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畜禽生长激素释放因子(GRF)的研究进展 总被引：4，自引：0，他引：4
生长激素释放因子(growth hormone- releasing factor,GRF)又称生长激素释放激素(growth hormone- releasinghorm one,GHRH) ,是存在于脊椎动物体内的一种生物活性多肽,由下丘脑合成并分泌,对脊椎动物的生长、发育及代谢调控起着极其重要的作用。其主要功能是,作为脑垂体生长激素(growth hormone,GH)的正性调控因子,能特异地诱导生长激素的合成与分泌,增高动物机体内的GH水平。而生长激素释放抑制因子(som atostain,SS)则抑制GH的合成与释放。GRF与其伴随的SS低谷诱发形成GH的分泌峰,峰的高度取决于GRF的强度及垂体对GRF的敏感… 相似文献
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生长激素释放因子 (GRF)是由动物下丘脑合成并分泌的一种多肽激素 ,能特异性的诱导生长激素的合成与分泌 ,提高体内生长激素的水平 ,从而促进动物的生长。本实验是将含GRF重组质粒的 JM1 0 9菌株大量培养 ,制备原生质体 (所含质粒进行定量 ) ,用 1 0 m L / L的戊二醛处理后 ,注射于小鼠后肢胫骨部肌肉 ,给予电刺激。与含有 GRF基因的裸质粒注射组对比观察对小鼠增长的影响。研究结果表明 :原生质体能够与小鼠肌肉细胞融合 ,同时 ,以原生质体介导的外源性 GRF基因可以提高小鼠的增长速度 ,其效果与裸质粒无显著差别。 1 0 0 V,50ms的低压、短脉冲电刺激对 GRF在动物体内的表达量上无显著差异 相似文献
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动物生长轴的激素调控 总被引：6，自引：0，他引：6
1 生长轴动物生长是一个复杂的生物代谢过程 ,受基因型、激素、营养、环境等多方面的影响。这些因素对生长的影响作用都是通过直接或间接影响动物内分泌系统来实现的。人和动物的生长是由促生长激素轴来调控的 ,促生长激素轴由生长激素释放因子 (GRF)、生长激素 (GH)和胰岛素样生长因子 (IGF)构成 ,其中生长激素是调控整个机体生长的最重要的激素。生长轴是动物体内从下丘脑———垂体———靶器官的一系列激素及其受体所组成的神经内分泌系统 ,如图 1所示。注 :GRF :生长激素释放因子 SS :生长抑制激素 GH :生长激素 IGF :胰… 相似文献
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通过免疫技术调控动物生长和胴体品质 总被引：3，自引：0，他引：3
1 生长激素的免疫调控 生长激素(GH)是一种重要的促进生长和调节代谢的激素。免疫调控技术通过瞄准生长激素轴,主要以三种方式达到提高生长速度,改善胴体品质的目的。这三种方式是促进生长激素分泌、提高生长激素活性、模拟生长激素的作用。 1.1 免疫中和环状脑肠肽及促进内源GH的分泌 生长激素的分泌,受多种因素影响,其中生长抑素(SS)和生长激素释放因子(GRF)是两种最主要的影响因子。SS抑制GH的分泌,而GRF促进GH的分泌。因此通过免疫中和SS,能提高机体内源性GH的分泌,从而促进动物生长。 相似文献
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动物生长是个复杂的代谢过程,受基因、激素、营养、环境等多方面的影响,这些因素直接或间接作用内分泌系统而实现对生长的影响。生长激素（GH）是由脑垂体分泌的激素,主要作用是促进RNA的合成,使器官得到生长和发育。动物的生长是由下丘脑一垂体一生长激素调节系统来调节。下丘脑分泌的生长激素释放因子（GRF）和生长素抑制激素（SS）属于高位调节因子,他们可以调节动物体内激素的整体水平, 相似文献
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生长激素释放因子(growth hormone-releasing factor,GRF)主要是由下丘脑弓状核的神经细胞分泌产生的,是一种蛋白类激素,不同动物物种的GRF有所不同.成熟的GHRH一般含有40～44个氨基酸残基,是生长激素的正性调控因子,可与生长激素释放抑制因子(somatostain,SS)共同调节生长激素(growth hormone,GH)的分泌.GRF能特异性地增加生长激素的mRNA,从而增加生长激素的生成,达到加快核酸和蛋白质的合成,减少脂肪沉积,进而影响动物的生产性能. 相似文献
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动物生长受到多种激素的调控,其中生长激素能促进胰岛素样生长因子的合成,促使组织细胞的生长与分化,增加动物体蛋白合成,降低脂肪沉积,提高瘦肉率;生长抑素抑制生长激素的分泌,从而抑制动物的生长;而生长激素释放因子促进生长激素的分泌,有利于动物的生长;胰岛素样生长因子Ⅰ能促进动物的细胞分化、泌乳、繁殖以及代谢等;新近发现的Ghrelin是生长激素促分泌素受体的内源性配体,起促生长激素释放作用。通过对上述各种激素的调控可在一定程度上提高动物的生长。 相似文献
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Orexin-B modulates luteinizing hormone and growth hormone secretion from porcine pituitary cells in culture 总被引：3，自引：0，他引：3
