Comparison of serum estradiol to urinary estrone conjugates in the rhesus macaque (Macaca mulatta)

Paired urine and serum samples were collected daily during fourteen nonconceptive (7 females) and ten conceptive (9 females) ovarian cycles from a total of 12 female rhesus monkeys (Macaca mulatta). Daily urine samples were analyzed for concentrations of estrone conjugates (Ei Conj). Serum samples were evaluated for concentrations of estradiol (E2) and progesterone (P) by radioimmunoassay (RIA), and bioactive luteinizing hormone (bLH) and monkey chorionic gonadotropin (mCG) were analyzed by a mouse Leydig cell bioassay. Linear correlation (r) between urinary E1 Conj and serum E2 (r range = -0.176-0.948) during nonconceptive cycles aligned by the preovulatory E1 Conj peak (Day 0) improved when daily hormone values were realigned to account for an approximately 24-h delay in the excretion of hormonal metabolites in urine (r range = 0.465-0.967). Similarly, correlation between urinary E1 Conj and serum E2 during conceptive cycles aligned by Day 0 (r range = 0.300-0.824) improved when values were offset by 24 h (r range = 0.408-0.876). When conceptive cycles were compared to nonconceptive cycles, serum P levels were significantly elevated over nonconceptive levels by Day +12 (p less than 0.001), and urinary E1 Conj levels by Day +13 (p less than 0.02), whereas serum E2 and bLH were both significantly elevated by Day +14 (p less than 0.0006 and p less than 0.01, respectively). In both nonconceptive and conceptive cycles, urinary E1 Conj paralleled serum E2 and demonstrated incremental increases above baseline levels, which were greater than for serum E2.     

Monitoring luteal function in the lion-tailed macaque (Macaca silenus) through urinary progesterone metabolite measurements

A direct radioimmunoassay for measuring urinary 20-hydroxyprogesterone cross-reactivity to monitor and assess luteal function and detect pregnancy in the lion-tailed macaque (Macaca silenus) is described. Urine samples were collected daily during ten nonconceptive and five conceptive ovarian cycles of five dult female lion-tailed macaques. Urine was analyzed for concentrations of 20α-hydroxypro-gesterone cross-reactivity, estrone conjugates, and creatinine. The strength of the luteal phase in normal nonconceptive cycles (n = 8) is characterized by a maximum sevenfold increase (day 9) in mean 20α-hydroxyprogesterone cross-reactivity over follicular phase levels; the duration, by a 13-day sustained elevation of mean 20α-hydroxyprogesterone cross-reactivity levels. Pregnancy is detectable from 20α-hydroxyprogesterone cross-reactivity values approximately 20 days after the periovulatory estrone conjugate peak (n = 4). Apparent anovulation (n = 1), extended follicular phase (n = 1), and early abortion (n = 1) also are detectable using 20α-hydroxyprogesterone cross-reactivity measurements.     

Urinary steroid evaluations to monitor ovarian function in exotic ungulates: VIII. Correspondence of urinary and plasma steroids in the llama (Lama glama) during nonconceptive and conceptive cycles

Ovarian function was evaluated in mature female llamas (n = 2) during seven ovulations in 2 conceptive and 5 nonconceptive ovarian cycles by measuring urinary and plasma hormone concentrations. Ovulation was induced by three different methods; administration of gonadotropin-releasing hormone (GnRH), copulation with a vasectomized male and copulation with an intact male. Plasma estradiol and progesterone concentrations, and urinary concentrations of estrogen conjugates and two progesterone metabolites, pregnanediol-3-glucuronide (PdG), and immunoreactive (iPdG), concentrations were compared to determine their value in monitoring ovarian function. Estrogen concentrations in urine corresponded to estradiol levels in plasma and accurately reflected changes in follicular activity when evaluated over several daily samples. Plasma progesterone and urinary iPdG were reliable indicators of luteal function. These data represent the first comparison of blood and urinary hormone measurements for monitoring the complete ovarian cycle of an ungulate, and demonstrates that either can be used to assess changes in ovarian activity in this species.     

