Levels of prostaglandin F (PGF) in bovine endometrium uterine venous, ovarian arterial and jugular plasma during the estrous cycle (38789).

Prostaglandins F (PGF) were measured in uterine vein, ovarian artery, and jugular vein plasma and in the endometrial tissues at various times during the bovine estrous cycle, and were compared to peripheral plasma progesterone levels. Four groups of heifers at days 1-5, 10-14, 15-17 and 20-0 of the estrous cycle were studied. Low levels of PGF (48 plus or minus 12 ng/g dry tissue were measured in the endometrium on days 1-14 of the cycle. Higher values (131 plus or minus 9.0) were found at days 15 until the day of estrus (p less than 0.001). Similarly, very low levels of PGF were observed in the uterine vein plasma at days 1-14 (0.162) plus or minus 0.044) ng/mlM plus or minus S.E.), whereas on days 15 until the day of estrus the levels ranged from 1.5 to 3.0 ng/ml. The increases in uterine vein PGF on day 15 occurred even while peripheral plasma progesterone levels were still high. However, PGF was not elevated in either the ovarian artery or the jugular vein at any time during the cycle, even when uterine vein levels were greatly elevated. No differences in PGF content were detected in endometrial tissue from uterine horns adjacent or opposite to the functional corpus luteum.     

小熊猫繁殖周期血清雌二醇和孕酮含量变化

为研究小熊猫繁殖周期血清雌二醇、孕酮含量变化规律,采用化学发光免疫分析法连续16 次测定了2只成体雌性小熊猫血清雌二醇和孕酮含量变化,历经发情间期、发情期和两次妊娠期;连续9次测定了7只小熊猫妊娠期的孕酮含量变化。结果:(1)发情间期,小熊猫血清雌二醇的水平一直维持在低水平(基础水平),进入发情前期,血清雌二醇水平明显升高,在发情期一直维持高水平,配种后迅速降至基础水平; (2)小熊猫血清孕酮含量在发情间期和发情期均维持在较低水平,直至发情期过后才出现升高,在妊娠期一直维持高水平,峰值出现在5 月;(3)发情的小熊猫不论妊娠与否,在妊娠期内血清孕酮含量均维持在高水平。研究表明:小熊猫血清雌二醇、孕酮含量变化能直接反映其繁殖规律,雌二醇对启动雌性小熊猫季节性繁殖起重要作用;在妊娠期内小熊猫血清孕酮含量升高不能作为判断小熊猫妊娠的标准;雌性小熊猫在妊娠期有假孕现象。     

Changes in uterine secretion of prostaglandin F2 alpha and luteal secretion of progesterone in response to oxytocin during the porcine estrous cycle.

The purpose of this experiment was to determine whether the ability of oxytocin to stimulate uterine secretion of prostaglandin F2 alpha (PGF2 alpha) and luteal secretion of progesterone changes during the porcine estrous cycle. Nineteen multiparous sows were observed for estrus. After one estrous cycle of normal length, sows were assigned randomly to receive an injection of oxytocin (30 IU, i.v.) in the EARLY (Days 4-6; n = 6), MID (Days 9-11; n = 7), or LATE (Day 15; n = 6) stage of the estrous cycle. Concentrations of 13, 14-dihydro-15-keto-PGF2 alpha (PGFM) and progesterone were determined in jugular venous serum samples collected at -60, -45, -30, -15, 0, 2, 5, 10, 15, 30, 45, 60, 90, and 120 min after injection of oxytocin. The magnitudes of the PGFM and progesterone responses and the area under the respective response curves (AUC) were calculated for each sow. Concentrations of PGFM did not change in response to oxytocin administered during the EARLY or MID portions of the estrous cycle. Concentrations increased rapidly in 4 of 6 sows that received oxytocin LATE in the estrous cycle. Both magnitude and AUC were greater LATE in the estrous cycle than at either EARLY or MID cycle (p less than 0.05). Thus, uterine secretory responsiveness to oxytocin develops between Days 11 and 15 postestrus in the sow. For progesterone, a transient increase was observed immediately following injection of oxytocin at MID cycle (p less than 0.05), but not at the other times examined. Therefore, oxytocin appears to be capable of stimulating secretion of progesterone from the functionally mature corpus luteum.     