To test the hypothesis that orexin-B acts directly on the anterior pituitary to regulate LH and growth hormone (GH) secretion, anterior pituitary cells from prepuberal gilts were studied in primary culture. On day 4 of culture, 10(5) cells/well were challenged with 0.1, 10 or 1000 nM GnRH; 10, 100 or 1000 nM [Ala15]-hGRF-(1-29)NH2 or 0.1, 1, 10 or 100 nM, orexin-B individually or in combinations with 0.1 and 1000 nM GnRH or 10 and 1000 nM GRF. Secreted LH and GH were measured at 4 h after treatment. Basal LH and GH secretion (control; n = 6 pigs) was 183 +/- 18 and 108 +/- 4.8 ng/well, respectively. Relative to control at 4 h, all doses of GnRH and GRF increased (P < 0.0001) LH and GH secretion, respectively. All doses of orexin-B increased (P < 0.01) LH secretion, except for the 0.1 nM dose. Basal GH secretion was unaffected by orexin-B. Addition of 1, 10 or 100 nM orexin-B in combinations with 0.1 nM GnRH increased (P < 0.001) LH secretion compared to GnRH alone. Only 0.1 nM (P = 0.06) and 100 nM (P < 0.001) orexin-B in combinations with 1000 nM GnRH increased LH secretion compared to GnRH alone. All doses of orexin-B in combination with 1000 nM GRF suppressed (P < 0.0001) GH secretion compare to GRF alone, while only 0.1 nM orexin-B in combination with 10 nM GRF suppressed (P < 0.01) GH secretion compared to GRF. These results indicate that orexin may directly modulate LH and GH secretion at the level of the pituitary gland. 相似文献
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The control of growth is a complex mechanism regulated by several metabolic hormones including growth hormone (GH) and thyroid hormones. In avian species, as well as in mammals, GH secretion is regulated by hypothalamic hypophysiotropic hormones. Since thyrotropin-releasing hormone (TRH) and growth hormone-releasing factor (GRF) are potent GH secretagogues in poultry, we were interested in determining the influence of daily intravenous administration of either peptide or both simultaneously on circulating GH and IGF-I concentrations and whether an improvement in growth rate or efficiency would be obtained.
Male broiler chicks were injected once daily for a period of 21 days with either GRF (10 μg/kg), TRH (1 μg/kg) or both GRF and TRH (10 and 1 μg/kg respectively) between four and seven weeks of age. On the last day of the experiment, following intravenous injection of TRH, GRF or a combination of GRF and TRH, plasma GH levels were significantly (P<.05) increased to a similar extent in control chicks and in those which had received daily peptide injections for the previous 21 days. Circulating GH levels between 10 and 90 min post-injection were significantly (P<.05) greater and more than additive than GH levels in chicks injected with both GRF and TRH when compared to those injected with either peptide alone. Mean plasma T3 concentrations during that same time period were significantly elevated (P<.05) above saline-injected control chick levels in birds treated with TRH or GRF and TRH respectively, regardless of whether the chicks had received peptide injections for the previous 21 days. There was no evidence of pituitary refractoriness to chronic administration of either TRH or GRF injection in terms of growth or thyroid hormone secretion.
