促性腺激素释放激素类似肽主动免疫对公猪生殖机能的影响

10头公猪在3月龄时用促性腺激素并列体二聚体(GnRHTD)主动免疫,观测内源GnRH被免疫中和所产生的内分泌和生殖机能的变化。注射GnRHTD与卵清蛋白(OVA)的偶联物2次,结果发现GnRHTD主动免疫能降低外周血清睾酮浓度,睾丸重量也明显下降。组织切片显示,曲细精管有少数退化的精原细胞。这些变化表明:公猪接种GnRHTDOVA能诱发免疫反应,中和内源GnRH的生物活性,且抑制睾酮的合成,从而导致性器官发育受阻。     

GnRH类似肽主动免疫对公猪生产性能的影响

将30头公猪分成3组,给免疫组的 10头公猪注射促性腺激素释放激素并列体二 聚体 卵清蛋白复合物,初次免疫时间是3月 龄,5月龄加强免疫1次。同时阉割10头公 猪作为阴性对照组,其余的10头注射卵清蛋 白作阳性对照组。试验期间,统计每头公猪 的平均饲料消耗量和日增重。7月龄时屠宰, 测其活重、屠宰率、料肉比指标。结果表明, 免疫组公猪平均日增重、最终活重(P< 0.05)、屠宰率、料肉比均高于阴性对照组,略 低于阳性对照组。提示GnRH并列体二聚体主动免疫能提高公猪的生产性能。     

促性腺激素释放激素并列体主动免疫对公猪性腺的影响

用GnRH并列体主动免疫公猪 ,并观察了免疫对公猪性腺的影响。结果表明 ,免疫使公猪睾丸体重降低 ,睾丸周长缩短 ,曲细精管管腔空荡 ,性腺萎缩     

促性腺激素释放激素二聚体对公猪繁殖机能的影响

应用促性腺激素二聚体(GnRH-TD)对12头4月龄公猪进行主动免疫,观测内源促性腺激素(GnRH)的变化.注射GnRH-TD与卵清蛋白(OVA)的偶联物3次,结果发现GnRH-TD能降低血清睾酮浓度和睾丸重量.组织切片显示,曲细精管的精原细胞有少数退化.实验结果表明:公猪接种GnRH-TD-OVA能诱发免疫反应,中和内源GnRH的生物活性,且抑制睾酮的合成,从而导致性器官发育受阻,达到去势的目的.     

GnRH并列体二聚体主动免疫对公兔性腺的影响

用GnRH并列体二聚体主动免疫公兔，观察了免疫对公兔性腺及体重的影响。结果表明，免疫不影响公兔体重的工，而使公兔睾丸重量降低，就纵长缩短，表明性腺有萎缩的趋势。     

主动免疫GnRH疫苗对公犬生殖功能的影响

为了探究促性腺激素释放激素(GnRH)疫苗对公犬生殖功能的影响,试验将GnRH基因克隆至原核表达载体中,转化到大肠杆菌BL21(DE3)感受态细胞中,用终浓度为1 mmol/L IPTG诱导蛋白表达,通过SDS-PAGE和Western-blot对表达产物进行蛋白鉴定,将鉴定正确的GnRH蛋白纯化后制备成抗原。选取6只2～4月龄健康公犬随机分成2组,每组3只,其中免疫组每只犬免疫GnRH蛋白1 mg,共免疫3次,每次间隔4周,分别于免疫前和一免、二免、三免后14天采血,通过ELISA检测血清GnRH抗体及睾酮水平,并于最后一次采血结束后制备睾丸组织切片,观察睾丸组织形态。结果表明：3次免疫后免疫组GnRH抗体水平均显著高于对照组(P<0.05),睾酮水平均显著低于对照组(P<0.05),免疫组睾丸相对较小,曲精小管中生精细胞数量较少,管径较细。说明主动免疫GnRH疫苗抑制了公犬的性腺发育和生殖器官的成熟。     

GnRH并列体二聚体主动免疫对雄兔血清睾酮的影响

用GnRH并列体二聚体主动免疫雄兔,并观察了免疫对雄兔血清睾酮与睾丸重量的影响。结果表明该方法能使雄兔血清睾酮水平降低,睾丸重量下降。     

GnRH类似物疫苗免疫去势效果的影响因素

利用GnRH类似物疫苗主动免疫动物机体可达到与手术去势类似的效果,同时避免了手术去势对动物机体产生的影响。抗原、佐剂、免疫次数、免疫剂量以及免疫时间都会对其免疫效果产生影响。采用GnRH类似物疫苗免疫动物通常需要有力的佐剂以及多次加强免疫来克服个体反应的差异性。     

