Expression of luteal estrogen receptor, interleukin-1, and apoptosis-associated genes after PGF2α administration in rabbits at different stages of pseudopregnancy

The dynamic expression for estrogen receptor subtype-1 (ESR1), interleukin-1beta (IL1B), and apoptosis-associated genes, as well as nitric oxide synthase activity, were examined in corpora lutea (CL) of rabbits after prostaglandin F(2alpha) (PGF(2alpha)) administration on either day 4 or day 9 of pseudopregnancy. By reverse transcriptase polymerase chain reaction, the steady-state level of ESR1 transcript was lower (P < 0.01) and that of anti-apoptotic B-cell CLL/lymphoma 2 (BCL2) -like 1 (BCL2L1) was greater in day 4 (P < 0.01) than in day 9 CL. Western blot analysis revealed that BCL2-associated X protein (BAX) abundance was greater in day 4 (P < 0.01) than in day 9 CL, whereas BCL2L1 protein was undetectable at both luteal stages. After PGF(2alpha), ESR1 transcript decreased (P < 0.01) in day 9 CL, whereas IL1B mRNA showed a transitory increase (P < 0.01) at both stages. The pro-apoptotic tumor protein p53 (TP53) gene had diminished (P < 0.01) on day 4 and on day 9 after a transitory increase (P < 0.01), whereas the BAX/BCL2L1 expression ratio increased (P < 0.01) in day 9 CL 24 h after treatment. Following PGF(2alpha), TP53 protein increased (P < 0.01) at both luteal stages, and BAX decreased (P < 0.01) in day 4 CL but increased (P < 0.01) 24 h later in day 9 CL; BCL2L1 became detectable 6 h later in day 4 CL. Nitric oxide synthase activity temporarily increased (P < 0.01) following PGF(2alpha). These findings suggest that PGF(2alpha) regulates luteolysis by ESR1 mRNA down-regulation and modulation of pro- and anti-apoptotic pathways in CL that have acquired a luteolytic capacity.