathetic nerve activity in rats with HF. Sprague-Dawley rats underwent left anterior descending coronary artery ligation to induce HF, with left ventricular dysfunction confirmed by echocardiography. One week after coronary artery ligation or sham operation, small interfering (si)RNAs targeting ERK1/2 or a nontargeting control siRNA was microinjected bilaterally into the PVN. Experiments were conducted 5-7 days later. Confocal images revealed reduced phosphorylated ERK1/2 immunofluorescence in the PVN of HF rats treated with ERK1/2 siRNAs compared with HF rats treated with control siRNA. Western blot analysis confirmed significant reductions in both total and phosphorylated ERK1/2 in the PVN of HF rats treated with ERK1/2 siRNAs along with reduced expression of renin-angiotensin system components and inflammatory mediators. HF rats treated with ERK1/2 siRNAs also had reduced PVN neuronal excitation (fewer Fos-related antigen-like-immunoreactive neurons), lower plasma norepinephrine levels, and improved peripheral manifestations of HF compared with HF rats treated with control siRNAs. These results demonstrate that ERK1/2 signaling in the PVN plays a pivotal role in mediating sympathetic drive in HF induced by myocardial infarction and may be a novel target for therapeutic intervention.
Immunohistochemistry Myocardial Infarction - genetics Echocardiography Heart Failure - physiopathology Rats Heart Failure - genetics Sympathetic Nervous System - physiopathology Rats, Sprague-Dawley Sympathetic Nervous System - metabolism Blotting, Western Cerebral Cortex - metabolism Gene Knockdown Techniques Myocardial Infarction - complications Norepinephrine - blood Animals MAP Kinase Signaling System - genetics Renin-Angiotensin System Paraventricular Hypothalamic Nucleus - metabolism Myocardial Infarction - physiopathology RNA, Small Interfering Heart Failure - etiology

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