GnRH‐agonist deslorelin implant alters the progesterone release pattern during early pregnancy in gilts

The aim of this study was to investigate the relationship of progesterone (P) and luteinizing hormone (LH) during recognition and establishment of pregnancy in the gilt. Therefore, the effects of eliminating episodic LH pulses on P patterns were determined during early pregnancy. To this end, a slow‐release GnRH implant deslorelin was used for GnRH down‐regulation. A group of gilts (GnRHa, n = 8) was implanted with the GnRH‐agonist on Day 11 of pregnancy, while a control group (C, n = 5) was treated with a non‐impregnated placebo implant. Blood was collected via a vena cava caudalis catheter at 10‐min intervals for 8 hr on Day 16 and 21 of pregnancy. As expected, the GnRH implant reduced LH secretion (p < 0.01) and abolished LH pulses completely at Day 16 and Day 21 of pregnancy. On Day 16, there was no difference in P levels between the treatments. However, on Day 21, the GnRH‐agonist treatment led to significantly increased P concentrations (p < 0.01) compared with the control gilts. Progesterone was secreted in a pulsatile manner in both treatment groups and no relationship between LH pulsatility and P pulsatility was observed. In conclusion, abolishment of LH pulsatility did not affect the pulsatile pattern of P secretion but led to an unexpected overall increase in P on Day 21 of pregnancy; this effect was delayed and occurred 10 days after commencing treatment with the GnRH depot agonist. The elevation of P on Day 21 of pregnancy in the GnRHa group suggests either a reduced negative feedback effect or an increased autocrine response by the corpora lutea.     

重度联合免疫缺陷（SCID）小鼠排卵,胚胎发育能力及妊娠母体激素动态

为探讨先天性Ｔ－Ｂ淋巴细胞联合缺陷对生殖功能的影响，用正常ＢＡＬＢ／ｃ小鼠作对照，对重度联合免疫缺陷（ＳＣＩＤ）小鼠的排卵，胚胎（胎儿）发育能力及妊娠体外周血浆促黄体素（ＬＨ）和孕酮（Ｐ）水平的变化进行了研究。首先，观察了妊娠期、窝产仔数，发现ＳＣＩＤ小鼠大多在妊娠第２０天（检栓当天为第１天）凌晨分娩，平均窝产卫数为３．８６±１．６７）只，ＢＡＬＢ／Ｃ小鼠多在妊娠第２０天较晚或第２１天凌晨分娩，平     

孕酮在反刍动物早期妊娠中的免疫耐受作用

孕酮的内分泌调节与免疫功能对动物早期妊娠建立和维持十分重要。目前,在反刍动物生产中,胚胎丢失、早期流产等问题一直困扰着养殖户,而孕酮引起的免疫耐受机制还不很清楚。作者通过介绍孕酮的来源及作用方式、孕酮与机体免疫、孕酮介导妊娠免疫耐受等内容,阐述了孕酮在反刍动物早期妊娠中的免疫耐受作用,为孕酮在妊娠免疫耐受方面的研究提供理论参考。     

Recombinant Equine Luteinizing Hormone Stimulates Production of Progesterone from Murine Leydig, Ovine Small Luteal, and Equine Granulosal Cells

Recombinant equine luteinizing hormone (reLH) was evaluated for its ability to stimulate production of progesterone in cell lines from three species including murine Leydig tumor (MA-10), equine granulosal, and ovine small luteal cells (SLC). The response to reLH was compared with that obtained with human chorionic gonadotropin (hCG), equine chorionic gonadotropin, ovine luteinizing hormone, and equine luteinizing hormone (eLH). Media were collected hourly for 6 hours and assayed for progesterone content through radioimmunoassay. In MA-10 cells, production of progesterone was stimulated above baseline by reLH and hCG (P < .05). Ovine SLC responded to treatment with eLH, reLH, ovine luteinizing hormone, and hCG by increasing production of progesterone above that stimulated by vehicle control (P < .05). Production of progesterone in equine granulosal cells was maximally stimulated by treatment with hCG (P < .05), followed by reLH and eLH (P < .05). In conclusion, reLH elicited a progesterone response in MA-10, ovine SLC, and equine granulosal cells. Thus, reLH stimulates the production of progesterone in cell lines from three species.     

