Foetal loss in dairy goats: function of the adrenal glands, corpus luteum and the foetal-placental unit

Steroid sulfates in domestic mammals and laboratory rodents

Historically steroid sulfates have been considered predominantly as inactive metabolites. It was later discovered that by cleavage of the sulfate residue by steroid sulfatase (STS), they can be (re-)converted into active forms or into precursors for the local production of active steroids. This sulfatase pathway is now a very active field of research, which has gained considerable interest particularly in connection with the steroid metabolism of human steroid hormone-dependent cancer tissue. In comparison, there is much less information available on the occurrence of the sulfatase pathway in physiological settings, where the targeted uptake of steroid sulfates by specific transporters and their hydrolysis could serve to limit steroid effects to a subgroup of potentially steroid responsive cells. In humans, steroid sulfates of adrenal origin circulate in intriguingly high concentrations throughout most of life. Thus, ample substrate is available for the sulfatase pathway regardless of sex. However, the abundant adrenal output of steroid sulfates is a specific feature of select primates. Compared to humans, in our domestic mammals (dogs, cats, domestic ungulates) and laboratory rodents (mouse, rat) research into the biology of steroid sulfates is still in its infancy and information on the subject has so far been largely limited to punctual observations, which indicate considerable species-specific peculiarities. The aim of this overview is to provide a summary of the relevant information available in the above-mentioned species, predominantly taking into account data on concentrations of steroid sulfates in blood as well as the expression patterns and activities of relevant sulfotransferases and STS.

Monitoring of embryonic and fetal losses in different breeds of goats using real-time B-mode ultrasonography

Compared to cattle and sheep, few studies had been undertaken to evaluate the incidence of embryonic and fetal losses (EFL) in goats. The objectives of the present study were to characterize the timing of EFL and to identify the factors that are associated with EFL in goats such as breed, age, parity, method of estrous synchronization, and breeding. Moreover, this study aimed to ensure whether a relationship existed between serum progesterone (P4) and EFL. Goats (n = 151) of different breeds (70 Zaraiebi, 42 Damascus, and 39 Cross goats [Baladi × Damascus]) were evaluated by ultrasonography to monitor EFL during different stages of gestation (D20-23, D26-29, D33-36, D40-45, and D47-54 after breeding). Blood samples were collected at D7, D20, and at each ultrasonographic scanning to clarify changes of serum P4 levels concurrently with EFL. Results revealed that 45 of 109 goats (41.28%) were exposed to EFL. A higher EFL % was observed between D20 to 23 and D47 to 54 (19.61%) compared with D47 to 54 to birth (11.76%). Moreover, a higher EFL % was observed in Zaraiebi goats compared with others. Age and goat parity had no significant effect on the EFL % in all goats. A high EFL % were observed in goats synchronized by P4 sponge, as well as artificially inseminated goats compared with goats with spontaneous estrus, and bred by natural mating, respectively. Serum P4 at D7 or D20 after breeding showed nonsignificant difference between normal pregnant goats and goats that experienced EFL. Unlike goats that experienced partial EFL, goats that experienced total EFL between D20 to 23 and D26 to 29 showed an abrupt P4 reduction (85.06%; P < 0.01) suggesting the probability of endocrine disruption of the CL. However, goats that were exposed to total EFL between D26 and 29 to D33 to 36 showed a low P4 reduction (24.90%; P < 0.05), which might be considered as an effect rather than a cause of EFL. In conclusion, different factors such as breed, estrous synchronization, breeding, and stage of pregnancy may be involved in EFL in goats. Therefore, improvement of the goat management in the early stage of pregnancy is important to decrease EFL % in goats. Although the P4 did not show any significant difference between normal pregnancy goats and goats that experienced EFL, CL disruption should be taken into the consideration, at least, in goats exposed to total embryonic losses.

