Uterine blood flow of cows during the oestrous cycle and early pregnancy: effect of the conceptus on the uterine blood supply.

Blood flow to each uterine horn of cows during the oestrous cycle and early pregnancy was determined daily by use of electromagnetic blood flow probes placed around both middle uterine arteries. The pattern of blood flow to uteri of pregnant and non-pregnant cows was similar until Day 14 after mating or oestrus. Between Days 14 and 18 of pregnancy blood flow to the uterine horn containing the conceptus increased (P less than 0.01) 2- to 3-fold, whereas blood flow to the non-gravid uterine horn in these cows remained constant. No corresponding increase in blood flow to the uterine horn ipsilateral to the ovary bearing the CL was observed in non-pregnant cows during this 4-day period. By Day 19 of pregnancy, blood flow to the gravid uterine horn had returned to a level similar to that observed on Day 13. Blood flow to both uterine horns of pregnant cows remained constant from Days 19 to 25 and then increased to the gravid horn (P less than 0.01) markedly until Day 30 whereas blood flow to the non-gravid horn remained low. Uterine blood flow during the oestrous cycle of non-pregnant cows was positively correlated (P less than 0.01) with systemic concentrations of oestradiol and the ratio of oestradiol (pg/ml) to progesterone (ng/ml). There was no association between oestradiol concentrations and blood flow to the gravid uterine horn. These data indicate local control of uterine blood flow by the bovine conceptus which may function to create optimal conditions for the continuation of pregnancy.     

Acid phosphatase and leucine aminopeptidase activity in the uterine flushings of non-pregnant and pregnant gilts

The activities of uteroferrin, measured as acid phosphatase (AP), and an aminoacylpeptidase (AA) were measured in uterine flushings collected from gilts on Days 6, 8, 10, 12, 14, 15, 16 and 18 of the oestrous cycle and pregnancy (N = 37). Changes in AP (P less than 0.05) were associated with day for both specific and total AP in non-pregnant and pregnant gilts. For pregnant and non-pregnant gilts, AP activity was greatest between Days 14 and 16 and then decreased to Day 18. The AA specific activity increased (P less than 0.01) between Days 10 and 12 of the oestrous cycle and pregnancy, but neither effects of pregnancy nor day by pregnancy status interaction were detected. The AA total activity was greater for pregnant gilts (P less than 0.01). These data suggest an inhibitory effect of oestrogens of blastocyst origin on synthesis and/or secretion of uteroferrin, but not AA.     

Influence of pregnancy on the onset of oestrus and luteal function after prostaglandin-induced luteolysis in cattle

Luteolysis was induced by an injection of 500 micrograms cloprostenol (a prostaglandin (PG) analogue) in pregnant (P) Holstein heifers on Days 17 or 24 of gestation and in non-pregnant (NP) Holstein heifers on Day 17 of the oestrous cycle (oestrus = Day 0). Heifers in Groups P-17 (N = 8) and P-24 (N = 8) were inseminated twice whereas those in Group NP-17 (N = 8) were not inseminated. Immediately after PG injection, embryos were recovered by uterine flushing (400 ml) to confirm pregnancy in Groups P-17 and P-24. Uterine flushing with an equivalent volume of physiological saline was also done in Group NP-17. The interval from PG injection to oestrus and to the peak of luteinizing hormone (LH) as well as profile of increase in plasma oestradiol concentrations during that period did not differ (P greater than 0.1) among the groups. However, the proportion of heifers exhibiting abnormal luteal phases (primarily of short duration) during the oestrous cycle after PG injection was greater (P less than 0.01) in Group P-24 than in Groups NP-17 + P-17 pooled (6/8 vs 3/16). These results suggest that the previous presence of a conceptus did not have any effect on the onset of oestrus, or on plasma concentrations of oestradiol and LH after PG-induced luteolysis on Days 17 or 24 of gestation. However, luteal function during the subsequent oestrous cycle was impaired if heifers were 24 days pregnant when luteolysis was induced.     

