Patterns Of Progesterone Concentrations Research Articles

The Interaction Between Photoperiod and Nutrition and Its Effects on Seasonal Rhythms of Reproduction in the Ewe1

In sheep, the seasonal patterns of reproductive activity are driven primarily by the annual photoperiodic cycle, but can also respond to other environmental factors, such as nutrition, yet little is known about the mechanisms underlying this interaction. This study was designed to define the interaction between photoperiodic and nutritional cues on seasonal patterns of ovarian activity, and to determine if there is a central interaction between these cues. Groups of Ile-de-France ewes were maintained in two nutritional states (restricted and well fed) under a simulated annual photoperiod of 8-16 h of light per day over two breeding seasons. At the end of the first breeding season, half of the animals of each group were ovariectomized (OVX) and fitted subcutaneously with estradiol implants. Low nutritional status shortened the season of ovarian activity, determined from the pattern of progesterone concentrations, by modifying the timing of seasonal transitions between periods of ovarian activity and anestrus. The same results were observed for the seasonal rhythm of neuroendocrine activity, assessed in the OVX ewes, from the pattern of luteinizing hormone concentrations. These results were then confirmed for neuroendocrine activity induced by a photoperiodic treatment. We conclude that nutrition centrally modulates the interpretation of photoperiod to affect seasonal reproductive transitions. The mechanisms of this interaction are discussed in the paper.

Intrapulse temporality between pulses of a metabolite of prostaglandin F 2α and circulating concentrations of progesterone before, during, and after spontaneous luteolysis in heifers

Pulses of the prostaglandin F 2α (PGF) metabolite 13,14-dihydro-15-keto-PGF 2α (PGFM) and the intrapulse concentrations of progesterone were characterized hourly during the preluteolytic, luteolytic, and postluteolytic periods in seven heifers. The common hour of the end of preluteolysis and the beginning of luteolysis was based on a progressive progesterone decrease when assessed only at the peaks of successive oscillations. The end of the luteolytic period was defined as a decrease in progesterone to 1 ng/mL. Blood samples were taken hourly from 15 d after ovulation until luteal regression as determined by color-Doppler ultrasonography. Between Hours −2 and 2 (Hour 0 = PGFM peak) of the last PGFM pulse of the preluteolytic period, progesterone decreased between Hours −1 and 0, and then returned to the prepulse concentration. Concentration did not change significantly thereafter until a PGFM pulse early in the luteolytic period; progesterone decreased by Hour 0 and transiently rebounded after Hour 0, but not to the prepulse concentration. In the later portion of the luteolytic period, progesterone also decreased between Hours −1 and 0 but did not rebound. After the defined end of luteolysis, progesterone decreased slightly throughout a PGFM pulse. Results demonstrated for the first time that the patterns of progesterone concentrations within a PGFM pulse differ considerably among the preluteolytic, luteolytic, and postluteolytic periods.

Effect of prostaglandin F 2α dosage and stage of estrous cycle on the estrous response and corpus luteum function in beef heifers

Ninety-five normal cyclic crossbred beef heifers were used to determine if the proportions of heifers showing estrus, intervals to estrus and corpus luteum (CL) function were influenced by PGF 2α dosage and (or) the stage of luteal phase when PGF 2α was administered. Heifers were assigned randomly to treatments in a 4 × 3 factorial arrangement. Treatments were 5, 10, 25 or 30 mg PGF 2α injected either in early (5 to 9 d), mid (10 to 14 d) or late (15 to 19 d) stages of the luteal phase. Jugular samples were taken at 0 h and at 8 h-intervals for 48 h and again at 60 h after PGF 2α treatment for progesterone assay. Heifers were observed for estrus continuously for 120 h PGF 2α treatment. The proportion of heifers showing estrus was dependent upon (P<0.05) both dosage of PGF 2α and stage of luteal phase. Heifers given 5 mg of PGF 2α showed estrus only if treated during the late stage, while those given 10 mg of PGF 2α showed a progressive increase of heifers in estrus as stage of luteal phase advanced. The proportion of heifers showing estrus after 25 and 30 mg of PGF 2α increased from 56% for the early stage to 100% for the mid and late stages. Interval to estrus in heifers showing estrus within 120 h after PGF 2α treatment did not differ (P>0.05) among dosages but tended (P=0.10) to be longer in heifers treated during the mid luteal stage (67 h) than in heifers treated in the two other stages (56 h). A greater proportion of heifers (P<0.05) showed estrus by 60 h after PGF 2α when treated during the early and late luteal stages (75.5%) than for heifers treated during the mid luteal stage (30.4%). Patterns of progesterone concentrations were influenced (P=0.08) by the three way interaction of dosage, stage and time. In heifers that showed estrus, rate of decline in progesterone tended (P=0.07) to be slower during the mid luteal stage than during the early and late stages. Progesterone did not drop below 1 ng/ml until 32 h in heifers treated during the mid luteal stage; whereas progesterone dropped below 1 ng/ml by 24 h in heifers treated during the early and late stages. These data may be useful in designing more efficient systems for using PGF 2α or its analogues in estrus synchronization of beef cattle.

