Equine Chorionic Gonadotropin (eCG) improves bucks’ semen quality during the nonbreeding season

In most goat breeds, testosterone serum concentration and semen quality decrease during the nonbreeding season. However, bucks reproductive activity may be stimulated with the administration of equine chorionic gonadotropin (eCG). Therefore, the aim of this study was to determine whether the repeated administration of eCG stimulates the reproductive status of bucks during the nonbreeding season. The study was performed with 19 bucks that were assigned to a group that was treated with eCG (GeCG) and an untreated control group (GCon). The GeCG bucks received an initial dose of 800 IU of eCG (Day 0), followed by four doses of 500 IU administered every 5 days beginning on Day 5. Serum testosterone and anti‐eCG antibody concentrations, testicular and seminal traits were determined until Day 60. Testosterone concentration (from Day 3 to 21: p < 0.0001), anti‐eCG titre (from Day 12 to 44: p ≤ 0.01), percentage of motile spermatozoa (Day 6: p = 0.006 and 14: p = 0.001) and of spermatozoa with progressive motility (Day 6: p = 0.01 and 14: p = 0.002) and the percentage of spermatozoa with functional membrane (Day 6: p = 0.02 and 22: p = 0.008) were higher in GeCG than in GCon bucks. Also in frozen‐thawed samples, the percentage of motile spermatozoa tended to be higher in GeCG than that of GCon bucks (p = 0.07). In conclusion, the administration of eCG during the nonbreeding season stimulated the secretion of testosterone and improved fresh and possibly frozen‐thawed semen quality. However, it also resulted in an increase in anti‐eCG antibody titre.     

The Use of Equine Follicle Stimulating Hormone to Increase Equine Chorionic Gonadotropin in the Pregnant Mare

Equine chorionic gonadotropin (eCG), obtained from pregnant mares, is used for assisted reproductive technologies in laboratory rodents and livestock. The objective of the present study was to use equine follicle-stimulating hormone (eFSH) to increase the incidence of twin pregnancies, through multiple ovulations, and increase eCG. Nineteen light horse–type mares were enrolled in the study. The control group (n = 9) was bred with fresh or cooled semen and given human chorionic gonadotropin (hCG) at the time of breeding. The second group (n = 10) was given 12.5 mg of eFSH intramuscularly twice a day beginning 5–7 days after ovulation. Prostaglandin F2α was administered intramuscularly the second day of eFSH treatment. Treatment with eFSH continued until follicles were >35 mm in diameter, and mares were then given no treatment for 36 hours. The mares were then bred with fresh or cooled semen from the same stallion as the control group and given hCG. Blood samples were taken weekly from day 35 to day 105 after ovulation. Serum concentration of eCG was obtained, and data were analyzed with multivariate analysis using the mixed procedure. Significance was set at P < .05. Data were combined for all mares carrying twins and compared with those carrying singletons. The group of mares carrying twins had higher peak concentrations of eCG and higher values for area under the curve compared with mares carrying singletons (P < .05). These results suggest inducing twins could be a method used to increase eCG production.     

蒙古马、纯血马eCG分泌水平的研究

本实验通过ELISA检测不同生理状态下的蒙古马和纯血马妊娠母马在妊娠30～100d体内eCG的表达水平,比较品种、母马年龄、胎儿性别对母马eCG分泌水平的影响。结果表明:蒙古马eCG效价在妊娠第60天出现峰值,平均值为82.1IU/mL,100d出现最低值16.6IU/mL,年龄对蒙古马eCG表达水平有影响,3～5岁组极显著高于大于10岁组(P0.01)。纯血马在妊娠60deCG效价到达峰值,平均值为64.8IU/mL,在妊娠第30天出现最低值10.8IU/mL。怀雌性胎儿纯血马eCG分泌水平极显著高于怀雄性胎儿的纯血马(P0.01)。蒙古马eCG的表达水平极显著高于纯血马(P0.01)。     

Ultrasonographic Characteristics of Ovulatory Follicles and Associated Endocrine Changes in Cyclic Ewes Treated with Medroxyprogesterone Acetate (MAP)-releasing Intravaginal Sponges and Equine Chorionic Gonadotropin (eCG)