Monitoring ovulation and implantation in the lion-tailed macaque (Macaca silenus) through urinary estrone conjugate evaluations

Urine samples were collected daily during ten nonfertile and four fertile ovarian cycles of four adult female lion-tailed macaques (Macaca silenus). Urine was analyzed for concentrations of total immunoreactive estrogen (Et), estrone conjugates, and bioactive luteinizing hormones (LH). The estrone conjugates of selected samples were separated by high-performance liquid chromatography (HPLC) to evaluate the relative proportions of estrone glucuronide (E1 G) to estrone sulfate (E1 S) contributing to the sum total of the conjugate measured in the samples. The estrone conjugate profile was found to accurately reflect the preovulatory estrogen peak in both nonfertile and fertile cycles as well as the early pregnancy increase which was found to be statistically significant on Day + 14 postovulation (P = 0.003). Estrone conjugate levels rose in the early follicular phase from 126.00 +/- 24.07 (SEM) ng/mg creatinine to a preovulatory peak of 471.90 +/- 62.95 ng/mg creatinine. Fertile cycles exhibited a postovulatory climb to a peak of 515.00 +/- 38.00 ng/mg creatinine on Day + 19, in contrast to the secondary rise observed in nonfertile cycles that peaked at 148.11 +/- 13.80 ng/mg creatinine on Day + 10. Bioactive LH evaluations confirmed ovulation and, in the fertile cycles, reflected the subsequent elevation of chorionic gonadotropin on Day + 18. The estrone conjugate profile of fertile cycles and early pregnancy compared favorably to the Et profile: both showed the same time course and increases in estrogen excretion.     

Measurement of urinary and fecal steroid metabolites during the ovarian cycle in captive and wild Japanese macaques, Macaca fuscata

We measured the concentration of steroid hormones from urine, feces, and blood samples of two captive Japanese macaques, Macaca fuscata, during nonconceptive ovarian cycles to compare the patterns of the excreted steroids with those of circulating steroids. Urine and feces were analyzed for estrone conjugates (E1C) and pregnanediol-3-glucronide (PdG) using enzyme immunoassays (EIAs), while plasma was analyzed for estradiol-17beta(E2), progesterone (P), and luteinizing hormone (LH) using radioimmunoassays (RIAs). Urinary and fecal E1C and PdG levels were approximately parallel to plasma E2 and P levels, respectively. The E1C profiles of daily urinary and fecal samples revealed a midcycle peak, followed by a sustained PdG increase lasting up to two weeks from the E1C peak. A fecal E1C peak was one day later than the urinary E1C peak. One of the captive females exhibited a discrete plasma LH peak, one indicator that ovulation has occurred, on the day following the urinary E1C peak, i.e., the same day of fecal E1C peak. We measured excreted steroids in nine wild females and determined the timing of ovulation by comparing fecal steroid profiles to those obtained in captive monkeys. Data from wild females indicated that eight of nine females conceived during their first ovulatory cycle of the sampling period, whereas the remaining female failed to conceive during the sampling period even though she ovulated. In the eight females that conceived, E1C increased again following the detected or estimated E1C peak, with levels comparable to the preovulatory peak levels, and sustained elevations of PdG for over 40 days. These data illustrate that the urinary and fecal profiles of ovarian steroid excretion obtained through the application of these noninvasive techniques provide an accurate approach for monitoring conceptive and nonconceptive ovarian cycle in captive and free-living Japanese macaques.     

Urinary steroid evaluations to monitor ovarian function in exotic ungulates: III. Estrone sulfate and pregnanediol-3-glucuronide excretion in the Indian rhinoceros (Rhinoceros unicornis)

A study was undertaken to identify urinary estrogen and progesterone metabolites in the female Indian rhinoceros (Rhinoceros unicornis). Measurements of these metabolites were then used to monitor ovarian function and establish normal levels and patterns of steroid excretion during the estrous cycle and pregnancy. Urine samples were analyzed for estrone sulfate and pregnanediol-3-glucuronide (PDG) by direct radioimmunoassays. Both hormones produced discrete profiles reflecting ovarian activity in nonconceptive cycles. The estrous cycle was observed to be 48 days (range 39–64) with a mean follicular phase of 14.8 days (range 13–19), followed by a mean luteal phase of 19 days (range 17–21). Of the single gestation monitored, PDG levels rose above luteal phase levels by the third month after breeding and remained elevated throughout gestation. The combined estrogen and progesterone metabolite profiles present a complete evaluation of ovarian steriod production in the mature female Indian rhinoceros.     