Determination of steroid hormones in goats' milk and plasma as an aid to pregnancy diagnosis using an ELISA

Commercial ELISA kits for the determination of steroid hormones in milk and blood of domestic animals have been used by veterinary surgeons in practice as a method of pregnancy diagnosis in cattle, horses and pigs. In goats, the complex metabolism of steroid hormones in the mammary gland has made the test unsatisfactory. In five non-pregnant Saanen does, milk and blood samples were taken daily through a complete oestrous cycle, and the concentrations of progesterone measured by ELISA. A wide variation in the pattern of progesterone concentration was recorded. In seven non-pregnant and early pregnant does (less than 35 days) the mean concentration of oestrogens in milk was 0.5 ng/ml. Pregnancy in 88 does was subsequently predicted, based upon a concentration of oestrone sulphate in milk over 0.5 mg/ml, and was approximately 80 per cent accurate for determination of both pregnancy and non-pregnancy when compared with actual kidding data. Reasons are given for these errors.

A survey of reproductive performance in dairy herds. Characteristics of the patterns of progesterone concentrations in milk

ABSTRACTProgesterone concentrations were measured by radioimmunoassay in fat-free milk samples obtained three times weekly from calving until day 60 of pregnancy from over 700 cows in commercial dairy herds. Profiles of progesterone concentration during the ovulatory cycle and early pregnancy were also examined. In 94% of the animals cycling had commenced by 60 days post partum and a further 3% had shown some ovarian activity. In 34% of cows, the resumption of regular ovulatory activity was preceded by short periods of progesterone secretion which did not meet the criteria for a 'normal cycle’. Peaks of progesterone cross-reactivity (&gt;0·75 ng/1) were detected at the time of ovulation in proportionately 0·06 of all cycles. There was no relationship between the detection of oestrus and the length of the following progesterone cycle or the concentrations during that cycle. However, there was a tendency for the first progesterone cycle post partum to be more variable in length than later cycles (0·56 within the range 18 to 24 days compared with 0·70 of later cycles; P &lt; 0·001). Extension of the length of the luteal phase occurred in 58 second and later cycles (proportionately 0·141) following inseminations which did not result in calving. However, since the comparable figure for 1053 cycles where no insemination was given was 0·048, the overall figure for embryo mortality later than 24 days after insemination was estimated as 9·3%. Concentrations of progesterone in pregnant animals, compared to non-pregnant animals, and the distributions of luteal lengths between 8 and 21 days long following inseminations not resulting in calving could both be explained by early maternal recognition of pregnancy.

Functional assessment of the autotransplanted uterus and ovary in the ewe.

The ovary, uterus or ovary and uterus were autotransplanted to the neck of the ewe. The success rate in transplanting the ovary alone (17/22) or the ovary with the uterus (7/9) was much higher than transplantation of the uterus alone (3/8). Angiographic evidence was obtained for the patency of the uterine and ovarian arteries anastomosed to the carotid artery and utero-ovarian vein anastomosed to the jugular vein in ewes with all three types of autotransplants. Ewes with utero-ovarian autotransplants showed regular oestrous cycles and had normal luteal phases, as judged by the pattern of progesterone concentration in peripheral jugular venous plasma. However, ewes with ovarian autotransplants failed to show oestrus due to maintenance of the corpus luteum as indicated by the fact that the concentration of progesterone remained elevated for up to 220 days. The relatively high success rate in this series indicates that more extensive use could be made of these techniques.

LH, FSH and ovarian steroids in serum during normal menstrual cycles and cycles with corpus luteum insufficiency in the human female (author's transl)

LH, FSH, estradiol-17beta, progesterone, 20alpha-dihydroprogesterone, 17alpha-hydroxyprogesterone, delta4-androstenedione and testosterone are determined by radioimmunoassay in serum daily during 11 menstrual cycles. Three of them had to be considered as cycles with corpus luteum insufficiency on the basis of basal body temperature, length of the luteal phase and the pattern of progesterone concentration in serum. One woman conceived during the investigated cycle. The present concepts of the regulation of ovulation are discussed on the basis of the chronological relationshp of changing endocrine parameters in serum during the cycles. The analysis of the hormone concentrations in serum during the cycles with corpus luteum insufficiency supports the view that corpus luteum insufficiency could be caused by an insufficient stimulation of the growing follicle, but other ethiological factors have also to be considered.