Steroid metabolism by endometrial and conceptus tissues during early pregnancy and pseudopregnancy in gilts

Endometrial and conceptus tissues were obtained on Days 10.5, 11, 12, 16 and 25 of pregnancy and Day 25 of pseudopregnancy of gilts and incubated for 6 h in Minimal Essential Medium (5 ml) containing 35 ng [3H]progesterone. Metabolism of [3H]progesterone to oestrone, oestradiol and oestriol was determined by gas and high-pressure liquid chromatography and successive recrystallizations with unlabelled standards. Conceptuses collected between Days 10.5 and 12 were spherical, tubular or filamentous and incubated with 500 mg endometrium and [3H]progesterone. Production of oestrone by spherical conceptuses was not detected, but was 44-47 pg/tubular conceptus and 21 pg/filamentous conceptus. A similar trend was observed for oestradiol. Conceptus tissues from Days 16 and 25 (chorion) were most active in producing oestrone (123 and 520 pg/mg tissue, respectively) and oestradiol (277 and 876 pg/mg tissue, respectively). Endometrial oestrogen production was less than that for conceptus tissue for oestrone and oestradiol on Days 16 and 25 of gestation. Coincubations of endometrium and conceptus tissues had lower oestrogen production than conceptus alone. Endometrium from Day 25 of pseudopregnancy metabolized [3H]progesterone to several non-polar metabolites, but no oestrogens were detected. An unidentified phenolic metabolite of [3H]progesterone was detected in higher quantities than either oestrone or oestradiol; 445 to 461 pg/conceptus at the tubular stage. These results indicate temporal changes in the conversion of [3H]progesterone to oestrogens by conceptus and endometrial tissue from pregnant gilts, but not endometrium from pseudopregnant gilts.     

Effects of prolactin on conceptus survival and uterine secretory activity in pigs

Hypoprolactinaemia was induced by bromocriptine (CB154; 100 mg/day) which decreased circulating prolactin by 40% (P less than 0.06), but did not affect conceptus survival at Day 25 when administered on Days 10-16 when compared to saline:ethanol-treated control gilts. Bromocriptine or vehicle was administered to cyclic gilts on Days 10-11, oestradiol valerate was injected on Day 11 and uterine flushings were collected on Day 12. Total recoverable protein and uteroferrin in uterine flushings were not affected by treatment. However, leucine aminopeptidase activity (P less than 0.02) and total recoverable Ca2+, Na+, K+ and Cl- (P less than 0.05) were decreased in uterine flushings of gilts that received bromocriptine, suggesting that hypoprolactinaemia decreased general secretory activity of the endometrial epithelium and modulated ionic changes, respectively, in the uterine environment of pigs. Subcutaneous administration of pig prolactin (1 mg/12 h) increased (P less than 0.001) serum prolactin 4.5-fold. The interaction between hyperprolactinaemia and progesterone, without oestrogen, on components of uterine flushings were determined using gilts that received progesterone (200 mg/day) and prolactin or saline on Days 4-14 after ovariectomy on Day 4. On Day 15, there were no differences (P greater than 0.05) in any of the uterine secretory components measured. Hyperprolactinaemia (1 mg pig prolactin on Days 6-11) enhanced overall uterine secretory response on Day 12 to oestradiol (5 mg) administered on Day 11 compared to gilts that received 1 ml saline on Days 6-11 of the oestrous cycle. Total recoverable protein and leucine aminopeptidase activity were greater (P less than 0.05) for oestradiol-treated gilts, but effects of prolactin were not significant. Total recoverable glucose (P less than 0.01), PGF-2 alpha (P less than 0.02), uteroferrin (P less than 0.01) and specific activity of uteroferrin (P less than 0.001) were increased by prolactin and oestradiol, but not oestradiol alone. Calcium (P less than 0.05), chloride (P less than 0.05) and potassium (P less than 0.01) were increased in response to oestradiol. These results indicate an interaction between oestradiol and prolactin, but not progesterone and prolactin, which enhances secretion of some products of the pig uterine endometrium.     