Plasma estrone sulfate, clinical biochemistry, and milk yield of dairy cows carrying a fetus from a bull or its clone

The aim of this article was to compare plasma estrone sulfate (E1SO4), clinical biochemistry, and milk yield of dairy cows carrying a female fetus from a bull (BULL) or from its clone (CLONE), evaluating also the relationship between the former variables and the birth weight of the newborn. Sixteen recipient dairy Friesian heifers (10 BULL and 7 CLONE) received a female embryo, obtained by in vitro embryo production and sexing by polymerase chain reaction with the semen of the BULL or the CLONE. Blood samples on all cows were obtained before feed distribution in the morning from jugular vein from 4 weeks before to 4 weeks after calving, to be analyzed for metabolic profile. The samples from late gestation were also analyzed for E1SO4 concentration. To separately assess the effect of calf birth weight (CBW), data were categorized as follows: low (<39 kg; BWT-A), mid (39-46 kg; BWT-B), and high (>46 kg; BWT-C). The plasma concentrations of β-hydroxybutyric acid (BHB, P=0.019), Na (P=0.002), Cl (P=0.026), strong cation-anion balance (P=0.020), total bilirubin (P=0.054), and α1-globulin (P=0.044) were higher in prepartum BULL recipients than those in CLONE, whereas BHB (P=0.021) and Mg (P=0.090) were higher in postpartum BULL recipients, while no differences were recorded in the remaining postpartum parameters. The CBW class had significant interaction with week of gestation on antepartum plasma estrone sulfate (P=0.021), whereas CBW per se affected antepartum plasma BHB (P=0.021), and nonesterified fatty acids (NEFA; P=0.011) being higher in BWT-C which also had the lower NEFA concentration during postpartum. Milk yield was unaffected by the sire used, both for quantitative and qualitative aspects. Cows carrying heavier fetus (BWT-C) had a different lactation affected by month compared with the other 2 CBW groups. From these results, there were no differences between BULL and CLONE recipients. Estrone sulfate, BHB, and NEFA may be used to predict CBW and provide different nutritional management during gestation.

Tissue-specific promoter methylation coincides with Cyp19 gene expression in buffalo (Bubalus bubalis) placenta of different stages of gestation

Aromatase is the key enzyme for estrogen biosynthesis and is encoded by Cyp19 gene. Placental cotyledons are the main site of Cyp19 gene expression during pregnancy. The present study was aimed to investigate if DNA methylation and thus epigenetic mechanisms play a potential role in stage-specific regulation of Cyp19 expression in placental cotyledons of pregnant water buffaloes (Bubalus bubalis). Significantly higher expression of Cyp19 gene (p<0.05) in placental cotyledons of early gestation period and post parturition period was found in comparison to mid-gestation placenta. Tissue-specific promoter driven transcript analyses showed that the change in expression was mainly due to change in the relative abundance of transcripts from exon I.1 while the transcripts from exon II showed comparatively less variation. Methylation analysis of 5 CpG dinucleotides of placenta-specific promoter I.1 and proximal promoter, PII showed hypo-methylation of PI.1 in early and term placenta while hyper-methylation in mid-placenta. However, PII was found to be hypomethylated in all the three tissues. In conclusion, result of the present study demonstrated that stage-specific methylation status of PI.1, the major promoter responsible for aromatase expression in buffalo placental cotyledons, coincides with the change in expression of Cyp19 gene in different stages of pregnancy.

Upstream stimulating factors 1 and 2 enhance transcription from the placenta-specific promoter 1.1 of the bovine cyp19 gene

Background

Placenta-derived oestrogens have an impact on the growth and differentiation of the trophoblast, and are involved in processes initiating and facilitating birth. The enzyme that converts androgens into oestrogens, aromatase cytochrome P450 (P450arom), is encoded by the Cyp19 gene. In the placenta of the cow, expression of Cyp19 relies on promoter 1.1 (P1.1). Our recent studies of P1.1 in vitro and in a human trophoblast cell line (Jeg3) revealed that interactions of placental nuclear protein(s) with the E-box element at position -340 are required for full promoter activity. The aim of this work was to identify and characterise the placental E-box (-340)-binding protein(s) (E-BP) as a step towards understanding how the expression of Cyp19 is regulated in the bovine placenta.

