title: Efficacy of a low dose of estrogen on antioxidant defenses and heart rate variability.
abstract: This study tested whether a low dose (40% less than the pharmacological dose of 17-β estradiol) would be as effective as the pharmacological dose to improve cardiovascular parameters and decrease cardiac oxidative stress. Female Wistar rats (n = 9/group) were divided in three groups: (1) ovariectomized (Ovx), (2) ovariectomized animals treated for 21 days with low dose (LE; 0.2 mg), and (3) high dose (HE; 0.5 mg) 17-β estradiol subcutaneously. Hemodynamic assessment and spectral analysis for evaluation of autonomic nervous system regulation were performed. Myocardial superoxide dismutase (SOD) and catalase (CAT) activities, redox ratio (GSH/GSSG), total radical-trapping antioxidant potential (TRAP), hydrogen peroxide, and superoxide anion concentrations were measured. HE and LE groups exhibited an improvement in hemodynamic function and heart rate variability. These changes were associated with an increase in the TRAP, GSH/GSSG, SOD, and CAT. A decrease in hydrogen peroxide and superoxide anion was also observed in the treated estrogen groups as compared to the Ovx group. Our results indicate that a low dose of estrogen is just as effective as a high dose into promoting cardiovascular function and reducing oxidative stress, thereby supporting the approach of using low dose of estrogen in clinical settings to minimize the risks associated with estrogen therapy.
authors.affiliation: Universidade Federal do Rio Grande do Sul, Sarmento Leite, 500 Bairro Farroupilha, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Cristina
authors.identifier: 0000-0001-6054-4243
authors.initials: C
authors.lastname: Campos
authors.affiliation: Instituto de Cardiologia do Rio Grande do Sul, 90620-001 Porto Alegre, RS, Brazil.
authors.forename: Karina Rabello
authors.initials: KR
authors.lastname: Casali
authors.affiliation: Universidade Federal do Rio Grande do Sul, Sarmento Leite, 500 Bairro Farroupilha, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Dhãniel
authors.initials: D
authors.lastname: Baraldi
authors.affiliation: Universidade Federal do Rio Grande do Sul, Sarmento Leite, 500 Bairro Farroupilha, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Adriana
authors.initials: A
authors.lastname: Conzatti
authors.affiliation: Universidade Federal do Rio Grande do Sul, Sarmento Leite, 500 Bairro Farroupilha, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Alex Sander da Rosa
authors.initials: AS
authors.lastname: Araújo
authors.affiliation: Medical Sciences Division, Northern Ontario School of Medicine, Lakehead University, Thunder Bay, ON, Canada P7B 5E1.
authors.forename: Neelam
authors.initials: N
authors.lastname: Khaper
authors.affiliation: Universidad de Buenos Aires, C1053ABJ Buenos Aires, Argentina.
authors.forename: Susana
authors.initials: S
authors.lastname: Llesuy
authors.affiliation: Universidade Federal de Ciências da Saúde de Porto Alegre, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Katya
authors.initials: K
authors.lastname: Rigatto
authors.affiliation: Universidade Federal do Rio Grande do Sul, Sarmento Leite, 500 Bairro Farroupilha, 90050-170 Porto Alegre, RS, Brazil.
authors.forename: Adriane
authors.initials: A
authors.lastname: Belló-Klein
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D000975:Antioxidants / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005978:Glutathione / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects*; D006352:Heart Ventricles / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006861:Hydrogen Peroxide / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism / Q000473:pathology; D010052:Ovariectomy; D010084:Oxidation-Reduction / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D013481:Superoxides / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase
chemical_list: D000975:Antioxidants; D004967:Estrogens; D007527:Isoenzymes; D013481:Superoxides; D004958:Estradiol; D006861:Hydrogen Peroxide; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D005978:Glutathione
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