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C. J. Ashworth, I. Wilmut, A. J. Springbett and R. Webb


The effect of an inhibitor of 3β-hydroxysteroid dehydrogenase on peripheral progesterone concentration during the luteal phase of the oestrous cycle and on embryo survival was determined in sheep. Following administration of 10, 50, 100 or 250 mg epostane (4,5-epoxy-17-hydroxy-4,17,dimethyl-3-oxo-androstane-2-carbonitrile) progesterone concentrations were significantly lower than control levels 4 h after injection, from 2·5 to 22 h, 1·5 to 24 h and 1 to 24 h after injection respectively. There appeared to be no effect on peripheral oestradiol concentrations. Adrenal progesterone production was small and not influenced by epostane treatment.

Epostane was administered on day 9 of the oestrous cycle to cause a reduction in progesterone concentrations for approximately 12-18 h on day 9 only (group 1, 250 mg epostane on day 9), or a series of such reductions on 3 consecutive days (group 2, 50 mg epostane on days 9, 10 and 11) or a continuous reduction for 3 days (group 3, 250 mg epostane on days 9, 10 and 11). The proportion of ewes that were pregnant was significantly (P<0·05) lower in ewes treated to give a continuously low progesterone concentration for 3 days than in either controls or ewes in which progesterone concentration was reduced for less than 24 h (in controls and groups 1, 2 and 3 the proportion was 85, 92, 54 and 18% of ewes treated respectively). Embryo survival was not affected by administration of 250 mg epostane on days 9, 10 and 11 if luteal phase levels of progesterone were maintained by insertion of a silicone elastomer implant of the steroid. The proportion of embryos surviving was 72% in controls compared with 78% in the treated animals.

J. Endocr. (1987) 112, 205–213

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C. J. Ashworth, M. F. V. Fliss and F. W. Bazer


The formation of new capillaries, both in extraembryonic membranes and in the maternal endometrium, is an essential prerequisite for appropriate feto-maternal relationships throughout pregnancy. At present there is no indication of the nature of the uterine angiogenic stimulus. In-vitro, degradation products of hyaluronic acid, following its catalysis by hyaluronidase, have been shown to have angiogenic properties. In the current study, levels of hyaluronic acid in endometrial tissues and of hyaluronidase and hyaluronic acid in uterine flushings were measured during the oestrous cycle and early pregnancy.

The concentration of both hyaluronic acid and hyaluronidase in uterine flushings followed the growth and regression of the corpus luteum, in that basal levels detected on days 0 and 6 increased to peak concentrations on days 12 and 15. By day 18, levels of both hyaluronidase and hyaluronic acid had decreased in cyclic gilts, but remained increased in pregnant pigs. Tissue concentrations of hyaluronic acid were not affected by pregnancy or by the day of the oestrous cycle. In a subsequent experiment, four groups of gilts were ovariectomized on day 4 and thereafter received daily injections of corn oil, progesterone, oestrogen or a combination of oestrogen and progesterone. Hyaluronidase was undetectable in uterine flushings collected on day 15 from corn oil-and oestrogen-treated gilts, but present in similar amounts in uterine flushings from gilts treated with progesterone and progesterone plus oestrogen. Similarly, uterine fluid concentrations of hyaluronic acid were increased in progesterone- and progesterone plus oestrogen-treated gilts, but not in corn oil-or oestrogen-treated pigs. Tissue concentrations of hyaluronic acid were unaffected by steroid treatment.

These results indicate that progesterone stimulates secretion of hyaluronidase and hyaluronic acid; both substances believed to be associated with the presence of an angiogenic factor in the pig uterus, but there was no evidence of a synergistic interaction between progesterone and oestrogen.

Journal of Endocrinology (1990) 125, 15–19

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J. L. Vallet, F. W. Bazer, C.J. Ashworth, H. M. Johnson and C. H. Pontzer


A radioimmunoassay has been developed for quantitation of ovine trophoblast protein-1 (oTP-1), a sheep conceptus secretory protein which allows for maintenance of the corpus luteum during early pregnancy. The assay was validated for dialysed and undialysed culture medium and pregnant uterine flushings ranging from no dilution (neat) to dilutions of 1:2500 for dialysed media, 1:100-1:1000 for undialysed media and 1:50-1:1000 for pregnant uterine flushings. The assay accurately measured oTP-1 added to undiluted and diluted dialysed and undialysed culture media and pregnant uterine flushings. No cross-reaction was detectable for bovine α or γ interferon, bovine calmodulin, feline conceptus secretory proteins, equine conceptus secretory proteins, porcine conceptus secretory proteins, bovine conceptus secretory proteins and proteins in a uterine flushing collected from a non-pregnant ewe. Immunoreactivity in the assay matched that for oTP-1 throughout oTP-1 purification. This assay is the first validated assay which may be used to quantitate production of oTP-1 in culture or content of oTP-1 in uterine flushings.