Abstract P110: Mrgd Expression in Cardiovascular Related Areas
Recently a new peptide was discovered as part of the Renin Angiotensin System, the heptapeptide alamandine. This new component is a product of the catalytic hydrolysis of Angiotensin A or can also be formed from decarboxilation of Angiotensin-(1-7). Interestingly, alamandine effects were independent of Angiotensin-(1-7) receptor Mas and the Mas-related G protein receptor member D (MrgD) was described as an alamandine receptor. Previous studies have reported that MrgD is expressed predominantly in small diameter IB4(+) neurons in the dorsal root ganglion (DRG). However, functional experiments performed in our lab showed that alamandine has antihypertensive and cardioprotective effects, indicating that MrgD might be also expressed in another tissues. Objective: Identify the anatomical localization of MrgD receptors in blood vessels, heart and in cardiovascular- related centers of the mouse brain. Materials and Methods: Mice were euthanized and then perfused. Brain, Aorta and heart were removed and postfixed. Serial sections were made in a cryostat, hydrated with PBS and permeabilized with 0.2% Tween 20, blocked with 5% of BSA, followed by a rabbit anti-MrgD and an Alexa 488-labeled anti-rabbit antibodies. Immunostaining specificity was characterized by performing experiments using MrgD receptor knockout mice as control. Results: Differently than described before, MrgD expression is not restricted to neurons at DRG. Immunofluorescence for MrgD receptor was detected throughout the trigeminal tract, Cerebellum, Cortex, Insular Cortex, Hypothalamus and in some nuclei of the brainstem. In addition, corroborating previous functional studies from our laboratory showing that Alamandine has an endothelium-dependent vasorelaxant effect we also observed positive fluorescence in aorta endothelial and smooth muscle cells Moreover, MrgD-positive immunofluorescence was also detected in cardiomyocytes, in the membrane and particularly in the nuclear and perinuclear area expanding the evidence that alamandine-induced effects are mediated by MrgD receptor. These observations are in keeping with previous functional studies and unmasked new targets for exploring the biological relevance of alamandine/MrgD.
Author Disclosures: A.C. Oliveira: None. A.A.B. Peluso: None. F. Qadri: None. N. Alenina: None. M. Bader: None. R. Santos: None.
- © 2015 by American Heart Association, Inc.