Prostaglandin E-2 as a potential luteotrophic agent during early pregnancy in cattle

Heifers slaughtered on Day 18/19 of pregnancy had significantly higher (P less than 0.001) concentrations of PGE-2 (measured as its methyl oxime) in uterine flushings than did animals slaughtered on Days 6 or 12 of pregnancy, or on Days 6 or 12 of the oestrous cycle. In addition, concentrations were higher in the uterine horn ipsilateral to the corpus lueum on Days 12 (P less than 0.05) and 18/19 (P less than 0.01) than in the contralateral horn. Incubation of dispersed luteal cells for 3 h with LH (0.1 or 100 ng/ml) and/or PGE-2 (0.01-1000 ng/ml) in vitro showed no differences in basal progesterone production or in the responses to exogenous hormones between pregnant and non-pregnant cattle. However, low doses of PGE-2 (0.01-10 ng/ml) inhibited the stimulation of progesterone secretion by the lower dose of LH. These findings indicate that although PGE-2 can stimulate progesterone synthesis by luteal cells it may also have inhibitory effects, and therefore its role in pregnancy requires further definition.     

Steroid hormones in uterine washings and in plasma of gilts between days 9 and 15 after oestrus and between days 9 and 15 after coitus

Between Days 9 and 15 after oestrus, concentrations of pregnenolone, pregnenolone sulphate, dehydroepiandrosterone (DHEA), DHEA sulphate, androstenedione, oestrone and oestrone sulphate in free uterine fluid collected from non-pregnant gilts were greater than respective values in plasma (P less than 0.05). The total contents of pregnenolone, progesterone, DHEA, testosterone, oestrone and oestradiol in washings from pregnant uteri exceeded (P less than 0.05) respective non-pregnancy levels during this same period. Concentrations of pregnenolone, pregnenolone sulphate, DHEA, DHEA sulphate, androstenedione, oestrone, oestrone sulphate and oestradiol in free uterine fluid recovered from gravid uteri were also higher (P less than 0.05) than respective plasma values. By contrast, the progesterone concentration in uterine fluid from pregnant animals was lower (P less than 0.001) than the plasma value. Concentrations of DHEA, DHEA sulphate, androstenedione and oestrone sulphate in plasma of pregnant gilts between Days 9 and 15 after mating exceeded (P less than 0.05) the respective concentrations in unmated gilts between Days 9 and 15 after oestrus. Plasma levels of pregnenolone sulphate were lower (P less than 0.05) in the pregnant animals. We therefore suggest that the endometrium of the pig can concentrate steroid hormones in uterine fluid and that increases in steroid levels in this milieu between Days 9 and 15 after coitus reflect steroidogenesis by embryonic tissues and modification of enzyme activities within uterine tissues under the influence of progestagens. The pool of steroid sulphoconjugates present in uterine fluid between Days 9 and 15 post coitum could serve as an important precursor source for progestagen, androgen and oestrogen synthesis by tissues of pig embryos before implantation.     

Hormonal and physical changes associated with bovine conceptus development.

Conceptus (placental membranes, fetal fluids and fetus) development was characterized between Days 27 and 111 of gestation. Progestagens, oestrone, oestradiol, oestrone sulphate and prostaglandins (PG) F were measured in maternal plasma and allantoic and amniotic fluids. Protein concentrations are described for fetal fluids. The early increase in placental membrane weight from 1.12 g (27 days) to 58.45 g (50 days) was associated with oestrogen production presumably of conceptus origin. Oestrogens increased significantly in allantoic and amniotic fluids throughout the period studied with oestrone being the primary free oestrogen, rising from 2 pg/ml (Day 33) to 144 ng/ml by 111 days in allantoic fluid. Changes in plasma oestrogens of the maternal circulation were not detected until after Day 70 at which time oestrone concentration was greater than that of oestradiol. Fetal fluid concentrations of progestagens, oestrone sulphate and PGF were not related to maternal plasma levels and a sequestration of these hormones by the allantois is postulated.     