Effects of selenium supplementation on plasma progesterone concentrations in pregnant heifers

It is known that selenium (Se) has various functions in animals. Many investigations on the biochemical and physiological effects of Se have been previously reported; however, the detailed function of Se in reproduction is not yet clear. We proposed the possibility that Se plays a notable role in progesterone production. The aim of this study was to clarify the effects of Se supplementation on progesterone levels of pregnant Holstein heifers. Eight Holstein heifers (?Se) were fed basal diet (containing 0.022 ppm of Se) throughout the experiment. While a 0.3 ppm diet of Se (sodium selenite) was fed to another seven animals (+Se) with basal diet. Blood sampling was carried out every week. Plasma Se concentrations were higher in Se‐supplemented cows compared with controls (?Se) (P < 0.01) throughout the experiment. Se supplementation increased plasma progesterone in the 29–39 weeks of pregnancy from 4.98 ± 0.64 to 6.86 ± 0.49 ng/mL on average (P < 0.05). The present findings suggest that Se contributes to maintaining the function of the corpus luteum and/or placenta in the latter period of pregnancy.     

Luteinizing hormone secretion in hypophysial stalk-transected gilts given hydrocortisone acetate and pulsatile gonadotropin-releasing hormone.

The site within the hypothalamic-pituitary axis at which cortisol acts to inhibit luteinizing hormone (LH) secretion was investigated in female pigs. Six ovariectomized, hypophysial stalk-transected (HST) gilts were given 1 microgram pulses of gonadotropin releasing-hormone (GnRH) iv every 45 min from day 0 to 12. On days 6-12, each of 3 gilts received either hydrocortisone acetate (HCA; 3.2 mg/kg body weight) or oil vehicle im at 12-hr intervals. Four ovariectomized, pituitary stalk-intact gilts served as controls and received HCA and pulses of 3.5% sodium citrate. Jugular blood was sampled daily and every 15 min for 5 hr on days 5 and 12. Treatment with HCA decreased serum LH concentrations and LH pulse frequency in stalk-intact animals. In contrast, serum LH concentrations, as well as the frequency and amplitude of LH pulses, were unaffected by HCA in HST gilts and were similar to those observed in oil-treated HST gilts. We suggest that chronically elevated concentrations of circulating cortisol inhibit LH secretion in pigs by acting at the level of the hypothalamus.     

The effects of luteinizing hormone as a suppression factor for apoptosis in bovine luteal cells in vitro

The fate of the corpus luteum, a transient endocrine gland formed and degraded during an oestrous cycle, is decided by various physiological factors, such as luteinizing hormone (LH). As a stimulator of progesterone, LH is known to maintain corpus luteum functional and structural integrity by inhibiting apoptosis, a programmed cell death. Therefore, we aim to investigate its action during the mid-luteal phase hypothesized that LH suppresses the death mechanism of bovine luteal steroidogenic cells (LSC) by analysing the expression of proteins involved. Cultured bovine LSC obtained from corpus luteum were treated for 24 hr with recombinant TNF and IFNG in the presence or absence of LH. The result showed that LH proved to have a protective effect by increased cell viability (p < .05) and prevented DNA fragmentation (p < .05), as demonstrated by the WST-1 colorimetric assay and TUNEL assay. Expression analysis of mRNA and protein levels showed that LH altered the expression of BCL2 (p < .05), CASP3 (p < .05), FAS (p < .05), and BAX (p < .05) to support cell survival. In conclusion, our study suggests that LH prolongs the corpus luteum life span through the anti-apoptotic mechanism by increasing cell viability and suppressing apoptosis-related genes and protein expression.     