Prostacyclin, prostaglandin F2 alpha and progesterone production by bovine luteal cells during the estrous cycle

Corpora lutea (CL) were collected from Holstein heifers on Days 5, 10, 15 and 18 (5/day) of the estrous cycle. Dispersed luteal cell preparations were made and 10(6) viable luteal cells were incubated with bovine luteinizing hormone (LH) and different amounts of arachidonic acid in the presence and absence of the prostaglandin (PG) synthetase inhibitor indomethacin. The concentrations of progesterone, PGF2 alpha and 6-keto-PGF1 alpha, the stable inactive metabolite of prostacyclin (PGI2), were measured. Day 5 CL had the greatest initial content of 6-keto-PGF1 alpha (1.01 +/- 0.16 ng/10(6) cells), and synthesized more 6-keto-PGF1 alpha (2.55 +/- 0.43) than CL collected on Days 10 (0.57 +/- 0.11), 15 (0.08 +/- 0.05) and 18 (0.19 +/- 0.03) during a 2-h incubation period. Arachidonic acid stimulated the production of 6-keto-PGF1 alpha by Days 10, 15 and 18 luteal tissue. PGF2 alpha was produced at a greater rate on Day 5 (0.69 +/- 0.17 ng/10(6) cells) than on Days 10 (0.06 +/- 0.01), 15 (0.04 +/- 0.02) and 18 (0.08 +/- 0.01). Arachidonic acid stimulated and indomethacin inhibited the production of PGF2 alpha, in most cases. The initial content of 6-keto-PGF1 alpha was higher than that of PGF2 alpha on all days of the cycle and more 6-keto-PGF1 alpha was synthesized in response to arachidonic acid addition. The ratio of 6-keto-PGF1 alpha content to PGF2 alpha content was 4.39, 2.30, 1.25 and 1.13 on Days 5, 10, 15 and 18, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Levels of lutenizing hormone, estradiol and progesterone in serum during the estrous cycle and pregnancy in the beagle bitch (38491).

Levels of luteinizing hormone (LH), estradiol-17 beta and progesterone were determined by specific radioimmunoassays in sera obtained from Beagle bitches during proestrus, estrus and diestrus. Concentrations of LH (expressed as NIH-LH-SI equivalents) were 2.8 plus or minus 0.1 ng/ml in proestrus, 35.5 plus or minus 10.0 ng/ml during early estrus and 2.2 plus or minus 0.1 ng/ml in early diestrus. Peak levels of estradiol-17beta (68.9 plus or minus 11.0 ng/ml) were detected 24 hr prior to the LH peak, declined rapidly and reached basal levels (17.8 plus or minus 6.3 ng/ml) by five days following the LH peak. Levels of progesterone were 1.7 plus or minus 0.3 ng/ml during proestrus, 3.5 plus or minus 0.3 ng/ml during early estrus and 23.3 plus or minus 2.8 ng/ml on day 5 after the LH peak . Progesterone levels remained elevated through day 28 of diestrus and pregnancy. A significant decrease (p smaller than 0.05) in levels of prosgesterone occurred between day 28 of pregnancy and one day prior to shelping (3.3 plus or minus 1.2 ng/ml, with a further decrease on the day of whelping (1.1 plus or minus 0.2 ng/ml). Levels of estradiol-17beta and LH did not change significantly (p smaller than 0.0k) during diestrus or pregnancy.     