Results

The significance of the E-box was confirmed in cultured primary bovine trophoblasts. We enriched the E-BP from placental nuclear extracts using DNA-affinity Dynabeads and showed by Western blot analysis and supershift EMSA experiments that the E-BP is composed of the transcription factors upstream stimulating factor (USF) 1 and USF2. Depletion of the USFs by RNAi and expression of a dominant-negative USF mutant, were both associated with a significant decrease in P1.1-dependent reporter gene expression. Furthermore, scatter plot analysis of P1.1 activity vs. USF binding to the E-box revealed a strong positive correlation between the two parameters.

Conclusion

From these results we conclude that USF1 and USF2 are activators of the bovine placenta-specific promoter P1.1 and thus act in the opposite mode as in the case of the non-orthologous human placenta-specific promoter.

Expression of P450-aromatase in the goat placenta throughout pregnancy

The enzyme P450-aromatase (P450-Aro) is essential for the conversion of androgens to estrogens. The objective was to study the expression and distribution of P450-Aro in goat placentae throughout pregnancy. For this purpose, we used reverse transcription-polymerase chain reaction (RT-PCR) with primers derived from the ovarian cDNA sequence found by our group. The expression of P450-Aro mRNA was first detected by in vitro RT-PCR in cotyledons at 4 months and was still present at term. Based on in situ RT-PCR, cotyledon microvilli expressed P450-Aro mRNA early in pregnancy; the signal was detected in the syncytiotrophoblast and in non-fused cytotrophoblasts inside the microvilli, but was scarce in the interstitial cells of the villous core. In the last 2 months of pregnancy (including at term), the expression of P450-Aro mRNA was still detected in the syncytiotrophoblast. However, P450-Aro was never detected in the caruncule (regardless of stage of pregnancy). In conclusion, P450-Aro was expressed in the goat placenta microvilli starting early in pregnancy; the expression and distribution of the enzyme increased throughout pregnancy and was still present at term.

DNA methylation and chromatin accessibility of the proximalCyp19 promoter region 1.5/2 correlate with expression levels in sheep placentomes

Placental oestrogens play an important role as local regulators of placental growth and differentiation during gestation, and toward term they are also involved in the preparation of parturition. They are synthesized within the fetal cotyledons of placentomes by aromatase cytochrome P450 (P450arom; EC 1.14.14.1), the product of the Cyp 19 gene. The first step of regulation of P450arom expression, and hence enzyme activity and oestrogen production, takes place at the level of Cyp 19 transcription, which is driven by a proximal promoter region, P1.5/2, in the sheep placenta. The aim of the present study was to find out if different Cyp 19 expression levels, which previously had been observed in ovine placentome tissues, correlate with the tissue-specific chromatin structure of the promoter. To this end, we investigated the chromatin structure across the P1.5/2 region in caruncles and cotyledons from 100 and 125 days pregnant ewes, and in term placentae, respectively, by analyzing the DNA methylation and the accessibility to restriction digestion. Our data show that: (1) cotyledonal DNA was significantly lower methylated than caruncular DNA; (2) methylation of cotyledonal DNA was low at 100 and 125 days of pregnancy, and increased to a significant higher level in term placentae; and (3) concurrently, cotyledonal chromatin became inaccessible to restriction digestion at term of gestation. The results imply that DNA methylation and chromatin accessibility of the P1.5/2 promoter region correlate with expression levels of the Cyp 19 gene.

