一种新型的生长抑素活载体基因工程苗的构建及其动物免疫小试

生长抑素（ＳＳ）是一种抑制动物生长的多肽类激素,主要由下丘脑分泌。它通过抑制体内多种促进生长的激素如：生长激素（ＧＨ）、胰岛素、胰高血糖素（ＧＧ）、促甲状腺激素（ＴＳＨ）等的分泌而抑制生长。一般认为ＧＨＩＧＦ１是动物生长的调控中心。ＧＨ的分泌同时受ＳＳ和生长激素释放激素（ＧＲＦ）所控制,前者抑制ＧＨ分泌,后者促进ＧＨ分泌。ＧＨ通过与受体结合,诱导肝细胞产生ＩＧＦ１,而ＩＧＦ１能直接作用于动物体内的多种组织,促进蛋白质的合成,促进细胞增殖,从而促进肌肉、内脏和骨骼的生长〔１〕。利用免疫中和…     

鸡生长激素受体研究的新进展

禽类生长的调控机制与哺乳动物相比有许多方面的差异。在哺乳动物，如猪、羔羊和肉牛，外源性生长激素（ＧＨ）可通过上调肝脏ＧＨ受体，提高血液中ＩＧＦ－Ⅰ（胰岛素样生长因子）的水平，促进动物生长。而在禽类，慢性注射ＧＨ并不提高血浆ＩＧＦ－Ⅰ水平和动物的生长速...     

铜促生长与动物生长轴激素调控的关系

日粮中添加适量的铜可促进动物的生长，其作用机制可能是多方面的。已有研究表明，铜促生长与动物生长轴的激素调控密切相关，其机理可能是铜能调控促生长调节肽的合成和释放。     

山羊GnRH和促性腺激素的释放特点

通过外科手术分别连续收集活体山羊中黄体期及早卵泡期的垂体门脉血样和外周血样，经放射免疫测定，山羊中黄体期和早卵泡期的促性腺激素释放激素（ＧｎＲＨ）、促黄体生成素（ＬＨ）和促卵泡素（ＦＳＨ）均呈波动式释放。在早卵泡期，ＦＳＨ单位时间内波动次数和血浆平均水平显著高于中黄体期；ＧｎＲＨ与ＬＨ的波动型基本一致，ＦＳＨ的变化不太规则。表明山羊垂体促性腺激素的释放受丘脑下部ＧｎＲＨ的调节，但ＦＳＨ似乎还存在其他调节机理。     

生长激素和类胰岛素生长因子－1与睾丸功能

生长激素（ＧＨ）和雄性动物丘脑下部－垂体－性腺轴相互作用的动物试验主要集中在ＧＨ与性类固醇的相互作用上，或集中在ＧＨ的代谢效应上，很少注意ＧＨ对精子发生的可能作用。近年来，已用体外系统和不同的动物模型（小鼠和大鼠）对ＧＨ及其主要介质──类胰岛素生长因子－（ＩＧＦ—１）与丘脑下部－垂体－性腺轴的相互作用进行了研究。间质细胞和支持细胞培养、ＧＨ／ＩＧＦ—１与促性腺激素对不同细胞功能影响的相互作用等，在细胞水平上已显示出类固醇生成与细胞分化的关系。用非成熟和成熟而切除垂体的大鼠及ＧＨ缺乏的突变雄性小鼠和大鼠所做的体内研究指出，ＩＧＦ—１在类固醇生成和精子发生的调节中具有重要作用。促卵泡素和促黄体素不仅是睾丸产生ＩＧＦ—１的主要调节者，而且可以通过调节睾丸ＩＧＦ—１的含量加强ＧＨ所起的间接作用。     

