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Results for “Luteolytic Effects”

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At least 271 records · Page 15Linked to original sources
PubMed1975

Induction of abortion in cattle with prostaglandin F2alpha and oestradiol valerate.

Twenty, 2 to 5 months pregnant heifers were injected with 25 mg. and 12.5 mg. Prostaglandin F2alpha on two consecutive days or with a single dose of 20 mg. of a long acting oestrogen (oestradiol valerate). Abortion occurred at an average interval of 3,6 days in the 10 PG F2alpha treated animals and after 10,8 days in 8 out of 10 oestradiol valerate treated heifers. The foetuses of the PG F2alpha treated heifers were in a fresh state while the oestradiol foetuses were already degenerating at the time of abortion. A rather severe vaginal discharge after abortion was more often observed in oestradiol valerate induced abortion. Development of the mammary glands and prolonged oestrus periods also was more pronounced in these animals. In both treatments the concentration of progestins in peripheral blood dropped to less than 1 ng/ml at the time of abortion. The decline was very rapid after administration of PG F2alpha and rather slow after oestradiol valerate. Based on its rapid luteolytic effect and rapid elimination after administration which prevents interferring with the endocrine system for a prolonged time, PG F2alpha is preferred as an abortifacient during the first 4 to 5 months of pregnancy in cattle.

Abortion, Induced↗
PubMed1975

Luteolysis with prostaglandin F2alpha or an antiserum against an equine pituitary fraction in hysterectomized mares.

Luteolysis, determined by corpus luteum weight and progesterone concentration in jugular blood, occurred in uterine-intact and in hysterectomized mares after injection of prostaglandin F2alpha or of an antiserum against an equine pituitary fraction. Results indicated that luteolytic effects of exogenous prostaglandin F2alpha and inhibition of the endogenous luteotrophic activity of the hypophysis (pituitary gland) by antiserum did not involve the uterus.

Animals↗
PubMed1992

Influence of cloprostenol in the experimentally induced ulcer in rats.

We have tested the action of cloprostenol a relatively stable analogue of PGF2 alpha in experimentally induced gastric ulcer in rats by contention stress or indomethacin. Our results show that CIPG, administered at higher doses than those inducing an luteolytic effect, has a gastroprotective effect both in the contention stress-induced ulcer (2.30 + 0.26 in series III as compared to 3.80 +/- 0.73 in series III, p < 0.01) and in indomethacin-induced ulcer (2.69 +/- 0.38 in series V as compared to 3.61 +/- 0.34 in series IV, p < 0.01).

Animals↗
PubMed2006

Inhibition of luteolysis and embryo-uterine interactions during the peri-implantation period in pigs.

Inhibition of luteolysis and establishment of pregnancy in pigs results from oestrogen secretion by the conceptuses and requires progesterone produced by the corpus luteum (CL). An integral part of maternal recognition of pregnancy in the pig is the redirection of prostaglandin (PG) F2alpha secretion from endocrine (blood) to exocrine (uterus) direction and an increase of PGE2 synthesis in both the endometrium and conceptus. Uterine and conceptus PGE2 synthases play an integrated role in establishing the PGE2:PGF2alpha ratio necessary for luteal maintenance. The luteolytic or luteotrophic changes in the CL are synchronised with the release of maternal pituitary and ovarian hormones. The presence of uterine oxytocin (OT) and luteinising hormone (LH) receptors are important for the luteolytic effect of PGF2alpha. Conceptus oestrogen secretion coincides with autocrine and paracrine dialogue between the multiple conceptuses and uterine biological compounds and their receptors in trophoblast and endometrium.

Animals↗
PubMed1991

[The onset and course of estrus in young heifers].