Despite the large elevation in GH concentration each day, growth rate, feed efficiency and circulating IGF-I concentrations were not enhanced. Thus the quantity or secretory pattern of GH secretion induced by TRH or GRF administration was not sufficient to increase plasma IGF-I concentration or growth. 相似文献
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To investigate the effects of long-term growth hormone-releasing factor (GRF) administration on plasma growth hormone (GH), LH and progesterone and body weight gain in growing buffalo calves, 12 female Murrah buffaloes within the age group of 6-8 months of age were divided into two groups (treatment and control groups) of six each in such a way so that average body weights between the groups did not differ (p > 0.05). Control buffaloes were not given any hormonal treatment and treatment group buffaloes were treated with synthetic bovine GRF [bGRF (1-44)-NH(2)] at the rate of 10 microg/100 kg body weight intravenously at an interval of 15 days from week 6 (5-week pre-treatment period) till 18 injections were completed (week 6-42 treatment period) and thereafter, effect of exogenous GRF were observed for 10-week post-treatment period. Jugular blood samples were drawn twice a week at 3-4-day intervals for plasma GH, LH and progesterone quantification. Body weight of all animals was recorded twice a week. During pre-treatment period, mean plasma GH, LH and progesterone did not differ (p > 0.05) between the groups. But during treatment as well as post-treatment period, mean plasma GH levels were found to be significantly (p < 0.01) higher in treatment than control group of buffaloes. Administration of GRF for longer term sustained a higher level of plasma GH even after cessation of treatment. GRF-treated buffaloes attained higher (p < 0.01) body weight than the controls. Repeated GRF administration for long-term significantly (p < 0.01) increased plasma LH and progesterone. In conclusion, repeated long-term exogenous GRF administration induces and even enhances GH release without any sign of refractoriness. GRF may, therefore, be used to induce daily GH release without loss of responsiveness over an extended period of time in young growing female buffaloes and it may assist these animals to grow faster. 相似文献
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Stimulation of pig growth performance by porcine growth hormone and growth hormone-releasing factor 总被引：10，自引：0，他引：10
T D Etherton J P Wiggins C S Chung C M Evock J F Rebhun P E Walton 《Journal of animal science》1986,63(5):1389-1399
The current study was undertaken to determine the effects of human growth hormone-releasing factor [hpGRF-(1-44)-NH2] on growth performance in pigs and whether this response was comparable to exogenous porcine growth hormone (pGH) treatment. Preliminary studies were conducted to determine if GRF increased plasma GH concentration after iv and im injection and the nature of the dose response. Growth hormone-releasing factor stimulated the release of pGH in a dose-dependent fashion, although the individual responses varied widely among pigs. The results from the im study were used to determine the dose of GRF to use for a 30-d growth trial. Thirty-six Yorkshire-Duroc barrows (initial wt 50 kg) were randomly allotted to one of three experimental groups (C = control, GRF and pGH). Pigs were treated daily with 30 micrograms of GRF/kg body weight by im injection in the neck. Pigs treated with pGH were also given 30 micrograms/kg body weight by im injection. Growth rate was increased 10% by pGH vs C pigs (P less than .05). Growth rate was not affected by GRF; however, hot and chilled carcass weights were increased 5% vs C pigs (P less than .05). On an absolute basis, adipose tissue mass was unaffected by pGH or GRF. Carcass lipid (percent of soft-tissue mass) was decreased 13% by GRF (P less than .05) and 18% by pGH (P less than .05). Muscle mass was significantly increased by pGH but not by GRF. There was a trend for feed efficiency to be improved by GRF; however, this was not different from control pigs. In contrast, pGH increased feed efficiency 19% vs control pigs (P less than .05). Chronic administration of GRF increased anterior pituitary weight but did not affect pituitary GH content or concentration. When blood was taken 3 h post-injection, both GRF- and pGH-treated pigs had lower blood-urea nitrogen concentrations. Serum glucose was significantly elevated by both GRF and pGH treatment. This was associated with an elevation in serum insulin. These results indicate that increasing the GH concentration in blood by either exogenous GH or GRF enhances growth performance. The effects of pGH were more marked than for GRF. Further studies are needed to determine the optimal dose of GRF to administer in growth trials and the appropriate pattern of GRF administration in order to determine whether GRF will enhance pig growth performance to the extent that exogenous pGH does. 相似文献
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P. Pastoureau J. Charrier M.M. Blanchard G. Boivin J.P. Dulor M. Theriez B. Barenton 《Domestic animal endocrinology》1989,6(4):321-329
The effects of a long term treatment with human GRF(1–29)NH2 on plasma growth hormone (GH), somatomedin C (Sm-C), histomorphometric parameters of bone growth and body composition were investigated in normal and low birthweight male lambs. The animals were divided into two groups according to their birthweight: 24 normal birthweight (NBW) lambs weighing more than 4 kg and 22 low birthweight (LBW) lambs weighing less than 2.5 kg at birth. Half of the animals in each group received two daily subcutaneous injections (8 μg/kg body weight) of hGRF(1–29)NH2 (GRF) from birth to slaughter at 45 or 90 days of age. The other animals received the solvant only. At the beginning and at the end of the treatment, plasma GH and serum Sm-C concentrations were measured in all groups. After slaughter, a histomorphometric study was performed on undecalcified sections of metacarpal growth plates, and the remaining of the carcass was pulverized to study the chemical body composition.
