Structural and molecular evaluation of neuromuscular junction in the diaphragm muscle of rats with heart failure submitted to aerobic training

• Grant number: 12/17369-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2012
• End date: October 31, 2013
• Field of knowledge: Biological Sciences - Morphology - Cytology and Cell Biology
• Principal Investigator: Maeli Dal Pai
• Grantee: Luana Campos Soares
• Host Institution: Instituto de Biociências (IBB). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

Heart failure (HF) is a syndrome characterized by reduced cardiac function and activation of compensatory mechanisms in the body. The most common symptoms are muscle fatigue and dyspnea, changes in muscle fiber types from fast to slow, atrophy, and increased expression of nicotinic acetylcholine receptors (nAChR) at the neuromuscular junction (NMJ). Activation of nAChR and stability occurs through the interaction of trophic factors with proteins of the sarcolemma of the muscle fiber. The diaphragm is affected by the HF and physical training is considered a widely accepted practice to minimize the consequences of symptoms caused by HF. The hypothesis is that in HF, the increased expression of nAChRs is associated with changes in the release of trophic factors that act in protein expression sarcolemma, leading to changes in the morphological characteristics of JNMs in the diaphragm. Additionally, exercise minimizes changes in the JNMs and morphofunctional characteristics of the muscle. This study will evaluate the gene and protein expression of trophic factor agrin and of the sarcolemma protein rapsina and musk; we also will evaluate the structure and morphology of NMJs in the diaphragm muscle of rats with HF undergoing aerobic training. We will use 112 male Wistar rats (90 to 100g) divided into four groups: control (C) Aortic Stenosis (AS - inserting a silver clip with 0.6 mm of diameter in the ascending aorta), Trained (TR), Aortic Stenosis Training (ASTR). After 18 weeks of surgery induction of AS, part of the control animals and with AS will be randomly divided into trained or not. The animals will be subjected to aerobic training on a treadmill for 10 weeks (5days/week). The clinical parameters of the IC will be assessed. The gene and protein expression of trophic factor agrin and the sarcolemma proteins musk and rapsina will be analyzed by RT-PCR and Western blot, respectively, and structural characterization of NMJs will be performed by confocal laser scanning. Data will be analyzed statistically.(AU)