日粮烟酸水平对肉鸭后期生产性能和脂肪代谢的影响

７２只２１日龄樱桃谷鸭平均分成４组,分别添加０、３０、６０、９０ｍｇ／ｋｇ烟酸进行３周饲养试验。测定平均日采食量（ＡＤＦＩ）、平均日增重（ＡＤＧ）、料重比（Ｆ／Ｇ）、血清总胆固醇（ＴＣＨ）、血清总甘油三酯（ＴＧ）、低密度脂蛋白胆固醇（ＬＤＬ－Ｃ）、高密度脂蛋白胆固醇（ＨＤＬ－Ｃ）。结果表明：①日粮烟酸水平不影响ＡＤＦＩ、ＡＤＧ、Ｆ／Ｇ（Ｐ＞０．０５）,但与ＡＤＦＩ、ＡＤＧ、Ｆ／Ｇ存在显著（Ｐ＜０．０５）或极显著二次曲线关系（Ｐ＜０．０１）。②日粮烟酸水平可能影响ＴＣＨ、ＴＧ、ＬＤＬ－Ｃ、ＨＤＬ－Ｃ,但差异不显著（Ｐ＞０．０５）。当基础日粮烟酸和色氨酸水平分别为３５ｍｇ／ｋｇ和０．１６％时,建议肉鸭后期烟酸添加水平为６０ｍｇ／ｋｇ。     

初乳中生长因子对肠道生长发育的影响

初乳可刺激初生动物肠道组织的生长发育，增增肠道粘膜重量和肠道长度，促进粘膜细胞ＤＮＡ，ＲＮＡ和蛋白质的合成，刺激细胞的分裂，增殖与分化。研究发现，初乳中的促生长物质主要是其中的多肽性生长因子，特别是表皮生长因子（ＥＧＦ）和类胰岛素生长因子（ＩＧＦ－１），ＥＧＦ的主要作用是促使细胞分裂与增殖。ＩＧＦ－Ｉ处于药理浓度时，可以加快细胞的生长与分化。ＥＧＦ和ＩＧＦ－１都能调节部分消化酶的活性，并加快内腔器     

胰岛素样生长因子I（IGF—I）的研究进展

胰岛素样生长因子Ｉ（ＩＧＦ－Ｉ）的研究进展沧州市农林科学院钟艳玲王振来胰岛素样生长因子Ｉ（ＩＧＦ－Ｉ）是生长激素发挥促生长作用的重要调节因子。生长激素具有促进体内蛋白质沉积、骨骼生长等功能，但是生长激素的以上作用并不是直接的，而是ＩＧＦ－Ｉ作用的结果...     

生长抑素基因工程疫苗对生长肥育猪促生长效果试验

生长抑素基因工程疫苗是应用鸡胚培养重组疫苗病毒制备的用于促进动物生长的基因工程ＳＳ活载体疫苗 ,是由国家科委生物技术开发中心资助 ,南京农业大学和中牧股份成都药械厂联合开发的“863”高科技项目。该苗已于 1 999年 1 2月获农业部基因工程安全委员会商品化生产审批书 (农基安审字 99Ｂ -0 3 -0 8)。应用生长抑素基因工程苗促生长的原理是 :动物生长受生长激素 (ＧＨ)调控 ,而ＧＨ的释放又受生长激素释放因子 (ＧＲＦ)和生长抑制激素 (ＳＳ)双向调节 ,前者促进释放 ,后者抑制释放。动物接种生长抑素苗后 ,体内即产生ＳＳ抗体 ,能中和…     

铜与体外培养的猪胰岛细胞SS分泌及其mRNA表达相关性的研究

铜作为促生长剂已广泛应用于养猪生产,但在饲料中长期添加高铜可造成肉品和环境的严重污染.研究表明,铜的促生长作用可能与提高猪的采食量、酶活性等因素有关.一般认为,动物生长受SS/GHRH-GH-IGF Ⅰ生长激素轴调控,研究铜促生长作用是否与胰腺分泌的SS有关,对研究铜促生长的机理具有重要的意义.     

Role of the somatotropic axis in the mammalian metabolism

The metabolism in mammalian is regulated by multiple levels of hormone action, with complex feedback and control mechanisms. The somatotropic axis, essentially consisting of growth hormone (GH), insulin-like growth factors (IGF-I and -II), their associated carrier proteins, and receptors, plays a key role in the control of the regulation of metabolism and physiological process. Among this axis, other hormones like insulin, leptine, glucocorticoids or thyroid hormones are involved in this mechanism by modulating GH and/or IGF-I synthesis and availability. This review summarizes the complexity of the regulation of the metabolism by the somatotropic axis using different examples such as special nutritional situations or growth promoters administration.     

