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Results for “Luteolytic Effects”

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PubMed1982

Lack of luteolytic effect of gonadotropin releasing hormone (GnRH) with therapeutic and repeated doses in dairy cows.

Two experiments were conducted with multiparous cycling dairy cows in the post-partum period. They were assigned randomly to GnRH treatment or to saline injection (control groups) during the mid-luteal phase. In experiment 1, seven cows were treated with five consecutive injections of GnRH (100 micrograms i.m.) at hourly intervals and four controls were similarly treated with saline. In experiment 2, (seven treated and three control cows) treatment consisted of 10 i.m. injections of 500 micrograms GnRH or saline twice a day (8 h and 18 h) over a period of 120 h (five days). In both experiments injections started on day 12 of the oestrous cycle. LH immediately following treatment and subsequent progesterone concentrations for the next 35 days were assayed in peripheral blood samples. Most of the cows were inseminated at the oestrus following the treatment period. Profiles of progesterone after GnRH-treatment varied slightly but transiently between days two and four post-treatment in experiment 1. By contrast in experiment 2, there were no significant changes in the progesterone patterns during that period when compared to controls. Moreover two cows had a prolonged oestrous cycle. There was no difference in the conception rates according to groups and the progesterone patterns of the following cycle in the non-pregnant cows did not seem to be modified. In conclusion, repeated therapeutic doses of GnRH administered in the mid-luteal phase did not induce early luteolysis and appeared not to impair fertility.

Animals↗
PubMed1980

Pharmacologic induction of luteolysis in cynomolgus monkeys (Macaca fascicularis).

Earlier studies reported from this laboratory demonstrated the luteolytic effect of a 5-day sequential regimen of 3 days of estrogen overlapped with 3 days of PGF2 alpha administered during the midluteal phase to cynomolgus monkeys. In this study, a different regimen, containing estrogen, lower doses of PGF2 alpha, and methylergonovine maleate (MEM), was used. Individual components of this modified sequential regimen were not effective as luteolytic agents. When 3 days of estrogen (40 micrograms of depoestradiol cypionate [DEC] on the first day and 40 micrograms of estradiol benzoate [EB] on second and third day) was followed by 3 days of MEM (400 micrograms, twice daily) overlapping 1 day of estrogen treatment, there was a significant shortening of the length of the menstrual cycle (less than 26 days) in eight of 10 animals, with a concomitant decline in plasma levels of progesterone. When a low dose of MEM (100 micrograms, twice daily), which was completely ineffective in shortening cycle lengths with the same estrogen treatment, was administered alternately with PGF2 alpha (5 mg twice daily, 11 of 14 animals had shortened cycles, with an associated decline in levels of progesterone. PGF2 alpha and MEM without the estrogen pretreatment did not have a significant effect on cycle lengths or blood levels of progesterone, thus demonstrating a synergism between estrogen and the other compounds in inducing luteolysis. Since the agents used in these sequential regimens have potent effects on the uterus, the treatments were repeated in hysterectomized monkeys to determine whether the uterus was involved in the mediation of luteolysis. These treatments caused a significant drop in plasma levels of progesterone by the tenth day after the preovulatory estrogen peak, thus demonstrating that the uterus is not essential to the luteolytic action.

Animals↗
PubMed1989

Enclomiphene induces luteolysis in the nonpregnant guinea pig.

The effect of two antiestrogens, enclomiphene and tamoxifen, on luteal function in the guinea pig was compared to that of estradiol, a known luteolysin. Enclomiphene caused premature luteolysis when administered during the early or mid-luteal phase of the cycle, but was not as potent as estradiol. Tamoxifen had no effect. The luteolytic effect of enclomiphene was mediated by the uterus, as has been shown for estradiol.

Animals↗
PubMed1990

Antifertility effects of leaf extracts of some plants in male rats.

Ethanolic leaf extracts of different local folklore plants (Azadirachta indica, Beaumontia grandiflora, Chordia dichotoma, Casiarea tomentosa, Diospyros embryopteris, Milletia auriculata and Melia azedarach) were investigated for antifertility effects on male rats in oral doses of 100 mg/kg daily for 21 days. Though, none of these extracts interfered with spermatogenesis, anti-implantational and abortifacient effects were observed in females mated by the males fed with leaf extracts of A. indica and C. dichotoma. Leaf extract of B. grandiflora besides having anti-implantational and abortifacient effects, had luteolytic effects. Abolition of libido in 100% males by leaf extracts of D. embryopteris and M. azedarach and in 60% of males by extract of C. tomentosa preclude these plants for antifertility use.

Animals↗
PubMed1986

The relation between the effects of hysterectomy, decidual tissue, prolactin, or luteinizing hormone (LH) and the ability of indomethacin to prevent luteolysis in rats bearing LH-dependent corpora lutea.

In adult rats hysterectomized on day 8 of pseudopregnancy, the mean serum progesterone (P) level fell from 88 ng/ml on day 8 to 44 ng/ml on day 15 (n = 61). In response to a single sc injection of 0.5 ml of a specific antiserum to LH (LHAS) on day 10, the P level fell to less than 10 by day 15 in 29 of 33 rats; however, this fall, which was indicative of luteolysis, was briefly interrupted by a return to the control level 36 h after treatment. Indomethacin (400 micrograms, sc) administered 12 h before, during, and 12 h after the LHAS injection prevented the luteolysis that followed the 36 h surge in 10 of 15 rats (P less than 0.001). Treatment with 400 micrograms 2Br-alpha ergocryptine (CB 154), sc, on day 10, with or without indomethacin, however, induced a rapid, uninterrupted, and permanent fall to less than 10 in 13 of 13 rats. Treatment with both LHAS and CB 154 reduced the luteolytic effect of CB 154 (P less than 0.001), and indomethacin treatment combined with both LHAS and CB 154 tended to further reduce the luteolytic effect of CB 154 (P less than 0.01). Hypophysectomy on day 10, however, induced rapid, uninterrupted and permanent luteolysis in all rats (15); this was not affected by indomethacin (7 rats) or LHAS (8 rats). Pituitary homotransplantation on day 8 prevented the luteolytic effect of LHAS on day 10 in 6 of 6 rats (P less than 0.003). In decidual tissue (DT)-bearing rats, LHAS on day 10 induced rapid, uninterrupted, and permanent luteolysis in 18 of 18 rats. The response to LHAS on day 10 changed to that of the hysterectomized rat when the DT-bearing uterus was removed on day 8 (12 of 12 rats) or 10 (7 of 7 rats) (P less than 0.001), but did not change when it was removed on day 11 (5 of 5 rats). In DT-bearing rats hysterectomized on day 8, indomethacin in intrabursal Silastic wafers prevented luteolysis in response to LHAS on day 10 (6 of 6 rats; P less than 0.001). Intrabursal indomethacin had no effect on the response to LHAS in intact DT-bearing rats (3 of 3 rats). These results suggest that even when the corpus luteum becomes LH dependent, PRL may retard or prevent LHAS-induced luteolysis in hysterectomized rats. (ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