GnRH一次性主动免疫对公猪血清睾酮含量的影响

采用以促性腺激素释放激素(GnRH)并列体(GnRH-tandem)为基本结构的免疫去势苗对公猪进行一次性主动免疫。结果表明免疫组的公猪睾酮浓度极显著地低于完整组;睾丸长度极显著地小于完整组;屠宰体重明显高于完整组。因此,GnRH一次性免疫有望取代传统的外科阉割,在实际养猪生产中得到推广和应用。     

GnRH免疫去势研究进展

促性腺激素释放激素 (GnRH)是由丘脑下部产生并贮存于该腺体内 ,当机体受到一定的刺激时通过血液循环到达靶组织 ,调节丘脑 垂体 性腺轴 ,影响生殖内分泌和生殖细胞的发育。随着生物学、免疫学以及生殖内分泌等多学科的发展 ,出现了一个新的边缘性学科———激素免疫学 ,并由此出现了激素免疫技术 ,即外源的激素作用于机体使机体产生抗体并利用抗体中和机体的内源性激素使其失去生物活性 ,进而使丘脑 垂体 性腺轴的正常生理活动受破坏。文章对GnRH免疫去势在生产中的可行性、作用机制、影响因素、免疫制剂研究及其存在问题等作了综述     

Effect of active immunization against LHRH or LH in boars: reproductive consequences and performance traits

Forty crossbred boars were equally divided into eight groups at birth. Four groups were immunized (200 micrograms/boar) at 12 wk of age against either luteinizing hormone-releasing hormone (LHRH) conjugated to human serum globulin (LHRH-hSG) in complete Freund's adjuvant (CFA), LHRH-hSG in muramyldipeptide adjuvant (PEP), procine luteinizing hormone (LH) conjugated to hSG (pLH-hSG) in CFA or ovine LH (oLH) in CFA. Equal doses of boosters were given in either PEP or incomplete Freund's adjuvant (IFA) at 16 and 18 wk of age. Two groups of boars were immunized with either hSG + CFA or hSG + PEP (adjuvant controls). Two groups were castrated either at the time of weaning (castrate weaning) or at 16 wk when immunized boars were given their first booster injections (castrate booster). All pigs were slaughtered at 24 wk of age. Serum levels of LH and testosterone (T), LHRH or LH antibody titers, as well as testicular and accessory sex gland weights and histology were determined. By wk 16, LHRH antibody titers began to rise in those boars immunized against LHRH-hSG. Luteinizing hormone-releasing hormone antibody titers on wk 18, 20 and 22 were greater than those at wk 16. By 22 wk of age, LHRH-hSG boars had non-detectable plasma LH and T and reduced weights of testes and acessory sex glands. Boars immunized against oLH did not respond to treatment, whereas pLH-hSG boars showed a reduction in serum T levels and accessory sex gland weights. Immunization had no effect on average daily gain, hot carcass weights or loin eye area.(ABSTRACT TRUNCATED AT 250 WORDS)     

Active immunization against ghrelin decreases weight gain and alters plasma concentrations of growth hormone in growing pigs

Ghrelin has been implicated in the control of food intake and in the long-term regulation of body weight. We theorize that preventing the ability of ghrelin to interact with its receptors, would eventually lead to decreased appetite and thereby decrease body weight gain. To test our hypothesis, pigs were actively immunized against ghrelin. Ghrelin((1-10)) was conjugated to BSA and emulsified in Freund's incomplete adjuvant and diethylaminoethyl-dextran. Primary immunization was given at 19 weeks of age (WOA), with booster immunizations given 20 and 40 days after primary immunization. Body weight (BW) and plasma samples were collected weekly beginning at 19 WOA, and feed intake was measured daily. Fourteen days after primary immunization, the percentage of bound (125)I-ghrelin in plasma from immunized pigs was increased compared with control animals (P<0.001). Voluntary feed intake was decreased more than 15% in animals that were actively immunized against ghrelin compared with controls. By the end of the experiment, immunized pigs weighed 10% less than control animals (P<0.1). Concentrations of GH were increased (P<0.05) in immunized pigs. Apoptosis was not observed in post-mortem samples obtained from the fundic region of the stomach. Our observations suggest that immunization against ghrelin induces mild anorexia. This procedure could potentially be used as a treatment to control caloric intake and obesity.     

Effect of active immunization against GnRH on testosterone concentration,libido and sperm quality in mature AI boars

Background

The aim of the present study was to investigate the efficacy of the Improvac on testosterone concentration in blood serum, sexual behavior and sperm quality in matured AI boars. A total of nine Danish Landrace AI boars were included in the analysis.