Luteinizing hormone and growth hormone secretion in early lactating Spanish beef cows

The episodic release of luteinizing hormone (LH) and growth hormones (GH) was studied in three suckling regimens and two breeds of Spanish suckled cows. Parda de Montaña (PA) cows (n = 21) were assigned to once‐daily, twice‐daily or ad libitum (ADLIB) suckling. Pirenaica (PI) cows (n = 7) were used to evaluate the breed effect in twice‐daily suckling. Coccygeal blood samples were collected twice weekly during lactation to determine the interval from calving to first ovulation through peripheral progesterone. On day 32 ± 3 post‐partum, jugular blood samples were drawn at 15 min intervals during 8 h to analyse circulating LH and GH. The interval to first ovulation was greater in PA cows suckling ADLIB than in restricted suckling treatment (RESTR1), whereas in RESTR2 it did not differ from the other two treatments. There were no differences between PA and PI cows in the interval to first ovulation. RESTR1 cows showed a tendency to have shorter LH peak widths than ADLIB cows. PA cows showed a tendency to have longer LH peak widths than their PI counterparts. There were no differences across treatments or breeds in any of the GH measures of secretion. The LH release was more affected by breed than by suckling frequency, whereas that of GH was not influenced by any of these parameters. The variables that best allowed discrimination between ADLIB and restricted nursing systems were the interval to post‐partum first ovulation, LH peak number and the mean GH concentration.     

Progesterone Profiles in the Caudal Vena Cava and Jugular Vein in Response to Pulsatile Luteinizing Hormone Stimulation Induced by GnRH Treatment During the Mid-luteal Phase in Lactating Dairy Cows

The aim of this study was to examine whether increased frequency of luteinizing hormone (LH) pulses influences luteal progesterone (P₄) secretion by measuring progesterone concentrations at the secreted (caudal vena cava) and circulating levels (jugular vein) in lactating dairy cows. Cows received six intravenous administrations of 2.5 μg of GnRH (gonadorelin acetate, n=4) or 2 ml saline (n=3) at 1-h intervals on 12.4 ± 0.4 (mean ± SE) days after ovulation. Blood samples were collected from the caudal vena cava and jugular vein every 12 min for 12 h (6 h before and after treatment). During the 6 h after treatment, frequency of LH pulses (5.3 ± 0.3 and 3.0 ± 0.0 pulses/6 h) and mean LH concentration (0.50 ± 0.06 and 0.38 ± 0.05 ng/ml) were greater (P<0.05) in GnRH-treated cows than in saline-treated cows. Mean P₄ concentration and amplitude of P₄ pulses in the caudal vena cava during the 6 h after treatment were greater (P<0.05) in GnRH-treated cows than in saline-treated cows, but the frequency of P₄ pulses was not different between the groups. Mean P₄ concentration in the jugular vein during the 6 h after treatment was also higher (P<0.05) in GnRH-treated cows than in saline-treated cows (7.0 ± 1.3 and 5.4 ± 0.9 ng/ml). These results indicate that the increased frequency of LH pulses stimulates progesterone secretion from the functional corpus luteum and brings about higher P₄ concentrations in the circulating blood in lactating dairy cows.     

The secretion of luteinizing hormone in ewes of Finnish landrace during estrus

The secretion of luteinizing hormone in ewes of Finnish Landrace during estrus. Acta vet. scand. 1979, 20, 216–223. — Luteinizing hormone immunoreactivity was measured in the venous plasma of four cycling Finnish Landrace sheep during the breeding season in connection with one synchronized estrus and the subsequent one. The ewes were slaughtered after the second estrus to establish the number of ovulations. To determine the LH concentration, a heterologous method of assay was used; this was based on the cross reaction of sheep plasma LH in a human LH radioimmunoassay system.As a result of the investigation, it was found that the peaks of LH were lower during the time of synchronized estrus and that these peaks occurred earlier than in the subsequent estrus. However, the differences were not statistically significant. On account of the limited material, the effect of the occurrence of the LH peak on the number of ovulations could not be established.     

