Luteal inadequacy during the early luteal phase of subfertile cows

Abstract

A study was made of early luteal function (up to Day 6) in cyclic and pregnant heifers and also in older, subfertile cows. There were no differences in vivo or in vitro between cyclic and pregnant heifers, indicating no luteotrophic effect of the embryo at this stage, but the increase in postovulatory peripheral progesterone concentrations was delayed (P less than 0.01) and occurred more slowly (P less than 0.001) in the subfertile cows than in the heifers. The corpora lutea of the subfertile cows were heavier (P less than 0.001) than those of the heifers on Day 6. Basal progesterone production by dispersed luteal cells was similar between heifers and subfertile cows, but there was a difference (P less than 0.001) in the pattern of response to exogenous LH and PGE-2. Cells from subfertile cows were less sensitive to the stimulatory effects of PGE-2 and although LH increased (P less than 0.001) progesterone production by all cells, this stimulation by a low dose of LH was inhibited by PGE-2 in luteal cells from subfertile cows. This effect did not occur in the luteal cells from heifers. These results indicate the possibility that luteal inadequacy, due to a diminished response to circulating luteotrophic hormones, may contribute to embryo mortality in subfertile cows.

Prostaglandin E-2 as a potential luteotrophic agent during early pregnancy in cattle

“…A stimulation of progesterone secretion by bovine luteal cells or slices in response to PGE-2 has previously been reported (Speroff & Ramwell, 1970;Hansel et ai, 1973;Shelton et al, 1990) and increases in peripheral progesterone concentrations have been reported following the administration of PGE-2 into the ovarian vascular pedicle of ewes (Weems et al, 1985) or when administered, in combination with oestradiol, by the intrauterine route to heifers (Reynolds et al, 1983). In addition, extension of the luteal phase has been induced by intrauterine infusion of PGE-2 to heifers (Chenault, 1983;Giménez & Henricks, 1983), although Dalla Porta & Humblot (1983) found such administration to be ineffective.…”

“…Mature Hereford Friesian heifers, used between May and September, were either artificially inseminated with frozen semen (pregnant, = 15) or sham-inseminated using killed semen from the same source (cyclic, = 10), as previously described (Shelton et al, 1990 (v/v), pH 5-6-5-8) and allowed to stand overnight at room temperature for the oximation reaction to proceed to completion, before radioimmunoassay using a specific antiserum raised against the methyl oxime of PGE-2 (Kelly et al, 1986).…”

“…Each corpus luteum was dissected free of connective tissue, weighed and the luteal cells isolated, as described previously (Shelton et al, 1990). Briefly, luteal tissue was minced finely and dispersed using 0-2% collagenase (Type II; Sigma Chemical Co. Ltd, Poole, Dorset, UK), the cells counted and their viability assessed using the trypan blue exclusion test (Tennant, 1964).…”

Evaluation of treatments with hCG and carprofen at embryo transfer in a demi-embryo and recipient virgin heifer model

“…Early and late embryonic losses are significantly greater in lactating cows than in heifers (Chagas e Silva et al, 2002;Sartori et al, 2002). This is related to the higher prevalence of sub-optimal post-ovulatory plasma progesterone (P 4 ) concentrations (CRRP NE-161, 1996; Chagas e Silva et al, 2002) and to the lesser steroidogenic capacity of luteal cells (Shelton et al, 1990;Pretheeban et al, 2010) of cows, compared with heifers. Embryonic survival is dependent on the timely elongation and secretion of interferon tau by the blastocyst, in order to inhibit the luteolytic signal, features that are regulated by maternal concentrations of P 4 (Garrett et al, 1988;Kerbler et al, 1997; -E-mail: lcosta@fmv.utl.pt Mann and Lamming, 2001).…”

Reconsideration of the proposed luteotropic and luteoprotective actions of ovine placental lactogen in sheep: in vivo and in vitro studies

“…Inadequate corpus luteum (CL) production of progesterone is likely to be a presumptive cause of early embryonic loss and pregnancy failure in sheep and cattle (Ayalon 1978, Ashworth et al 1989, Shelton et al 1990, Thatcher et al 1994. Thus, researchers have specifically proposed progesterone supplementation after breeding to compensate for poor luteal steroidogenic activity in beef cattle (Garrett et al 1988), dairy cows (Robinson et al 1989), ewe lambs (Davies & Beck 1992) and mature ewes (Kleemann et al 1994, Nephew et al 1994).…”