Relaxin in the marmoset monkey: secretion pattern in the ovarian cycle and early pregnancy.

Relaxin is a peptide hormone with a broad range of biological activities, related not only to parturition and lactation but possibly also to decidualization, implantation, and early pregnancy. The present study was designed to investigate the secretion pattern of relaxin throughout the cycle and early pregnancy in the common marmoset monkey in relation to ovarian function and the systemic hormone milieu. First, a novel relaxin ELISA was developed and validated to confirm the pattern of relaxin secretion during pregnancy. Secondly, serum relaxin profiles were determined through nonconceptive and conceptive cycles and analyzed in relation to the concentration of other hormones and to the development of ovarian follicles and corpora lutea (CL). Blood samples were collected 2-3 times per week from the experimental animals and analyzed for relaxin, progesterone, and LH. The animals from the conceptive cycles were also ultrascanned at these time points to determine the ovarian status up to Day 25 of pregnancy. During early pregnancy, the relaxin levels in serum were approximately 1 ng/ml, increasing up to 15 ng/ml in the second trimester, at a time when progesterone levels had declined. In the third trimester, when progesterone levels were increasing again, the levels of relaxin decreased, returning to basal levels by term of pregnancy. In early pregnancy there was a parallel increase in both relaxin and LH/hCG, with the relaxin rise in the conceptive cycle appearing sooner than in the nonconceptive cycle, suggesting that, like chorionic gonadotropin (CG), relaxin may be a useful and early marker for pregnancy. Unlike the situation in the human, there was no correlation between the levels of either hormone and the number of CL detected, infants born, mother's age, or parity. Relaxin levels increased in early pregnancy before bioactive LH/CG, implying that relaxin is not directly regulated by this gonadotropin. Furthermore, hCG applied to nonconceptive females during the expected time of implantation caused an increase in progesterone but not in relaxin concentrations. In summary, the results obtained indicate that relaxin may be a reliable indicator of early pregnancy status in the common marmoset, but it is independent of direct CG influence.     

The relationship of maternal characteristics and circulating progesterone concentrations with reproductive outcome in the bottlenose dolphin (Tursiops truncatus) after artificial insemination, with and without ovulation induction, and natural breeding

Bottlenose dolphins (Tursiops truncatus) undergoing natural breeding and artificial insemination (AI) were examined to characterize serum progesterone concentrations and determine relationships among age, parity, and reproductive outcome. Progesterone profiles of five cycle types (n = 119 total cycles from 54 animals) were characterized as follows: (i) conception and production of a live term calf (conceptive-term, n = 73); (ii) conception and abortion after Day 60 (conceptive-abortion, n = 12); (iii) unknown conception status with prolonged, elevated progesterone and absence of a fetus (conceptive-unknown, n = 14); (iv) conception failure with normal luteal phase progesterone concentrations (non-conceptive, n = 14, AI cycles only); and (v) conception failure with progesterone insufficiency occuring after spontaneous ovulation or owing to premature ovulation induction using GnRH (non-conceptive-PI, n = 6, AI cycles only). By Day 21 post-insemination (PI), progesterone concentrations were similar (P > 0.05) among conceptive-term, conceptive-abortion and conceptive-unknown, and higher (P < 0.05) for conceptive-term than non-conceptive and non-conceptive-PI cycles. Progesterone concentrations of known conceptive cycles peaked by Week 7 PI (P < 0.05) and remained elevated for the remainder of pregnancy (Weeks 8 up to 54, ≥5 days pre-partum). During midpregnancy (Days 121-240), conceptive-term cycles had higher (P > 0.05) progesterone concentrations than conceptive-abortion and unknown conception status cycles. Parity was not associated with reproductive outcome based on cycle type (P > 0.05). Age of females in conceptive-unknown (26.5 ± 10.1 yrs) and conceptive-abortion (22.1 ± 9.4 yrs) groups was higher (P < 0.05) than in conceptive-term (15.7 ± 7.2 yrs). The conceptive-unknown cycle type possibly represents undetected early embryonic loss occurring before Day 60 PI. Length of gestation using known conception dates was 376.1 ± 11.0 days and the range of this parameter (355-395 days) has implications for peri-parturient management procedures for the species.     