The somatotropic axis of the dairy cow revisited

The greater understanding of the somatotropic axis in the lactating dairy cow that has been achieved in recent years is briefly reviewed in this article. Specifically discussed are: the significance of multiple forms of insulin‐like growth factor messenger RNA (ribonucleic acid) caused by alternative splicing, and the possible functions of the various translated extension proteins; the possible roles of multiple sites of growth hormone secretion other than in the pituitary, and the implications for possible autocrine or paracrine growth hormone secretion; the consequences for increased circulating growth hormone half‐life, and possibly biological effectiveness, caused by growth hormone binding proteins; and the increasing evidence for the presence of growth hormone receptors in the bovine mammary gland. The need for further research is highlighted in the present review; published information regarding the bovine, in many of these areas, is still largely insufficient.     

Selection for growth rate or against back fat thickness in pigs is associated with changes in growth hormone axis plasma protein concentration and mRNA level.

Selection for increased growth rate or decreased back fat thickness results in concomitant changes in endocrine and metabolic status. Growth hormone (GH) changes in blood plasma concentration related to selection for growth rate and fat deposition were reported in pigs. The molecular mechanisms regulating selection-induced changes in GH plasma concentration remain largely unknown. We investigated selection-associated changes in GH axis parameters in 2 pig lines selected for increased growth rate (F-line), or decreased back fat thickness (L-line), respectively. First, we investigated selection-associated changes in GH pulse parameters. In both selection lines we found each generation a declining GH peak maximum concentration and area under the GH curve. GH pulse width was not associated with generation number. In both lines generation number was associated with a declined pulse interval, indicating that the number of pulses per day increased on average with 1 pulse per 24 h per generation. Second, plasma concentration of GH axis related Insulin-like growth factor-I (IGF-I) and insulin were investigated. Plasma IGF-I concentration was not associated with generation number in the F-line. Mean plasma insulin concentration declined each generation in both lines. Third, we investigated changes in GH and Pit-1 mRNA levels. In both selection lines GH and Pit-1 mRNA levels increased approximately 50% each generation. The high SD of the GH mRNA levels in both lines may suggest that the GH mRNA levels are pulsatile in vivo. We postulate a molecular mechanism that may explain how selection is associated with increased GH mRNA levels and GH pulse numbers, while lowering GH release per pulse.     

Effect of dietary methionine on growth performance and insulin‐like growth factor‐I mRNA expression of growing meat rabbits

An experiment was conducted to determine the effects of different amounts of dietary methionine on growth performance, serum protein, growth hormone (GH), insulin‐like growth factor‐I (IGF‐I) concentrations and IGF‐I mRNA expression of growing meat rabbits. One hundred weaned growing meat rabbits were allocated to individual cages and randomly divided into five groups. The methionine addition concentrations of the five groups were 0, 2, 4, 6 and 8 g/kg diet (as‐fed basis) and sulphur amino acids (SAA) concentrations ranging from 3.8 to 11.6 g/kg diet, respectively. The results obtained were as follows: the average daily gain of 2, 4 and 6 g/kg diet groups was higher than that of 0 g/kg diet group (p < 0.01). The feed gain ratio of the 4 g/kg diet group was lower than those of 0 and 8 g/kg diet group (p < 0.01). Methionine concentrations did not affect serum urea nitrogen, total protein, insulin and IGF‐I concentration (p > 0.05). The quadratic effects of methionine on the serum concentration of albumin (Alb) and GH were obtained (p = 0.013, p = 0.018). The quadratic effect of methionine amount on IGF‐I mRNA expression was obtained (p = 0.045). The serum concentration of Alb of the 4 g/kg diet group was higher than those of 0 and 8 g/kg diet group (p < 0.01). The serum concentration of GH of 8 g/kg diet group was higher than that of the 0 g/kg diet group (p < 0.05). The liver IGF‐I mRNA expression of 4 g/kg diet group was higher than those of the 0 and 8 g/kg diet group (p < 0.05). Providing a diet mainly consisted of corn, wheat bran and peanut vine, the optimum dietary methionine addition concentration and SAA concentration for a weaner to 2‐month‐old growing meat rabbits were shown to be 2 and 5.7 g/kg diet respectively.     

