Hormone receptor control of pulsatile secretion of PGF2α from the ovine uterus during luteolysis and its abrogation in early pregnancy

McCracken, J. David; Schramm, Willfried; Okulicz, William C.

doi:10.1016/0378-4320(84)90027-7

Cited by 256 publications

(155 citation statements)

References 40 publications

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“…This does not appear to be due to a lack of precursors or a decrease in enzyme activity since a second injection of oxytocin is able to elicit a large release of prostaglandin. This does, however, support the opinion that, at least after more than 7 days of progesterone priming, oestradiol stimulates prostaglandin release through a mechanism different from that of oxytocin, possibly by increasing the number of oxytocin receptors and thus increasing the sensitivity of the uterus to oxytocin stimulation, as occurs in the sheep endometrium (McCracken et al, 1984).…”

Section: Resultsmentioning

confidence: 39%

“…In sheep, oestradiol is essential for inducing the response to oxytocin (McCracken et al, 1984). However, progesterone priming for at least 10 days is required before oestradiol is able to exert its effect.…”

Section: Resultsmentioning

confidence: 99%

“…(McCracken et al, 1984). In the cow, as in the sheep, there is a pulsatile release of oxytocin, presumably from the corpus luteum (Walters et al, 1984), which appears to be responsible for the pulsatile release of PGF-2a at the time of luteolysis (Flint & Sheldrick, 1983;Vighio & Liptrap, 1986).…”

Section: Resultsmentioning

confidence: 99%

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Effects of progesterone and oestradiol-17 on oxytocininduced release of prostaglandin F-2 in heifers

Lafrance

Goff²

1988

Reproduction

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Summary. Seven bilaterally ovariectomized heifers were used in 4 experiments and received: (1) saline injections, as control; (2) one injection of oestradiol (3 mg; i.v.); (3) two i.v. injections of oxytocin (100 i.u.) 6 h apart; or (4) one oestradiol injection 30 min after the first oxytocin injection and a second oxytocin injection 6 h later. All experiments were performed without progesterone and then after 7, 14 and 21 days of progesterone treatment. Frequent blood samples were taken for 1 h before and 7 h after the first injection of oxytocin or oestradiol for the measurement of 13,14-dihydro-15-keto-PGF-2\g=a\ (PGFM) by radioimmunoassay. After 7, 14 and 21 days of progesterone priming, oestradiol caused a significant increase (P < 0\m=.\001) in plasma PGFM after 6 h but not before. After 7, 14 and 21 days of progesterone, there was a significant increase (P < 0\m=.\005) in PGFM after the first oxytocin injection and a similar increase following the second. The oxytocin-induced increase in PGFM after 14 and 21 days of progesterone was significantly higher (P < 0\m=.\001) 6h after oestradiol injection than before the oestradiol injection. There was no significant effect of oestradiol on the response to oxytocin in animals that received no progesterone or in those animals that received progesterone for only 7 days. These results show that, under the influence of progesterone, oestradiol enhances the oxytocin-induced release of PGF-2\g=a\, and suggest a possible synergistic action of these hormones for the induction of luteolysis in heifers.

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Section: Resultsmentioning

confidence: 39%

Section: Resultsmentioning

confidence: 99%

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Effects of progesterone and oestradiol-17 on oxytocininduced release of prostaglandin F-2 in heifers

Lafrance

Goff²

1988

Reproduction

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“…Corpus luteum regression depends on PGF2a as the uterine luteolysin, the surge of which increases rapidly following coupling of oxytocin to its receptor in the endometrium (McCracken et al, 1984). This release is correlated to oxytocin receptor concentrations in the endometrium (Flint et al, 1990).…”

Section: Introductionmentioning

confidence: 99%

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

Lassoued¹,

Khaldi²,

Chemineau³

et al. 1997

Reprod. Nutr. Dev.

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Summary -The involvement of the uterus in early regression of corpora lutea induced by the ram effect was studied in seasonally anoestrous Barbarine ewes. In experiment 1, group I was only submitted to the male effect (control, n = 15) while group II (n = 14) was injected every 12 h with flunixin meglumine, a PGF2a synthetase inhibitor (finadyne), from day 3 to day 6 (day 0: day of ram introduction). The preovulatory LH surge appeared at the same time (around 21 h after ram introduction) in both groups. Finadyne treatment significantly decreased 13-14-dihydro-15-keto-PGF2a (PGFM) pulses ( 1.3 ± 0.3 versus 0.4 ± 0.2; P < 0.05), the number of short cycles (50 versus 14%, P < 0.05), and provided a single peak of oestrus, 15-16 days after the introduction of the rams, instead of between day 14 and day 23 (P < 0.01 In experiment 2, 17 hysterectomized ewes were allocated into two groups: group III (n = 8) was injected with oil and group IV (n = 9) received an intramuscular injection of 20 mg of progesterone immediately before introduction of rams. An additional group of intact ewes was used as control (group V, n = 9). Hysterectomy did not affect the ovulation response to the ram effect, but completely suppressed short cycles (0 versus 78% , P < 0.001). The preovulatory LH surge was delayed in hysterectomized females (36.0 ± 14.1 versus 16.6 ± 11.4 h; P < 0.004). Treatment with progesterone significantly (P < 0.01) increased the interval between introduction of rams and the preovulatory LH surge. In conclusion, suppression of short cycles by hysterectomy and an inhibitor of PGF2a synthetase suggest that the uterus is essential for determining the lifespan of ram-induced corpora lutea and that premature release of PGF2a is the cause of early luteal regression. The hypothesis that lower secretion of progesterone before D5 could be the initial cause of the premature induction of the luteolytic signal is discussed.

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“…Levels of oxytocin receptor increase at luteal regression in both myometrium and endometrium (Roberts et al, 1976;, and there is a parallel increase in uterine sensitivity in terms of both contractility (McCracken, Schramm & Okulicz, 1984) and PGF-2a secretion (Roberts et al, 1976).…”

Section: Introductionmentioning

confidence: 99%

Continuous infusion of oxytocin prevents induction of uterine oxytocin receptor and blocks luteal regression in cyclic ewes

Flint¹,

Sheldrick²

1985

Reproduction

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Hormone receptor control of pulsatile secretion of PGF2α from the ovine uterus during luteolysis and its abrogation in early pregnancy

Cited by 256 publications

References 40 publications

Effects of progesterone and oestradiol-17 on oxytocininduced release of prostaglandin F-2 in heifers

Effects of progesterone and oestradiol-17 on oxytocininduced release of prostaglandin F-2 in heifers

Role of the uterus in early regression of corpora lutea induced by the ram effect in seasonally anoestrous Barbarine ewes

Continuous infusion of oxytocin prevents induction of uterine oxytocin receptor and blocks luteal regression in cyclic ewes

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