反刍动物妊娠识别及早期胚胎死亡

反刍动物妊娠识别及早期胚胎死亡张家骅（西北农业大学兽医系，陕西杨陵７１２１００）孕酮为胚胎发育、维持适宜的子宫内妊娠环境所必需，因此黄体寿命延长并持续分泌孕酮是早期妊娠得以维持的必要条件。本文着重讨论反刍动物母体如何识别胚胎的存在而使黄体得以维持；同...     

反刍动物胚胎附植阶段干扰素-τ对子宫内膜基因表达的影响

胚胎附植是哺乳动物生殖过程中的关键步骤。干扰素-τ是反刍动物特有的妊娠识别信号,在妊娠早期特异表达并发挥重要作用。本文综述了干扰素-τ在反刍动物胚胎附植及胎盘形成早期发挥的作用,总结该阶段受干扰素-τ调控的相关基因,以及干扰素-τ与孕酮、前列腺素、皮质醇在影响子宫内环境中的相互作用,为深入研究反刍动物胚胎附植相关基因和进一步了解其胚胎附植机制提供理论基础。     

奶牛孕酮单克隆抗体的制备及鉴定

奶牛妊娠的早期诊断,对奶牛生产具有重要意义,对于未妊娠母牛失误诊断,会错失下一个情期配种任务的安排,造成产犊间隔延长、繁殖率降低等问题。对早期妊娠的检测有多种方法,临床上通常把血、奶中孕酮的含量作为判断反刍动物怀孕与否的可靠依据。以甾体类激素孕酮为研究对象,利用琥珀酸酐法将11α-羟孕酮活化,运用碳二亚胺法选择BSA为免疫抗原载体,OVA为检测抗原载体与孕酮进行偶联反应,聚丙烯酰胺凝胶电泳表明偶联成功。P-BSA乳化后皮下免疫小鼠,3次免疫后血液效价最大达到1∶(243#10~3)。通过淋巴细胞杂交瘤技术获得针对孕酮的3株单克隆抗体细胞株2H3、2C3、C3H11。3株单抗诱生的腹水经纯化柱纯化,均未与雌二醇发生反应,特异性较好,为尽早检测出未妊娠牛,以适时治疗不孕牛、尽早淘汰劣质牛提供简便迅速的方法。     

酶免疫分析测定法诊断奶牛早期妊娠诊断的研究与应用进展

介绍了酶免疫分析测定法的概念、种类、作用机理,及其在奶牛早期妊娠诊断的研究应用和孕酮酶免疫试剂盒的研究与应用。     

妊娠相关糖蛋白及其在反刍动物早期妊娠诊断中的应用

妊娠相关糖蛋白(pregnancy-associated glycoprotein,PAG)是由胎盘组织产生并释放到母体外周血液中的大分子蛋白,在妊娠过程中发挥着重要作用.目前,母畜妊娠早期诊断的研究多集中在对奶牛伤害小、准确性高、特异性强的间接检测方法上,如检测血液或乳汁中孕酮等激素,而近年来发展起来的对血液中PAG的检测就是一种主流的方法.作者现就PAG的功能、生化特性、母畜怀孕期间PAG的浓度变化及其在反刍动物早期妊娠诊断中的应用情况进行综述.     

米非司酮对怀孕家兔子宫平滑肌收缩影响的观察

哺乳动物妊娠期间，作为同种半异体移植物的胎儿能够在母体子宫内正常生长、分化，并最终发育成为一个完整的个体而不被母体免疫系统所排斥，这一现象已成为生殖免疫学研究的热点。妊娠母体不排斥胎儿的这一免疫耐受现象的调控机理涉及神经、内分泌、免疫等诸多因素，其中孕酮是一种重要因素。近代生殖免疫学观点认为，孕酮是一种天然免疫抑制剂，能够抑制子宫免疫细胞和细胞因子水平的上升，使子宫局部处于免疫抑制状态，而有利于妊娠。同时，生理学观点认为，孕酮“安宫保胎”的作用在于抑制子宫平滑肌的收缩，使子宫对刺激的敏感性降低，…     

