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Ghrelin, the natural ligand of the growth hormone secretagogue receptor (GHS-R1a), has been shown to stimulate growth hormone (GH) secretion. Regulation of ghrelin secretion in ruminants is not well studied. We investigated the effects of oxyntomodulin (OXM) and secretin on the secretions of ghrelin, insulin, glucagon, glucose, and nonesterified fatty acids (NEFA) in pre-ruminants (5 wk old) and ruminants (10 wk old) under normal physiological (feeding) conditions. Eight male Holstein calves (pre-ruminants: 52 ± 1 kg body weight [BW]; and ruminants: 85 ± 1 kg BW) were injected intravenously with 30 μg of OXM/kg BW, 50 μg of secretin/kg BW, and vehicle (0.1% bovine serum albumin [BSA] in saline as a control) in random order. Blood samples were collected, and plasma hormones and metabolites were analyzed using a double-antibody radioimmunoassay system and commercially available kits, respectively. We found that OXM increased the concentrations of insulin and glucose but did not affect the concentrations of ghrelin in both pre-ruminants and ruminants and that there was no effect of secretin on the concentrations of ghrelin, insulin, and glucose in these calves. We also investigated the dose-response effects of OXM on the secretion of insulin and glucose in 8 Holstein steers (401 ± 1 d old, 398 ± 10 kg BW). We found that OXM increased the concentrations of insulin and glucose even at physiological plasma concentrations, with a minimum effective dose of 0.4 μg/kg for the promotion of glucose secretion and 2 μg/kg for the stimulation of insulin secretion. These findings suggest that OXM takes part in glucose metabolism in ruminants. 相似文献
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The effects of increased postruminal supply of casein, corn starch, and soybean oil on plasma concentrations of the gastrointestinal hormones ghrelin and oxyntomodulin (OXM) were investigated. Four mid-lactation Holstein cows were used in a 4 × 4 Latin square. Treatments were continuous abomasal infusions (23 h/d) for 7 d of water, soybean oil (500 g/d), corn starch (1100 g/d), or casein (800 g/d). Jugular vein plasma was obtained every 30 min for 7 h on days 1 and 7. Soybean oil and casein infusion decreased preprandial plasma ghrelin concentration by approximately 20% on both d (time-by-treatment P < 0.10); however, dry matter intake (DMI) was depressed only after 7 d of oil infusion. Infusion of soybean oil, corn starch, or casein did not change the plasma OXM concentration (P > 0.20). The present data indicate that plasma ghrelin concentration is depressed immediately before feeding by the postruminal infusion of soybean oil and casein, but it is not affected during the postprandial period. Plasma ghrelin concentration was not altered (P > 0.20), pre- or postfeeding, by increased postruminal supply of corn starch. In addition, plasma OXM concentration did not respond (P > 0.20) to postruminal nutrient infusion. In conclusion, a decrease in DMI when fat is infused could be partially explained by the decrease in prefeeding plasma ghrelin concentration, but a decrease in prefeeding plasma ghrelin concentration is not always associated with a decrease in DMI, as observed for the infusion of casein. Plasma OXM concentration was not affected by postruminal infusion of macronutrients. 相似文献
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S. ThanThan C. MekaruN. Seki K. HidakaA.Ueno H. ThidarMyint H. Kuwayama 《Domestic animal endocrinology》2010
