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Articles by Andrea Linares in JoVE
Receptor Autoradiography Protocol for the Localized Visualization of Angiotensin II Receptors Andrea Linares1, Leena E. Couling2, Eduardo J. Carrera3, Robert C. Speth2 1Farquhar College of Arts and Sciences, Nova Southeastern University, 2Department of Pharmaceutical Sciences, College of Pharmacy, Nova Southeastern University, 3School of Medicine, University of Colorado Here we present a protocol to describe the localization of angiotensin II Type 1 receptors in the rat brain by quantitative, densitometric, in vitro receptor autoradiography using an iodine-125 labeled analog of angiotensin II.
Other articles by Andrea Linares on PubMed
Acute Repeated Intracerebroventricular Injections of Angiotensin II Reduce Agonist and Antagonist Radioligand Binding in the Paraventricular Nucleus of the Hypothalamus and Median Preoptic Nucleus in the Rat Brain Brain Research. Oct, 2014 | Pubmed ID: 25108041 Angiotensin II (Ang II) stimulates water and saline intakes when injected into the brain of rats. This arises from activation of the AT1 Ang II receptor subtype. Acute repeated injections, however, decrease the water intake response to Ang II without affecting saline intake. Previous studies provide evidence that Ang II-induced water intake is mediated via the classical G protein coupling pathway, whereas the saline intake caused by Ang II is mediated by an ERK 1/2 MAP kinase signaling pathway. Accordingly, the different behavioral response to repeated injections of Ang II may reflect a selective effect on G protein coupling. To test this hypothesis, we examined the binding of a radiolabeled agonist ((125)I-sarcosine(1) Ang II) and a radiolabeled antagonist ((125)I-sarcosine(1), isoleucine(8) Ang II) in brain homogenates and tissue sections prepared from rats given repeated injections of Ang II or vehicle. Although no treatment-related differences were found in hypothalamic homogenates, a focus on specific brain structures using receptor autoradiography, found that the desensitization treatment reduced binding of both radioligands in the paraventricular nucleus of the hypothalamus (PVN) and median preoptic nucleus (MnPO), but not in the subfornical organ (SFO). Because G protein coupling is reported to have a selective effect on agonist binding without affecting antagonist binding, these findings do not support a G protein uncoupling treatment effect. This suggests that receptor number is more critical to the water intake response than the saline intake response, or that pathways downstream from the G protein mediate desensitization of the water intake response.
Distribution of Non-AT1, Non-AT2 Binding of 125I-sarcosine1, Isoleucine8 Angiotensin II in Neurolysin Knockout Mouse Brains PloS One. 2014 | Pubmed ID: 25147932 The recent identification of a novel binding site for angiotensin (Ang) II as the peptidase neurolysin (E.C. 18.104.22.168) has implications for the renin-angiotensin system (RAS). This report describes the distribution of specific binding of 125I-Sarcosine1, Isoleucine8 Ang II (125I-SI Ang II) in neurolysin knockout mouse brains compared to wild-type mouse brains using quantitative receptor autoradiography. In the presence of p-chloromercuribenzoic acid (PCMB), which unmasks the novel binding site, widespread distribution of specific (3 µM Ang II displaceable) 125I-SI Ang II binding in 32 mouse brain regions was observed. Highest levels of binding >700 fmol/g initial wet weight were seen in hypothalamic, thalamic and septal regions, while the lowest level of binding
Structure and Vascularization of the Ventricular Myocardium in Holocephali: Their Evolutionary Significance Journal of Anatomy. Jun, 2015 | Pubmed ID: 25994124 It was generally assumed that the ventricle of the primitive vertebrate heart was composed of trabeculated, or spongy, myocardium, supplied by oxygen-poor luminal blood. In addition, it was presumed that the mixed ventricular myocardium, consisting of a compacta and a spongiosa, and its supply through coronary arteries appeared several times throughout fish evolution. Recent work has suggested, however, that a fully vascularized, mixed myocardium may be the primitive condition in gnathostomes. The present study of the heart ventricles of four holocephalan species aimed to clarify this controversy. Our observations showed that the ventricular myocardium of Chimaera monstrosa and Harriotta raleighana consists of a very thin compacta overlying a widespread spongiosa. The ventricle of Hydrolagus affinis is composed exclusively of trabeculated myocardium. In these three species there is a well-developed coronary artery system. The main coronary artery trunks run along the outflow tract, giving off subepicardial ventricular arteries. The trabeculae of the spongiosa are irrigated by branches of the subepicardial arteries and by penetrating arterial vessels arising directly from the main coronary trunks at the level of the conoventricular junction. The ventricle of Rhinochimaera atlantica has only spongy myocardium supplied by luminal blood. Small coronary arterial vessels are present in the subepicardium, but they do not enter the myocardial trabeculae. The present findings show for the first time that in a wild living vertebrate species, specifically H. affinis, an extensive coronary artery system supplying the whole cardiac ventricle exists in the absence of a well-developed compact ventricular myocardium. This is consistent with the notion derived from experimental work that myocardial cell proliferation and coronary vascular growth rely on distinct developmental programs. Our observations, together with data in the literature on elasmobranchs, support the view that the mixed ventricular myocardium is primitive for chondrichthyans. The reduction or even lack of compacta in holocephali has to be regarded as a derived anatomical trait. Our findings also fit in with the view that the mixed myocardium was the primitive condition in gnathostomes, and that the absence of compact ventricular myocardium in different actinopterygian groups is the result of a repeated loss of such type of cardiac muscle during fish evolution.