Direct measurements of urinary estrone conjugates during the normal menstrual cycle of the gorilla (Gorilla gorilla)

A direct immunoassay for urinary estrone conjugates (estrone sulfate and estrone glucuronide) was used to assess the preovulatory estrogen rise in normal gorilla menstrual cycles. Immunoreactive estrone conjugates in samples concomitantly assessed for total estrogen immunoreactivity reflected similar profiles throughout the cycle; however, the speed and resolution of the direct assay for conjugates indicate this method to be more accurate in monitoring ovulation than the measurement of total immunoreactive estrogens. In a single conceptive ovarian cycle, urinary estrone conjugate continued to rise in the luteal phase, indicating that this test may also be useful for detecting early pregnancy. The application of this technique provides clear profile of ovarian function in gorillas as well as in other primate species.     

Relationship between variation in conceptus development and differences in estrous cycle duration in ewes

The objective of this study was to examine conceptus development on Day 13 in ewes with estrous cycles of different durations. Ewes (n = 80) were screened according to the length of their estrous cycles. Subsequently, ewes that had either SHORT or LONG cycles were utilized (15.9 +/- 0.1 or 18.6 +/- 0.4 days; mean +/- SEM, p less than 0.01; 10 ewes per group). Jugular blood samples were collected twice daily from Days 0-6 after mating and then once a day until slaughter on Day 13. Concentrations of progesterone in plasma and amounts of ovine trophoblast protein-1 (oTP-1), protein, and prostaglandins (PG) E2 and F2 alpha (PGF2 alpha) in uterine flushings were determined. Concentrations of progesterone were greater (Day by treatment interaction, p less than 0.01) on Days 2-4 for ewes in the SHORT group. On Day 5 and thereafter, progesterone concentrations were not different between groups. More (p less than 0.05) oTP-1 and protein (8.1 +/- 1.3 micrograms and 1.8 +/- 0.3 micrograms versus 2.4 +/- 1.3 micrograms and 0.8 +/- 0.3 mg) were recovered from uterine flushings from ewes in the SHORT versus LONG groups, respectively. The ratio of PGE2:PGF2 alpha was higher (p less than 0.06) in flushings from ewes in the SHORT versus LONG group (1.4 +/- 0.2 versus 0.9 +/- 0.2, respectively). Conceptuses were classified by stage of morphological development. Conceptus development was accelerated (p less than 0.01) in ewes of the SHORT group, as shown by filamentous conceptuses recovered from 78% versus 0% of SHORT versus LONG ewes, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Assessment of fetal number, and fetal and placental viability throughout pregnancy in cattle

Production of identical twin calves by embryo demisection requires a reliable system for continual monitoring of pregnancy. Both halves of bisected embryos were replaced nonsurgically into one uterine horn on Day 7 in 80 recipients. Monthly blood sampling began on Day 22 of pregnancy and transrectal echography took place between 50 and 80 days. Fifty-four recipients had elevated plasma progesterone concentrations on Day 22 (67% pregnancy rate). Of 21 pregnancies diagnosed as twins by echography, 15 live sets were born, 3 singles accompanied by a stillbirth, and 3 complete abortions. Twenty-five singleton pregnancies resulted in 23 live calves, 1 still-birth and 1 abortion. It was not possible to monitor echographically the remaining 8 pregnancies. At all stages of pregnancy studied, mean concentrations of bovine pregnancy-specific protein B (bPSPB) and estrone sulphate were higher (P<0.01) in twin (n = 17) than in single (n = 26) pregnancies, but the high individual variation obviated any predictive value for fetal number. Although bPSPB and estrone sulphate concentrations were positively correlated at most stages of normal pregnancies after Day 100, divergence was observed in the unsuccessful pregnancies between the concentrations of all 3 hormones, suggesting synthesis/release is under independent control. Measurement of bPSPB may be useful for prediction of fetal well-being, whereas estrone sulphate may reflect placental viability.     