Monitoring ovarian function and pregnancy by evaluating excretion of urinary oestrogen conjugates in semi-free-ranging Przewalski's horses (Equus przewalskii).

Immunoreactive urinary oestrogen conjugates were assessed in daily urine samples (approximately 5 samples/week) collected from 8 Przewalski's mares maintained under semi-free-ranging pasture conditions. The relative percentage contributions of immunoreactive urinary oestrogens during different reproductive stages (oestrus, luteal phase, early, mid- and late gestation) were determined using high-pressure liquid chromatography. In general, conjugated forms of oestrone (oestrone sulphate and oestrone glucuronide) were the major excreted immunoreactive oestrogens in nonpregnant and pregnant Przewalski's mares. Variations in urinary oestrogen conjugates indicated that the onset of oestrous cyclicity coincided with increasing daylengths, and the non-conception oestrous cycle was 24.1 +/- 0.7 days (n = 17) in duration. Most copulations (29/35, 82.9%) were observed between Day -4 and Day +1 from the preovulatory oestrogen conjugates peak (Day 0). Based on known copulation dates, the mean gestation length was 48.6 +/- 0.4 weeks (range 47.3-50.3 weeks). During pregnancy, urinary excretion of oestrogen conjugates increased approximately 300-fold over levels in non-pregnant mares, reaching peak concentrations by Week +24 (51% of gestation). These results demonstrate that longitudinal reproductive events, including oestrous cyclicity and pregnancy, can be monitored precisely by evaluating urinary oestrogen conjugates in samples from Przewalski's mares maintained under semi-free-ranging conditions.     

Immunosuppressive activity associated with early pregnancy in the bovine

Immunosuppressive activity was assessed in uterine flushings (UF) and uterine vein serum and plasma from nonpregnant and early-pregnant cows, and in media from the short-term culture of Day 18 bovine embryos. The preparations were tested for their ability to inhibit [3H] thymidine (3H-TdR) incorporation into phytohemagglutinin-stimulated bovine lymphocytes. On Days 2-3 (called Day 3), Days 9-10 (called Day 10), and Days 17-19 (called Day 18) of the estrous cycle (estrus = Day 0) and pregnancy, untreated and superovulated cows were anesthesized and jugular vein and uterine vein blood was collected. The uteri were removed and flushed to obtain UF and embryos. Uterine flushings were concentrated and tested for immunosuppressive activity at 400 micrograms uterine protein/ml culture fluid. Uterine flushings from both Day 18 pregnant and Day 18 nonpregnant cows were immunosuppressive (8/8), whereas Day 10 UF were usually not immunosuppressive (7/10). Day 3 UF were usually stimulatory or only marginally suppressive (8/8). Uterine vein serum and plasma from Day 18 cows were not suppressive when compared to jugular vein serum or plasma from the same cow; neither were Day 18 uterine vein serum or plasma suppressive when compared to those same samples taken from Day 3 cows. Embryo culture media obtained from the 48-h culture of Day 18 embryos was consistently suppressive. The activity was lost after dialysis in 1000-Mr cut-off tubing, removed by charcoal, and reduced by protease digestion. These results suggest two mechanisms whereby the embryo could escape immune rejection: 1) the progesterone-induced secretion of a uterine immunosuppressive substance(s) and 2) the production by the embryo of a low molecular weight immunosuppressive substance(s).     

Oestrogen pattern during early pregnancy in the mare.

Plasma total (conjugated + unconjugated) oestrogens were measured from Day 0 to 100 of pregnancy and compared with the levels found during the oestrous cycle. From Day 0 to 35 of gestation, the concentrations were similar to those during dioestrus. An increase in total oestrogens between Days 35 and 40 was followed by a plateau of 3 ng/ml between Days 40 and 60 which was slightly higher than preovulatory concentrations. This first increase in total oestrogen level was produced by the ovaries since values were suppressed after ovariectomy; stimulation may be due indirectly to PMSG causing follicular growth. After Day 60, a second increase was detected and considered to be of feto-placental origin as the levels at this time were not suppressed after ovariectomy. By Day 85, oestrogen concentrations exceeded thos detected in non-pregnant mares so that a direct measurement of total oestrogens in plasma by a simplified radioimmunoassay after Day 85 of gestation offers a reliable method of pregnancy diagnosis.     

