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Results for “Luteolytic Effects”

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At least 55 records · Page 3Linked to original sources
PubMed1990

Luteolytic effect of the antiprogestin and antiglucocorticoid agent RU486 in rats.

Ovarian cells of pregnant rats were cultured with synthetic progestins (R5020, R2323), dexamethasone and RU486. Progesterone and 20 alpha-hydroxy-pregn-4-en-3-one (20 alpha-dihydroprogesterone) in the medium were measured by specific radioimmunoassay. Both R5020 and R2323 increased concentrations of these intrinsic progestins. RU486 decreased concentrations of progesterone, however, the addition of R5020 or R2323 counteracted this action. Immature hypophysectomized rats treated with pregnant mare serum gonadotropin (PMS) and human chorionic gonadotropin (hCG) were administered with RU486; the serum levels of progesterone and 20 alpha-dihydroprogesterone tended to decrease. R5020 and R2323 inhibited the effect of 3 beta-hydroxysteroid dehydrogenase (3 beta-HSD), whereas RU486 did not. Inhibition of the cholesterol side chain cleavage enzyme (CSCC) by RU486 was more marked than that by R5020 or R2323. These results show that RU486 decreases progesterone synthesis in cultured ovarian cells. A part of the mechanism may involve an inhibition of CSCC.

Algestone↗
PubMed1981

Determination of clinical and luteolytic effectiveness of a prostaglandin analog in mares by a dose response study.

In trials covering two seasons, 124 thoroughbred and 40 quarterhorse mares with either normal cycles (55 diestrous mares, 33 postpartum mares after foal heat) or in anestrus during the breeding season (76) were treated with either a novel PGF analog K 11941 or with the PGF analog prostalene (Synchrocept(trade mark)). K 11941 was used over a range of doses from 0.5 to 4.5 mg, while prostalene was applied at the recommended dose level of 2 mg. Blood progesterone determinations, clinical observations and the results of breeding confirmed that K 11941, at doses of 2 mg or larger, and prostalene, were effective and safe luteolysins; heat and ovulations occurred within the expected time intervals and fertility was satisfactory. Clinical data were converted into a response score (CRS) and an added fertility score (CRSF) for statistical evaluation and the establishment of a dose response curve. In both scores, 0.5 to 1.5 mg were significantly less effective than the higher dose levels (p<.0001). No significant differences were found for the 2 and 3 mg dose of K 11941 in diestrous and anestrous mares. In both indications, prostalene scored less (p<.05). Data analysis and establishment of a dose response curve point to 3 mg of K 11941 as the optimal dose.

Journal Article↗
PubMed1996

Luteolytic effects of prostaglandin F2alpha on day 8 to 19 corpora lutea in the bitch.

Luteolysis was induced in 5 experimental Beagle (8 cycles) and 7 client-owned bitches treated with 150 to 200 microg/kg, sc of prostaglandin F2alpha administered twice daily for 4 d, starting on Days 8 to 19 after the onset of cytological diestrus. Five experimental Beagle bitches had been mated during the estrus preceding treatment, and copulation had been confirmed in 2/7 client-owned bitches presented for termination of unwanted pregnancy. Serum progesterone concentration (mean +/- SD) declined from 26.1 +/- 66 ng/ml before treatment to 0.3 +/- 0.4 ng/ml on the fourth day of treatment One of the 7 client-owned bitches maintained her pregnancy even though serum progesterone concentrations were less than 0.5 ng/ml on the third and fourth day of treatment. Mean (+/- SEM) inter-estrous intervals before and following prostaglandin-induced luteolysis were 207.3 +/- 12.4 (n = 11 cycles in 6 bitches) and 95.5 +/- 20.0 d (n = 6 cycles in the same 6 bitches; P < 0.0001), respectively These results suggest that effective prostaglandin-induced luteolysis can be achieved with administration of 180 microg/kg during the third week of diestrus in pregnant and nonpregnant bitches.

Journal Article↗
PubMed1979

Luteolytic effect of intranasal administration of [D-Ser(TBU)6,DES-Gly-NH2(10)]-luteinizing hormone-releasing hormone ethylamide in normal women.

