Effect of active immunization of pre-partum and post-partum cows against prostaglandin F-2  on lifespan and progesterone secretion of short-lived corpora lutea

Abstract

Summary. Mature

Concentrations of progesterone and oxytocin receptors in endometrium of postpartum cows expected to have a short or normal oestrous cycle

“…The following evidence indicates that the short luteal phase in cattle and sheep is due to a premature uterine secretion of prostaglandin F20 (PGF2a): (i) hysterectomy prevents regression of corpora lutea anticipated to have short lifespans in prepuber¬ tal ewe lambs (Keisler et al, 1983), anoestrous ewes (Southee et al, 1988) and postpartum cows (Copelin et al, 1987) oxytocin induces a release of PGF2a in cattle on day 5 of a short but not a normal luteal phase (Zollers et al, 1989); (iii) basal and oxytocin-induced secretion of prostaglandins (in vitro) from bovine endometrium is greater on day 5 of a short compared with a normal luteal phase (Zollers et al, 1991); (iv) mean con¬ centrations of PGF2a in the vena cava on days 4-9 following first postpartum oestrus are higher in cows exhibiting a short compared with a normal oestrous cycle (Cooper et al, 1991); ( ) mean concentration of 15-keto-13,14-dihydroprostaglandin F2a (PGFM; the stable metabolite of PGF2a) in plasma increases from day 3 to day 5 in ewes expected to have short oestrous cycles (Hunter et al, 1989); and (vi) active immunization of beef cows early post partum against PGF2a extends the lifespan of corpora lutea that are expected to be short-lived (Copelin et al, 1989 (Copelin et al, 1989 (Fig. 2a and b (Fig.…”

Luteal function after intrauterine infusion of recombinant bovine interferon- I1 into postpartum beef cows expected to have short or normal luteal phases

“…Reduced luteal lifespan is associated with a premature luteolytic influence of the uterus (presumably PGF2a). Corpora lutea, for example, were maintained in cows (Copelin et al, 1987) and ewes (Southee et al, 1988) hysterectomized prior to first spontaneous oestrus and ovulation and in postpartum cows immunized against PGF2a (Copelin et al, 1989). Secretion of progesterone was similar to that observed in cows during a normal oestrous cycle (Copelin et al, 1987(Copelin et al, , 1989.…”

“…Corpora lutea, for example, were maintained in cows (Copelin et al, 1987) and ewes (Southee et al, 1988) hysterectomized prior to first spontaneous oestrus and ovulation and in postpartum cows immunized against PGF2a (Copelin et al, 1989). Secretion of progesterone was similar to that observed in cows during a normal oestrous cycle (Copelin et al, 1987(Copelin et al, , 1989. In other studies, pulse amplitude and basal concentrations of plasma PGF2a were increased on days 4-9 for postpartum cows having a short rather than a normal length oestrous cycle (Cooper et al, 1991), and secretion of PGF2a in vitro from endometrial tissue from cows anticipated to have short (Zollers et al, 1991b).…”

Efeito do tratamento com progesterona e do diâmetro folicular nas características histológicas e moleculares uterinas em vacas Nelore em anestro pós-parto

“…Além disso, a sensibilidade à PGF2α não diferiu entre CL com expectativa de luteólise prematura ou de duração normal (COPELIN et al, 1989 (GARVERICK et al, 1988;BRADEN et al, 1989a,b). Lamming & Mann (1995a,b) Zollers et al (1993), no qual a pré-exposição à P4 é o fator mais importante na prevenção da luteólise prematura; Painel C: Modelo hipotético proposto por Mann & Lamming (2000), no qual a concentração circulante de E2 no período pré-ovulatório é o fator mais importante na prevenção da luteólise prematura.…”