Estrogen dynamics in the female rhesus monkey

The metabolic clearance rates (MCR) and interconversions [( rho]BB) values for estrone (E1) and estradiol (E2) in female rhesus (Macaca mulatta) monkeys on Days 9, 14, and 23 of the menstrual cycle were measured using constant infusions of [3H] estradiol and [14C] estrone. The menstrual cycles in these monkeys were reproduced by using Silastic capsules of E2 and progesterone after bilateral ovariectomy. The serum levels of E2 and progesterone were measured by radioimmunoassay and were similar to those for the intact menstrual cycle. The MCR of E2 on Day 14 (52.8 +/- 6.8 l/day/kg) was significantly greater (p less than 0.05) than that measured on Day 9 (31.1 +/- 3.6 l/day/kg) or Day 23 (35.4 +/- 2.1 l/day/kg). The MCR of E1 was also different (p less than 0.05) on Day 14 (77.6 +/- 14.9 l/day/kg) compared to the values on Days 9 and 23 (50.2 +/- 4.9 and 48.2 +/- 3.9 l/day/kg, respectively. There was no change in percentage of free E2, percentage of albumin-bound E2, or sex hormone-binding globulin levels on those 3 days of the cycle. The interconversions between E2 and E1 were not influenced by the day of the cycle. We conclude that the high levels of E2 occurring at the time of the E2 peak result in increases in the MCRs of both E2 and E1 that are not associated with changes in the pattern of protein-binding or in the activity of the 17 beta-hydroxy steroid dehydrogenase.     

Monitoring ovarian function and pregnancy in Eld's deer (Cervus eldi thamin) by evaluating urinary steroid metabolite excretion

Direct radioimmunoassays (RIA) for urinary oestrone conjugates and pregnanediol-3 alpha-glucuronide (PdG) were used to study ovarian activity patterns and pregnancy in Eld's deer. In 2 does, urinary metabolite patterns were compared to temporal patterns of plasma LH, oestradiol-17 beta and progesterone. Preovulatory LH peaks occurred coincident with behavioural oestrus, and plasma progesterone secretion paralleled PdG excretion. Although plasma oestradiol-17 beta levels fluctuated between 5 and 10 pg/ml throughout the oestrous cycle, no preovulatory oestrogen surge was observed. Based on PdG excretion, non-conception oestrous cycles averaged 21.5 +/- 2.1 days (+/- s.e.m., n = 65); however, 2 of 13 does exhibited prolonged oestrous cycles (30.1 +/- 4.4 days; range 14-62 days, n = 14) characterized by sustained PdG excretion. Excluding these 2 females, the mean oestrous cycle was 18.5 +/- 0.3 days (range 14-23 days, n = 51). Behavioural oestrus (12-24 h duration) was observed in 42 of 65 cycles (64.6%), and always corresponded with intercyclic troughs in PdG excretion (2-5 days duration). Mean gestation duration (n = 10) was 33.5 +/- 0.4 weeks. PdG concentrations increased (P less than 0.05) by Week -32 (3rd week of gestation), plateaued between Weeks -31 and -25, increased (P less than 0.05) markedly by Week -22 and then rose steadily until parturition, declining (P less than 0.05) rapidly thereafter. Mean excretion of oestrone conjugates remained low until Week -30, increased (P less than 0.05) steadily to Week -24 (P less than 0.05) and then returned to baseline by Week -17. Increased (P less than 0.05) oestrone conjugates concentrations were detected again by Week -4 followed by a rapid increase to peak pregnancy levels by Week -1, declining (P less than 0.05) precipitously after parturition. The results confirm that the Eld's deer is seasonally polyoestrous with onset (January-March) and cessation (August-October) of regular, cyclic ovarian activity coinciding with increasing and decreasing daylengths, respectively. Urinary PdG excretion accurately reflects cyclic ovarian activity and markedly elevated concentrations of this metabolite provide an accurate index of pregnancy. The simultaneous monitoring of oestrone conjugates appears useful for estimating the stage of pregnancy and predicting parturition onset.     

Oxytocin and bovine parturition: a steep rise in endometrial oxytocin receptors precedes onset of labor.