建昌黑山羊繁殖期不同生殖激素变化规律的研究

为了揭示建昌黑山羊主要生殖激素在繁殖期不同阶段的分泌规律,试验选择12头建昌黑山羊健康母羊,分别于妊娠早期(妊娠1~90 d)、妊娠晚期(妊娠91~150 d)、泌乳期和空怀期采集血样,分离血清后采用酶联免疫法(ELISA)进行检测,根据标准回归方程得到繁殖期内各阶段雌二醇(E2)、孕酮(P4)、促卵泡激素(FSH)、促黄体素(LH)浓度。结果表明:雌二醇浓度在妊娠期达到峰值,分娩后急剧下降,空怀期比妊娠晚期下降了50.6%,差异显著(P0.05);孕酮浓度呈递减趋势,妊娠早期与空怀期相比差异显著(P0.05),妊娠早期与泌乳期相比差异显著(P0.05),空怀期和泌乳期比妊娠早期分别下降了44.9%和40.7%;促卵泡激素和促黄体素各时期相比均差异不显著(P0.05),两者变化规律一致。说明在建昌黑山羊繁殖周期中,雌二醇、孕酮、促卵泡激素、促黄体素对母羊妊娠、泌乳及间情等繁殖行为具有十分重要的作用。     

绵羊妊娠识别、建立和维持的信号系统

妊娠的建立和维持归因于胚体的信号和黄体对孕酮的产生,在反刍动物,胚体滋养层分泌的激素抑制子宫内膜产生前列腺素PGF2α。在发情周期的绵羊,孕酮下调子宫内膜腔上皮和子宫腺上皮孕酮受体基因的表达,并伴随着上皮雌激素受体和催产素受体的增加。在催产素的作用下,子宫开始分泌溶黄体作用的前列腺素F2α。在妊娠绵羊,孕体滋养层产生的干扰素可作用于子宫内膜而直接抑制雌激素受体基因和催产素受体基因的转录。孕酮、干扰素、胎盘催乳素和生殖激素共同组成了一个"作用网络"来调节子宫的功能分化和子宫腺的形态发生,从而维持绵羊妊娠。本文综述了绵羊妊娠识别、建立和维持的信号系统。     

绵羊妊娠识别、建立和维持的信号系统

妊娠的建立和维持归因于胚体的信号和黄体对孕酮的产生,在反刍动物,胚体滋养层分泌的激素抑制子宫内膜产生前列腺素PGF2α.在发情周期的绵羊,孕酮下调子宫内膜腔上皮和子宫腺上皮孕酮受体基因的表达,并伴随着上皮雌激素受体和催产素受体的增加.在催产素的作用下,子宫开始分泌溶黄体作用的前列腺素F2α.在妊娠绵羊,孕体滋养层产生的干扰素可作用于子宫内膜而直接抑制雌激素受体基因和催产素受体基因的转录.孕酮、干扰素、胎盘催乳素和生殖激素共同组成了一个"作用网络"来调节子宫的功能分化和子宫腺的形态发生,从而维持绵羊妊娠.本文综述了绵羊妊娠识别、建立和维持的信号系统.     

牛、羊妊娠的实验室诊断

1牛妊娠1.1血浆和乳汁孕酮测定法牛受精后血浆和乳汁孕酮含量升高,而且在长时间内保持稳定的水平,因此可以根据孕酮含量的变化进行早期妊娠诊断。测定孕酮现在多采用放射免疫分析法,但该法技术要求都比较高,而且还需要一定的仪器设备。酶联免疫分析可以替代放射免疫分析法用来测定乳孕     