GRF induced GH release in both GRF-treated groups. However, plasma GH reached higher (P<.001) concentrations and the GRF-induced GH peak lasted longer in LBW than in NBW lambs. At day 45, the GRF treatment increased (P<.05) serum Sm-C concentrations in LBW. Most of histomorphometric parameters reflecting the metacarpal growth in length, were not statistically modified under GRF treatment. However, the size of degenerative cells was smaller (P<.05) in LBW treated lambs as compared to controls. Consequently, the cell production in the growth plate was increased (P<.05) under GRF treatment. In both NBW and LBW groups at 45 days of treatment, GRF treatment reduced the amounts of lipids (P<.025) and energy (P<.05), while increased (P<.01) phosphorus deposition in the body. In contrast, there was no effect of GRF treatment on protein content.
We conclude from this experiment that the induction of GH secretion by a chronic treatment with GRF is able to modify some patterns of growth. However, most of the effects of GRF were observed in LBW lambs and after 45 days of treatment only. This suggests that treatment with GRF may serve to compensate for growth in growth-retarded animals. Further studies with different mode of GRF administration should indicate whether it is as much effective in normal animals. 相似文献
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The neurophysiological regulation of growth hormone secretion 总被引：3，自引：0，他引：3
With the advent of genetic engineering, the importance of GH in the regulation of growth and metabolism in domestic species has been clearly demonstrated. Ample evidence of an integral role for GH in the processes of growth and lactation exists in dairy cattle (1,2), sheep (3), beef cattle (4) and swine (5). For example, circulating GH levels are high during the period of rapid growth in several species including cattle (6), swine (7) and poultry (8). Endogenous GH secretion is primarily controlled by the central nervous system (CNS) via two specific hypothalamic neurohormones, growth hormone-releasing factor (GRF) and somatostatin (SRIF), an inhibitor of GH release. The secretion of GRF and SRIF is governed by a host of neuropeptides and neurotransmitters which provide a functional link between higher CNS centers and hypophysiotropic neurons. This review will focus on the CNS regulation of GH secretion and circulating factors which feedback to either stimulate or inhibit its release. 相似文献
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P. Dubreuil G. Pelletier D. Petitclerc H. Lapierre Y. Couture P. Brazeau P. Gaudreau J. Morisset 《Domestic animal endocrinology》1987,4(4):299-307
The aim of this study was to determine the effect of age and sex on basal secretory patterns of growth hormone (GH) and growth hormone-releasing factor (GRF) induced GH release. Eighteen pigs (9 castrated males and 9 females) were stimulated with pGRF(1–29)NH2 at 7,11,15,19 and 23 weeks of age. Blood samples were taken from each animal via jugular vein cannulate every 20 min, from 6 hr before to 5 hr after iv GRF administration at a dose of 4 μg/kg. GH baseline levels, amplitude of the GH peaks, area under the GH peaks and the overall mean of GH serum levels decreased (P<.001) with age in both sexes. Age also had a marked effect on GRF-induced GH release: the amplitude of GH peaks and area under the GH peaks decreased (P<.001) with age. The GH response to pGRF(1–29)NH2 varied considerably, depending on the timing of the episodic endogenous secretion of GH. An immediate response (<30 min) was observed when GRF was injected at the end of a trough period or at the beginning of a peak, but there was no immediate response when GRF was injected at the end of a peak or at the beginning of a trough period. Our results show that both endogenous GH secretion and pGRF(1–29)NH2-induced GH release declines with age, suggesting a decreased sensitivity of the somatotroph cells to GRF with age; and that the high variability of the GH response to pGRF(1–29)NH2 stimulation depends greatly on the timing of the episodic endogenous GH release, thus implying a possible episodic endogenous somatostatin secretion by the hypothalamus. 相似文献
