Alteration of oestrous cycle length, ovarian function and oxytocin-induced release of prostaglandin F-2α by intrauterine and intramuscular administration of recombinant bovine interferon-α to cows

摘要

Summary. An experiment was conducted to (i) determine whether administration of recombinant bovine interferon-αI 1 (rBoIFN-α) attenuates oxytocin-induced release of prostaglandin F-2α and (ii) confirm previous observations that rBoIFN-α causes acute changes in body temperature and circulating concentrations of progesterone. Cows were treated twice a day from Day 14 to Day 17 after oestrus with a control regimen (bovine serum albumin (BSA), i.m. + BSA intrauterine (i.u.)), rBoIFN-α, i.u. + BSA, i.m. (rBoIFN-IU) or rBoIFN-α, i.m. + BSA, i.u. (rBoIFN-IM). On Day 17, plasma concentrations of 13,14-dihydro,15-keto-prostaglandin F-2α (PGFM) were measured after injection of oxytocin. Cows treated with rBoIFN-IU and rBoIFN-IM had longer oestrous cycles and luteal lifespans than control cows. A hyperthermic response and decline in plasma concentrations of progesterone was noticed after administration of rBoIFN-α on Day 14. On other days, the hyperthermic response was not present and the decline in progesterone was less pronounced. There was no significant effect of rBoIFN-α on circulating concentrations of oestradiol between Days 14 and 17. The release of PGFM induced by oxytocin was lower in cows treated with rBoIFN-α than in control cows. Oxytocin caused increased plasma concentrations of PGFM in four of five control cows, two of five rBoIFN-IU cows and two of five rBoIFN-IM cows. The peak PGF-2α response to oxytocin (peak value after injection minus mean concentration before injection) was 257·8 ± 60·3 pg/ml for control cows, 100·7 ± 40·8 pg/ml for rBoIFN-IU and 124·9 ± 40·4 pg/ml for rBoIFN-IM. It is concluded that rBoIFN-α can reduce oxytocin-induced PGFM release and may therefore extend the lifespan of the corpus luteum by interfering with events leading to luteolytic release of PGF from the uterus. Administration of rBoIFN-α can cause acute changes in body temperature and circulating concentrations of progesterone that become less severe after repeated exposure to rBoIFN-α.