Effects of deficiency and surplus dietary threonine on reproductive performance of primiparous pregnant gilts

Dietary threonine imbalance is known to impair reproductive performances of gestating sows, but the underlying mechanisms are largely unknown. In this study, effects of deficiency and surplus dietary threonine during gestation on reproductive performance, serum metabolites and hormones concentration, and colostral nutrient and immunoglobulin contents of primiparous sows were investigated. Ninety primiparous pregnant gilts were assigned to one of the three dietary treatments with different standardized ileal digestible threonine/lysine ratios at 0.59, 0.72 and 0.85, which represented deficient (DT), adequate (AT) and surplus (ST) dietary threonine concentration respectively. Maternal body weight gain from day 80–110 of gestation was highest (p < .05) for gilts fed AT than for gilts fed DT or ST. On days 30 and 110, serum threonine concentration increases in a dose‐dependent manner with the increasing of dietary threonine concentration in (p < .01), serum urea nitrogen concentration was lower (p < .01) in gilts fed AT than DT or ST, and serum insulin‐like growth factor‐I (IGF‐I) was lowest (p < .05) for gilts fed DT. On day 110, gilts fed AT had lower serum progesterone concentration but higher concentrations of serum prolactin (p < .05) compared to DT and ST. Concentration of colostral immunoglobulin A and G from gilts fed DT was lower (p < .05) compared with gilts fed AT or ST. In conclusion, gilts with the adequate threonine intake were more able to conserve dietary amino acids to support foetal and maternal tissue gain. Deficient or ST threonine intake may induce a delay in changes in progesterone and prolactin concentrations during the prepartum period impeding the transition from pregnancy to lactation.     

Luteinizing hormone secretion in ovariectomized gilts: effects of age, reproductive state and estrogen replacement

Crossbred gilts were ovariectomized (OVX) at 120, 150, 180 and 210 d of age to determine whether various characteristics of luteinizing hormone (LH) concentrations are influenced by age and reproductive state (prepuberal vs postpuberal). All 120-d-old gilts were prepuberal and all 210-d-old animals were postpuberal, whereas gilts 150 and 180 d old included both prepuberal and postpuberal animals. Blood was collected at 15-min intervals for 2 h, 2 d before OVX (d -2), and 2 (d +2), 8 (d +8) and 14 (d +14) d after OVX. Mean LH concentrations for prepuberal gilts were similar among age groups (P greater than .05) on d -2 and +2; however, LH increased (P greater than .05) from d -2 to +2. No change in LH secretion was found in postpuberal gilts during these two periods. After OVX, LH increased from d +2 to +14 in both prepuberal and postpuberal gilts in all age groups. In postpuberal gilts, LH increased linearly (P less than .05) between d +2 and +14; rate of increase accelerated with advancing age (P less than .01). In prepuberal gilts, LH increased in a nonlinear manner, but it did not increase between d +2 and +8. The increase observed in prepuberal and postpuberal gilts after OVX resulted primarily from an increase in magnitude of peak concentrations of LH. Implants of estradiol-17 beta (E2) were used to determine whether the postovariectomy increase in LH is affected differently by E2 in prepuberal and postpuberal gilts during advancing ages.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of Kisspeptin on Regulation of Growth Hormone and Luteinizing Hormone in Lactating Dairy Cows

