Substance P Receptor in the Rat Heart and Regulation of Its Expression in Long-Term Diabetes

Abstract

Substance P (SP) is a neuropeptide engaged in the signal transmission of neural C fibers afferents in the myocardium. The actions of SP in the heart are extensive and they are mediated by the neurokinin 1 receptor (NK1R), a member of the tachykinin subfamily of G-protein coupled receptors. The receptors have been found in the heart, but to our knowledge, their exact localization in the heart has not been described yet. Here, we investigated the presence of NK1R protein in separate rat heart compartments by means of western blot and its tissue distribution by means of immunofluorescence. Specificity of NK1R immunolabeling was controlled by preabsorption of the antiserum with its corresponding peptide. Additionally, we investigated abundance of gene for NK1R in separated heart chambers by means of quantitative real-time PCR (RT-PCR). Relative abundance of NK1R mRNA was expressed as a ratio of target gene Cq value to Cq value of control gene – beta-actin. Finally, we studied abundance of NK1R mRNA in different cell types of heart isolated by laser capture microdissection. Immunofluorescence showed NK1R immunoreactivity on the surface of some intracardiac neurons and smooth muscle cells of coronary vessels. The results of quantitative RT-PCR indicate abundance of mRNA for NK1R in all heart chambers with highest level in the left atrium. The presence of NK1R mRNA was detected in some samples of dissected intracardiac neurons, but not in cardiomyocytes or smooth muscle cells of coronary vessels. In the course of long-term diabetes, a significant downregulation of the NK1R mRNA was seen in the right atrium and upregulation in the right ventricle 53 weeks after the induction of diabetes. Our results indicate localization of NK1R in some intracardiac neurons and smooth muscle cells. Impaired transcription of the NK1R gene in the diabetic heart may be induced by unidentified genes or factors involved in the development of diabetic cardiomyopathy.

Identification of NPB, NPW and Their Receptor in the Rat Heart

“…The whole procedure was done according to a protocol published earlier [24]. Briefly, sections of heart atria were stained with alum hematoxylin solution, washed with water and dehydrated with ethanol.…”

Neuropeptides: Roles and Activities as Metal Chelators in Neurodegenerative Diseases

“…The wide range of distribution of the neuropeptides in the signaling system in the human body is varied and extensively reviewed elsewhere. 46 Some of the neuropeptides are distributed in the central nervous system (CNS); others are in the peripheral nervous system (PNS), and others are in the peripheral tissues. 46 Herein, we provide a few examples of the distribution of only several neuropeptides.…”

Substance P/neurokinin1 receptor is associated with the expression of cardiac stem/pluripotency-associated genes in diabetic right and left atria

“…Our previous studies have noted the local activation of c-Kit + cells by SP/NK1R signaling in RA in heart damage 10 . According to a recent study that constructed a rat model of right heart disease (RHD), RA can play an important role in AF maintenance with RA re-entrant activity caused by atrial fibrosis and conduction abnormalities [6][7][8][13][14][15] . To determine whether SP/NK1R affects CSC-related gene expression in LA and RA of LETO and OLETF groups, we selected well-studied genes of cardiac transcription factors and stem cell markers.…”

“…Substance P (SP), an 11-amino acid neuropeptide of the tachykinin neuropeptide family, is an evolutionarily older neurotransmitter than acetylcholine and the catecholamines 10,12,13 .…”

“…Neurokinin1 receptor (NK1R), a G protein coupled receptor found in the central and peripheral nervous systems, is important for the biological actions of SP 10,12,13 . Interestingly, the expression and localization of SP and NK1R have already been described for RA of diabetic patients and rat models, shown to be significantly impaired 13,14 . Our recent, previous studies have demonstrated that treatment of SP enhanced the local activation of cardiac progenitor c-Kit + cells (CSCs) in LV and RA after myocardial infarction 10,12 .…”