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Results for “PROGESTATIONAL HORMONES”

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

Rhythms of progesterone and corticosterone in the pms-treated rat: relationship to ovulation.

Precocious ovulation was induced in 26-day-old rats by means of 25 IU pregnant mare's serum gonadotrophin (PMS). Rats were given injections at either 09.00 or 16.00 in order to determine whether the course of pubertal changes in corticosterone (B), progesterone (P) or time of ovulation would be dependent upon the time of injection. Blood samples were collected by decapitation at 4-h intervals on the day of expected ovulation (day 28). In saline-treated controls at 28 days of age there was a demonstrable daily variation in both serum B and P with maximum values at 16.00 and minimum values at 08.00. In rats given PMS at 09.00, there was a peak of P and B at 16.00 on day 28 but the values were higher than in controls. Ovulation took place at 24.00 on day 28-29. In rats given PMS at 16.00 the pattern of P and B was different, with continual high values from 16.00 to 04.00 at 28 days of age; ovulation took place later in this group (between 02.00-08.00 on day 28). It can be concluded that there is a daily rhythm of P a few days before puberty and that the induction of precocious ovulation with PMS is associated with a different pattern of B and P and a different time of ovulation depending upon when PMS is administered.

Adrenal Glands↗
PubMed1975

Ovulation induction during the anovulatory season in Saimiri sciureus.

Captive squirrel monkeys show a seasonal response to a subtle ovulation induction regime of the five days of progesterone, four days FSH (1 mg/day) and a dose of HCG (500 IU), with the minimal response occurring from July to September. A 3 times 3 factorial design with 18 adult female monkeys was used to determine the effects of increasing doses of HCG (500, 1,000, OR 1,500 IU) and increasing dose of duration of FSH (1 mg for four days, 2 mg for four days, or 1 mg for five days) on ovulation between early July and mid-October. An increase in either dose or duration of FSH increased ovulation while increasing HCG was ineffective.

Animals↗
PubMed1979

Failure of estrogen-induced discharge of luteinizing hormone in lactating women.

Pituitary-ovarian relationships were studied in seven lactating women by measuring the basal plasma concentrations of pituitary and ovarian hormones and their responses to an estrogen provocation test at 7, 30, and 100 days after delivery. The results were compared to a similar group of seven women who did not breast feed. The first ovulation occurred in five of the nonlactating women beteen 43-87 days after delivery, as judged by the urinary excretion of total estrogen and pregnanediol. In all lactating women, ovarian cyclicity was suppressed for at least 150 days after delivery or until weaning. The basal concentration of PRL in lactating women was significantly higher than in the nonlactating women at all three times measured. At 30 and 100 days, the concentration of estradiol was significantly lower in the lactating women, although the basal concentrations of FSH were similar in the two groups. After an injection of 1 mg estradiol benzoate, the concentrations of FSH and LH in plasma were suppressed to a greater extent in lactating than in nonlactating women. In addition, fewer of the lactating group (one of seven and none of seven at 30 and 100 days, respectively) than the nonlactating group (two of seven and five of seven) subsequently showed a rise in the concentration of LH 58--96 h after the estrogen injection (positive feedback). These results suggest that during lactation the hypothalamic-pituitary system is more sensitive to the negative feedback and relatively insensitive to the positive feedback of estrogen.

Adult↗
PubMed1976

Prenancy diagnosis in dairy cattle by progesterone concentration in milk.

Concentration of progesterone in whole milk was used to diagnose pregnancy in lactating dairy cows. Milk samples were taken 21 to 22 days postbreeding and analyzed for progesterone by radioimmunoassay. Progesterone in milk greater than 11 ng/ml, 8 to 11 ng/ml, and less than 8 ng/ml was used classify animals as pregnant, questionable, and not pregnant. In this classification for 123 cows, 67 were classified pregnant, 7 questionable, and 49 not pregnant. A comparison of progesterone diagnosis with actual calving results showed agreement of 73 and 98% for the cows classified as pregnant and not pregnant. Thirteen of 19 animals, in which there were discrepancies between diagnoses by milk progesterone and calving results, were not detected in estrus within 30 days after breeding. One animal classified not pregnant by milk progesterone was pregnant.

Animals↗
PubMed1976

Peripheral plasma progesterone during egg transport in the rabbit.

Peripheral plasma progesterone concentrations were measured in New Zealand rabbits every 6 hr beginning 12 hr before and continuing until 96 hr after either natural mating, hCG injection, or saline injection. The number of ovulation points in naturally mated animals (9.3 +/- 0.6, mean +/- SE) was not significantly different from that in hCG-injected animals (8.6 +/- 1.5). There was a surge in progesterone secretion following both mating and hCG injection. Plasma progesterone concentrations reached a peak prior to ovulation and then fell to basal levels at the time of ovulation. Beginning at approximately 30 hr after the ovulation-inducing stimulus, there was a progressive, significant (P less than 0.001) increase in plasma progesterone concentration, which continued for the duration of the sampling period. The initiation of the postovulatory increase in progesterone secretion corresponds temporally with the movement of eggs from the ampullary-isthmic junction into the isthmus. The progressive increase in plasma progesterone between 30 and 72 hr after the induction of ovulation corresponds with the gradual movement of eggs through the isthmus into the uterus. The data suggest that movement of eggs through the oviductal isthmus is influenced by the postovulatory secretion of progesterone.

Animals↗
PubMed1975

Temporal relationships critical to progesterone-induced acceleration of ovum transport.

Previous investigators have demonstrated that 2.5 mg fo progesterone, administered intramuscularly to rabbits on the day of ovulation and the 2 preceding days (Days -2, -1, and 0) significantly and consistently accelerates ovum transport. In contrast, when given on the day of ovulation and the 2 following days (Days 0, +1, and +2), progesterone does not accelerate ovum transport. The experiments reported were designed to define more precisely the temporal relationships critical to progesterone-induced acceleration of tubal ovum transport. Our observations suggest 3 important conclusions: 1) Progesterone, when given at least 1 day, and not more than 2 days, prior to ovulation does induce accelerated ovum transport. 2) The progesterone responsive mechanism is dose dependent. 3) The acceleration is partially antagonized if progesterone treatment is begun 3 days prior to ovulation.

Animals↗