Circulating oestrogen concentrations during pregnancy in the African elephant (Loxodonta africana)

Oestrone, oestradiol-17 beta and oestriol were measured in plasma samples from non-pregnant and pregnant African elephants shot in the wild. Enzymic hydrolysis of plasma showed that approximately 90 and 96% of the total (i.e. conjugated plus unconjugated) concentrations of oestrone and oestradiol-17 beta, respectively were represented by conjugated hormones. Unconjugated oestrogens remained low (less than 50 pg ml) in all samples, with no distinction between non-pregnant and pregnant animals. Levels of total oestrone during pregnancy varied between 160 and 594 pg/ml but were not significantly different from non-pregnant values. Total oestradiol-17 beta concentrations were significantly elevated during pregnancy (P less than 0 X 01) and, despite considerable individual variation (193-1428 pg/ml), were consistently higher than non-pregnant values after 6 months of gestation. The elevated levels of oestradiol-17 beta resulted in a reversal of the total oestradiol-17 beta: oestrone concentration ratio at about 6 months of pregnancy. Concentrations of total oestriol did not exceed 103 pg/ml. An indirect method of measurement indicated that oestradiol-17 beta sulphate was probably the most abundant circulating oestrogen during pregnancy in the African elephant.     

Concentrations of oestradiol-17 beta in plasma and corpora lutea throughout pregnancy in the tammar, Macropus eugenii

Oestradiol-17 beta concentrations were measured by radioimmunoassay in peripheral blood samples from 10 tammar wallabies after their pouch young were removed to terminate embryonic diapause. Oestradiol concentrations rose from 8.3 +/- 1.2 pg/ml on Days 3 and 4 to peak of 15.8 +/- 2.9 pg/ml on Day 5, coincident with an increase in 'progesterone' concentrations, and then fell to 10.5 +/- 2.7 pg/ml on Day 7. No changes in oestradiol concentrations were associated with parturition. Five females came into oestrus and mated 9.8 +/- 6.1 h post partum; peak concentrations of plasma oestradiol (20.9 +/- 2.1 pg/ml) occurred around the time of mating. None of the females that did not mate up to the end of the experiment at Day 30 had a rise in plasma oestradiol concentrations. Corpora lutea contained 20-100 pg oestradiol during pregnancy. The highest ovarian oestradiol content (greater than 1200 pg) was measured in whole ovaries containing Graafian follicles from full-term pregnant females. The rise in oestradiol concentrations at Day 5 may be important in the termination of diapause. The post-partum increase in plasma oestradiol concentrations coincides with oestrus. The source of this oestrogen appears to be the preovulatory follicle.     

Plasma and uterine cortisol, progesterone and protein changes in pseudopregnant gilts treated with hydrocortisone acetate

To determine the effects of cortisol concentrations during pregnancy, gilts, made pseudopregnant through twice daily administration of 5 mg estradiol benzoate on Days 11 to 15 (Day 0 = first day of estrus), received either 5 mg/kg body weight of hydrocortisone acetate (HA) in sesame oil (n=5) or sesame oil alone (n=6) twice daily on Days 21 to 30. Blood samples (20 ml) were collected on Days 11, 21 and 31. Uterine flushings were obtained surgically on Day 31. The HA-treated gilts had higher (P<0.01) plasma cortisol (295.7 vs 35.6 ng/ml) and lower (P<0.01) plasma progesterone (8.9 vs 17.8 ng/ml) concentrations than did controls. Uterine flushings recovered from HA-treated gilts had significantly (P<0.01) higher cortisol (9.9 vs 5.6 ng/ml), lower progesterone (2.1 vs 6.8 ng/ml) and lower total protein (8.3 vs 21.4 mg/ml) levels than the control animals. Cortisol measured in the uterine flushings of the gilts was more than 85% unbound. Plasma corticosteroid binding globulin binding capacity was lower (P<0.05) in HA-treated gilts (7.4 nmol/l) than in the control (38.7 nmol/l) animals on Day 31. Corpora lutea (CL) number and weight were lower (P<0.05) in HA-treated than control gilts. However, progesterone concentration per CL did not differ between the 2 groups. These results indicate that elevated cortisol levels can alter endocrine and uterine functions related to pregnancy using the pseudopregnant gilt as a model.     