Pregnancy recognition signaling mechanisms in ruminants and pigs

Maternal recognition of pregnancy refers to the requirement for the conceptus (embryo and its associated extra-embryonic membranes) to produce a hormone that acts on the uterus and/or corpus luteum (CL) to ensure maintenance of a functional CL for production of progesterone; the hormone required for pregnancy in most mammals. The pregnancy recognition signal in primates is chorionic gonadotrophin which acts directly on the CL via luteinizing hormone receptors to ensure maintenance of functional CL during pregnancy. In ruminants, interferon tau (IFNT) is the pregnancy recognition signal. IFNT is secreted during the peri-implantation period of pregnancy and acts on uterine epithelia to silence expression of estrogen receptor alpha and oxytocin receptor which abrogates the oxytocin-dependent release of luteolytic pulses of prostaglandin F2-alpha (PGF) by uterine epithelia; therefore, the CL continues to produce progesterone required for pregnancy. Pig conceptuses secrete interferon delta and interferon gamma during the peri-implantation period of pregnancy, but there is no evidence that they are involved in pregnancy recognition signaling. Rather, pig conceptuses secrete abundant amounts of estrogens between Days 11 to 15 of pregnancy required for maternal recognition of pregnancy. Estrogen, likely in concert with prolactin, prevents secretion of PGF into the uterine venous drainage (endocrine secretion), but maintains secretion of PGF into the uterine lumen (exocrine secretion) where it is metabolized to a form that is not luteolytic. Since PGF is sequestered within the uterine lumen and unavailable to induce luteolysis, functional CL are maintained for production of progesterone. In addition to effects of chorionic gonadotrophin, IFNT and estrogens to signal pregnancy recognition, these hormones act on uterine epithelia to enhance expression of genes critical for growth and development of the conceptus.     

Therapeutic Approaches to Pregnancy Loss of Non‐infectious Cause During the Late Embryonic/Early Foetal Period in Dairy Cattle. A Review

The problem of pregnancy loss during the late embryonic/early foetal period due to non‐infectious causes in dairy cattle is on the rise, especially in high milk producing cows. This review discusses recent therapeutic approaches designed to reduce the incidence of early foetal loss. These strategies are based on the fact that low plasma concentrations of progesterone are commonly related to foetal loss. Progesterone supplementation during the late embryonic/early foetal period has proven useful in curtailing losses, mainly in single pregnancies, whereas a more positive effect of treatment with GnRH than progesterone has been found in twin pregnancies. Therapeutics is not necessary in cows with an additional corpus luteum. In practical terms, suggestions include recording the number of embryos and corpora lutea on first pregnancy diagnosis and checking for normal pregnancy progression on day 60 post‐insemination.     

Physiology of the periparturient period and its relation to severity of clinical mastitis

Incidence of clinical mastitis is highest at drying off and during the periparturient period. Intramammary Escherichia coli infection in high-yielding cows can show a severe clinical response during the early post-partum period. Severe clinical mastitis is mainly determined by cow factors, in particular the functionality of the circulating polymorphonuclear leukocytes (PMN) which are recruited to the mammary gland during the inflammatory reaction. There is a co-incidence between the periods of highest incidence of clinical mastitis and specific structural changes in the mammary gland. During the periparturient period, marked changes in various systemic and local hormones are related to the secretory state of the mammary gland epithelium (lactogenesis). Estrogen and progesterone induce proliferation of the mammary epithelium throughout gestation and act as survival factors in different tissues, although conflicting data have been reported on their effect on PMN oxidative burst. Somatotropin (STH), responsible for maintenance of lactation in ruminants, has been shown to positively influence innate immunity and a more rapid recovery in milk production of severely affected animals. The concentration of STH, and as a result also IGF-I levels is, however, quite low during early lactation. IGF-I and its regulating binding proteins are associated with cell survival, modulation of apoptosis and functionality of PMN in humans. During early lactation, bio-availability of IGF-I is decreased, which might reduce its stimulating effects on PMN quality and functionality. PRL, concomitantly known as a lactogenic hormone and an immunoregulatory cytokine, has also been associated with modulation of the immune system. It is expected that in periparturient animals, hormone changes could interfere with the immune response and the clinical response of mastitis.     