Blood levels of progesterone and 15-Keto-13, 14-dihydro prostaglandin F(2alpha) during the estrous cycle of oxytocin-treated cows

Six non-lactating Holstein cows were injected with 230 iu oxytocin subcutaneously twice daily from days 2 through 6 of the cycle. Controls (n=6) were given saline injections using the same schedule. Blood samples were collected at frequent intervals before and after each saline or oxytocin injection. Progesterone and 15-Keto-13, 14-dihydro prostaglandin F(2alpha) (PGFM), the major metabolite of prostaglandin F(2alpha), were analysed by radio-immunoassay. Oxytocin injections significantly increased plasma prostaglandin concentrations on days 2 and 3 when compared with the controls. In two oxytocin-treated cows, the cycle was shortened to 10 and 12 days. Estrus was preceded by a PGF(2alpha) release very similar to that preceding spontaneous estrus. Two of the oxytocin-treated cows showed estrus on day 21 and 22 preceded by luteolytic release of PGF(2alpha). Two oxytocin-treated cows developed cystic corpora lutea and had not shown heat when the ovaries were removed four weeks later. All oxytocin-treated cows showed a slower progesterone increase through day 8 than the controls. The study shows that endocrine events preceding cycle alterations in oxytocin-treated cows involve release of PGF(2alpha) and lowered levels of progesterone.     

Influence of luteinizing hormone and prostaglandin F(2alpha) on progesterone secretion in superfused minced bovine luteal tissue in the early stage of the estrous cycle

Minced luteal tissue of bovine corpora lutea from Day 4, 5, and 6 of the estrous cycle (n = 4 corpora lutea each) was superfused for 9 h, and the progesterone secretion under the influence of 100 ng luteinizing hormone (LH)/ml and/or 1,000 ng prostaglandin F(2alpha) (PGF(2alpha))/ml was determined. In vivo, this period of the estrous cycle is characterized by a transition from PGF(2alpha) refractoriness to PGF(2alpha) sensitivity. The investigations were carried out in order to examine whether this transition is reflected by a change in the hormone secretion pattern in vitro. The basal secretion was higher on Day 6 than on Day 4 and 5 (P < 0.01). PGF(2alpha) slightly increased the progesterone secretion, but there was no statistically significant difference (P > 0.05). LH, however, stimulated the progesterone secretion by about 30% in luteal tissue collected from Day 4 and 5 (P < 0.01). In luteal tissue collected from Day 6, the LH-induced increase in hormone secretion was not statistically significant due to two corpora lutea that showed no response at all to LH. The progesterone secretion of the two other corpora lutea, however, was increased by 30% (P < 0.01). When PGF(2alpha) and LH were simultaneously added, the LH-induced progesterone secretion was not inhibited; PGF(2alpha) even seemed to intensify the action of LH. The difference between the hormone secretion under the influence of LH alone and that under the influence of a combination of LH and PGF(2alpha), however, was not statistically significant. It is concluded that in cattle the end of the refractoriness to PGF(2alpha) in vivo is not reflected by a corresponding change of the hormone secretion pattern in vitro.     

In vitro effects of progesterone and estradiol on uterine prostaglandin production in the pregnant rat.

Uterine prostaglandin (PG) levels increase markedly at the end of pregnancy in the rat and steroid hormones appear to be important regulators of this augmentation. The purpose of the present study was to examine the in vitro effects of progesterone (P) and estradiol (E2) on uterine PGE and PGF production in the pregnant rat. Uterine tissue was removed at Days 19 and 21 of pregnancy and incubated with P or E2 (0.1, 1, 10, 100, and 1,000 ng/ml) for 48 h in Ham's F-10 medium at 37 degrees C. P significantly (p less than 0.05) inhibited PGE and PGF production in a dose-dependent manner at Day 19, but not at Day 21 of pregnancy. In contrast, E2 had no effect (p greater than 0.05) at either day of pregnancy. In a second study, P was found to inhibit uterine PGE production at Days 15 and 19, but not at Day 21 or at delivery. A third study determined that the levels of P were greatly reduced in media containing uterine tissue from delivery when compared to media containing tissue from day 15 of pregnancy (p less than 0.05). In a fourth experiment, no difference in tritium-labeled P uptake was detected between media containing uterine tissue from Day 15 of pregnancy and media containing uterine tissue removed at delivery. This observation in association with data from the literature suggests that the disappearance of P from the media in experiment 3 might be due to enhanced P metabolism rather than to differential uptake of P by the tissue.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biosynthesis and catabolism of prostaglandin F2alpha (PGF2alpha) are controlled by progesterone in the rat uterus during pregnancy

