Testosterone secretion during early pregnancy in the goat

Increased peripheral concentrations of testosterone were detected on Days 12 and 13 of the estrous cycle (estrus = Day 0), at the onset of luteolysis in goats. In pregnant goats no increases in testosterone occurred between Days 10 and 18 after mating, and luteal regression was inhibited. It is suggested that testosterone is required for luteolysis in goats, and that the absence of any increase in testosterone concentrations is another manifestation of the mechanisms involved in the maternal recognition of pregnancy.     

Hemostatic profile during late pregnancy and early postpartum period in mares

Hemostasis is a physiological process that prevents excessive blood loss and represents a protective mechanism at the time of delivery. Peripartum hemorrhage is a recurring hazardous condition to mare's health; therefore, we aimed to study mares' hemostatic profile to investigate whether physiological adjustments occur during late pregnancy and early postpartum. Fifteen pregnant mares have been monitored from the 34th week of pregnancy until the third week after foaling. Fifteen nonpregnant mares were used as control group. Jugular blood samples were analyzed for platelet count (Plt), prothrombin time (PT), activated partial thromboplastin time (aPTT), and fibrinogen (Fb). Platelet count showed significant changes at foaling (P < 0.05) and a negative correlation (r = −0.968; P = 0.032) with postpartum. Prothrombin time changed (P < 0.05) showing a significant correlation (r = 0.675; P = 0.016) with late pregnancy. Fibrinogen concentrations changed throughout the experimental period (P < 0.0001). The linear regression model revealed a positive correlation (r = 0.9210; P < 0.0001) between Fb and late pregnancy and a negative correlation (r = −0.9583; P = 0.042) between Fb and early postpartum. The shortening in PT recorded in the imminence of parturition along with the increase in Plt and Fb at foaling might reflect a physiological hypercoagulable state that constrains excessive bleeding, enhancing mares' odds of surviving. Our research improves the knowledge about blood coagulation in periparturient mares providing specific information on routine coagulation tests that may support in monitoring mare's hemostatic profile during late pregnancy and early postpartum.     

Uterine contractile activity in mares during the estrous cycle and early pregnancy

Transrectal ultrasonography was used to quantitate uterine contractile activity during the estrous cycle and early pregnancy in pony mares (nonbred, n = 9; pregnant, n = 16). Continuous 1-min scans of longitudinal sections of the uterine body were videotaped, and uterine activity scores (1=minimal activity, 5=maximal activity) were assigned to each tape segment. There was a tendency (P<0.06) for a main effect of reproductive status (nonbred versus pregnant), a main effect of day (P<0.0001), and a reproductive status by day interaction (P<0.006). Uterine activity scores were higher (P<0.05) in pregnant mares on Days 1, 11, 12, and 17 (Day 0=day of ovulation) than in nonbred mares. Maximal activity in pregnant mares occurred on Days 11 to 14 during the reported period of maximal embryo mobility. Activity scores decreased (P<0.05) between the day prior to and the day of fixation (mean = Day 15) of the embryonic vesicle. Activity scores were maintained at an intermediate level for several days following fixation before declining to minimal levels by 7 d postfixation. A postovulatory decrease (P<0.04) in activity scores was observed in nonbred mares, but not in pregnant mares, between Days 0 and 1 followed by a progressive increase (P<0.03) between Days 2 and 4. Maximal activity in nonbred mares occurred during the late luteal phase (Days 13 to 14), corresponding temporally to the reported onset of luteolysis.     