The effect of intrauterine and cervical manipulation on the equine oestrous cycle and hormone profiles.

Endometrial biopsy or endometrial biopsy and uterine culture taken on Day 4 after oestrus induced lysis of the corpus luteum (CL), resulting in a sharp decline in serum progesterone concentration and shortened the interoestrous interval in 8/12 and 32/33 oestrous cycles, respectively, during 2 experiments. Cervical dilatation 4 days after oestrus shortened the interoestrus interval in 5/10 and 0/5 oestrous cycles. Endometrial biopsy and culture on Days 1 and 3 after oestrus also induced CL lysis during 4 of 7 cycles. Total oestrogen (oestrone plus oestradiol) concentrations increased at the onset of the subsequent oestrus in mares biopsied on Day 4 of dioestrus or in control cycle oestrous periods. Endometrial biopsy also induced lysis of the CL in mares with persistent luteal function. It is postulated that intracervical or intrauterine manipulations during the luteal phase of the oestrous cycle may directly, or indirectly, stimulate the release of an endogenous luteolysin (prostaglandin) resulting in CL regression, followed by oestrus and ovulation in the mare.     

Episodic secretion of gonadotrophins and ovarian steroids in jugular and utero-ovarian vein plasma during the follicular phase of the oestrous cycle in gilts

Blood samples were collected simultaneously from the jugular and utero-ovarian veins of 13 gilts from Days 11 through 16 of the oestrous cycle. A luteolytic dose (10 mg) of PGF-2 alpha was given on Day 12 to facilitate the natural occurrence of luteolysis and standardize the associated decrease in concentrations of progesterone. The mean interval from PGF to oestrus was 5.5 +/- 0.7 days (mean oestrous cycle length = 17.5 +/- 0.7 days). Mean concentrations, pulse amplitudes and pulse frequencies of oestradiol and progesterone were greater (P less than 0.05) in the utero-ovarian than jugular vein. Secretory profiles of LH and FSH were similar (P greater than 0.05) in plasma collected simultaneously from both veins. Based on these data, temporal relationships among hormonal patterns of FSH and LH in the jugular vein and oestradiol and progesterone in the utero-ovarian vein were examined. Concentrations of progesterone declined (P less than 0.05) between Days 12 and 14, while all secretory variables for oestradiol increased (P less than 0.05) from Day 12 through 16 of the oestrous cycle. The pulsatile secretion of FSH remained relatively constant during the experiment. However, both pulse amplitude and mean concentration tended (P less than 0.2) to be lower on Day 16 compared with Day 12. The episodic secretion of LH shifted from a pattern characterized by high-amplitude, low-frequency pulses to one dominated by numerous pulses of diminishing magnitude between Days 13 and 14. From Days 14 to 16 of the oestrous cycle, 91% of all oestradiol pulses were temporally associated with gonadotrophin pulses composed of both FSH and LH episodes. However, pulses of oestradiol (52%) not associated with an episode of LH and/or FSH were observed on Days 12 and 13. These data demonstrate that during the follicular phase of the pig oestrous cycle substantial oestradiol production occurred coincident with luteolysis and before the shift in the episodic secretion of LH. The pool of follicles which ovulated was probably the source of this early increase in the secretion of oestradiol. Therefore, we propose that factors in addition to FSH and LH are involved in the initial selection of follicles destined to ovulate during the early stages of the follicular phase of the pig oestrous cycle. In contrast, high-frequency, low-amplitude pulses composed of LH and FSH were the predominant endocrine signal associated with oestradiol secretion during the second half of the oestrous cycle.(ABSTRACT TRUNCATED AT 400 WORDS)     