Taxa de gestação em cabras Alpinas e Saanen tratadas com hCG no terceiro dia após o estro

Avaliou-se o efeito da aplicação da gonadotrofina coriônica humana (hCG) sobre a taxa e duração da gestação e sobre a concentração plasmática de progesterona (P4) em cabras lactantes das raças Alpina (83) e Saanen (60), na estação de acasalamento induzida pelo programa de fotoperíodo artificial. Os animais foram distribuídos em dois tratamentos após a cobrição; as cabras do tratamento 1 (T1 controle) receberam solução salina via intramuscular (1ml), e as do tratamento 2 (T2) receberam 250UI do hCG, no terceiro dia no pós-estro. As taxas de gestação, detectadas por exame ultra-sonográfico, realizado no 35º após a cobrição, para as cabras das raças Alpina e Saanen controle e tratadas, foram de 80,4; 70,3; 72,7; 81,5%, respectivamente, não diferindo entre os tratamentos e entre as raças (P>0,05). A taxa média de gestação foi 77,2 e 75,0% para os animais controle e tratados, respectivamente. A duração da gestação não foi influenciada pelos tratamentos (P>0,05). As amostras de sangue para análise da concentração plasmática de progesterona (P4) foram coletadas de cinco cabras Alpina por tratamento, no dia do estro (dia 0) e aos 3, 8, 15, 21, 42 e 60 dias após o estro. Não houve diferença na concentração plasmática média de P4 entre os tratamentos (P>0,05), sendo de 5,84ng/ml para T1 e 5,76ng/ml para T2. Observou-se diferença em relação aos dias de coleta (P<0,05). O hCG aplicado no terceiro dia pós-estro não alterou a taxa de gestação e nem a concentração de P4.

Administration of hCG 5 days after Breeding and Reproductive Performance in Nulliparous Dairy Goats

The objective of this study was to investigate the effect of hCG administration 5 days after breeding on plasma progesterone (P4) concentration and reproductive performance of oestrous-induced nulliparous dairy goats. A total of 59 nulliparous goats (36 Alpine and 23 Saanen) received intravaginal sponges with 60 mg medroxyprogesterone acetate for 9 days plus 200 IU equine chorionic gonadotrophin (eCG) and 22.5 microg d-cloprostenol 24 h before sponge removal. After detection of oestrus (day of oestrus = day 0) and breeding, 49 females were randomly assigned, according to the breed, into two treatments (T1 and T2). In T1 (n = 25) and T2 (n = 24), animals received intramuscular injection of 1 ml of saline solution (control) or 250 IU hCG, respectively, 5 days after breeding. Plasma P4 concentration (ng/ml) was determined from blood sampled on days 0, 5, 7, 13, 17, 21, 28 and 45 after breeding. Animals were scanned by transrectal ultrasound (5 MHz probe) on days 35 and 70 after breeding for detection of pregnancy. Plasma P4 concentration did not differ (p > 0.05) between treatments in all days, but it was increased (p < 0.05) in Saanen than in Alpine goats from days 13 to 45. Pregnancy and parturition rates, litter size and gestation period were similar (p > 0.05) to treatments and breeds. Results of this study indicate that human chorionic gonadotrophin (hCG) administration 5 days after breeding did not significantly alter reproductive performance in dairy nulliparous goats and that plasma P4 differed between Saanen and Alpine goats.

Endocrinology of pregnancy and early pregnancy detection by reproductive hormones in reindeer (Rangifer tarandus tarandus)

The endocrinology was studied throughout pregnancy in reindeer (Rangifer tarandus tarandus) located in Oulu, Finland (65 degrees N, 25 degrees E) with 13 captive, semi domestic adult females. Blood samples were analyzed for plasma progesterone (P4), estradiol (E2) and estrone sulphate (E1SO4), 15-ketodihydro-PGF2alpha (PG-metabolite) and pregnancy associated glycoproteins (PAG). The mean plasma P4 concentration peaked twice during gestation: at around 24 and three weeks prior to calving. In pregnant females the plasma PAG concentration increased over basal concentrations 21-30 days after the estimated day of conception and peaked at the time of calving. The concentrations of E2 and E1SO4 remained low until 60 days before calving when a rapid increase was found for both hormones. The mean plasma concentration of PG-metabolite increased throughout pregnancy to a maximum at parturition. The estimated mean (range) gestation length was 216 (212-220) days. Judged from measures on reproductive organs collected from 86 free-ranging, semi-domestic female reindeer of unknown age presented for slaughter at Roros, Norway (63 degrees N, 11 degrees E) in the second week of December 1999, it was concluded that the breeding season lasted from early September until the end of November. The results also showed that plasma PAG concentration could provide a tool for detection of pregnancy in reindeer.