Reproduction in the European Mink, Mustela lutreola: Oestrous Cyclicity and Early Pregnancy

Despite efforts undertaken to conserve the endangered European mink, its reproduction is still poorly studied. The aim was to study its reproductive cyclicity, faecal progesterone concentration and ovarian changes during early pregnancy, with the emphasis on the pre-implantation period and implantation. During the 2004 breeding season, oestrous cycle was monitored in 39 females as well as ovarian changes during early pregnancy in 22 females. During the 2007 breeding season, faecal progesterone concentration measured by radioimmunoassay was monitored during pregnancy in 10 females throughout their pregnancy. The breeding season 2004 started on March 18 and ended on May 10, with the peak recorded in April. The duration of first oestrus was 1–12 days. If not mated, the vast majority of females entered second oestrus after 12–55 days. In general, relatively low faecal progesterone values were detected in European mink; an average of 42.69 ± 4.70 ng/g faeces in oestrous females with a maximum of 176.44 ± 23.01 ng/g faeces on pregnancy day 12. anova indicated a significant effect of the pregnancy stage. Post hoc comparisons with Fisher least significant difference (LSD) test revealed that faecal progesterone concentrations on days 8 and 12 post coitum (p.c.), but not at the end of pregnancy (day 40), were higher when compared with the initial oestrous level. Implantation in this species occurs on day 12 p.c. and was indicated by prominent uterine swellings and failure to flush the uterine horns beyond this day. Advanced luteogenesis was observed with prominent corpora lutea found in ovaries around the time of implantation. To conclude, European mink is a seasonally polyoestrous species; the early pregnancy of European mink resembles that of European polecat, i.e. in both species, implantation occurs on day 12 p.c. without any implantation delay.     

Effect of post-insemination progesterone supplementation on pregnancy rate in dairy cows

Progesterone plays an important role in maintenance of pregnancy. It is hypothesized that insufficient progesterone early in pregnancy may result in embryonic loss, and that supplemental progesterone would decrease pregnancy loss in dairy cows. In Experiment 1, 84 cows and 16 heifers from a single dairy operation were selected randomly. Within each age category, controlled internal drug release (CIDR) devices were inserted into the vagina of every other female on Day 4 post-insemination and removed on Day 18 post-insemination. Transrectal ultrasonography was performed to determine pregnancy at 4 time periods [days 30 to 37 (week 5), days 44 to 51 (week 7), days 58 to 65 (week 9), and days 86 to 93 (week 13)]. Progesterone supplementation had no effect on pregnancy rate. In Experiment 2, there were no differences in progesterone concentrations between cows that did and did not receive a CIDR. Further, cows receiving CIDR devices did not have an increase in circulating progesterone concentrations 30 min or 1 h after CIDR insertion. It appears that progesterone supplementation does not increase circulating levels of progesterone in the early pregnant lactating dairy cow. Alterative methods to influence progesterone concentrations and/or early embryonic loss need to be investigated.     

Differential expression of ISG 15 mRNA in peripheral blood mononuclear cells of nulliparous and multiparous pregnant versus non‐pregnant Bos indicus cattle

Embryonic mortality is found to be the main source of reproductive wastage in domestic ruminants. Many genes are involved in the growth and development of the embryo, and the interferon‐stimulated gene 15 (ISG 15) is one of the major gene stimulated by interferon tau, the maternal recognition of pregnancy signal in ruminants. In this study, both genomic and cDNA sequences of ISG 15 from Bos indicus (Deoni breed) were amplified and characterized. The genomic sequence of Deoni ISG 15 exhibited 99% identity with Bos taurus and 97% identity with that of Bos mutus and Bubalus bubalis. Moreover qRT‐PCR analysis revealed constitutive expression of the ISG 15 mRNA in peripheral blood mononuclear cells of Deoni heifers and multiparous cows during early pregnancy. Fourteen Deoni heifers and fifteen multiparous Deoni cows were synchronized for timed AI by CIDR‐Ovsynch protocol, and six animals were kept as cyclic control in each group. Blood samples were collected on days 7, 14, 16, 18, 21, 30 and 45 from the day of AI. Pregnancy was confirmed by plasma progesterone level through ELISA. A significantly higher expression of ISG 15 mRNA was found on day 16 (p < .05) and day 18 (p < .05) of pregnancy in nulliparous heifers. Although in multiparous Deoni cows ISG 15 expression was greater in pregnant cows, difference was statistically non‐significant. The result of this study indicates that ISG 15 gene expression is upregulated during 16–18 days of pregnancy and could be used as an early pregnancy marker in dairy cows especially in heifers.