Growth and skeletal development in the dog in relation to nutrition; a review

Summary

Longitudinal growth of the appendicular skeleton in the growth plates and the adjacent metaphyseal area includes chondrocyte differentiation, proliferation, maturation, and hypertrophy in the physis and bone (re‐)modelling in the metaphysis. The rate and extent of longitudinal growth are regulated by interactions between biomechanical factors and endogenous growth regulators, i.e., systemic endocrine factors, and local paraor autocrine factors, that act on the growth plate chondrocytes. The most important endogenous regulators of growth and skeletal development are growth hormone (GH) and insulin‐like growth factors (IGFs), and calciotropic hormones, i.e., parathyroid hormone (PTH), vitamin D (vitD), and calcitonin (CT).

The biochemistry, synthesis, secretion, target organs, and effects of these endogenous factors are reviewed, and the calcium homeostatic mechanisms, dietary intake, bone turnover, and calcium excretion are discussed. Energy, protein, and calcium are nutritional factors of great importance to (skeletal) growth. The effects of low and high dietary intake of these nutrients are discussed, especially with reference to longitudinal growth and disturbances in endochondral ossification.     

Insulin administration suppresses an increase in insulin-like growth factor binding protein-2 gene expression stimulated by fasting in the chicken

1. We examined the changes in plasma IGF-I concentration and tissue IGFBP-2 gene expression of young fasted chickens refed a commercial diet or administered bovine insulin intravenously. 2. Plasma IGF-I concentration was decreased by fasting for 2 d. Although plasma IGF-I concentration was increased by refeeding, it didn't recover to the level of chickens fed a commercial diet ad libitum. 3. Insulin administration lowered plasma IGF-I concentration compared to other groups. 4. Hepatic IGFBP-2 mRNA was increased by fasting for 2 d and decreased by refeeding for 6 h. Insulin administration also decreased hepatic IGFBP-2 gene expression stimulated by fasting to the level of refed chickens. 5. IGFBP-2 mRNA in the gizzard was increased by fasting for 2 d and tended to decrease after refeeding for 6 h. Insulin administration decreased gizzard IGFBP-2 gene expression to less than that in refed chickens. 6. There was no between-treatment difference in IGFBP-2 mRNA in the brain and kidney. 7. These results suggest that the changes in IGFBP-2 gene expression in the liver and gizzard by fasting and refeeding might be partly regulated by the alteration in plasma insulin concentration.     

金雀异黄素对雌性大鼠体内促性腺激素及胰岛素样生长因子表达的影响

本试验旨在研究金雀异黄素(genistein,GEN)对雌性大鼠体内促性腺激素及胰岛素样生长因子表达的影响。选取40只SD雌性大鼠[体重(200±20)g],随机分为5组,分别为阴性对照(NC)组、GEN低(L)、中(M)、高剂量(H)组及阳性对照(PC)组,每组8只,NC组灌胃花生油(其他组灌胃试剂以此为溶剂);L、M、H组分别灌胃15、30、60 mg/(kg BW·d)GEN,PC组灌胃己烯雌酚0.5 mg/(kg BW·d)。试验期30 d。采用酶联免疫吸附试验(ELISA)法检测血清中卵泡刺激素(FSH)、黄体生成素(LH)、胰岛素样生长因子-1(IGF-1)、胰岛素样生长因子结合蛋白-1(IGFBP-1)含量;实时定量PCR法检测卵巢IGF-1、IGFBP-1 mRNA表达水平。结果表明:与NC组比较,试验组血清中FSH、LH含量有升高趋势,但差异不显著(P0.05),作用效果与PC组一致;试验组血清IGF-1含量略有降低,但差异不显著(P0.05),PC组显著降低(P0.05);试验组血清IGFBP-1含量显著或极显著升高(P0.05或P0.01),PC组显著升高(P0.05);试验组卵巢组织中IGF-1、IGFBP-1 mRNA表达水平均升高,其中M、H组显著升高(P0.05),与PC组变化一致。由此可见,GEN能够提高雌性大鼠血清FSH、LH含量、降低血清IGF-1含量、提高血清IGFBP-1含量,同时提高卵巢中IG FBP-1、IG F-1 mRNA的表达水平,这些指标协同作用于卵巢,能够促进卵泡的成熟,调节卵巢功能。     