In 1990 three experiments were performed in heifers 184 to 505 day-old with the weight 190 to 390 kg to test some biotechnical methods while studying the level of reproduction functions. Heifers were examined in 4 to 24-hour intervals by direct observations of animal behaviour, by clinical and gynaecological examinations of larger animals. The progesterone concentration in the peripheral blood was determined by the RIA method and simultaneously with the blood samplings, the values of impedance of vaginal mucosa were measured by means of several types of the Estral device (CSFR) for cattle. To detect the functional responses to prostaglandins administered, the following forms of substances were used: racemic mixture of optically active forms D (+) and L (-) in the Czechoslovak preparation Oestrophan inj. Spofa (0.25 mg of cloprostenol in 1 ml of solution) and the dextrorotatory D isomer--cloprostenol (0.075 mg in 1 ml of solution) in the Czechoslovak preparation Remophan inj. Spofa. Evaluating the results of the group 1 based on clinical and ethological examinations, the values of impedance of vaginal mucosa and progesterone levels (Tab. I), the functional maturity of sexual organs in heifers were determined. No significant differences were found while compared the luteolytic effects between D-cloprostenol in the Remophan preparation and the conventional mixture of optically active forms of Oestrophan. All methods used confirm the functional maturity of sexual organs (including a response to prostaglandin analogues administered) in heifers 11-12 month old. The values of impedance of vaginal mucosa varied during oestrus in some heifers and this fact is to be taken into account in practice.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1989

Interferon in pregnancy.

The cells of the immune system exchange information by a complex network of molecules referred to as lymphokines: these include the interferons. The physiology of the interferons, both in terms of control and function, is poorly understood. However, there is ample evidence that production of alpha-interferon is characteristic of the fetoplacental unit in both the human and other species. Indeed, the major trophoblast protein in early pregnancy in the sheep is alpha-interferon and in this species the molecule appears to have an important anti-luteolytic effect. The function of the interferons in human pregnancy is not known but, by analogy with information from other experimental systems, it might reflect aspects of the immune relationship between the mother and the fetus.

Animals↗
PubMed1989

Comparative aspects of maternal recognition of pregnancy between sheep and pigs.

Sheep conceptuses secrete a protein, oTP-1, between Days 10 and 21 of gestation which is responsible for establishment of pregnancy. oTP-1 inhibits uterine production of luteolytic amounts of PGF-2 alpha (PGF) produced in response to oestradiol and oxytocin. oTP-1 does not compete with oxytocin for binding to oxytocin receptors, but may interfere with oxytocin stimulation of the inositol phospholipid system. Pig conceptuses secrete oestrogens between Days 10 and 15 of pregnancy which are essential for establishment of pregnancy. Oestrogens, directly or indirectly, alter secretion of PGF from an endocrine direction (towards uterine vasculature) to an exocrine direction (towards the uterine lumen). PGF sequestered in the uterine lumen is unavailable to exert a luteolytic effect on the CL. Pig conceptus secretory proteins stimulate uterine production of PGF and PGE. Conceptus secretory proteins of sheep and pigs include proteins which have antiviral activity and may be considered interferons. In sheep, oTP-1 has both antiluteolytic and antiviral properties. The specific pig conceptus secretory proteins(s) possessing antiviral activity has not been established. Unlike oTP-1, however, it does not appear to possess antiluteolytic activity.

Animals↗
PubMed1987

Failure of the prostaglandin F2 alpha analogue, cloprostenol, to induce functional luteolysis in the olive baboon (Papio cynocephalus anubis).

The prostaglandin F2 alpha analogue, cloprostenol, which is an effective luteolytic agent in the common marmoset, was administered intramuscularly to olive baboons to determine if it possessed luteolytic properties in this species. The results showed that functional luteolysis was not induced when cloprostenol was administered during the mid- to late luteal phase or during early pregnancy.

Animals↗
PubMed1985

Prostaglandin F2 alpha-induced estrus in open cows and presumed abortion in pregnant cows with unobserved estrus in a herd monitored by milk progesterone assay.

Data were obtained in a large Florida herd of about 1800 Holstein cows. All cows were inseminated by the herdsman who did the pregnancy checks and who also administered drugs. The herdsman injected 103 cows with prostaglandin F2 alpha during the time this herd was under continuous observation by the authors who were conducting an unrelated research project. These cows consisted of 86 open (never bred) cows which had no estrus observed during the first 70 days postpartum, or no second estrus observed within 30 days after a previous estrus, and 17 cows previously inseminated. Two-thirds (57) of the 86 open cows were in estrus within 4 days. The 17 previously inseminated cows appeared to be pregnant, based upon progesterone profiles, when these were inadvertently given prostaglandin F2 alpha by the herdsman. Progesterone declined in all cows and they were in estrus in 7 +/- 4 days (mean +/- standard error). This result of presumed abortion reflects the luteolytic effectiveness of the drug and the importance of instructing any laymen users to follow necessary precautions to avoid undesirable effects.

