Effect of ovine conceptus secretory proteins and purified ovine trophoblast protein-1 on interoestrous interval and plasma concentrations of prostaglandins F-2α and E and of 13,14-dihydro-15-keto prostaglandin F-2α in cyclic ewes

摘要

Summary. Conceptus secretory proteins (oCSP) were obtained from medium in which sheep conceptuses, collected on Day 16 of pregnancy, were cultured for 30 h. A portion of the culture medium (500 ml) was prepared for intrauterine infusion by concentrating the proteins by Amicon ultrafiltration (Mr 500 cutoff). A second portion (500 ml medium) was used to purify sheep trophoblast protein one (oTP-1). Proteins remaining after oTP-1 purification were concentrated and then passed through an anti-oTP-1 sepharose CL-4B affinity column to remove any remaining oTP-1 (oCSP – oTP-1). Serum proteins (oSP) were collected from a Day-16 pregnant ewe and diluted for infusion. Catheters were placed in the uterus of cyclic (Day 10) ewes. The following combinations of proteins were infused: 0·75 mg oCSP + 0·75 mg oSP (5 ewes), 0·75 mg oCSP – oTP-1 + 0·75 mg oSP (4 ewes), 0·05 mg oTP-1 + 1·45 mg oSP (5 ewes) and 1·5 mg oSP only (5 ewes). Infusions were twice daily on Days 12 and 13 (08:00 and 17:00 h) and once on Day 14 (08:00 h). On Day 14, ewes were injected intravenously at 08:00 h with 0·5 mg oestradiol-17β. Blood sampling began 30 min before oestradiol injection and continued every 30 min for 10 h. On Day 15 ewes received 10 i.u. oxytocin intravenously (08:00 h). Blood samples were collected 10 min before oxytocin and every 10 min for 1 h after oxytocin injection. Concentrations of prostaglandin (PG) F, PGE-2/PGE-1 (PGE) and 13,14-dihydro-15-keto-PGF-2α (PGFM) were measured by specific radioimmunoassay. Ewes treated with oTP-1 and oCSP had longer (P < 0·05) interoestrous intervals (27 and 25 days, respectively) compared to ewes treated with oSP and oCSP – oTP-1 (19 and 19 days, respectively) (s.e.m. = 1·56 days). These results indicate that oTP-1 alone is as potent as total conceptus secretory proteins in extending luteal maintenance. Ewes treated with oTP-1 and oCSP had no increase in PGF after oestradiol injection while production of PGF did increase 6–10 h after oestradiol in ewes treated with oSP and oCSP – oTP-1. PGFM was correlated with PGF concentrations (r = 0·57, P < 0·01) although presence or absence of increases in production of PGFM for the treatment groups were not the same as those for PGF. No effects of treatment on PGE were detected. Ewes treated with oTP-1 had lower (P < 0·05) PGF and PGFM values after oxytocin injection than did ewes in the other 3 treatment groups (P < 0·05). PGFM and PGF values were correlated (r = 0·69, P < 0·01). No differences in PGE values were detected between the 4 treatment groups