Transrectal Doppler sonography of uterine blood flow during early pregnancy in mares

Transrectal color Doppler sonography was used for the noninvasive investigation of uterine blood flow in five mares. Both the left and right uterine arteries were scanned to obtain blood flow velocity waveforms during two consecutive estrous cycles and two early pregnancies in each mare. Blood flow was expressed as the time-averaged maximum velocity (TAMV) and the resistance index (RI). In all pregnancies the embryonic vesicle could be detected for the first time on Day 11 (day of ovulation: Day 0). No differences in mean TAMV and RI values of both uterine arteries were observed in comparison to the corresponding days of the estrous cycle until Day 11 of pregnancy (P>0.05). From Day 11 onwards, mean TAMV values were higher and mean RI values lower in pregnant mares than in cyclic mares (P<0.05). During the estrous cycle TAMV and RI values did not differ between the right and left uterine arteries (P>0.05). From Days 15 to 29 of pregnancy, TAMV values were consistently higher and RI values lower in the uterine artery ipsilateral to the conceptus and they had a more distinct rise and decline, respectively, compared to the contralateral uterine artery (P<0.05). The variance component estimates for the effect of mare on TAMV and RI values during pregnancy were 60 and 53%, respectively, and for the effect of day of pregnancy, they were 29 and 34%, respectively (P<0.0001). Within mares there were no significant differences between the two pregnancies with regard to blood flow (P>0.05). The results show that uterine blood supply increases in mares during the second week of pregnancy compared to cyclic mares. Furthermore there are individual variations in blood flow between mares.     

Endogenous prostaglandin secretion during cloprostenol-induced abortion in mares

Repeated administration of prostaglandin is the treatment of choice for the termination of pregnancy in mares more than 40 days pregnant. Even though it is well documented that PGF-2 or analogue needs to be administered every 12–24 h for successful induction of abortion, little is known about the underlying endocrine changes and the mechanism by which abortion occurs. The aim of this study was to characterize the changes in PGF-2, progesterone and estrogen secretion during prostaglandin-induced abortion. Six mares, 82–102 days pregnant, were treated daily with 250 μg cloprostenol, blood was collected at 1-h intervals until fetal expulsion and pregnancy examination was performed daily. Four mares, 92–97 days pregnant, received no treatment but were subjected to the same hourly blood collections and daily genital examinations described for cloprostenol-treated mares for 3 days. Mean time from first cloprostenol administration until fetal expulsion was 48.6 ± 5.6 h and required 2.8 ± 0.2 cloprostenol administrations. In all mares, progesterone concentrations decreased in a near linear manner after the first cloprostenol administration and were invariably low (1.3 ± 0.2 ng ml⁻¹, mean ± SEM) at the time of fetal expulsion. Mean estrogen secretion remained unchanged until 5 h before fetal expulsion and then decreased rapidly to non-pregnant levels. Endogenous PGF-2 secretion rate increased with each cloprostenol administration and culminated in sustained PGF-2 secretion which persisted until fetal expulsion was completed. From these results we conclude that cloprostenol-induced abortion is associated with endogenous PGF-2 secretion, fetal expulsion coincides with sustained PGF-2 secretion and low progesterone concentrations and plasma estrogen concentrations remain unchanged until hours before fetal expulsion.     

Uterine and oviducal protein secretion during early pregnancy in the mouse

Changes in the protein composition of the embryo's environment during early development were studied by analysis of proteins synthesized and secreted by oviducal and uterine explants on Days 1-6 of pregnancy. Although secretions from ampullar and isthmic oviduct and uterus contained many proteins in common, each area also produced its own characteristic proteins. In the uterus, changes in the secretion pattern were found during the peri-implantation period, including both increases and decreases in particular proteins which appear to be dependent on the presence of embryos. Embryo-induced effects on uterine secretion began between 09:00 h of Day 4 and 09:00 h of Day 5. Oviducal secretions exhibited many of the embryo-dependent proteins found in the uterus, but the expression of these proteins did not appear to be influenced by the presence of embryos on Day 1 or Day 3. The characteristic pattern of secreted protein expression by each portion of the reproductive tract may reflect the specialization of each area for certain developmental events.     