Abortion, Veterinary↗
PubMed1984

[Prostaglandins and the physiology of human and animal reproduction].

This review of 417 publications in the literature covers various aspects of the role of prostaglandins in human and animal reproductive physiology. The author points out that there are a variety of prostaglandins all belonging to a family of substances that derive from arachadonic acid. They are present in many human and animal tissues, are extremely labile and are involved in reproduction in the ovary in follicular development and release of the follicle, in the tube in migration of the gametes, and in the uterus in implantation and delivery. The author says that the role of prostaglandins is not an exclusive one but they are linked with the hypothalamo-pituitary hormones, as well as with progesterone and oestrogens. It may be possible that PGE helps to initiate follicular development by stimulating the appearance of LH and FSH receptors. PGE is also luteotrophic. Indomethacin which is a prostaglandin inhibitor however does not modify the ability of LH to stimulate luteinization and maturation of the oocyte. The author postulates on the origin and the identification of the luteolytic factor and gives schematic illustration of the arterio-venous blood supply between the uterus and the ovary which is so important for the good function of the prostaglandins. It is possible that PGF type prostaglandins which are vasoconstrictor may reduce the flow of blood around the ovary, perhaps even specifically to luteal tissue. He postulates that PGF2 alpha in its relationship to its receptors is necessary but insufficient to explain the full luteolytic effect. Turning to the semen he shows that the nature and concentration of prostaglandins in semen varies from one species to another. He thinks that there is a triple role for prostaglandins with semen, which is: a participation in the events of ejaculation, an effect on the female genital tract, and an effect on the mobility of spermatozoa. He speaks of the role of prostaglandins on the Fallopian tubes and believes that they do have an effect on determining the movement of the tubes but cannot explain exactly what.

Animals↗
PubMed1981

Effects of four prostaglandin analogues on menstrual cycle length and peripheral levels of 17 beta-oestradiol and progesterone in the chacma baboon.

Four different prostaglandin analogues were studied with regard to their effects on menstrual cycle length and peripheral in th chacma baboon (Papio ursinus). Pooled data showed that the luteal phase was shortened by more than 4 days and that both hormone levels were reduced significantly after treatment. In terms of the inhibition of progesterone production as an absolute index of corpus luteum function, PGF2 alpha, 1,15-lactone, and 11 alpha (15S)-17-phenyl-ent-18-19,20-trinor-PGE2 methyl ester were found to be the most effective luteolytic compounds.

Animals↗
PubMed1981

Estradiol-17 beta cyclopentylpropionate and prostaglandin F for induction of abortion during the first trimester of pregnancy in feedlot heifers.

The ability of estradiol-17 beta cyclopentylpropionate (ECP, 20 mg) and prostaglandin F2 alpha (PGF2 alpha; 5, 10, 20, and 40 mg) to induce abortion during early gestation (days 40 to 90, as estimated by palpation per rectum) in pregnant feedlot heifers was compared. All treatments were given by IM injection. All heifers treated with 20 and 40 mg of PGF2 alpha aborted within 7 days after treatment. Six of 10 heifers aborted in the same period after ECP treatment; 1 additional heifer aborted by day 13. Abortions did not occur by day 13 in 10 placebo-treated heifers. Five and 10 mg of PGF2 alpha aborted 2 of 3 and 8 of 10 heifers, respectively, within 7 days of treatment. Quantitation of serum progesterone by specific radioimmunoassay showed that a luteolytic effect was evident in aborting heifers. Complications were not detected in any heifers after treatment or abortion. Ten of the 20 heifers that aborted in response to the 20- and 40-mg doses of PCF2 alpha developed a new corpora lutea by day 20 after treatment. However, none of the heifers that aborted after ECP treatment had a corpus luteum by day 20. It was concluded that PGF2 alpha is a more effective compound than ECP for induction of abortion during the 1st trimester of pregnancy in feedlot heifers, that a wide range of PGF2 alpha doses are capable of inducing abortion in at least some animals treated, and that heifers are likely to resume ovarian activity sooner if aborted with PGF2 alpha than with ECP.

Abortion, Induced↗
PubMed1997

Immune-endocrine interactions affecting luteal function in pigs.

