title: The periovulatory endocrine milieu affects the uterine redox environment in beef cows.
abstract: BACKGROUND
  In cattle, recent studies have shown positive associations between pre-ovulatory concentrations of estradiol (E2), progesterone (P4) at early diestrus and fertility. However, information on cellular and molecular mechanisms through which sex steroids regulate uterine function to support early pregnancy is lacking. Based on endometrial transcriptome data, objective was to compare function of the redox system in the bovine uterus in response to different periovulatory endocrine milieus.
  
  
  METHODS
  We employed an animal model to control growth of the pre-ovulatory follicle and subsequent corpus luteum (CL). The large follicle-large CL group (LF-LCL, N=42) presented greater levels of E2 on the day of GnRH treatment (D0; 2.94 vs. 1.27 pg/mL; P=0.0007) and P4 at slaughter on D7 (3.71 vs. 2.62 ng/mL, P=0.01), compared with the small follicle-small CL group (SF-SCL, N=41). Endometrium and uterine washings (N=9, per group) were collected for analyses of variables associated with the uterine redox system.
  
  
  RESULTS
  The SF-SCL group had lower endometrial catalase (0.5 vs. 0.79 U/mg protein, P<0.001) and glutathione peroxidase (GPx; 2.0 vs. 2.43 nmol β-nicotinamide adenine dinucleotide phosphate reduced/min/mg protein, P=0.04) activity, as well as higher lipid peroxidation (28.5 vs. 17.43 nmol malondialdehyde/mg of protein, P<0.001) and superoxide dismutase (SOD) activity (44.77 vs. 37.76 U; P=0.04). There were no differences in the endometrial reactive species (RS) or glutathione (GSH) concentrations between the groups. The uterine washing samples showed no differences in the concentrations of RS or GSH or in total SOD activity (P>0.1). Additionally, catalase, GPx4, SOD1 and SOD2 gene expression was lower in the SF-SCL group than in the LF-LCL group.
  
  
  CONCLUSIONS
  We concluded that the intrauterine environment of cows from the LF-LCL group exhibited higher antioxidant activity than that of the cows from the SF-SCL group. We speculate that uterine receptivity and fertility are associated with an optimal redox environment, such as that present in the animals in the LF-LCL group.
authors.affiliation: Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, SP, 13635-900, Brazil. roney.ramos@yahoo.com.br.
authors.forename: Roney S
authors.initials: RS
authors.lastname: Ramos
authors.affiliation: Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, SP, 13635-900, Brazil. mileoliveira@usp.br.
authors.forename: Milena L
authors.initials: ML
authors.lastname: Oliveira
authors.affiliation: Laboratory of Reproductive Biotechnology (Biotech), Federal University of Pampa, Uruguaiana, Brazil. aryeleizaguirry777@gmail.com.
authors.forename: Aryele P
authors.initials: AP
authors.lastname: Izaguirry
authors.affiliation: Laboratory of Reproductive Biotechnology (Biotech), Federal University of Pampa, Uruguaiana, Brazil. laumusacchio@gmail.com.
authors.forename: Laura M
authors.initials: LM
authors.lastname: Vargas
authors.affiliation: Laboratory of Reproductive Biotechnology (Biotech), Federal University of Pampa, Uruguaiana, Brazil. melina_bucco@hotmail.com.
authors.forename: Melina B
authors.initials: MB
authors.lastname: Soares
authors.affiliation: School of Veterinary Medicine, Federal University of Pampa, Uruguaiana, Brazil. fernando.mesquita@unipampa.edu.br.
authors.forename: Fernando S
authors.initials: FS
authors.lastname: Mesquita
authors.affiliation: Laboratory of Reproductive Biotechnology (Biotech), Federal University of Pampa, Uruguaiana, Brazil. francielliweber@yahoo.com.br.
authors.forename: Francielli W
authors.initials: FW
authors.lastname: Santos
authors.affiliation: Department of Animal Reproduction, School of Veterinary Medicine and Animal Science, University of São Paulo, Pirassununga, SP, 13635-900, Brazil. binelli@usp.br.
authors.forename: Mario
authors.initials: M
authors.lastname: Binelli
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D002417:Cattle; D004031:Diestrus / Q000378:metabolism*; D004958:Estradiol / Q000097:blood; D030762:Estrous Cycle / Q000378:metabolism*; D005260:Female; D005298:Fertility; D015227:Lipid Peroxidation; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D011374:Progesterone / Q000097:blood
chemical_list: D000975:Antioxidants; D011374:Progesterone; D004958:Estradiol