Growth hormone stimulation of serum insulin concentration in cattle: Nutritional dependency and potential mechanisms

Previous studies on the effect of growth hormone (GH) on serum insulin concentration in cattle had generated seemingly conflicting results, and little was known about the mechanism by which GH affects serum insulin concentration in cattle, if it does. In this study, we determined whether the effect of GH on serum insulin concentration in cattle could be affected by the nutritional levels of the animal and whether GH increased serum insulin concentration in cattle by directly stimulating insulin release or insulin gene expression in the pancreatic islets. Administration of recombinant bovine GH increased serum insulin concentration in nonlactating, nonpregnant beef cows fed a daily concentrate meal in addition to ad libitum hay, but it had no effect in those cows fed hay only. Both GH treatments for 1 and 24 h increased insulin concentrations in cultures of pancreatic islets isolated from growing cattle. Growth hormone treatment for 24 h increased insulin mRNA expression in cultured bovine pancreatic islets. Growth hormone treatment for 16 h increased reporter gene expression directed by a ∼1,500-bp bovine insulin gene promoter in a rat insulin-producing β cell line. Taken together, these results suggest that exogenous GH can increase serum insulin concentration in cattle, but this effect depends on the nutritional levels of fed cattle, and that GH increases serum insulin concentration in cattle by stimulating both insulin release and insulin gene expression in the pancreatic islets.     

Gene expression and hormonal regulation of adiponectin and its receptors in bovine mammary gland and mammary epithelial cells

Although the functions of adiponectin, a differentiated adipocyte‐derived hormone, in regulating glucose and fatty acid metabolism are regulated by two subtypes of adiponectin receptors (AdipoRs; AdipoR1 and AdipoR2), those in ruminants remain unclear. Therefore we examined the messenger RNA (mRNA) expression levels of adiponectin and its receptors in various bovine tissues and mammary glands among different lactation stages, and the effects of lactogenic hormones (insulin, dexamethasone and prolactin) and growth hormone (GH) on mRNA expression of the AdipoRs in cultured bovine mammary epithelial cells (BMEC). AdipoRs mRNAs were widely expressed in various bovine tissues, but adiponectin mRNA expression was significantly higher in adipose tissue than in other tissues. In the mammary gland, although adiponectin mRNA expression was significantly decreased at lactation, AdipoR1 mRNA expression was significantly higher at peak lactation than at the dry‐off stage. In BMEC, lactogenic hormones and GH upregulated AdipoR2 mRNA expression but did not change that of AdipoR1. In conclusion, adiponectin and its receptor mRNA were expressed in various bovine tissues and the adiponectin mRNA level was decreased during lactation. These results suggest that adiponectin and its receptors ware changed in mammary glands by lactation and that AdipoRs mRNA expression was regulated by different pathways in BMEC.     

Effect of Different Weaning Age on Related-growth Gene Expressions of Spleen in Piglets

In order to study the effect of different weaning age on related-growth gene expressions of spleen in piglets,24 similar body weight and healthy piglets were selected (Duroc×Landrace×Yorkshine).All piglets were randomly divided into 4 groups (14,21,28 and 35 days of age weaning groups),and each group had 6 replications including 1 piglet separately.They were slaughtered at 24 days of age and spleen samples were acquired.The relative expression of growth hormone receptor (GHR),insulin like growth factor-1 (IGF-1),insulin like growth factor-1 receptor (IGF-1R) mRNA in spleen were measured by RT-PCR.The results showed that the relative expression of GHR mRNA in 14 and 21 days of age weaning groups was significantly higher than that in 35 days of age weaning group (P<0.05);The relative expression of IGF-1 mRNA in spleen at different weaning age groups was no significant difference (P>0.05);The relative expression of IGF-1R mRNA in 35 days of age weaning group was significantly higher than that in 28 days of age weaning group (P<0.05).The results indicated that the patterns of weaning age on related growth gene expressions of spleen are different;The expressions of spleen IGF-1R mRNA in different weaning age groups were possibly effected by the spleen self regulation of IGF-1.