The aim of this study was to assess the ultrasonographic characteristics of ovulatory follicles in cyclic Western White Face ewes (December) that had received intravaginal sponges containing medroxyprogesterone acetate (MAP; 60 mg) for 12 days, with or without an injection of 500 IU of equine chorionic gonadotropin (eCG) at sponge removal. We hypothesized that quantitative echotextural attributes of the follicles in ewes treated only with MAP would differ from those in MAP/eCG-treated ewes, reflecting the increased antral follicular growth and secretory function under eCG influence. Digital images of ovulatory follicles obtained at 0 and 24 h after MAP sponge removal and at 24 h before ovulation in the eCG-treated (five ewes, 13 follicles) and control (six ewes, 9 follicles) animals, were subjected to computerized analyses. The mean diameter of ovulatory follicles increased (p < 0.001) 24 h after eCG treatment. The mean pixel intensity and heterogeneity of the follicular antrum (p < 0.001), as well as mean pixel intensity of the follicular wall and perifollicular ovarian stroma (p < 0.05), were greater in eCG-treated animals compared with control ewes 24 h after sponge removal and at 24 h before ovulation. Mean serum concentrations of oestradiol-17beta tended to increase (p = 0.06) 24 h after eCG treatment and the eCG-treated ewes exceeded (p < 0.05) control animals in progesterone concentrations from days 9-15 after ovulation. Our results support the hypothesis that large antral follicles in eCG-treated ewes exhibit distinctive echotextural characteristics. Follicular image attributes in eCG-treated ewes appear to be indicative of the changes in follicular morphology and secretory activity caused by the administration of the exogenous gonadotropin, which has both FSH- and LH-like activities.     

马绒毛膜促性腺激素单克隆抗体的制备及鉴定

本研究采用马绒毛膜促性腺激素(equine chorionic gonadotropin,eCG)纯品免疫BALB/c小鼠,取其脾细胞与同系小鼠骨髓瘤细胞SP2/0按1∶10融合,间接酶联免疫吸附法(ELISA)筛选阳性克隆和有限稀释法克隆,扩大培养后于小鼠腹腔制备腹水,共得到8株能稳定分泌单克隆抗体的杂交瘤细胞株,采用间接ELISA测定抗体效价,效价均达10^-5以上。用获得的杂交瘤细胞株制备单克隆抗体,为eCG分泌水平的ELISA检测方法的建立确立了条件。     

The Role of Equine Chorionic Gonadotropin in the Stimulation of Luteal Steroidogenesis in Mares Carrying Horse or Mule Pregnancies

The stimulatory role of equine Chorionic Gonadotropin (eCG) in the production of steroid hormones was evaluated during the first 4 months of pregnancy in mares impregnated by either stallions or jack donkeys. Twenty mares were divided in two groups: Mares in the first group were inseminated with stallion semen (horse pregnancies), and those in the second group were inseminated with donkey semen (mule pregnancies). Blood samples were collected twice weekly from day 30 to day 120 of pregnancy to determine the concentrations of eCG, progesterone, androstenedione, and testosterone. Analysis of variance for repeated measures was used to compare the concentrations of each hormone between groups. Linear regression models that considered the linear and quadratic effects of week of gestation as well as the linear and quadratic effects of the concentrations of eCG on the production of each steroid hormone were carried out. Concentrations of eCG, progesterone, and androstenedione were higher in horse than in mule pregnancies (P < .01 for eCG and P < .05 for progesterone and androstenedione). Testosterone concentrations were also higher in horse pregnancies than in mule pregnancies at weeks 7, 9, and 10 (P < .05). Regression analysis indicated that eCG had considerable stimulatory effects on the secretion of progesterone and androstenedione and weaker effects on the secretion of testosterone. The results suggest that eCG stimulates luteal production of progesterone, androstenedione, and testosterone in horse and mule pregnancies, these effects being more evident in horse pregnancies than in mule pregnancies due to the higher concentrations of eCG in horse pregnancies.     

Equine Chorionic Gonadotropin and Human Chorionic Gonadotropin Stimulation Increase the Number of Luteinized Follicles and the Progesterone Level Compared with Cabergoline Stimulation in Anoestrus Bitches