Endometrial protein secretion during early pregnancy in entire and ovariectomized ewes

The secretion and synthesis of protein in vitro by explants of endometrium were examined in entire ewes during the first 10 days of the oestrous cycle and during an equivalent interval in ovariectomized ewes which received injections of oestradiol and progesterone. The schedule of steroid injections given was designed to simulate endogenous ovarian secretion of progesterone during the luteal phase before oestrus, of oestradiol around oestrus and of progesterone during the luteal phase after oestrus. The rate of protein synthesis and tissue RNA:DNA and protein:DNA ratios in intercaruncular and caruncular endometrium were generally higher in entire than in ovariectomized ewes. In ovariectomized ewes oestradiol increased these activities at 2-4 days after oestrus, whereas progesterone preceding oestradiol caused increases at oestrus, but not thereafter. In entire ewes and in ovariectomized ewes receiving the full steroid treatment regimen, protein secretion was high at oestrus and declined markedly during the next 4-6 days. In ovariectomized ewes not receiving progesterone before oestradiol, secretion increased between 4 and 6 days after oestrus, or during the equivalent stage of treatment in ewes which did not show oestrus. The omission of this progesterone did not modify secretion by caruncular endometrium. Oestradiol increased protein secretion by both tissues. The data suggest that progesterone given before oestradiol (or its equivalent in entire ewes) inhibits the secretion, at about 4-7 days after oestrus, of uterine proteins which may impair embryo development in ovariectomized ewes which do not receive this progesterone.     

Immunohistochemical localisation of progesterone and oestrogen receptors at the placental interface in mares during early pregnancy

Previous reports documenting progesterone receptors (PR) and oestrogen receptors (ER) in the endometrium of early pregnant mares included specimens only up to Day 20 post ovulation. This study aimed to localise PR and ERα on equine feto-maternal tissues between Days 20 and 68 to encompass the period around fixation of the conceptus, development of the endometrial cups and attachment and initial interdigitation of the allantochorion. During early pregnancy mares had the same pattern of PR in the endometrium as that reported for other mammals; namely, a loss of PR from the endometrial epithelia but continued localisation in stromal cells. The spatial arrangement of ERα over the same time period showed cytoplasmic staining of endometrial epithelia and in the nuclei of occasional stromal cells. In the fetal tissues, no cells had PR although ERα was evident in some tissue compartments. No major change in localisation of either receptor was noted throughout the time period examined despite important changes occurring at the placental interface. Nevertheless, these steroid receptor molecules probably play important roles in the production of histotroph and growth factors by the endometrium which go on to stimulate differentiation and growth of the feto-maternal tissues.     

The effect of human chorionic gonadotrophin and exogenous progesterone on luteal function during early pregnancy in pony mares

Previous reports have indicated that repeated administrations of human chorionic gonadotrophin (hCG) to pony mares before day 38 of gestation caused pregnancy failure, but that this could be prevented by the prior or simultaneous administration of progesterone. The present paper describes the circulating progestagen concentrations during these experiments, and shows that pregnancy failure resulted from luteolysis after hCG administration. Most of the mares which received progesterone maintained their pregnancies after hCG injection, but progestagen concentrations fell, suggesting that partial lysis of the corpus luteum occurred. After day 38 of gestation repeated doses of hCG had no effect on plasma progestagen concentrations.     

Concentration of prostaglandins F in uterine venous plasma of anesthetized mares during the estrous cycle and early pregnancy

Prostaglandins F were quantitated by radioimmunoassay in uterine venous plasma of anesthetized mares on day 7 of estrus, days 2, 6, 10, 14 or 18 of diestrus and days 10, 14 or 18 of pregnancy. The PGF concentration was greater (P<.01) at day 14 of diestrus than at all other days studied. The concentrations at days 10 and 18 of diestrus and at days 10, 14 and 18 of pregnancy were greater (P<.05) than at day 7 of estrus and days 2 and 6 of diestrus. PGF concentrations at days 10 and 14 were greater (P<.01) for diestrous than for pregnant mares.     