Hormonal changes during luteal regression in farmed fallow deer, Dama dama

Concentrations of progesterone, oxytocin and PGFM (pulmonary metabolite of PGF-2 alpha) were measured in plasma from peripheral blood samples collected from 5 fallow does every hour or 2 h for 12-h periods on Days 15-20 inclusive of the oestrous cycle (i.e. luteolysis). For 3 does that exhibited oestrus on Day 21, plasma progesterone concentrations fluctuated between 3 and 10 ng/ml on Days 15-18 inclusive. Thereafter, values declined progressively to attain minimum concentrations of less than 0.05 ng/ml on Day 20. Basal concentrations of plasma oxytocin and PGFM fluctuated between 5 and 20 pg/ml and 10 and 100 pg/ml respectively. Episodic pulses of plasma oxytocin (greater than 300 pg/ml) occurred on Days 15 and 16, whereas pulses of plasma PGFM (greater than 400 pg/ml) occurred on Days 19 and 20. There was little apparent correlation between episodic pulses of the two hormones. For 2 does that exhibited oestrus on Day 22, plasma progesterone concentrations declined to minimum values of 1.0-1.5 ng/ml by Day 20. One of these does showed very high levels of oxytocin secretion throughout the sampling period while the other showed an apparent paucity of oxytocin secretory periods. Two does hysterectomized on Day 13 of their second oestrous cycle failed to exhibit further oestrous cycles. Continual elevation of plasma progesterone concentrations (2-6 ng/ml) for an 8-month period indicated persistence of the corpus luteum after hysterectomy. It is concluded that luteolysis in fallow deer involves episodic secretion of both oxytocin and PGF-2 alpha.     

Prostaglandin production by the early pregnant guinea-pig uterus in relation to implantation and luteal maintenance, and the effect of oestradiol

The outputs of prostaglandin (PG) F-2 alpha and PGE-2, but not of 6-oxo-PGF-1 alpha, from the guinea-pig uterus were significantly lower on Days 7 and 15 of pregnancy than on the corresponding days of the cycle. Uterine PGF-2 alpha output increased 28-fold between Days 7 and 15 of the cycle but only 4- to 5-fold between these same days of pregnancy. Uterine PGE-2 and 6-oxo-PGF-1 alpha outputs increased 2- to 3-fold between Days 7 and 15 of the cycle and of pregnancy. Endometrial PGF-2 alpha synthesizing capacity was 60-70% lower on Days 7 and 15 of pregnancy than on the corresponding days of the cycle, although it increased 2-fold and 2.5-fold between these days of pregnancy and of the cycle, respectively. Endometrial PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities showed no significant variation amongst Days 7 and 15 of the cycle and of pregnancy, except that endometrial PGE-2 synthesizing capacity was lower on Day 7 of the cycle. Oestradiol treatment (10 micrograms s.c. daily from Days 10 to 14 of pregnancy) did not affect plasma progesterone concentrations, uterine 6-oxo-PGF-1 alpha output, and endometrial PGF-2 alpha, PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities in 9/12 guinea-pigs when examined on Day 15. Uterine PGF-2 alpha and PGE-2 outputs increased 3- and 1.5-fold, respectively, in these guinea-pigs, but were still much lower than the outputs from the Day-15 non-pregnant uterus. The pregnancies appeared unaffected in these oestradiol-treated guinea-pigs. In the other 3 oestradiol-treated animals, uterine PGF-2 alpha output was 20- to 30-fold higher than in untreated, pregnant guinea-pigs on Day 15, and 2- to 3-fold higher than in Day-15 non-pregnant guinea-pigs. Uterine PGE-2 and 6-oxo-PGF-1 alpha outputs also tended to be higher in these treated guinea-pigs. In these 3 guinea-pigs, endometrial PGF-2 alpha, PGE-2 and 6-oxo-PGF-1 alpha synthesizing capacities were 4.0-, 3.4- and 2.5-fold higher, respectively, than in untreated, pregnant guinea-pigs on Day 15, and tended to be higher than in Day-15 non-pregnant guinea-pigs. Plasma progesterone concentrations were much lower in these 3 animals than in the other 9 treated with oestradiol, and also much lower than in untreated, pregnant guinea-pigs on Day 15.(ABSTRACT TRUNCATED AT 400 WORDS)     