In this study, ovarian morphologies and blood progesterone concentrations following oestrous induction in bitches were examined. Fifty‐three clinically healthy anoestrus bitches received cabergoline at a daily dose of 5 μg/kg of body weight per os for 21 days (group I) or subcutaneous equine chorionic gonadotropin at a dose of 20 IU/kg of body weight for five consecutive days with an additional 500 IU s.c. per bitch of human chorionic gonadotropin on the last day of treatment (group II). Twenty bitches that spontaneously displayed oestrous signs were left untreated and served as controls (group III). The induced oestrous rates and ovulation rates in groups I and II were 60.0% vs 64.3% and 86.7% vs 83.3%, respectively. Morphological assessments of the ovarian structures after ovariohysterectomy revealed an increase in the number of luteinized follicles and cysts in group II compared with the two other groups (p < 0.001). In contrast, the numbers of corpora lutea and follicles were similar in all groups. In accordance with the above‐mentioned alteration, the progesterone concentration in the gonadotropin group (II) was increased (p < 0.001) in the periovulatory period compared with the other two groups. During the entire sampling period, the progesterone profiles in the cabergoline (I) and control (III) groups were similar and typical of normally cycling bitches. In conclusion, gonadotropin treatment is associated with an increased progesterone level during the periovulatory period that probably originates from luteinized follicles, whereas cabergoline treatment induces cycles with both physiological progesterone concentrations and ovarian morphologies.     

人绒毛膜促性腺激素(HCG)对杂交黄牛、水牛受胎率的影响

近年来,广西象州县的多个牛人工授精品改点的受胎率,黄牛为33%～51%,水牛为35%～55%,母牛的受胎率仍有较大的提升空间。该试验利用HCG能够促进母牛卵泡发育和排卵这一特性,在母牛发情时肌肉注射HCG后进行输精,并观察其对母牛受胎率的影响,以及是否能够提高牛人工授精的效果。试验结果表明,使用HCG能够明显提高牛人工授精的受胎率,同时也提高了工作效率。     

Collection Rates and Morphology of Equine Oocytes Obtained from Immature Follicles after Treatment with Equine Pituitary Extract (EPE) and Human Chorionic Gonadotropin

This study examined the effect of treating mares with equine pituitary extract (EPE) in combination with human chorionic gonadotropin (hCG; EPE/hCG) on the recovery rate of immature oocytes by ovum pick-up (OPU) and on oocyte morphology. Ten mares were subjected to each of two treatments in a random sequence: superstimulated with EPE (25 mg, twice daily) and treated with hCG (2,500 IU) or control (no exogenous treatment). The cytoplasmic morphology of oocytes recovered was evaluated through transmission electron microscopy. Follicular fluid was collected at aspiration for progesterone analysis, which was performed by radioimmunoassay. The EPE/hCG did not increase the oocyte recovery rate from immature follicles when compared with the controls (15.5% and 16.7%, respectively). A significantly higher oocyte recovery rate per mare was observed (70% versus 50%). However, precocious granulosa cell expansion was observed with EPE/hCG treatment in contrast to the control (64.4% and 33% of follicles with expanded cumulus, respectively), and increased intrafollicular progesterone concentration was also seen (158.80 ng/mL versus 82.05 ng/mL). The ultrastructural analysis of oocytes from both groups showed morphologic features related to immaturity. Numerous vesicles containing cortical granules were found, distributed in clusters into the cytoplasm, and junctional complexes were still seen between oocyte and granulosa cells. In conclusion, EPE/hCG treatment induced some follicular modifications, but the recovery rate was not increased. All oocytes examined presented signs of immaturity.     

Use of Equine Chorionic Gonadotropin to Control Reproduction of the Dairy Cow: A Review

Equine chorionic gonadotropin (eCG) is a member of the glycoprotein family of hormones along with LH, FSH and thyroid‐stimulating hormone. In non‐equid species, eCG shows high LH‐ and FSH‐like activities and has a high affinity for both FSH and LH receptors in the ovaries. On the granulosa and thecal cells of the follicle, eCG has long‐lasting LH‐ and FSH‐like effects that stimulate oestradiol and progesterone secretion. Thus, eCG administration in dairy cattle results in fewer atretic follicles, the recruitment of more small follicles showing an elevated growth rate, the sustained growth of medium and large follicles and improved development of the dominant and pre‐ovulatory follicle. In consequence, the quality of the ensuing CL is improved, and thereby progesterone secretion increased. Based on these characteristics, eCG treatment is utilized in veterinary medicine to control the reproductive activity of the cow by i) improving reproductive performance during early post‐partum stages; ii) increasing ovulation and pregnancy rates in non‐cyclic cows; iii) improving the conception rate in cows showing delayed ovulation; and finally, iv) eCG is currently included in protocols for fixed‐time artificial insemination since after inducing the synchrony of ovulation using a progesterone‐releasing device, eCG has beneficial effects on embryo development and survival. The above effects are not always observed in cyclic animals, but they are evident in animals in which LH secretion and ovarian activity are reduced or compromised, for instance, during the early post‐partum period, under seasonal heat stress, in anoestrus animals or in animals with a low body condition score.     