Oxytocin receptors were measured in myometrium and intercaruncular endometrium of cows during pregnancy and parturition. Concentrations of estradiol-17 beta, estrone, and progesterone in peripheral blood were also measured. Receptor concentrations in the endometrium rose almost 200-fold from Day 20 to term (p < 0.0001, ANOVA), from 40 +/- 11 to 7300 +/- 1430 fmol/mg protein. Myometrial receptor concentrations increased 10-fold from 180 +/- 36 fmol/mg on Day 20 to 1850 +/- 360 fmol/mg protein at term (p < 0.0001, ANOVA). During labor, endometrial receptors (6600 +/- 1300 fmol/mg) remained at prelabor values, whereas myometrial receptor concentrations had decreased to 1190 +/- 316 fmol/mg (not significant) and declined further postpartum. Plasma concentrations of progesterone declined from 4-5 ng/ml to about 2 ng/ml between Days 250 and 282 and dropped to < 0.2 ng/ml shortly before delivery. Plasma concentrations of estrone and estradiol-17 beta were below 10-20 pg/ml until Day 230. Estrone concentrations were significantly (p < 0.05) increased by Day 250 and estradiol-17 beta by Day 270, and then both rose rapidly. During labor, plasma estrone was 1135 +/- 245 pg/ml and plasma estradiol-17 beta was 226 +/- 131 pg/ml. The molar ratio of estrone and estradiol-17 beta to progesterone rose from less than 0.01 to 4.4 during labor, and was correlated with oxytocin receptor concentrations in endometrium (r = 0.5160, p < 0.001), but not those in myometrium (r = 0.0122). The regulation of oxytocin receptors by ovarian hormones in the two tissues may therefore differ.(ABSTRACT TRUNCATED AT 250 WORDS)     

Urinary excretion of estrone glucosiduronate, 17 beta-estradiol-17-glucosiduronate, and estriol-16 alpha-glucosiduronate. Significance of proportionate differences during the menstrual cycle.

The urinary excretion of estrone glucosiduronate, 17 beta-estradiol-17-glucosiduronate, and estriol-16 alpha-glucosiduronate in men and throughout the menstrual cycle in women was measured by specific radioimmunoassay. In 9 men the mean +/- SE excretion of these conjugates was 15.9 +/- 1.4, 2.7 +/- 0.3, and 3.2 +/- 0.2 microgram/24 h respectively. In 15 women studied in the midfollicular phase (day 8) of the menstrual cycle, the excretion was 19.4 +/- 1.7, 2.9 +/- 0.2, and 5.4 +/- 1.3 micrograms/24 h. Excretion of each conjugate was significantly (P less than 0.01) elevated in the midluteal phase (day 22) to 41.9 +/- 3.9, 6.3 +/- 0.8, and 12.2 +/- 1.5 micrograms/24 h respectively (n = 14). The mean excretion of estriol-16 alpha-glucosiduronate was greater than that of 17 beta-estradiol-17-glucosiduronate in the luteal phase (P less than 0.05) but not in the follicular phase or in men (P greater than 0.05). The excretion of each of these specific conjugates measured throughout the menstrual cycle in 7 women was characterized by a sharp midcycle peak and a lower, broader luteal phase peak. The ratios of estriol-16 alpha-glucosiduronate to 17 beta-estradiol-17-glucosiduronate, estrone glucosiduronate to 17 beta-estradiol-17-glucosiduronate, and estriol-16 alpha-glucosiduronate to estrone glucosiduronate throughout the menstrual cycle were analyzed. When the mean ratio during the follicular phase was set at 1, a significant increase (P less than 0.01) occurred in the mean luteal phase ratio in each case: 1.00 +/- 0.03 to 1.66 +/- 0.09, 1.00 +/- 0.04 to 1.30 +/- 0.04, and 1.00 +/- 0.03 to 1.24 +/- 0.04 (mean +/- SE) respectively. The marked alteration in the proportions of these urinary estrogen conjugates may be due to altered metabolism of 17 beta-estradiol, but it more likely reflects a change in the pattern of estrogen secretion or production between the two phases of the menstrual cycle.     

Extension of oestrous cycles and prolonged secretion of progesterone in non-pregnant cattle infused continuously with oxytocin

