Suppression of plasminogen activator production in sheep embryos in vitro after treatment with cycloheximide or ouabain

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A. R. Menino Jr
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J. S. Williams
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Effects of the metabolic inhibitors cycloheximide and ouabain on development in vitro and plasminogen activator production by sheep embryos were investigated. Embryos (n = 152) from the eight-cell to the morula stage were surgically collected from naturally mated, oestrus-synchronized and superovulated Polypay ewes. In Expt 1, embryos (n = 104) were grouped by cell stage, cultured in Whitten's medium with 1.5% BSA containing 0, 0.1 or 1.0 μg cycloheximide ml−1 for 24 h, washed and cultured in this medium for 168 h. In Expt 2, morulae (n = 48) were cultured for 48 h in Whitten's medium with 1.5% BSA transferred to the same medium containing 0 or 1.0 mmol ouabain l−1 and cultured for 24 h, and then washed and cultured in this medium for 120 h. At 24 h intervals in both experiments, the medium was recovered and analysed for plasminogen activator. In Expt 1, eight-cell embryos underwent limited development; little difference in the production of plasminogen activator due to cycloheximide treatment was therefore observed. Compared with medium without cycloheximide, treatment with 1.0 μg cycloheximide ml−1 reduced the number of 16-cell embryos (P < 0.05) and morulae (P < 0.05) (60% versus 10% and 77% versus 8%, respectively) that began to hatch. The mean production of plasminogen activator was greatest in embryos cultured initially as morulae compared with that of 16-cell and eight-cell embryos (P < 0.05). Cycloheximide treatment suppressed the mean production of plasminogen activator in a dose-dependent manner (P < 0.05). In Expt 2, fewer embryos (P < 0.05) developed to the blastocyst and expanded blastocyst stages following ouabain treatment (83% and 4%, respectively) compared with embryos not exposed to ouabain (100% and 100%, respectively). Embryos treated with ouabain produced less plasminogen activator than did untreated embryos (P < 0.05). These results suggest that developmental changes caused by treating sheep embryos with cycloheximide or ouabain are reflected by changes in the production of plasminogen activator.

 

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