Effect of Weaning to Oestrus Interval and Equine Chorionic Gonadotropin on Vaginal Electrical Impedance During Peri‐oestrus in Sows

The influence of weaning to oestrus interval, its interaction with parity and equine chorionic gonadotropin (eCG) on changes of vaginal impedance in sows after weaning was examined. The impedance measurements were carried out by a four‐terminal method. Sows were monitored for oestrus via exposure to a sexually mature boar. The interval from weaning to oestrus was longer in primiparous than multiparous sows (p < 0.01). A significant negative correlation was found between the interval from weaning to oestrus and parity. Repeated measures analysis showed that the interval from weaning to oestrus and parity and their interactions had a significant effect on the vaginal impedance in peri‐oestrus. The vaginal impedance during pro‐oestrus gradually decreased in all groups of sows with the weaning to oestrus interval from 4 to 8 days (p < 0.05). In the subsequent period, the vaginal impedance increased and was significantly lower from 1 to 3 days after oestrus onset in sows with the weaning to oestrus interval 7–8 days than 4–6 days. Similarly, the vaginal impedance during pro‐oestrus gradually decreased in all groups of sows with parity 1–5 (p < 0.01). In the next period, the vaginal impedance increased and was significantly lower from 2–3 days after oestrus onset in sows of parity 1 than parity 2–5. Repeated measures analysis showed that eCG treatment had a significant effect on the vaginal impedance in peri‐oestrus. Sows treated with eCG displayed the decrease and increase of vaginal impedance due to oestrus onset earlier than untreated sows. The results indicate that the weaning to oestrus interval, its interaction with parity and eCG markedly affect the vaginal impedance in sows during peri‐oestrus.     

人绒毛膜促性腺激素对母驴促排卵效果的研究

[目的]研究人绒毛膜促性腺激素（human chorionic gonadotropin,hCG）对母驴卵泡发育、排卵率、受胎率以及血清生殖激素水平的影响。[方法]选择优势卵泡直径在30~35 mm以及大于35 mm的母驴各30头,不同优势卵泡直径的母驴群体分别设置1个500 IU/头hCG处理组（n=10）、1个1 000 IU/头hCG处理组（n=10）、1个不接受hCG处理的对照组（n=10）。采用肌肉注射方法对各组母驴进行hCG处理。每隔24 h进行1次B超检查,观察各组母驴卵泡发育情况,测量卵泡直径;记录各组发生排卵的母驴数量,计算排卵率。对各组母驴进行人工输精,输精后第18天进行孕检,记录各组受胎母驴头数,计算各组受胎率。于hCG处理后0、24、48、72 h分别测定各组母驴血清中雌二醇（estradiol,E₂）和孕酮（progesterone,PROG）水平。[结果]2个群体母驴的卵泡直径随hCG注射剂量的增加而增大;优势卵泡直径大于35 mm的母驴群体中,肌肉注射hCG的2个组在处理后24 h内均出现排卵,而对照组母驴没有排卵;优势卵泡直径不同的2个母驴群体,在hCG处理48 h后排卵母驴数和排卵率与对照组相比均有所提高,其中,hCG处理后72 h,优势卵泡直径大于35 mm的母驴群体中,1 000 IU/头 hCG处理组的排卵率达到100%。2个母驴群体中,接受hCG处理的母驴,受胎率均高于对照,并且随hCG剂量的增加,受胎率有所提高;优势卵泡直径大于35 mm的母驴群体中,1 000 IU/头 hCG处理组的受胎率达到50%。2个母驴群体中,1 000 IU/头处理组在hCG处理后24 h的血清E₂浓度均较0 h时有较大幅度的提升,在0~72 h内血清PROG浓度的总体提升幅度较大。[结论]hCG处理可提高母驴的排卵率、受胎率以及血清中E₂和PROG水平,1 000 IU/头剂量的效果更好。     

Effect of Timing of Postovulatory Insemination Relative to Human Chorionic Gonadotropin/Buserelin Treatment With 1 Straw of Frozen-Thawed Semen on Mare Fertility

The reproductive management of mares for frozen semen artificial insemination (AI) can be costly and labor intensive. Predicting the exact time of ovulation can be challenging even when ovulation-inducing drugs are used. The main objective of this retrospective study was to determine whether there was an effect of interval between examinations to detect ovulation on likelihood of pregnancy and early embryonic loss in mares after postovulatory breeding with a single straw of frozen/thawed semen. The second objective was to determine the efficacy of two different drugs (human chorionic gonadotropin vs. buserelin) for timely induction of ovulation. The length of the interval from penultimate check to ovulation had no significant effect on pregnancy or embryo loss rates (4 hours: 34.1% and 13.3% vs. 8 hours: 26.1% and 0% and 16 hours: 34.5% and 10%, respectively) nor did the ovulation-inducing drug used, number of the cycle, or the stallion. In conclusion, there appears to be no advantage of checking mares for ovulation during the late evening and night hours when using a postovulatory AI protocol and ovulation-inducing drugs.     