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C E Rexroad K Mayo D J Bolt T H Elsasser K F Miller R R Behringer R D Palmiter R L Brinster 《Journal of animal science》1991,69(7):2995-3004
Chimeric genes containing either the mouse transferrin (Trf) enhancer/promoter fused to the structural sequences encoding bovine growth hormone (GH) or the mouse albumin (Alb) enhancer/promoter fused to the gene for human growth hormone-releasing factor (GRF) were microinjected into sheep zygotes. A low percentage of resulting transgenic sheep chronically expressed the respective genes, resulting in elevated plasma concentrations of circulating GH or GRF, respectively. Growth hormone-releasing factor expression induced elevated plasma levels of endogenous GH production. In addition, elevated levels of circulating insulin-like growth factor-I were observed in the bovine GH-expressing Trf transgenic sheep. Growth of these founder transgenic sheep relative to controls were not enhanced. In part, this may be due to the development of the diabetic condition exhibited by both transgenic groups. These results demonstrate that the mouse Trf and Alb enhancer/promoters are active in sheep and suggest that alternate strategies for expressing growth-related genes may be required to modulate growth in sheep. 相似文献
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The effects of intravenous (IV) and intracerebroventricular (ICV) administration of either bovine growth hormone releasing hormone (GRF) or thyrotrophin releasing hormone (TRH) on plasma growth hormone (GH) and glucose levels have been examined in sheep. Intravenous GRF 1-29NH2 at 3 and 30 micrograms stimulated an increase in GH levels in a dose-dependent fashion; administration of GRF into a lateral cerebral ventricle, however, produced a smaller GH response which was similar at these two doses. Evaluation of somatostatin levels in petrosal sinus blood (which collects pituitary effluent blood) showed that ICV administration of GRF stimulated a release of somatostatin into the blood. Furthermore, concurrent administration of GRF and a potent anti-somatostatin serum ICV resulted in a much enhanced release of GH which was similar to that obtained with a comparable dose of GRF given IV. TRH (as another putative GH-secretagogue) was also administered both IV and ICV. When given IV, 200 micrograms (but not 100 micrograms) TRH produced an elevation in GH levels. By contrast, when 5 micrograms TRH was given ICV there was a decrease in circulating GH levels, but no change in plasma somatostatin concentrations. These results indicate that the smaller GH response to ICV- compared with IV-administered GRF is due to the release of somatostatin within the brain. In addition, it would seem that TRH is not a physiological GH-secretagogue in sheep. 相似文献
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Regulation of the growth hormone and luteinizing hormone response to endotoxin in sheep 总被引：4，自引：0，他引：4
Infectious disease processes cause physiological adaptations in animals to reorder nutrient partitioning and other functions to support host survival. Endocrine, immune and nervous systems largely mediate this process. Using endotoxin injection as a model for catabolic disease processes (such as bacterial septicemia), we have focused our attention on regulation of growth hormone (GH) and luteinizing hormone (LH) secretion in sheep. Endotoxin produces an increase in plasma GH and a decrease in plasma LH concentrations. This pattern can be reproduced, in part, by administration of various cytokines. Antagonists to both interleukin-1 (IL-1) and tumor necrosis factor (TNF) given intravenously (IV) prevented the endotoxin-stimulated increase in GH. Since endotoxin will directly stimulate GH and LH release from cultured pituitary cells, the data suggest a pituitary site of action of the endotoxin to regulate GH. Studies with portal vein cannulated sheep indicated that gonadotropin releasing hormone was inhibited by endotoxin, suggesting a central site of action of endotoxin to regulate LH. However, other studies suggest that endotoxin may also regulate LH secretion at the pituitary. Thus, IL-1 and TNF regulate GH release from the pituitary gland while endotoxin induces a central inhibition of LH release. 相似文献