The role of 17b-estradiol in the luteolytic process of non-pregnant bitches

• Grant number: 12/17367-1
• Support Opportunities: Scholarships in Brazil - Master
• Effective date (Start): November 01, 2012
• Effective date (End): September 30, 2014
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Paula de Carvalho Papa Keohane
• Grantee: Antenor Pereira Bonfim Neto
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The corpus luteum (CL) is a temporary endocrine gland, which goes trought different developmental phases: formation, maintenance and regression and reaches full secretory capacity when formation is complete. Steroidogenic profile differs over diestrus : progesterone (P4) is markedly elevated in the formation period; decreasing P4 and increasing 17b-estradiol (E2) are observed during maintenance and E2 highest diestrous levels on day 40 post ovulation (p.o.). Nevertheless, mechanisms regulating CL function and life span are not compeltely elucidated and show species specific differences. Special interest relies on the luteolytic phase, or regression phase, as some authors prefer when talking about the non-pregnant bitch, a moment that, differently from other species, PGF2a plays no important role. We hypothesize that E2 is one of the triggers for the non-pregnant dog luteolysis and that its variations over diestrus are instrumental in the induction of apoptosis and decreased expression of lutrotofics factors.To test this hypothesis 24 non-pregnant bitches will be submitted to ovariosalpingohysterectomy on days 10, 20, 30, 40, 50, 60, 70 e >70 p.o. (n = 4 per group). Blood samples will be collected prior to anesthesia for hormonal measurements of P4, E2. Some CL will be frozen in liquid nitrogen for posterior validation of the relative CL regression genes (FAS, caspase8, caspase3, caspase9 e BAX) cell proliferation (Ki67) for real time PCR, as well as the respective proteins encoded by the differentially expressed genes by western blotting and immunohistochemistry. For immunhistochemistry CL samples will be fixed in 4% paraformaldehyde. Remaining CL will be transported to the laboratory in phospahte buffer for cell culture and E2 and/or E2 receptor blocker experiments for further evaluation by gene validation protocols for real-time PCR, and protein by western blotting of involved genes in apoptosis, cell proliferation and steroidogenesis (3²-HSD, P450scc and aromatase). Data will be analyzed by MinitabÒ statistical program and differences will be considered when p < 0.05.

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

BONFIM NETO, Antenor Pereira. The role of 17b-estradiol in the luteolytic process of non-pregnant bitches. 2014. Master's Dissertation - Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD) São Paulo.