Soybean-derived phytoestrogens regulate prostaglandin secretion in endometrium during cattle estrous cycle and early pregnancy

Phytoestrogens acting as endocrine disruptors may induce various pathologies in the female reproductive tract. The purpose of this study was to determine whether phytoestrogens present in the soybean and/or their metabolites are detectable in the plasma of cows fed a diet rich in soy and whether these phytoestrogens influence reproductive efficiency and prostaglandin (PG) synthesis during the estrous cycle and early pregnancy in the bovine endometrium. In in vivo Experiment 1, we found significant levels of daidzein and genistein in the fodder and their metabolites (equol and p-ethyl-phenol) in bovine serum and urine. The mean number of artificial inseminations (AIs) and pregnancy rates in two kinds of herds, control and experimental (cows fed with soybean 2.5 kg/day), were almost double in the soy-diet herd in comparison with the control animals. In in vivo Experiment 2, three out of five heifers fed soybean (2.5 kg/day) became pregnant whereas four out of five heifers in the control group became pregnant. The concentrations of a metabolite of PGF2alpha (PGFM) were significantly higher in the blood plasma of heifers fed a diet rich in soybean than those in the control heifers throughout the first 21 days after ovulation and AI. The higher levels of PGFM were positively correlated with equol and p-ethyl phenol concentrations in the blood. In in vitro experiments, the influence of isoflavones on PG secretion in different stages of the estrous cycle was studied. Although all phytoestrogens augmented the output of both PGs throughout the estrous cycle, equol and p-ethyl-phenol preferentially stimulated PGF2alpha output. The results obtained lead to the conclusion that soy-derived phytoestrogens and their metabolites disrupt reproductive efficiency and uterus function by modulating the ratio of PGF2alpha to PGE2, which leads to high, nonphysiological production of luteolytic PGF2alpha in cattle during the estrous cycle and early pregnancy.     

Testosterone secretion during gubernacular development and testicular descent in the dog

Serum testosterone concentrations ranged from 0.24 to 1.45 nmol/l between Day 53 post coitum (p.c.) until Day 40 post partum (p.p.) and did not show variations that could be correlated with the process of testicular descent. The intratesticular androgen appeared to be mainly testosterone, its concentration being about 5000-fold higher than that in serum whereas 5 alpha-dihydrotestosterone could not be demonstrated. The intratesticular testosterone concentration at the initiation of gubernacular regression (Day 0) was apparently, but not significantly, higher than at Day 49 p.c. and at Day 40 p.p. The ability of the neonatal canine testis to synthesize testosterone was indicated by increased serum testosterone concentrations after hCG stimulation.     

Concentration of prostaglandins F in uterine venous plasma of anesthetized mares during the estrous cycle and early pregnancy.

Prostaglandins F were quantitated by radioimmunoassay in uterine venous plasma of anesthetized mares on day 7 of estrus, days 2, 6, 10, 14 or 18 of diestrus and days 10, 14 or 18 of pregnancy. The PGF concentration was greater (P less than .01) at day 14 of diestrus than at all other days studied. The concentrations at days 10 and 18 of diestrus and at days 10, 14 and 18 of pregnancy were greater (P less than .05) than at day 7 of estrus and days 2 and 6 of diestrus. PGF concentrations at days 10 and 14 were greater (P less than .01) for diestrous than for pregnant mares.     

Ovarian estradiol secretion during early pregnancy in monkeys: luteal versus extra-luteal secretion and effect of chorionic gonadotropin.

To determine the locus of ovarian estradiol secretion during early pregnancy, six monkeys were luteectomized (CLx) on days 22 to 24 of pregnancy. Daily peripheral serum concentrations of progesterone were maintained or slightly elevated despite removal of the corpus luteum (CL), while serum estradiol concentrations fell precipitiously (P less than 0.05). It is concluded that the CL of early pregnancy in these monkeys is the primary source of serum estradiol, but that ovarian tissues other than the primary luteal body secrete estradiol at low levels. Further, preliminary results suggest that mCG may be an important stimulus of ovarian estrogen secretion, by both luteal and extra-luteal compartments, in these primates. MCG may stimulate the CL to sustain estradiol secretion even after luteal cells are no longer responsive to this endogenous gonadotropin as regards progesterone secretion.     