Myometrial quiescence is a key factor in all species to accomplish a successful gestation. PGs play a crucial role in mediating parturition events, and their synthesis and metabolism are regulated by cyclooxygenases (COXs) and NAD(+)-dependent 15-hydroxy-PG dehydrogenase (PGDH), respectively. Progesterone (P(4)) is the hormone responsible for maintaining uterine smooth muscle quiescence during pregnancy. In this work, we have studied the effect of P(4) on the activity of COXs and PGDH, the uterine enzymes involved in the biosynthesis and metabolism of prostanoids in the rat. We found that during pregnancy PGF(2alpha) production and also protein levels of COX-1 and COX-2 were decreased. The exogenous administration of P(4) significantly inhibited the uterine production of PGF(2alpha) and also the protein level of COX-2. PGF(2alpha), metabolism was assessed by PGDH activity, which resulted high during pregnancy and increased as a result of P(4) administration. These results indicate that PGs levels were negatively modulated by P(4), which could be exerting its effect by increasing PGs metabolism through stimulation on PGDH activity and an inhibition on COX and that is a major mechanism for maintain uterine quiescence in pregnancy.     

On the control of prostaglandin release during the bovine estrous cycle. Effects of progesterone implants

Progesterone implants were inserted subcutaneously on day 12 of the estrous cycle in three heifers. The implants were known to release an amount of progesterone sufficient to maintain the peripheral blood plasma at a level of about 1 ng/lm. All three heifers showed luteolysis in a similar way with peaks of 15-keto-13, 14-dihydro-PGF2 alpha of normal magnitude and duration. Concomitantly, progesterone levels declined, but due to the presence of the implants, progesterone was maintained at a level of about 1 ng/ml. The release of prostaglandins, however, continued throughout the experimental period and did not cease until the implants were removed.     

Effects of estradiol and progesterone on uterine prostaglandin levels in the pregnant rat

Prostaglandin D₂ was found to be a potent inhibitor of B-16 melanoma cell replication $\text{in vitro}$. The inhibition was dose-dependent between 3×10^?9M and 3×10^?6M (IC_50～ 0.3 μM after 6 days). On a molar basis, PGD₂ was a better inhibitor than PGA₂ or 16,16-dimethyl-PGE₂-methyl ester (di-M-PGE₂) and in higher concentrations (10^?6?10^?7M), comparable to retinoic acid. In higher concentrations, PGD₂ inhibited DNA, RNA and protein synthesis. The B-16 melanoma cell line which we used synthesized arachidonic acid metabolites which comigrated with PGA₂, PGD₂, PGE₂ and PGF_2α on a thin layer chromatography system.     

Changes in tissue histamine during the estrous cycle, pregnancy and pseudopregnancy in the golden hamster

The histamine content of reproductive tissues and skeletal muscle was determined in the golden hamster during the estrous cycle, pregnancy, and pseudopregnancy. Histidine decarboxylase activity was measured in uterine implantation sites and intersites from Day 4 to Day 10 of pregnancy. Histidine decarboxylase was also measured in mesometria and placentas on selected days of gestation. During the estrous cycle, uterine and skeletal muscle histamine levels were highest on Day 2 and lowest on Day 4 of the cycle. The ovarian histamine content did not change significantly among the different stages of the cycle. While the histamine content of uterine implantation sites of attachment was high on Days 4 and measurable on Days 5 and 6 of pregnancy, the levels were below the limits of detection by Day 7. On the other hand, the highest levels of histamine were in the uterine interimplantation sites on Days 8 and 9. The ovarian levels of histamine were highest on Day 13 of pregnancy. Histamine in skeletal muscle did not change significantly during pregnancy. The histidine decarboxylase activity in the implantation sites began rising on Day 9 and increased dramatically on Day 10. Placental histidine decarboxylase activity was very high on Days 13 and 15. Overall, we observed changes in uterine and skeletal muscle histamine during the estrous cycle that may be explainable in light of previously reported changes in mast cell numbers and circulating estrogens. During pregnancy, histamine levels of implantation sites and implantation intersites varied, as did the histamine content of ovarian tissue. Histidine decarboxylase activity rises in the uterus and placental tissue after the formation of the placenta.     