Influence of SLA haplotype on ovulation rate and litter size in miniature pigs

Systemic blood was collected from and surgery performed on sows of 3 strains of miniature swine bred for specific SLA (swine MHC) haplotypes (a, c and d) from Day 2 to Day 6 after mating (first day of mating = Day 0). Ovulation rate was determined by counting corpora lutea and embryos were flushed from the uterus. Progesterone, oestradiol-17 beta and oestrone were quantitated in blood plasma and uterine flushings by RIA. SLAd/d females had a higher ovulation rate than SLAa/a or SLAc/c females (11.50 +/- 0.87 vs 9.11 +/- 0.68 and 8.17 +/- 0.83, respectively; P less than 0.01). Oestrone was higher than oestradiol-17 beta in systemic plasma (56.5 +/- 6.4 vs 33.0 +/- 4.7 pg/ml, P less than 0.01) while oestradiol-17 beta was higher than oestrone in uterine flushings (19.8 +/- 1.4 vs 14.9 +/- 1.5 pg/horn, P less than 0.10). Systemic progesterone concentration was correlated with day after mating (r = 0.93, P less than 0.01). There was no effect of haplotype on any of the hormone concentrations measured. Litter size was analysed from 99 matings amongst SLAa/a, SLAa/c, SLAa/d, SLAd/c and SLAd/d sires and dams. Litter size from -/d and d/d sows or from d/d boars were larger (P less than 0.05) than for all other matings. Although ovulation rate was higher in SLAd/d sows, the significant effect of sire SLA genotype on litter size suggests an additional effect of the d haplotype on embryonic survival.     

A study of prostaglandin F2α as the luteolysin in swine: V comparison of prostaglandin F, progestins, estrone and estradiol in uterine flushings from pregnant and nonpregnant gilts

Uterine flushings were collected from 38 gilts representing Days 6,8,10,12,14,15,16 and 18 of the estrous cycle and pregnancy. The same group of gilts were represented within each of the respective days of the estrous cycle and pregnancy, i.e., three to six gilts per day per status. Uterine flushings (about 40ml) were assayed for prostaglandin F (PGF), estrone (E₁), estradiol (E₂), progestins (P) and protein. Nonpregnant gilts had higher (P<.01) concentrations of P in uterine flushings than pregnant gilts, but pregnant gilts had higher (P<.01) E₁ and E₂ concentrations. Significant day by status interactions were detected for E₁ (P<.05), but not for E₂ concentrations in uterine flushings. Total recoverable PGF and PGF concentrations in uterine flushings were greater (P<.01) in pregnant than nonpregnant gilts and significant (P<.01) day by status interactions were detected. In nonpregnant gilts, PGF increased between Days 12 and 16, i.e., during the period of corpora lutea (CL) regression. In pregnant gilts, PGF in uterine flushings increased markedly between Days 10 and 18. Total recoverable PGF on Day 18 of the estrous cycle was only 464.5 ± 37.6 ng as compared to 22,688.1 ± 1772.4 ng on Day 18 of pregnancy. Total recoverable protein was also higher (P<.01) in pregnant gilts. These data indicate that PGF synthesis and secretion by the uterine endometrium and/or conceptuses is not inhibited during pregnancy and suggest that PGF is sequestered within the uterine lumen of pregnant gilts, as is the total protein component of endometrial secretions referred to as histotroph.