title: Histological detection of catalytic ferrous iron with the selective turn-on fluorescent probe RhoNox-1 in a Fenton reaction-based rat renal carcinogenesis model.
abstract: Iron overload of a chronic nature has been associated with a wide variety of human diseases, including infection, carcinogenesis, and atherosclerosis. Recently, a highly specific turn-on fluorescent probe (RhoNox-1) specific to labile ferrous iron [Fe(II)], but not to labile ferric iron [Fe(III)], was developed. The evaluation of Fe(II) is more important than Fe(III) in vivo in that Fe(II) is an initiating component of the Fenton reaction. In this study, we applied this probe to frozen sections of an established Fenton reaction-based rat renal carcinogenesis model with an iron chelate, ferric nitrilotriacetate (Fe-NTA), in which catalytic iron induces the Fenton reaction specifically in the renal proximal tubules, presumably after iron reduction. Notably, this probe reacted with Fe(II) but with neither Fe(II)-NTA, Fe(III) nor Fe(III)-NTA in vitro. Prominent red fluorescent color was explicitly observed in and around the lumina of renal proximal tubules 1 h after an intraperitoneal injection of 10-35 mg iron/kg Fe-NTA, which was dose-dependent, according to semiquantitative analysis. The RhoNox-1 signal colocalized with the generation of hydroxyl radicals, as detected by hydroxyphenyl fluorescein (HPF). The results demonstrate the transformation of Fe(III)-NTA to Fe(II) in vivo in the Fe-NTA-induced renal carcinogenesis model. Therefore, this probe would be useful for localizing catalytic Fe(II) in studies using tissues.
authors.affiliation: Department of Pathology and Biological Responses, Nagoya University Graduate School of Medicine , Nagoya , Japan.
authors.forename: T
authors.initials: T
authors.lastname: Mukaide
authors.forename: Y
authors.initials: Y
authors.lastname: Hattori
authors.forename: N
authors.initials: N
authors.lastname: Misawa
authors.forename: S
authors.initials: S
authors.lastname: Funahashi
authors.forename: L
authors.initials: L
authors.lastname: Jiang
authors.forename: T
authors.initials: T
authors.lastname: Hirayama
authors.forename: H
authors.initials: H
authors.lastname: Nagasawa
authors.forename: S
authors.initials: S
authors.lastname: Toyokuni
mesh_terms: D000818:Animals; D063646:Carcinogenesis / Q000737:chemistry*; D004195:Disease Models, Animal; D005296:Ferrous Compounds / Q000032:analysis; D005456:Fluorescent Dyes / Q000737:chemistry*; D006861:Hydrogen Peroxide; D007501:Iron / Q000032:analysis*; D007680:Kidney Neoplasms / Q000139:chemically induced*; D008297:Male; D051381:Rats; D017208:Rats, Wistar
chemical_list: C045076:Fenton's reagent; D005296:Ferrous Compounds; D005456:Fluorescent Dyes; D006861:Hydrogen Peroxide; D007501:Iron
keywords: catalytic ferrous iron; fluorescent probe; kidney; morphometry; oxidative stress