Peripheral plasma levels of progesterone in goats treated with fluorogestone acetate and prostaglandin F2α during the estrous cycle

Intravaginal pessaries impregnated with 20 mg fluorogestone acetate (FGA) were inserted into fifteen does at various intervals after the end of estrus. After resumption of cyclical activity following withdrawal of the intravaginal pessaries, the does were divided into six groups and treated with prostaglandin F2_α. Each doe received 15 mg Prostaglandin F2_α administered intramusuclarly 2, 4, 6, 12, 14 or 16 days after the end of estrus. The animals were bred naturally on the first estrus following prostaglandin treatment. Jugular blood samples were collected from each doe throughout the experimental period. The plasma samples were assayed for progesterone. Intravaginal fluorogestone acetate treatment in does had no effect on the function of the corpus luteum, however, overt estrus was postponed during treatment and for a few days after removal of the pessaries. Prostaglandin injection into does, 4, 6, 12, 14 or 16 days after the end of estrus induced luteolysis and subsequent ovulatory estrus within 2 to 3 days. Fertility at PGF2_α induced estrus in these does was 77%. Prostaglandin treatment two days after the end of estrus had no effect on the corpus luteum function. It is concluded that prostaglandin is luteolytic when administered into does anytime beyond four days after the end of estrus.     

synthesis of progesterone and prostaglandin F by luteal tissue and prostaglandin F by endometrial tissue from the pig

The relationship between progesterone (P₄) synthesis by luteal tissue and prostaglandin F (PGF) synthesis by endometrium and luteal tissue from two stages of the cycle, Days 7 to 8 and 15 to 16, was determined. Luteal and endometrial tissues were collected from pigs in three experimental groups at two stages of the cycle: (A) 6 pigs on Days 7 to 8 with spontaneous, 5 to 6 day old corpora lutea (CL); (B) 5 pigs on Days 15 to 16 with spontaneous, 13 to 14 day old CL; and (C) 6 pigs on Days 15 to 16 with spontaneous, 13 to 14 day old CL and 5 to 6 day old CL induced by pregnant mares serum gonadotropin (PMSG) and human chorionic gonadotropin (HCG) injections. Pigs with spontaneous, 13 to 14 day old CL of the cycle and PMSG-HCG induced accessory, 5 to 6 day old CL were used so that P₄ and PGF synthesis in tissue from old and new CL could be compared in the same pig on Day 15 to 16 of the cycle. Tissues (100 mg minces) were incubated in 5 ml of Krebs Ringer solution in an atmosphere of 95% 0₂:5% CO₂ for 2 hours at 0° C, 37° C, or 37° C with 1.3 x 10⁻⁴M indomethacin (IND). An aliquot of the incubation medium and an aliquot of the supernatant after homogenization of the tissue in the remaining medium of each flask was quantified for P₄ and PGF by radioimmunoassay. P₄ and PGF release into the medium and total accumulation of P₄ and PGF in the flasks indicated that synthesis had occured at 37° C. Compared to tissue from 13 to 14 day old CL, tissue from 5 to 6 day old CL synthesized more P₄ per flask (53.9 25.0 ng/mg tissue, P<.001) and released more P₄ into the medium (20.8 8.8 ng/mg, P<.001). P₄ synthesis by luteal tissue from 5 to 6 day old and 13 to 14 day old CL from pigs in group C was similar to P₄ synthesis by luteal tissue from pigs in group A and group B, respectively. Luteul PGF synthesis was not affected significantly by either the age of the CL or by PMSG-HCG treatment. For endometrial samples, the synthesis of PGF was not significantly different among pigs in groups A, B and C. If uterine PGF is involved in luteal regression in the pig, the sensitivity of the CL to PGF may be more important than an increase in PGF secretion during the late luteal phase of the estrous cycle.