Production of interferon by red deer (Cervus elaphus) conceptuses and the effects of roIFN-tau on the timing of luteolysis and the success of asynchronous embryo transfer

Abstract

The role of interferon in early pregnancy in red deer was investigated by (a) measuring production of interferon by the conceptus, (b) testing the anti-luteolytic effect of recombinant interferon-tau in non-pregnant hinds, and (c) treatment of hinds with interferon after asynchronous embryo transfer. Blastocysts were collected from 34 hinds by uterine flushing 14 (n = 2), 16 (n = 2), 18 (n = 8), 20 (n = 13) or 22 (n = 9) days after synchronization of oestrus with progesterone withdrawal. Interferon anti-viral activity was detectable in uterine flushings from day 16 to day 22, and increased with duration of gestation (P < 0.01) and developmental stage (P < 0.01). When interferon-tau was administered daily between day 14 and day 20 to non-pregnant hinds to mimic natural blastocyst production, luteolysis was delayed by a dose of 0.2 mg day(-1) (27.3 +/- 1.3 days after synchronization, n = 4 versus 21 +/- 0 days in control hinds, n = 3; P < 0.05). Interferon-tau was administered to hinds after asynchronous embryo transfer to determine whether it protects the conceptus against early pregnancy loss. Embryos (n = 24) collected on day 6 from naturally mated, superovulated donors (n = 15) were transferred into synchronized recipients on day 10 or day 11. Interferon-tau treatment (0.2 mg daily from day 14 to 20) increased calving rate from 0 to 64% in all recipients (0/11 versus 7/11, P < 0.005), and from 0 to 67% in day 10 recipients (0/8 versus 6/9, P < 0.01). The increased success rate of asynchronous embryo transfer after interferon-tau treatment in cervids may be of benefit where mismatched embryo-maternal signalling leads to failure in the establishment of pregnancy.

Control of interferon-? secretion by in vitro-derived bovine blastocysts during extended culture and outgrowth formation

“…Given the pivotal role of IFN-t in the maintenance of pregnancy and the evidence that factors in the uterus can, in turn, modify IFN-t secretion support the view of the establishment of pregnancy as a coordinated exchange of information between ruminant conceptus and dam. This view is bolstered by studies of asynchronous embryo/uterus transfers, wherein sheep embryos out of synchrony with their host uterus are lost (Wilmut and Sales, 1981;Lawson et al, 1983), but can be rescued by the administration of IFN-t to the dam (Demmers et al, 2000). Moreover, several factors have been identi®ed that can alter the rate of blastocyst development, including transient transfer into advanced uteri (Wilmut and Sales, 1981), administration of progesterone or the length of the estrous cycle (Nephew et al, 1991).…”

Accessory corpora lutea formation in pregnant Hokkaido sika deer (<i>Cervus nippon yesoensis</i>) investigated by examination of ovarian dynamics and steroid hormone concentrations

“…Estradiol reportedly triggers the release of hypophysial oxytocin, and this stimulates release of a small quantity of uterine prostaglandin F 2α , which leads to luteolysis [ 35 ]. The reason why the CL of pregnancy did not regress completely is unclear, but it might be supported by interferon tau, which is known as the factor of maternal recognition of pregnancy and is also found in cervid species [ 36 ], since it is involved in regulation of luteolysis [ 37 ].…”