Intranasal administration of two doses of potent agonist of luteinizing hormone (LH)-releasing hormone (LHRH), [D-Ser(TBU)6,des-Gly-NH2(10)]LHRH ethylamide (500 micrograms), a 8 A.M. and 5 P.M. on 1 day between day 4 and 9 following the LH peak in six normal women during two consecutive menstrual cycles shortened the luteal phase from 13.6 +/- 0.3 days to 10.9 +/- 0.3 days (mean shortening, 2.7 days; range, 0.5 to 4.5 days) and reduced plasma progesterone levels to 61.3% +/- 9.2% of control. Hormone changes were followed by daily measurements of plasma LH, follicle-stimulating hormone, 17 beta-estradiol, and progesterone during two pretreatment cycles, two treatment cycles, and two post-treatment cycles. No side effect was observed, and apparently normal cycles occurred immediately after treatment. The present data indicate that the intranasal administration of a potent LHRH agonistic analog can induce luteolysis and control time of occurrence of menses in normal women. This finding opens the possibility of a new and physiologic approach to fertility control.

Administration, Intranasal↗
PubMed2001

Luteolytic effect of prolactin is dependent on the degree of differentiation of luteal cells in the rat.

We studied the morphological and quantitative changes in cyclic corpora lutea (CCL) and in CL of pregnancy (CLP) during structural luteolysis. Elimination of CCL takes several cycles, and cell death occurs as successive apoptotic bursts, from 2100 h in proestrus to 1300 h in estrus. Each apoptotic burst determined a 60% decrease in the CL volume and an 80% decrease in the number of steroidogenic cells (SC). All these changes were inhibited by blocking the preovulatory prolactin (PRL) surge with bromocryptine (CB154). Neither apoptotic cells nor changes in the number of SC were found in regressing CLP from Day 21 of pregnancy to Day 2 postpartum, although there was a 50% decrease in the CLP volume and a 30% decrease in the mean cross-sectional area of SC. Treatment with CB154 on the day of parturition did not modify these regressive changes. On Day 5 postpartum, the volume of the CLP and the number of SC were equivalent in lactating rats (showing high PRL concentrations induced by pup suckling) and nonlactating noncycling rats (in which cyclicity and, therefore PRL surges, were blocked by treatment with LHRH antagonist). However, on Day 10 postpartum, the CLP volume and the number of SC were significantly decreased in lactating rats, and apoptotic cells were frequent. In postpartum cycling rats, the CLP did not show apoptotic cells on the day of the second postpartum estrus (on Day 5 postpartum), whereas on the day of the third postpartum estrus (on Day 9 postpartum), apoptotic cells were abundant. These results indicate that PRL does not induce apoptosis in the CLP before Day 5 postpartum and strongly suggest that the proapoptotic effect of PRL is dependent on the degree of differentiation of luteal cells.

Animals↗
PubMed1977

The relation between the age of the corpus luteum (CL) and the luteolytic effect of an LH-antiserum (LH-AS): comparison of hysterectomized pseudopregnant rats with intact pregnant rats for their response to LH-AS treatment at four stages of CL activity.

At one of four stages during the period of corpus luteum (CL) activity (day 9, day 12, day 15, or day 18) groups of hysterectomized pseudopregnant (PSP) rats and of intact pregnant (PRG) rats were compared for the effect of a single sc injection of an antiserum to LH (LH-AS) on progesterone secretion. Groups of control rats were injected sc with normal horse serum (NHS) at these same stages, and in all rats, the progesterone level in jugular blood serum was measured by RIA on the day of treatment and 24 and 72 h after treatment. Among the PRG rats, the controls' progesterone levels rose to a peak on day 15, and then slowly declined. LH-AS on day 9 induced abortion and a rapid, drastic and permanent fall in the progesterone level in all rats. On day 12, it induced a similar fall in progesterone, and abortion, in 4 of 10 rats; in the 6 which remained pregnant, a much less severe fall occurred 24 h after treatment, and by 72 h the level had returned to close to the initial one. On days 15 or 18, LH-AS induced neither abortion nor a significant change in the progesterone level from that seen in the controls. Among the PSP rats, the controls' progesterone levels tended to fall progressively after day 9; the average length of diestrus was about 21 days. At each of the four stages the LH-AS induced a rapid, drastic and permanent fall in the progesterone level. Early termination of the diestrus was easily discernible in the groups injected on days 9 or 12, but was obscured in the other groups because of the similarity in length of the expected remaining diestrus and the duration of the neutralizing effect of the LH-AS on LH in the circulation. The PSP rats' CL, thus, once they become dependent on LH (about day 9), remain so to the end of PSP. The PRG rats' CL seem to lose this dependency after day 12, but the possibility could not be eliminated that the dependency may shift from LH to a placental LH-like hormone.

Abortion, Induced↗