Kisspeptin (KP),a neuroendocrine regulator of reproduction,is hypothesized to be an integrator of metabolism and hormones critical to the regulation of reproduction.Lactation is associated with enhanced growth hormone (GH) responsiveness and reduced fertility.Our study was designed to determine the effects of lactation on KP-stimulated GH and luteinizing hormone (LH) secretion.Five nonlactating and five lactating dairy cows were used in the study.Experiments were conducted with lactating cows at weeks 1,5 and 11 after parturition.The experimental treatments (saline and KP [ 100 and 400 pmol/kg body weight] ) were given intravenously and blood was collected and plasma was stored until later assay to determine concentrations of GH,LH,progesterone and non-esterified fatty acids.We found that neither dose of KP stimulated an increase in GH secretion.The low dose of KP increased (P ＜0.05)LH concentrations only in lactating cows.The higher dose of KP elicited an increase in circulating LH concentrations in both lactating and non-lactating cows.The lower dose of KP increased ( P ＜ 0.05 ) the area under the curve for LH only in cows during week 5 of lactation,and the area under the curve of LH following the highest dose of KP was greater ( P ＜ 0.05 ) in cows during week 5 of lactation than that for the other groups of cows.In summary,lactation status and stage of lactation did not change the sensitivity of the GH system to KP.However,an effect of stage of lactation on KP-stimulated LH secretion was detected in the dairy cows.Study of the KP system during lactation in dairy cows may provide critical insights into the mechanisms for lactation-associated changes in the reproductive axis.     

LH受体在山羊结状神经节中的分布

为了检测山羊迷走神经结状神经节中是否有促黄体生成素受体(LHR)的存在,探讨促黄体生成素(LH)是否能够影响结状神经节内脏感觉神经元的功能活动。本试验采用免疫组织化学SP法观察LHR在结状神经节中的分布特征,利用IPP 6.0图像半定量分析系统分析LHR在结状神经节中阳性神经元和阳性非神经元上的表达量差异。结果显示,LHR主要分布在神经元细胞膜和细胞质中,呈棕黄色为强阳性。在带核的神经元中,神经元细胞核呈圆形空泡状,LHR为阴性反应。神经元群间的神经纤维呈淡黄色,LHR为弱阳性。LHR在神经元胞体上的相对表达量极显著高于节内其他阳性非神经元结构(P0.01)。结果表明,山羊结状神经节内脏感觉神经元是LH作用的主要靶细胞,提示LH有可能通过作用于结状神经节内脏感觉神经元胞体上的LHR参与调节内脏器官感觉信息的传导。     

黑猩猩发情周期观察和促黄体生成素测定

为准确掌握雌性黑猩猩排卵时间以利于人工授精,自2008年1月至2009年6月对长春市动植物公园1只成龄雌性黑猩猩发情表现进行观察,记录发情周期天数,并用不孕检测试纸测定促黄体生成素(LH)的分泌情况。结果显示:黑猩猩发情周期平均35.6 d。跟踪测试黑猩猩的3个发情周期尿液中的LH分泌水平,结果为LH峰值在40~60之间,且峰值出现在发情周期的第21天左右。     

Luteal vascularity and embryo dynamics in mares during early gestation: Effect of age and endometrial degeneration

The present study characterized the luteal status and the dynamic of the conceptus during the first 20 days of gestation in mares with different ages and degrees of endometrial degeneration. Total area of the corpus luteum (CL), luteal vascularity, CL area with blood signals, progesterone concentrations (P4), embryonic vesicle diameter, number of embryonic location changes, embryonic fixation position and uterine contractility were evaluated. In Experiment 1, mares ≤6 years of age (Young group, 5.6 ± 0.2 years, n = 7 mares) and mares ≥15 years of age (Old group, 17.2 ± 0.9 years, n = 6 mares) were used to investigate the effect of age. In Experiment 2, the luteal and embryonic parameters were compared between mares with minimal (Mild group, endometrial category I, n = 9 mares) and severe (Severe group, endometrial category III, n = 7 mares) endometrial degeneration. The Old and Severe groups had greater (p ≤ 0.04) total CL area and reduced luteal vascularity (p ≤ 0.04) than the Young and Mild groups, respectively. However, P4 levels and CL area with blood signals were similar (p ≥ 0.8) between the groups. A negative effect of age (p < 0.01), but not of endometrial degeneration (p = 0.6), was found for the embryonic vesicle diameter. The conceptus mobility was high (p > 0.1) until day 14 of gestation in the Severe group, while a reduced number of changes of the embryo location was detected earlier (p < 0.05) in the Old group. In conclusion, the newly formed CL of aged mares and mares with severe endometrial degeneration suffered a structural remodelling to safeguard the local blood supply and the continuous P4 output during early gestation. Moreover, an earlier reduction of the embryonic mobility and a delayed development of the conceptus were associated with advanced age, regardless of the degree of endometrial degeneration.     

