title: Distribution of non-AT1, non-AT2 binding of 125I-sarcosine1, isoleucine8 angiotensin II in neurolysin knockout mouse brains.
abstract: The recent identification of a novel binding site for angiotensin (Ang) II as the peptidase neurolysin (E.C. 3.4.24.16) 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 <300 fmol/g initial wet weight was in the mediolateral medulla. 125I-SI Ang II binding was substantially higher by an average of 85% in wild-type mouse brains compared to neurolysin knockout brains, suggesting the presence of an additional non-AT1, non-AT2, non-neurolysin Ang II binding site in the mouse brain. Binding of 125I-SI Ang II to neurolysin in the presence of PCMB was highest in hypothalamic and ventral cortical brain regions, but broadly distributed across all regions surveyed. Non-AT1, non-AT2, non-neurolysin binding was also highest in the hypothalamus but had a different distribution than neurolysin. There was a significant reduction in AT2 receptor binding in the neurolysin knockout brain and a trend towards decreased AT1 receptor binding. In the neurolysin knockout brains, the size of the lateral ventricles was increased by 56% and the size of the mid forebrain (-2.72 to +1.48 relative to Bregma) was increased by 12%. These results confirm the identity of neurolysin as a novel Ang II binding site, suggesting that neurolysin may play a significant role in opposing the pathophysiological actions of the brain RAS and influencing brain morphology.
authors.affiliation: Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America; Department of Physiology and Functional Genomics, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Robert C
authors.initials: RC
authors.lastname: Speth
authors.affiliation: Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America; Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America.
authors.forename: Eduardo J
authors.initials: EJ
authors.lastname: Carrera
authors.affiliation: Department of Pharmaceutical Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America; Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America.
authors.forename: Catalina
authors.initials: C
authors.lastname: Bretón
authors.affiliation: Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America.
authors.forename: Andrea
authors.initials: A
authors.lastname: Linares
authors.affiliation: Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America.
authors.forename: Luz
authors.initials: L
authors.lastname: Gonzalez-Reiley
authors.affiliation: Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America.
authors.forename: Jamala D
authors.initials: JD
authors.lastname: Swindle
authors.affiliation: Farquhar College of Arts and Sciences, Nova Southeastern University, Fort Lauderdale, Florida, United States of America; College of Dentistry, University of Florida, Gainesville, Florida, United States of America.
authors.forename: Kira L
authors.initials: KL
authors.lastname: Santos
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
authors.forename: Ines
authors.initials: I
authors.lastname: Schadock
authors.affiliation: Max-Delbrück-Center for Molecular Medicine, Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Bader
authors.affiliation: Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, Texas, United States of America; Center for Blood-Brain Barrier Research, Texas Tech University Health Sciences Center, Amarillo, Texas, United States of America.
authors.forename: Vardan T
authors.initials: VT
authors.lastname: Karamyan
mesh_terms: D000804:Angiotensin II / Q000493:pharmacokinetics / Q000494:pharmacology; D000818:Animals; D007456:Iodine Isotopes / Q000493:pharmacokinetics / Q000494:pharmacology; D008666:Metalloendopeptidases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016548:Prosencephalon / Q000378:metabolism*; D044139:Receptor, Angiotensin, Type 2 / Q000235:genetics / Q000378:metabolism; D012084:Renin-Angiotensin System / Q000502:physiology*; D012521:Sarcosine / Q000493:pharmacokinetics / Q000494:pharmacology
chemical_list: D007456:Iodine Isotopes; D044139:Receptor, Angiotensin, Type 2; D000804:Angiotensin II; D008666:Metalloendopeptidases; C062316:neurolysin; D012521:Sarcosine