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

Magdalena Chottova Dvorakova,Jana Slavikova,Eliska Mistrova,Wolfgang Kummer,Renate Paddenberg

doi:10.3389/fphys.2018.00918

Magdalena Chottova Dvorakova, Jana Slavikova + Show 3 more

Open Access

https://doi.org/10.3389/fphys.2018.00918

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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.

Highlights

Cardiovascular autonomic neuropathy is a serious and one of the most common complications of diabetes mellitus which accompanies later stages of diabetes (Vinik et al, 2003)
Sections were placed onto special slides (Zeiss, Jena, Germany) and stained with alum hematoxylin solution for 8 min and washed by water
Intracardiac neurons, vascular smooth muscle cells, and cardiomyocytes were collected by use of microscope equipped with laser (Zeiss)

Summary

Introduction

Cardiovascular autonomic neuropathy is a serious and one of the most common complications of diabetes mellitus which accompanies later stages of diabetes (Vinik et al, 2003). SP Receptor in the Heart of cardiomyocytes and vessels which may cause abnormalities in heart functions and vascular dynamics (Ejaz et al, 2011b). Cardiac autonomic neurons contain a broad spectrum of neurotransmitters from which long-acting neuropeptides may serve as neuromodulators or trophic factors (Burnstock, 2013). Dysregulation of their expression or stimulation of their signaling pathways can negatively impact cardiac homeostasis (Ejaz et al, 2011b). This study is focused on a further component of a neuropeptide transmission in the heart, the specific receptor for substance P (SP)

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