促黄体素受体在母畜生殖道的分布与表达

在多种动物包括灵长类动物、猪、牛、火鸡和人,子宫内都发现有促黄体素(LH)或人绒毛膜促性腺激素(hCG)及其mRNA的结合位点.牛、猪在整个发情周期子宫内都存在LH受体(LHR)蛋白及其mRNA,并在黄体期表达最高.LH通过激活腺苷酸环化酶和磷脂酶C信号途径,增加前列腺素合成酶(PGSH),也称环加氧酶(COX)的活性,从而促进前列腺素(PG)的合成.牛、猪、羊在发情周期的15 d左右PGF2α升高,这与子宫内LHR的活化有关.在不同种动物的输卵管、子宫内膜、子宫肌层和子宫颈,LHR的释放呈现出动态特征,表明LH在发情周期和胚胎附植的分子自分泌-旁分泌调节中可能具有重要的作用.     

发情周期不同阶段牦牛子宫中黄体生成素受体的表达变化

为研究发情周期不同阶段牦牛子宫中黄体生成索受体(LHR)的定位及表达变化,笔者利用免疫组织化学SP法分别检测发情期、发情后期、间情期和发情前期牦牛子宫中LHR的表达,并进行光密度值分析.结果表明,LHR免疫阳性产物在牦牛子宫腺上皮细胞、基质细胞、血管内皮细胞、血管平滑肌细胞和肌层平滑肌细胞中均有表达;腺上皮细胞、基质细胞和肌层平滑肌细胞中LHR在发情前期和发情期表达最弱,发情后期表达增加,间情期表达最强(P＜0.05);子宫内膜血管平滑肌细胞中LHR的表达在发情期最强,间情期最弱(P＜0.05);血管内皮中LHR在发情期和发情前期表达很强,发情后期和间情期显著下降(P＜0.05).结果表明LHR参与了发情周期不同阶段牦牛子宫功能变化的调控.     

Corpus Luteum Vascularization and Progesterone Production in Autumn and Winter Cycles of the Mare: Relationship Between Ultrasonographic Characteristics of Corpora Lutea and Plasma Progesterone Concentration in the Last Cycles Before Anestrus

In 20 estrus cycles of 15 mares, Color Doppler ultrasound of corpora lutea and plasma progesterone concentration (P4) was analyzed on days 6, 10, 14, 16, and 18 after ovulation. Progesterone concentration was positively correlated with corpora lutea cross-sectional area (CSA), vascularized area (VA), and index of vascularization (IV = VA/CSA) (P < .0001). Cross-sectional area, VA, and IV in corpora lutea of mares with P4 < 1 ng/mL were significantly lower than in corpora lutea of mares with P4 > 1 ng/mL. Mares with CSA < 3,473 pixels, VA < 25.5 pixels, and IV < 7.6% were prone to express P4 < 1 ng/mL 25.4, 7.9, and 7.6 times more than mares with higher values, respectively. Corpus luteums analyzed parameters differed significantly between last cycles (LCs) of the breeding season and previous cycles until day 14 after ovulation (P < .05). No significant differences were found in P4 between LCs and previous ones.