The purpose of this study was to evaluate whether circulating ghrelin and growth hormone (GH) concentrations in cattle are regulated by endothelin-1 (ET-1), endothelin-3 (ET-3), and secretin. Six Holstein steers (242 ± 1 d old, 280.5 ± 4.4 kg body weight [BW]; mean ± SEM) were allocated randomly in an incomplete Latin square design to receive each of 4 treatment compounds (vehicle, ET-1, ET-3, and secretin) with 1-d intervals between successive treatments. The treatment compounds were injected intravenously via a catheter inserted into the external jugular vein of each steer. Blood was sampled from the indwelling catheter at -30, -15, 0, 5, 10, 15, 20, 30, 45, 60, 90, 120, 150, and 180 min. Plasma ghrelin and GH responses to the treatment compounds were measured by a double-antibody radioimmunoassay system. Data were analyzed by using a MIXED procedure of SAS, version 9.1. Plasma acyl ghrelin, total ghrelin, and GH concentrations were increased by both ET-1 and ET-3 injection (ET-1 injection: 311 ± 15 pg/mL vs 245 ± 15 pg/mL, 2.4 ± 0.2 ng/mL vs 1.61 ± 0.05 ng/mL, 4.73 ± 0.92 ng/mL vs 1.17 ± 0.09 ng/mL for acyl ghrelin, total ghrelin, and GH, respectively; ET-3 injection: 337 ± 27 pg/mL vs 245 ± 15 pg/mL, 2.6 ± 0.1 ng/mL vs 1.61 ± 0.05 ng/mL, 5.56 ± 0.97 ng/mL vs 1.17 ± 0.09 ng/mL for acyl ghrelin, total ghrelin, and GH, respectively; P < 0.01). Ghrelin and GH concentrations were not changed by secretin injection throughout the experimental periods. These results indicate that ET-1 and ET-3 stimulate ghrelin and GH secretion in cattle and demonstrate for the first time that endogenous ghrelin released in response to endothelin injection stimulates GH secretion in vivo in cattle. 相似文献
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【目的】探讨手术去势(阉割)、免疫去势对公猪下丘脑-垂体-睾丸轴上Ghrelin mRNA和功能性Ghrelin受体1a mRNA表达的影响。【方法】将21头公猪随机均分为免疫去势组、未去势组和手术去势组,免疫去势组于9周龄初次接种免疫去势疫苗,17周龄加强免疫;手术去势组在仔猪出生7d内进行阉割去势;未去势组不作任何处理。25周龄时屠宰所有公猪,取下丘脑、垂体和睾丸组织,以β-actin为内参基因,采用实时荧光定量PCR法检测公猪下丘脑-垂体-睾丸轴Ghrelin及其受体mRNA基因的相对表达量。【结果】手术去势、免疫去势和未去势公猪下丘脑Ghrelin及其功能性受体mRNA基因相对表达量的差异不显著(P0.05),未去势公猪垂体Ghrelin mRNA的相对表达量显著低于手术阉割去势公猪(P0.05),免疫去势公猪睾丸中Ghrelin受体mRNA的相对表达量显著高于未去势公猪(P0.05)。【结论】公猪生殖轴存在Ghrelin mRNA和功能性Ghrelin受体mRNA,且手术阉割去势导致垂体中Ghrelin mRNA的相对表达量增加,免疫去势增加了睾丸Ghrelin受体mRNA的相对表达量,提示Ghrelin可能对生殖轴有调节功能。 相似文献
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研究Ghrelin对奶山羊下丘脑神经肽Y(NPY)和刺鼠相关蛋白(AGRP)mRNA表达的影响。10只泌乳期莎能奶山羊随机分为试验组和对照组,每组5只。试验组静脉注射Ghrelin(3.0μg/kg),3h后宰杀,迅速取下丘脑,检测下丘脑脑神经肽Y和刺鼠相关蛋白mRNA的表达。结果表明,一定剂量的Ghrelin对NPY mRNA的表达具极显著上调作用(P0.01);对AGRP mRNA的表达也有显著促进作用(P0.01)。以上结果提示Ghrelin可能通过对这些神经肽的作用参与对奶山羊摄食和能量代谢等生理活动的调节。 相似文献
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猪Ghrelin基因表达质粒构建及其促生长作用 总被引：10，自引：0，他引：10
通过RT-PCR获得猪Ghlelin基因cDNA片段,克隆入pcDNA3.1( )质粒中构建真核表达质粒pcDNA-pGhl,并将该质粒注射到大鼠和新西兰兔后腿肌肉中,以研究pGhlelin真核表达质粒对动物生长和血液相关激素分泌的影响。大鼠试验表明:pcDNA-pGhl在注射初期的1个月内有增加大鼠体重及在整个试验期有降低料重比的趋势。在注射质粒后第6天,试验组个体增重提高10.6%,差异显著;饲料转化率提高10%,差异极显著。新西兰兔试验表明:试验组血液GH水平一直高于对照组,且在注射后2周高出35%,同时随着GH浓度的增加,血液中SS的浓度相应升高。注射重组质粒pcDNA-sGhl有增加血浆GH和SS水平趋势。以上结果表明,Ghrelin基因真核表达质粒通过促进GH的分泌促进生长,但其促生长效能较短暂,可能是由于同时促进生长抑素分泌。 相似文献
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根据文献报道的猪Ghrelin与生长激素促释放激素(GHRH)基因序列,设计了含Ghrelin信号肽及Ghrelin与GHRH部分核苷酸序列及lin-ker序列等共233 bp的基因序列,通过基因合成的方法获得基因片段,并将其连入克隆载体pUC57中,经双酶切将其克隆至PCI真核表达载体中。经PCR、酶切和测序鉴定,证明融合猪Ghrelin和GHRH基因的真核表达载体pCI-Ghrelin/GHRH构建成功;提取PCI-Ghrelin/GHRH质粒并体内转染小鼠腿部肌肉组织,观察25 d内pCI-Ghrelin/GHRH质粒对小鼠体重的影响,结果表明:0~10 d试验组小鼠平均日增重高于pCI-Ghrelin-28aa组及生理盐水组,但试验组后期增重缓慢。 相似文献
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【目的】阐明生长素(Ghrelin)及其mRNA在大鼠卵巢和睾丸中的分布。【方法】取成年SD大鼠的睾丸和卵巢,制成石蜡切片,采用免疫组化和原位杂交方法,分别检测Ghrelin和Ghrelin mRNA在大鼠性腺组织中的定位。【结果】雄性大鼠睾丸间质细胞、支持细胞、初级精母细胞、次级精母细胞中均有Ghrelin分布,而精原细胞、精子细胞、肌样细胞中均无Ghrelin分布;Ghrelin mRNA的分布规律与Ghrelin一致。在雌性大鼠卵巢中,Ghrelin主要分布在黄体细胞、卵巢门间质细胞、卵母细胞上;Ghrelin mRNA在黄体细胞、卵巢门间质细胞、原始卵泡、初级卵泡的颗粒层细胞、次级卵泡的卵泡膜层细胞和颗粒层细胞中均有分布。【结论】Ghrelin及其mRNA在大鼠性腺中均有分布,可能对大鼠性腺的发育及其功能有一定的调控作用。 相似文献