Methods

The trial period lasted for 15 weeks and was divided into four periods: Control period: three weeks before vaccination; Period I – four weeks after first vaccination; Period II – four weeks after second vaccination, Period III – four weeks after third vaccination. Blood and sperm samples were collected at weekly intervals. Freshly collected sperm samples were analyzed.

Results

Testosterone concentration correlated with libido (r = 0.531; p < 0.001), volume of ejaculate (r = 0.324; p < 0.001) and the percentage of morphologically normal spermatozoa (r = 0.207; p < 0.05). Testosterone concentration rised significantly (p < 0.05) in 5–6 week of trial, e. i. after the first dose of Improvac and after this peak the level of testosterone further progressively decreased (p < 0.05).

Conclusions

Results from this study indicate that active immunization of sexually matured boars against GnRH has negative impact on testosterone concentration, sexual behavior, volume of ejaculate and total number of normal spermatozoa in ejaculate.     

不同佐剂GnRH疫苗主动免疫对公猪睾丸发育和血清睾酮的影响

为探讨铝胶佐剂与白油Span佐剂的GnRH疫苗对公猪睾丸发育和血清睾酮的影响,12头初生公猪随机分为GnRH疫苗铝胶佐剂免疫组和GnRH疫苗白油Span佐剂免疫组(下简称铝胶组和白油组).9周龄初免,17周龄加强免疫,25周龄屠宰.游标卡尺测量猪阴囊直径和睾丸大小,石蜡切片观察睾丸组织发育,ELISA法和放射免疫分析(RIA)法分别检测GnRH抗体水平和血清睾酮水平.结果表明,铝胶组与白油组GnRH抗体效价差异不显著(P0.05).铝胶组血清睾酮水平于17,21周龄(P＜0.05)和25周龄(P＜0.01)显著地低于白油组,阴囊直径,睾丸直径、横径、周长及睾丸血量均显著地低于白油组(P＜0.05).铝胶组与白油组猪睾丸曲精小管均出现不同程度的空泡化,白油组零星分布少量精子,铝胶组无精子产生.这表明在公猪免疫去势的效果上,辅以铝胶佐剂的GnRH疫苗比辅以白油Span佐剂的GnRH疫苗好.     

Changes in spermatogenesis and endocrine function in the ram testis due to irradiation and active immunization against luteinizing hormone-releasing hormone

Spermatogonial stem cell transplantation is a technique that has potential in livestock to enhance genetic gain and generate transgenic offspring through the male germ line. A means for depletion of endogenous germ cells in a recipient's seminiferous tubules is necessary for this technology to be applied. The objectives of this study were to evaluate several methods for depletion of endogenous germ cells in the testes of adult rams and to evaluate ultrasound-guided injections into the rete testes as a means for infusing a suspension into the seminiferous tubules. Sixteen adult rams were randomly divided into 4 treatment groups (n = 4 per group). Treatments consisted of active immunization against LHRH (IMM), localized testicular irradiation (IR), LHRH immunization + irradiation (IMM+IR), and untreated control. Serial bleedings were conducted pretreatment and monthly after treatment for 4 mo, at which time all rams were castrated. Both IMM and IMM+IR rams received exogenous gonadotropin in the form of Perganol weekly for 8 wk before castration to bypass the immunization. All rams also received an ultrasound-guided injection of PBS containing 0.4% trypan blue into the rete testis of one testicle before castration. Rams receiving IMM and IMM+IR treatments had higher (P < 0.05) average percentages of seminiferous tubule cross sections with depleted germ cells compared with controls. Serum testosterone was decreased (P < 0.05) in IMM and IMM+IR rams 1 mo after treatment and throughout the remainder of the study compared with controls and IR rams, which were not different from each other. Serum inhibin concentration was unchanged in all rams following treatment indicating that Sertoli cell function was unaltered. A greater (P < 0.05) average percentage of the total testicular area could be filled with the trypan blue solution by rete testis injection in IMM and IMM+IR rams. These data demonstrate the depletion of endogenous germ cells in adult ram testes without alteration of Sertoli cell viability and function that have potential as methods for preparing recipient animals for germ cell transplantation.     