Folliculogenesis during the transitional period and early ovulatory season in mares

Individual follicles were monitored by ultrasonography in 15 mares during the transitional period preceding the first ovulation of the year and in 9 mares during the first interovulatory interval. During the transitional period, 7 mares developed 1-3 anovulatory follicular waves characterized by a dominant follicle (maximum diameter greater than or equal to 38 mm) that had growing, static, and regressing phases. The emergence of a subsequent wave (anovulatory or ovulatory) did not occur until the dominant follicle of the previous wave was in the static phase. After the emergence of the subsequent wave, the previous dominant follicle regressed. The mean (+/- s.d.) length of the interval between successive waves was 10.8 +/- 2.2 days. Before the emergence of waves (identified by a dominant follicle), follicular activity seemed erratic and follicles did not reach greater than 35 mm. During the interovulatory interval, 6 mares developed 2 waves (an anovulatory wave and a subsequent ovulatory wave) and 3 mares developed only 1 detected wave (the ovulatory wave). The ovulatory follicle at the end of the transitional period reached 20 mm earlier (Day - 15), grew slower (2.6 +/- 0.1 mm/day; mean +/- s.e.m.) but reached a larger diameter on Day - 1 (50.5 +/- 1.1 mm) than for the ovulatory follicle at the end of the interovulatory interval (Day - 10, 3.6 +/- 0.2 mm/day, 44.4 +/- 1.0 mm, respectively; P less than 0.05 for each end point). The interval from cessation of growth of the largest subordinate follicle to the occurrence of ovulation was longer (P less than 0.05) for end of the transitional period (9.5 +/- 0.7 days) than for the end of the interovulatory interval (6.8 +/- 0.6 days). Results demonstrated the occurrence of rhythmic follicular waves during some transitional periods and the occurrence of 2 waves during some of the first oestrous cycles of the year.     

Body condition during pregnancy and lactation and reproductive efficiency of mares

In Experiment I, 32 mares were equally allotted to the following treatments: mares fed to A) high body condition from 90 days prepartum to foaling and maintained in high body condition to 90 days postpartum, B) high body condition from 90 days prepartum to foaling and allowed to lose body condition to 90 days postpartum, C) lose body condition from 90 days prepartum to foaling and maintained in low body condition to 90 days postpartum, and D) lose body condition from 90 days prepartum to foaling and allowed to gain weight after foaling to attain a high level of body condition by 90 days postpartum. After three cycles, pregnancy rate at 30 days postovulation was lower (P<0.05) in C mares (50%) than in those in the other three groups (100%). Maintenance of pregnancy to 90 days was also reduced (P<0.05) in C mares (25%) when compared with A, D (both 100%) and B mares (88%). Foal growth to 90 days of age was similar in all treatments. In Experiment II, 927 mares were evaluated for body condition and monitored for reproductive performance. Pregnancy rate was lower (P<0.05) and number of cycles/conception was higher (P<0.05) for barren and maiden mares entering the breeding season in thin condition and for pregnant mares foaling in thin condition (condition score less than 5.0) when compared with mares with a higher level of condition. Also, onset of estrus and ovulation appeared to be delayed in barren and maiden mares entering the breeding season in thin condition. Breeding efficiency was enhanced in mares entering the breeding season or foaling at a condition of 5.0 or above. Initial excess stores of body fat enhanced fertility. There were no detrimental effects of excess body fat stored in late gestation.     

