146 DETRIMENTAL EFFECTS OF PROSTAGLANDIN F2α ON IN VITRO EMBRYO DEVELOPMENT IN BOVINE ARE INHIBITED BY A RECEPTOR ANTAGONIST

Numerous studies have demonstrated negative effects of prostaglandin F2α (PGF2α) on bovine reproduction. Discovery of a PGF2α receptor (FPr) in bovine embryos (Scenna et al. 2006 Reprod. Fertil. Dev. 18, 180) allows for development of new therapeutic strategies to improve success of embryo transfer. Therefore, two experiments were performed to investigate the occurrence of any toxic effect of AL-8810 (Cayman Chemical Inc., Ann Arbor, MI, USA), an FPr antagonist, on in vitro development of bovine embryos. In Exp. 1, pre-compacted embryos were cultured in (1) 100 AL (100 nm AL-8810 in potassium simplex optimized medium with polyvinyl alcohol (KSOM-PVA); n = 94); (2) 50 AL (50 nm AL-8810 in KSOM-PVA; n = 94); (3) 25 AL (25 nm AL-8810 in KSOM-PVA; n = 94); and (4) CON (control: KSOM-PVA; n = 95). In Exp. 2, pre-compacted embryos were cultured in (1) 1000 AL (1000 nm AL-8810 in KSOM-PVA; n = 282); (2) 500 AL (500 nm AL-8810 in KSOM-PVA; n = 274); (3) 250 AL (250 nm AL-8810 in KSOM-PVA; n = 274); and (4) CON (control: KSOM-PVA; n = 278). Embryos remained in treatments until blastocyst assessment. Next, two experiments were performed to determine the efficiency of AL-8810 on preventing detrimental effects of PGF2α on pre-compacted embryos. In Exp. 3, pre-compacted embryos were cultured in (1) 100 AL (100 nm AL-8810 in KSOM-PVA; n = 121); (2) 10 PGF (10 ng mL–1 of PGF2α (Cayman Chemical Inc.) in KSOM-PVA; n = 91); (3) AL100+PGF (100 nm AL-8810 and 10 ng mL–1 of PGF2� in KSOM-PVA; n = 116); (4) CON (control: KSOM-PVA; n = 96). In Exp. 4, embryos were cultured in (1) 1000 AL (1000 nm AL-8810 in KSOM-PVA; n = 87); (2) 10 PGF (10 ng mL–1 of PGF2α in KSOM-PVA; n = 87); (3) AL1000+PGF (1000 nm AL-8810 and 10 ng mL–1 of PGF2α in KSOM-PVA; n = 84); (4) CON (control: KSOM-PVA; n = 84). In Exp. 3 and 4, embryos remained in treatments for 48 h when development to morula was assessed. Data for all experiments were analyzed using the GLIMMIX procedure of SAS (SAS Institute, Inc., Cary, NC, USA). For Exp. 1, results indicated that addition of 100, 50, and 25 nm did not compromise embryonic development to the blastocyst stage compared to controls (60.2%, 55.8%, 55.4%, and 49.9%, respectively). In addition, orthogonal contrasts indicated that 100 nm AL-8810 improved development to the blastocyst stage (100 AL = 61% v. CON = 50.6%, P = 0.01). Similarly for Exp. 2, 1000, 500, and 250 nm AL-8810 did not affect in vitro development to the blastocyst stage compared to controls (40%, 39%, 34.8%, and 37.7%, respectively). In Exp. 3 and 4, addition of 1000 nm AL-8810, but not 100 nm, to culture medium of pre-compacted embryos exposed to PGF2α increased the ability of embryos to undergo compaction 48 h later (1000 AL+PGF = 51% v. PGF = 40%; P = 0.05). In conclusion, AL-8810 at a concentration of 1000 nm inhibits detrimental effects of PGF2α on the development of pre-compacted bovine embryos and may prove beneficial for other assisted reproductive techniques in cattle. Funding was provided by Ultimate Genetics and the Tennessee Agricultural Experiment Station for completion of these studies.