反亲和层析法纯化PMSG的试验研究

按PMSG粗品提取方法,从非孕马血清中获得“杂蛋白”提取物。以此“杂蛋白”为抗原制备兔抗“杂蛋白”抗血清,并从中提取IgG,制备多元性抗体免疫吸附柱,然后将PMSG粗品通过此柱,免疫吸附除去其中的杂蛋白,以提高PMSG的纯度和比活性。试验结果,杂蛋白除去率为61.4～70％,PMSG活性回收率为74～89％;PMSG比活性由原来的267IU/mg提高到630IU/mg,纯度提高约2.3倍;通过反亲和层析法部分纯化的PMSG,经电泳分析,主要为α—G部分,兼有少量其他血清杂蛋白。     

LH/CG受体研究进展

LH/CG受体是一种G蛋白偶联受体,与黄体生成素和绒毛膜促性腺激素结合后,主要激活G蛋白/腺苷酸环化酶系统从而产生一系列生物学效应.近年来对LH/CG受体基因结构、基因表达与调控以及信号传导机制等方面进行了深入研究,并取得了一定的进展.     

Effect of Deslorelin and/or Human Chorionic Gonadotropin on Inducing Ovulation in Mares During the Transition Period Versus Ovulatory Season

The objective of this study was to compare the rate of ovulation when deslorelin and/or human chorionic gonadotropin (hCG) was administered in mares in both the transition period and the ovulatory season. A total of 200 Paint Horses, Quarter Horses, and crossbred mares were used during the transition season (July to September) and the ovulatory season (October to February) of the southern hemisphere. The animals were divided into four groups. In the control group (n = 72), mares received 1 mL of saline; in deslorelin group (n = 171), 1.5 mg of deslorelin was administered by intramuscular (IM) injection; in hCG group (n = 57), 1,667 IU of hCG was administered IV; and in hCG + deslorelin group (n = 438), 1.5 mg of deslorelin (IM) and 1,667 IU of hCG (IV) were administered. The drugs were administered after follicles ≥35 mm in diameter were identified and grade III uterine edema was observed. At 48 hours after application, ultrasonography was performed to detect ovulation. During the transition period, the ovulation rates were 4.3% (control), 78.6% (deslorelin), 50% (hCG), and 73.3% (hCG + deslorelin). During ovulatory season, the ovulation rates were 16.4% (control), 68.8% (deslorelin), 60% (hCG), and 73% (hCG + deslorelin). There was no significant difference (P > .05) in the ovulation rate between the groups or the periods, except that the control group was lower than all others. Furthermore, both hCG and deslorelin are viable options for inducing ovulation during the transition period before ovulation season.     

Immunohistochemical Localization of Vascular Endothelial Growth Factor (VEGF) and its Two Receptors (Flt-I and KDR) in the Endometrium and Placenta of the Mare During the Oestrous Cycle and Pregnancy

Polyclonal antisera for vascular endothelial growth factor (VEGF) and its two main receptor molecules, VEGF-I (Flt) and VEGF-II (KDR), were used in a conventional immunocytochemical staining method to localize these angiogenic ligand molecules in the endometrium and placenta of the mare during the oestrous cycle and pregnancy. The anti-VEGF and anti-Flt sera both labelled the lumenal and glandular epithelia of the endometrium throughout the oestrous cycle and both the invasive trophoblast cells of the endometrial cups and the non-invasive trophoblast of the allantochorion in pregnancy. The anti-KDR serum likewise stained the maternal and foetal epithelial layers during the oestrous cycle and pregnancy and it also labelled fibroblast-like cells in the endometrial and allantoic stromas and the endothelium of foetal and maternal capillaries. The results demonstrated that constant supplies of the principal vasculogenic and angiogenic factor, VEGF, and its two major receptors, Flt and KDR, are available on both the maternal and foetal sides of the placental barrier throughout gestation in the mare. They are presumed to facilitate the continuing development of the extensive foetal and maternal capillary networks that are such prominent features within the microplacentomes of the diffuse, epitheliochorial equine placenta.