This biochemical dialogue occurs throughout pregnancy, and the first critical process for pregnancy recognition involves paracrine regulation of the uterine endometrium by the conceptus to abrogate the mechanism responsible for pulsatile release of luteolytic prostaglandin [F.
Uterine secretion of luteolytic pulses of PGF in sheep is dependent upon effects of P4, estradiol-17p (E2) and oxytocin (OXT) on uterine LE, sGE and glandular (GE) epithelia (Bazer et al.
This study was carried out to evaluate the effect of insemination number (timed artificial insemination: TAI, 2 versus 1) on pregnancy rate in beefheifers treated with two injections of a luteolytic agent (PGF, tiaprost), 12 days between each administration, and to evaluate whether if GnRH administration at one TAI produces similar pregnancy rate compared to two TAI.
Key words: heifer, timed artificial insemination, luteolytic agent, pregnancy.
Dependence on prolactin of the luteolytic
effect of prostaglandin F2alpha in rat luteal cell cultures.
Administration of a luteolytic
dose of PGF[alfa] at the time of AI.
Two pharmacological agents are frequently used to synchronize estrus in small ruminants during the breeding season: luteolytic
drugs (Thimonier, 1981) and progesterone or its analog progestagen (Gordon, 1975).
0 ml of luteolytic
hormone, prostaglandin F2[alpha] (PGF2[alpha]) (Ciosin[R], Lab.
Ghrelin affects the release of luteolytic
and luteotropic factors in human luteal cells.
5 ng/ml) at the time of estradiol benzoate injection in case of responding buffaloes due to luteolytic
action of [PGF.
Mann and Lamming (1995) demonstrated that low plasma P4 concentration results in the development of stronger luteolytic signal and provides an explanation for the fact that cows with lower plasma concentrations of P4 are more likely to experience early embryonic loss.
Progesterone inhibition of the development of the luteolytic signal in cows.