The experimental objective was to evaluate how continuous infusion of oxytocin during the anticipated period of luteolysis in cattle would influence secretion of progesterone, oestradiol and 13,14-dihydro-15-keto-prostaglandin F-2 alpha (PGFM). In Exp. I, 6 non-lactating Holstein cows were infused with saline or oxytocin (20 IU/h, i.v.) from Day 13 to Day 20 of an oestrous cycle in a cross-over experimental design (Day 0 = oestrus). During saline cycles, concentrations of progesterone decreased from 11.0 +/- 2.0 ng/ml on Day 14 to 2.0 +/- 1.3 ng/ml on Day 23; however, during oxytocin cycles, luteolysis was delayed and progesterone secretion remained near 11 ng/ml until after Day 22 (P less than 0.05). Interoestrous interval was 1.6 days longer in oxytocin than in saline cycles (P = 0.07). Baseline PGFM and amplitude and frequency of PGFM peaks in blood samples collected hourly on Day 18 did not differ between saline and oxytocin cycles. In Exp. II, 7 non-lactating Holstein cows were infused with saline or oxytocin from Day 13 to Day 25 after oestrus in a cross-over experimental design. Secretion of progesterone decreased from 6.8 +/- 0.7 ng/ml on Day 16 to less than 2 ng/ml on Day 22 of saline cycles; however, during oxytocin cycles, luteolysis did not occur until after Day 25 (P less than 0.05). Interoestrous interval was 5.9 days longer for oxytocin than for saline cycles (P less than 0.05). In blood samples taken every 2 h from Day 17 to Day 23, PGFM peak amplitude was higher (P less than 0.05) in saline (142.1 +/- 25.1 pg/ml) than in oxytocin cycles (109.8 +/- 15.2 pg/ml). Nevertheless, pulsatile secretion of PGFM was detected during 6 of 7 oxytocin cycles. In both experiments, the anticipated rise in serum oestradiol concentrations before oestrus, around Days 18-20, was observed during saline cycles, but during oxytocin cycles, concentrations of oestradiol remained at basal levels until after oxytocin infusion was discontinued. We concluded that continuous infusion of oxytocin caused extended oestrous cycles, prolonged the secretion of progesterone, and reduced the amplitude of PGFM pulses. Moreover, when oxytocin was infused, pulsatile secretion of PGFM was not abolished, but oestrogen secretion did not increase until oxytocin infusion stopped.     

Induction of parturition, progesterone secretion, and delivery of placenta in beef heifers given relaxin with cloprostenol or dexamethasone

Sixty primiparous beef heifers from a crossbreeding study were used to examine the effects of inducing parturition with relaxin (3,000 U/mg) combined with cloprostenol (500 micrograms, i.m., n = 30) or dexamethasone (20 mg, i.m., n = 30) at Day 273, 10 +/- 1 days before expected parturition (Day 283). Heifers were assigned at random within cloprostenol and dexamethasone groups to receive relaxin (1 mg, n = 5/treatment), i.m. or in the cervical os (OS), at 0 h (the same time as cloprostenol and dexamethasone) or 24 h later. Eleven and six first-calving heifers and sixteen and nine second-calving cows also received cloprostenol + relaxin and cloprostenol + phosphate-buffered saline, respectively. Radioimmunoassay of daily plasma samples indicated an abrupt decrease in progesterone with time (p less than 0.001), from 7.5 +/- 0.50 to 1.0 +/- 0.30 ng/ml (mean +/- SE) within 48 h for all groups. The mean rate of progesterone decrease (ng/ml in 24 h) was accelerated (p less than 0.01) in relaxin-treated heifers (5.3 +/- 0.36), in contrast to dexamethasone- and cloprostenol-treated control heifers (2.8 +/- 0.40). Relaxin combined with cloprostenol or dexamethasone shortened the calving period in these heifers by reducing the interval between treatment and calving (33 vs. 56 h; p less than 0.01). The incidence and duration of retained placenta were reduced by 22 vs. 75% and 14 vs. 34 h for relaxin combined with cloprostenol or dexamethasone as compared with cloprostenol- or dexamethasone-treated controls, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)     

Failure of human chorionic gonadotropin injections to sustain gonadotropin-releasing hormone-induced corpora lutea in postpartum beef cows

Anestrous postpartum (PP) Hereford cows (n =20) were used to determine the effects of repeated injections of human chorionic gonadotropin (hCG) on the progesterone (P4) secretion and functional lifespan of gonadotropin-releasing hormone (GnRH)-induced corpora lutea (CL). Suckling was reduced to once a day from Day 21 to Day 25 PP, and all cows received injections of 200 micrograms GnRH at 1500 h on Day 24 PP to induce ovulation. Treated cows (HCG, n = 10) received 200 IU hCG b.i.d. from 1900 h on Day 27 PP to 1900 h on Day 33 PP; control cows (CTRL, n=10) were not injected. Blood was collected on Days 21, 23, 25, and 27 to 33, 35, 37, and 39 PP. Serum P4 concentration was measured by radioimmunoassay and used to classify luteal lifespan and the associated estrous cycle as short (SHORT) or normal (NORM) in duration. Treatment with hCG resulted in more (p less than 0.01) cows with SHORT cycles (7 of 9 vs. 4 of 9). Serum P4 concentrations were similar (p greater than 0.20) between groups from 4 days before until 6 days after GnRH injection. Cows with NORM cycles (n = 7) had greater serum P4 concentrations (p less than 0.05) on Days 7 to 11 after GnRH than cows with SHORT cycles (n = 11). By Day 39 PP, all cows with SHORT cycles appeared to have undergone a second ovulation. Charcoal-stripped serum pools from before (PRE) and during hCG injection (INJ) were assayed for total luteinizing hormone-like bioactivity (LH-BA) using a dispersed mouse-Leydig cell bioassay.(ABSTRACT TRUNCATED AT 250 WORDS)     