The formation, normal function and destruction of corpora lutea are essential features of normal reproduction. Although the formation of corpora lutea from follicles is largely dependent on pituitary gonadotrophins, the process of luteolysis is locally regulated and poorly understood. The corpus luteum consists of several steroidogenic and nonsteroidogenic cell types that interact with each other in a paracrine manner. Under cell culture conditions, large luteal cells that stem from follicular granulosa cells can be identified easily under the microscope and collected individually for single cell RT-PCR. As each of the 120 large luteal cells express the gene encoding 3 beta-hydroxysteroid dehydrogenase, it appears that all large luteal cells are steroidogenic. Large luteal cells also express the oestrogen receptor gene and as they are known to produce oestradiol, it can be concluded that the steroid acts in an auto- or intracrine manner in large luteal cells. Since we showed previously that oestradiol stimulates progesterone release under in vitro and in vivo conditions, it can be concluded that the steroid is an important intraluteally acting luteotrophic signal. At the time of luteal regression, macrophages invade the corpora lutea and their cytokine products, particularly tumour necrosis factor alpha (TNF alpha), appear to be involved in reduced steroid secretion. Indeed, TNF alpha inhibits production of progesterone and oestradiol from cultivated luteal cells. In sows, oestradiol is a strong luteotrophic factor and the production of oestradiol and of its receptor is downregulated by TNF alpha. Thereby, TNF alpha not only exerts direct luteolytic effects but also prevents the luteotrophic effects of oestradiol. Hence, it has an anti-luteotrophic action. In most species, functional luteolysis is accompanied by morphological regression of the corpus luteum. This structural luteolysis also appears to involve TNF alpha, as we have shown in pigs that expression of TNF alpha gene is high during luteolysis. Furthermore, TNF alpha stimulates programmed cell death (apoptosis) in luteal cells kept under culture conditions.

Animals↗
PubMed1979

Ovarian responses of pregnant mare serum gonadotropin- and human chorionic gondotropin-primed rats: desensitizing, luteolytic, and ovulatory effects of a single dose of human chorionic gonadotropin.

We conducted a study to determine the morphological appearance and functional responsiveness of ovarian tissues after administration of hCG to 28-day-old rats primed 65 h earlier with PMS gonadotropin (PMSG) and after administration of a second dose of hCG 5 days later, i.e. to 33-day-old rats containing heavily luteinized ovaries. Sixty-five hours after the administration of 50 IU PMSG sc to 25-day-old rats, ovaries already contained an abundance of luteinized follicles and an adenylyl cyclase (AC) system that was responsive to LH, epinephrine, and NaF. The administration of 50 IU hCG sc at this time initially resulted in a loss of LH-responsive ovarian AC. Within 4 days of the hCG injection, the ovaries of the now 32-day-old rats were heavily luteinized, and ovarian AC was highly responsive to LH, epinephrine, and NaF. The administration of a single sc dose of 200 IU hCG to 33-day-old PMSC- and hCG-primed rats with luteinized ovaries resulted in a rapid desensitization of the ovarian AC to LH and a drop in serum progesterone levels, During the subsequent 7 days, serum progesterone levels continued to decline, while total ovarian AC reacquired responsiveness to LH by days 4--5 after the densensitizing dose of hCG. Dissection of ovarian components revealed, however, that the AC system of the corpora lutea originally present at the time of the second hCG injection remained permanently refractory to LH and that the AC in corpora lutea newly formed from freshly ovulated follicles exhibited a significant responsiveness to LH, epinephrine, and NaF. However, these new corpora lutea were not fully active, since serum progesterone never rose. Subcutaneous administration of 50 IU hCG to 33-day-old PMSG- and hCG-primed rats also promoted a rapid loss of AC responsiveness to LH. This lower concentration of hCG was not sufficient to promote follicular development or ovulation, and the ovarian AC remained refractory to LH for at least 7 days. Intravenous administration of 75 IU hCG to 33-day-old PMSG- and hCG-primed rats similarly promoted a rapid and permanent loss of luteal AC responsiveness to LH; again, follicles did not mature to a preovulatory state and, in fact, appeared to undergo atresia rather than ovulation. These results indicate that in heavily luteinized ovaries 1) hCG promotes desensitization of rat luteal AC to LH, 2) Desensitization of AC to LH stimulation in corpora lutea is permanent and irreversible, and 3) only under conditions where follicles mature and ovulate and new corpora lutea are formed does total ovarian AC reacqure responsiveness during the subsequent week.

Adenylyl Cyclases↗