Photoperiodic control of growth hormone secretion and body weight in rams

This study was undertaken to assess the influence of photoperiod on growth hormone (GH) secretion in rams and its possible influence on body weight. Twenty young adult rams were divided into two groups. One was subjected to an annual (AR) and the other to a semestral (SR) light regime during the same 18-month period. In both groups, daylength (DL) varied gradually between 8 to 17 hr. Plasma prolactin (PRL) and GH profiles consisting of 6 hr samples were determined and animals were weighed throughout the course of the experiment. Maximal PRL secretion was observed with largest DL. In contrast, GH secretion increased during increasing DL but it began to decrease before maximal DL was reached in both light regimes. Mean GH secretion was maximal when the DL was about 11 hr in SR and between 8 to 12 hr in AR. Similarly, body weight increased when DL increased and plateaued during decreasing DL in both AR and SR animal groups. Significant (P less than 0.05) differences were observed throughout the course of the experiment according to the effects of decreasing or increasing DL in each group. Analysis of variance showed that the effect of DL on plasma PRL and GH levels and weight velocity (WV) was significant (P less than 0.05) in both light regimes. This suggests that in SR, plasma PRL and GH levels and WV vary according to a six month period.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of active immunization against adrenocorticotropic hormone on cortisol, beta-endorphin, vocalization, and growth in pigs

Because the poor growth performance of intensively housed pigs is associated with increased circulating glucocorticoid concentrations, we investigated the effects of glucocorticoid suppression by inducing a humoral immune response to ACTH on physiological and production variables in growing pigs. Grower pigs (28.6 +/- 0.9 kg) were immunized with amino acids 1 through 24 of ACTH conjugated to ovalbumin and suspended in diethylaminoethyl (DEAE) dextran-adjuvant or adjuvant alone (control) on d 1, 28, and 56. The ACTH-specific antibody titers generated suppressed increases in cortisol concentrations on d 63 in response to an acute stressor (P = 0.002; control = 71 +/- 8.2 ng/mL; ACTH-immune = 43 +/- 4.9 ng/mL) without altering basal concentrations. Plasma beta-endorphin concentrations were also increased (P < 0.001) on d 63 (control = 18 +/- 2.1 ng/mL; ACTH-immune = 63 +/- 7.3 ng/mL), presumably because of a release from negative feedback on the expression of proopiomelanocortin in pituitary corticotropes. Immunization against ACTH did not alter ADG (P = 0.120; control = 1,077 +/- 25; ACTH-immune = 1,143 +/- 25 g) or ADFI (P = 0.64; control = 2,719 +/- 42; ACTH-immune = 2,749 +/- 42 g) and did not modify behavior (P = 0.681) assessed by measuring vocalization in response to acute restraint. In summary, suppression of stress-induced cortisol responses through ACTH immunization increased beta-endorphin concentrations, but it did not modify ADG, ADFI, or restraint vocalization score in growing pigs.     

Effect of active immunization against growth hormone releasing factor on concentrations of somatotropin and insulin-like growth factor I in lactating beef cows.

Two experiments were conducted to determine the effects of immunoneutralization of growth hormone-releasing factor [GRF(1-29)-NH2] on concentrations of somatotropin (ST) and insulin-like growth factor I (IGF-I) in lactating beef cows. In Experiment 1, multiparous Hereford cows were immunized against 2 mg GRF(1-29)-(Gly)4-Cys-NH2 conjugated to human serum albumin (GRFi, n = 3) or 2 mg human serum albumin (HSAi, n = 3) at 52 +/- 1 d prior to parturition. Boosters (1 mg) were administered on days 12, 40 and 114 postpartum (pp). Serum samples were collected at 15-min intervals for 5 hr on days 18, 46 and 120 pp, followed by administration (IV) of an opioid agonist (FK33-824; 10 micrograms/kg) and an antagonist (naloxone; .5 mg/kg) at hours 5 and 7, respectively. A GRF-analog ([desamino-Tyr1, D-Ala2, Ala15] GRF (1-29)-NH2; 3.5 micrograms/kg) and arginine (.5 g/kg) were administered at hour 10 on days 47 and 121, respectively. Percentage binding of [125I]GRF (1:100 dilution of serum) 28 d after primary immunization was greater in GRFi (14.3 +/- 4.9) than in HSAi (.7 +/- .3) cows. Binding increased to 29.3 +/- 6.5% after first booster in GRFi cows. Episodic release of ST was abolished by immunization against GRF; concentration and frequency of release of ST were lower (P less than .05) in GRFi than in HSAi cows on all days pp. Concentrations of IGF-I were lower in GRFi than in HSAi cows throughout lactation. Serum ST failed to increase following FK33-824 or arginine in GRFi; however, ST increased after both compounds in HSAi cows. Concentrations of ST following GRF-analog were greater (P less than .05) in HSAi than in GRFi cows. Experiment 2 was conducted to determine if a lower dose of antigen and a single booster would be sufficient to lower ST and IGF-I in lactating cows. Multiparous Hereford and Angus cows were assigned to GRFi (n = 6) or HSAi (n = 6). Primary (1.2 mg) and booster (.5 mg) immunizations were administered -14 and 8 d from calving, respectively. Cows were restricted to 60% of recommended intake of energy during lactation in order to elevate concentrations of ST. Serum samples were collected at 15-min intervals for 6 hr on days 26, 50, 73, 90 and 109 pp. Two of six GRFi cows had binding less than 10% (1:1,000 dilution of serum) and were omitted from further analyses.(ABSTRACT TRUNCATED AT 400 WORDS)     