Endocrine monitoring of the ovarian cycle and pregnancy in the saddle-back tamarin (Saguinus fuscicollis) by measurement of steroid conjugates in urine

Direct measurements of urinary immunoreactive estrone conjugates (E1C) and pregnanediol glucuronide (PdG), were applied to monitoring the ovarian cycle (n = 9) and pregnancy (3 full term pregnancies, 2 mid-term abortions) in Saguinus fuscicollis. During the ovarian cycle, urinary E1C concentrations revealed a high degree of day-to-day variability and appeared to be uninformative in reflecting cyclic ovarian function. In contrast, PdG was a reliable indicator of ovarian cyclicity with excretion patterns corresponding well with plasma progesterone profiles. Luteal phase PdG concentrations were on average 4–7–fold higher than corresponding follicular phase values. On the basis of changes in circulating progesterone, a mean cycle length of 25.7 ±1.0 days with an average follicular phase of 7.1 ± 0.6 days and a mean luteal phase of 18.6 ± 0.7 days, was found (n = 14 cycles). Following conception, both urinary steroid conjugate concentrations increased and elevated levels were maintained beyond the normal luteal phase length, allowing pregnancy to be determined at around day 25–30. During mid- to late pregnancy, PdG levels declined while E1C concentrations continued to be elevated until approximately 6 weeks before parturition when a decrease occurred. Both hormones showed a clear and rapid fall to follicular phase values following termination of pregnancy at either parturition or mid-term abortion. Post partum ovulations (n = 5) occurred on average 17–18 days following birth with four ovulations leading to conceptions. The results demonstrate the potential of urinary steroid conjugate analysis as a practical and reliable method for non-invasive monitoring of reproductive status in the female saddle-back tamarin. © 1995 Wiley-Liss, Inc.     

Urinary concentrations of ovarian steroid hormone metabolites and bioactive follicle-stimulating hormone in killer whales (Orcinus orchus) during ovarian cycles and pregnancy

Reproductive hormone profiles of six captive killer whales (Orcinu orcus) from three Sea World aquaria were studied for intervals up to 2 yr. Daily urine samples and bimonthly blood samples were collected and analyzed for hormone concentration. Immunoreactive estrone conjugates, pregnanediol-3-glucoruonide, 20-alpha-hydroxyprogesterone as well as bioactive follicle-stimulating hormone (FSH) were measured in urine samples and indexed by creatinine concentrations of the same sample. In selected cases, serum progesterone concentrations were also measured. Three of the animals in the study became pregnant during the study period and two of these animals were evaluated during the time of conception and throughout most of gestation. From the data of the three animals that conceived, hormone profiles of the complete ovarian cycle, early pregnancy, and mid- to late gestation are described. The remaining three animals did not conceive and only one of these demonstrated hormone changes that indicated regular ovarian activity. The female reproductive pattern of the killer whale is characterized by a gestation of 17 mo and an ovarian cycle of 6-7 wk in duration. The hormone changes associated with the ovarian cycle of the killer whale are similar to those of most other mammalian species. A bimodal pattern of bioactive FSH with a pronounced rise of estrogen predominates the preovulatory hormone profile. After ovulation, increased progesterone production is observed for approximately 4 wk in the nonconceptive ovarian cycle. During the luteal phase and early pregnancy, when progesterone metabolites are elevated, estrogen metabolite excretion remains low. These data extend the application of urine collections for longitudinal studies involving hormone changes, particularly those involving nondomesticated species.(ABSTRACT TRUNCATED AT 250 WORDS)