Fetal death: comparative aspects in large domestic animals

Although the majority of pregnancy failures occur during the embryonic period, reports indicate that approximately 5% of detected pregnancies are lost during the fetal period, underlining the fact that fetal death is a substantial cause of economic loss. However, examination for fetal development or death during pregnancy is not performed routinely in domestic animals, and reference curves for normal fetal growth are, therefore, scarce. In this paper, the numerous possible causes of fetal death are reviewed briefly, with emphasis on the role of placental problems in fetal death and impaired fetal viability. In this respect, the role of placental insufficiency as a cause of pregnancy loss in twin pregnancies in monotocous species is well known, whereas the abnormal placental development leading to retarded fetal growth during pregnancies in recipients of in vitro produced (IVP) or nuclear transfer (NT) embryos has been less extensively documented. Fetal viability or death can be evaluated using hormonal, chemical and ultrasonographic parameters. For example, the viability of the feto-placental unit can be examined by measuring maternal plasma concentrations of oestrone sulphate or the placental proteins, including pregnancy-associated glycoprotein (PAG) and pregnancy-specific protein B-60 (PSPB-60). Low concentrations of any of these three indicate either no pregnancy, or if pregnancy was confirmed earlier, fetal death and abnormally high or low levels can indicate fetal abnormality. Ultrasound can be used to examine the fetal heart rate (FHR), the incidence of fetal movements (FM), the appearance of fetal fluids and the development of the fetus and placenta. However, although abnormal FHRs have been correlated to subsequent fetal death, it is important to remember that there is a large physiological variation in FHR at the end of gestation, due to different behavioural states and differences in FM patterns. Although monitoring fetal viability and death using hormonal and ultrasonographic evaluations is possible during pregnancy in domestic animals, there is considerable physiological variations in the 'normal' values. Therefore, suitable combinations of tests need to be identified and more accurate reference values generated before such approaches can be considered reliable for monitoring the status of individual fetuses.

Cattle and sheep use different promoters to direct the expression of the aromatase cytochrome P450 encoding gene, Cyp19, during pregnancy

Gestagens and oestrogens are important regulators of pregnancy and parturition. The aim of the present study was the comparative quantification of steroidogenic transcripts in placenta and corpus luteum of cattle and sheep during pregnancy and post partum. Cyp19 transcript variants, derived from different promoters, as well as transcripts of Hsd3b, Cyp11A1, and Cyp17, encoding the steroidogenic enzymes P450arom, 3beta-HSD, P450SCC, and P450C17, respectively, were quantified by newly developed real-time PCR assays. All steroidogenic transcripts were detected in ovine and bovine corpus luteum and placenta during pregnancy, however at a very different concentration. In both species Cyp11A1 and especially Hsd3b transcripts predominated in corpus luteum, outnumbering transcripts of Cyp17 and Cyp19 by more than two and three orders of magnitude, respectively. Cyp19 transcript were found at high concentration in the placenta and at a very low concentration in corpus luteum. Cyp17 transcripts had a relatively low concentration in both, placenta and corpus luteum, however showed a peak of expression in the ovine and bovine term placenta. Tissue- and species-specific Cyp19 transcripts derived from different promoters were detected. In order to map all promoters, the bovine Cyp19 locus was reconstructed by in silico analysis. In the placenta, transcripts were primarily derived from the proximal promoter P1.5 in sheep, but from the distally located P1.1 in cattle. Corpora lutea of both species predominantly expressed P1.1 derived transcripts. Contrary to the bovine, the sheep corpus luteum also showed considerable P1.5 derived expression. This demonstrates that cattle and sheep use different promoters to direct Cyp19 expression during pregnancy.