Thyroidal and prolactin secretion in agalactic mares

A study was designed to examine serum concentrations of prolactin (PRL) and iodothyronines before and after thyrotropin releasing hormone (TRH) administration to agalactic (n = 26) and normally (n = 8) lactating mares. Two mg TRH was given intramuscularly (i.m.) twice daily on Day 1 (day of delivery) through Day 5. Jugular venous blood was collected on Days 1 and 5 before TRH (time 0) and at 1 and 3 h post-TRH. Basal serum concentrations of thyroxin (T(4)) were different (P < 0.05) on Day 1 (1.87 vs 1.37 mug/dl) and Day 5 (1.72 vs 1.13 mug/dl) in the normal mares and agalactic mares, respectively. There was no difference in the T(4) response to TRH. While basal serum concentrations of triiodothyronine (T(3)) were not different, agalactic mares responded with greater (P < 0.05) serum concentrations T(3) to TRH on Day 1. Following linear regression of the PRL response to TRH, slope of the lines between groups did not differ; however, elevations were significantly (P < 0.05) greater (1.79 vs 1.28 ng/ml) in control mares compared with agalactic mares, respectively, on Day 1.at 1 h post-TRH. A similar difference existed at time 0 and 1 h on Day 5. Consequently, agalactic mares had reduced basal serum T(4) values; the PRL data leads us to suggest that secretion of this hormone may be insufficient in agalactic mares.     

Transrectal Doppler sonography of uterine and umbilical blood flow during pregnancy in mares

Transrectal color Doppler sonography was used to investigate uterine and umbilical blood flow during pregnancy (duration, 46-48 weeks) in four mares. The resistance index (RI) and blood flow volume (VOL) of the uterine arteries ipsilateral and contralateral to the conceptus, and the presence of an early diastolic notch in the Doppler wave, were evaluated every 4 week throughout pregnancy. Fetal blood flow was calculated semiquantitatively every 2 week (from 20 to 40 weeks), using the RI of the umbilical arteries. During the entire period of investigation, there were no significant individual variations in uterine RI and VOL nor differences between the two uterine arteries. Mean RI decreased by more than half during pregnancy from 0.89 +/- 0.01 to 0.39 +/- 0.03, and mean VOL increased almost 400-fold from 69 +/- 37 to 27,467 +/- 8851 ml/min. There were relationships (P<0.0001) between week of pregnancy (x) and RI as well as VOL. These were described by the equations RI=0.938-0.150 ln(x) and VOL (ml/min)=7.621x(2.157). Log transformed total estrogen (TE) were related to RI (r=-0.879; P<0.05) as well as to VOL (r=0.888; P<0.05). The notch in the Doppler wave of the uterine artery disappeared between 18 and 26 weeks. There was a correlation (P<0.0001) between week of gestation (x) and RI values of the umbilical arteries; this was described by the equation RI=1.763-0.071x+0.001x2. Further studies are needed to determine whether transrectal color Doppler sonography could be used to identify mares at risk of abortion.     

Protein synthesis and secretion in human decidua of early pregnancy

Proteins synthesized and secreted by first trimester decidua in primary culture were identified. Explants were cultured for 24 h, in RPMI-1640 or Dulbecco's Modified Eagles Medium containing the radioactive amino acid 35S-methionine or 3H-proline. Electron microscopy of explants before and after 24 h of culture demonstrated the relative purity of the decidua, maintenance of cell integrity, and ultrastructural features indicative of active protein synthesis and secretion. Proteins synthesized and secreted by the explants into the medium were analyzed by fluorography of one-dimensional polyacrylamide gels in the presence of sodium dodecyl sulfate. By comparison of radiolabeled proteins from four women, eight 35S-methionine-labeled bands of 78, 70, 60, 50, 43, 34, 25, and 23 kDa were identified as common decidual peptides. A comparison of autoradiographs of the medium from decidual cultures to decidual cell homogenates showed that seven of these peptides were enriched in the culture medium. When labeled peptides from fibroblast cultures were compared to labeled proteins from decidual cultures each of the common decidual peptides (except the 70 kDa protein) occurred only in the decidual culture medium. Comparison of 3H-proline and 35S-methionine-labeled decidual proteins revealed that the 78, 70, 60, 50, and 34 kDa proteins were of similar fluorographic intensity when labeled with the two different amino acids. The 43, 25, and 23 kDa proteins appeared to contain more methionine, and proteins at 36, 20, 13, and 12 kDa were proline-rich, but contained less methionine. The seven decidual explant-specific, 35S-methionine-labeled secreted proteins were concentrated and purified by preparative gel electrophoresis, and antisera were generated to four of the putative decidual secretory proteins.