Effects of active immunization against gonadotropin releasing hormone on gonadotropin secretion after ovariectomy and testosterone propionate administration to mares

Five lighthorse mares were actively immunized against gonadotropin releasing hormone (GnRH) conjugated to bovine serum albumin (BSA) to study the involvement of GnRH in luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion following ovariectomy (OVX) and after administration of testosterone propionate (TP). Five mares immunized against BSA served as controls. Immunizations were started on November 1, and OVX was performed in June (d 1). All mares were treated with TP from d 50 to 59 after OVX. On the day of OVX, concentrations of LH were lower (P less than .05) in GnRH-immunized mares than in BSA-immunized mares and were generally nondetectable; FSH concentrations were reduced (P less than .05) by 50% in GnRH-immunized mares relative to BSA-immunized mares. In contrast to BSA-immunized mares, plasma concentrations of LH or FSH did not increase after OVX in GnRH-immunized mares. The LH response to GnRH analog (less than .1% cross-reactive with GnRH antibodies) on d 50 was reduced (P less than .05) by 97% in GnRH-immunized mares relative to BSA-immunized mares, whereas the FSH response was similar for both groups. Treatment with TP for 10 d reduced (P less than .01) the LH response and increased (P less than .01) the FSH response to GnRH analog in BSA-immunized mares, but it had no effect (P greater than .1) on the response of either gonadotropin in GnRH-immunized mares.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of active immunization against growth hormone-releasing factor on growth and onset of puberty in beef heifers.

Angus and Charolais heifers (195 +/- 7 kg) were actively immunized against growth hormone-releasing factor (GRF) to evaluate the effect on concentrations of somatotropin (ST), insulin-like growth factor I (IGF-I), insulin (INS), growth, and onset of puberty. Primary immunizations were given at 184 +/- 7 d of age (d 0 of experiment) by injecting (s.c.) 1.5 mg of GRF-(1-29)-Gly-Gly-Cys-NH2 conjugated to 1.5 mg of human serum albumin (GRFi, n = 22) or 1.5 mg of human serum albumin (HSAi, n = 21). Booster immunizations of .5 mg of antigen were given on d 62, 92, 153, and 251. Antibody binding (percentage at 1:2,000 dilution) to [125I]GRF on d 69 was greater (P less than .01) in GRFi (53.7 +/- 4.5) than in HSAi (10.1 +/- .6) heifers. Serum concentration (ng/ml) and frequency (peaks/5 h) of ST release, respectively, on d 78 were lower (P less than .01) in GRFi than in HSAi heifers (3.3 +/- .1 vs 5.6 +/- .2 and .9 +/- .3 vs 2.3 +/- .2). Serum IGF-I (ng/ml) was lower (P less than .01) in GRFi than in HSAi heifers on d 69 (41 +/- 5 vs 112 +/- 4). Serum INS (microU/ml) on d 78 was lower (P less than .05) in GRFi (2.2 +/- .1) than in HSAi (3.8 +/- .2) heifers. Feed intake, ADG, and feed efficiency were lower (P less than .05) in GRFi than in HSAi heifers. Hip height was lower (P less than .01) and fat thickness was greater (P less than .05) in GRFi than in HSAi heifers by d 132 and 167, respectively. Percentage of heifers attaining puberty (progesterone greater than 1 ng/ml for two consecutive weeks) by d 209 and 379 (12.9 and 18.5 mo of age), respectively, was lower (P less than .05) in GRFi (40.9 and 45.5) than in HSAi (81.0 and 100). In conclusion, growing heifers were successively immunized against GRF. Active immunization against GRF resulted in decreased serum concentration of ST, IGF-I, and INS. In addition, GRF immunization led to lowered feed intake, ADG, and feed efficiency, increased fat depth, and delayed onset of puberty in heifers. We propose that ST and IGF-I are important metabolic mediators involved in the initiation of puberty in heifers.