Expression of gastric ghrelin and H(+)-K(+)-ATPase mRNA in weanling piglets and effect of ghrelin on H(+)-K(+)-ATPase expression and activity in gastric mucosal cells in vitro

This study was designed to investigate the effect of ghrelin on gastric acid secretion in weaning piglets both in vivo and in vitro. Thirty newborn piglets were selected from six litters and on 28, 35 (weaning), 38, 42 and 45d of age, respectively, one piglet from each litter was killed and the mucosal tissue from gastric fundus was collected for detecting ghrelin mRNA as well as H(+)-K(+)-ATPase mRNA expression and activity. Primary cultures of gastric mucosal cells from 5-week-old weaning piglets were challenged with 3x10(-5), 3x10(-4), 3x10(-3), 3x10(-2) and 3x10(-1)nmol/ml h-ghrelin, respectively, for 4h in order to further clarify the effect of ghrelin on gastric H(+)-K(+)-ATPase mRNA expression and activity. Ghrelin mRNA expression in gastric fundus kept stable from 28d to 42d, followed by a sudden increase on 45d, exhibiting a peak that was significantly higher than any other age groups investigated. H(+)-K(+)-ATPase activity and mRNA expression showed similar trends of increase with slightly different timing. H(+)-K(+)-ATPase mRNA expression tended to increase on 42d, while H(+)-K(+)-ATPase activity started to rise from 35d, but neither of them reached significantly higher levels until 45d. In vitro, ghrelin significantly increased H(+)-K(+)-ATPase activity of gastric mucosal cells at 3x10(-4), 3x10(-3), and 3x10(-2)nmol/ml, but augmented H(+)-K(+)-ATPase mRNA expression only at 3x10(-4)nmol/ml. The results indicate that ghrelin mRNA expression is up-regulated 10 days after weaning in the gastric fundus of piglets, coinciding with the increase of H(+)-K(+)-ATPase mRNA expression and activity. Ghrelin acts on gastric mucosal cells to stimulate both mRNA expression and activity of H(+)-K(+)-ATPase in vitro.     

水牛发情前后血清瘦素与饥饿激素水平的动态变化及其相关性

[目的]了解水牛发情前后血清瘦素与饥饿激素水平的变化规律及其相关性。[方法]从发情前14天至发情后22天,从广西某水牛场23头摩拉水牛抽取血液,用ELISA方法测定血清瘦素和饥饿激素水平。[结果]水牛血清瘦素和饥饿激素水平在发情前逐步上升,发情后日变化剧烈,且两者呈极显著正相关。[结论]该研究为水牛营养代谢病机制的研究提供了新的途径。     

PCI-Ghrelin-28aa质粒微球对小鼠的促生长效应

以乳酸-乙醇酸共聚物为载体，采用复乳-液中蒸发法制备PCI-Ghrelin-28aa真核表达质粒微球，微球大小与文献报道相符，平均粒径分布在2~3 μm间，测得的包封率为99.27%，载药量6.8 μg/mg，回收率65.7%；将质粒微球肌肉注射小鼠，并记录25 d里小鼠的体重变化情况；体重统计结果表明，25 d时微球包裹质粒组累积增重比裸质粒组、生理盐水组分别高14.3%、27.9%(P<0.05)。结论认为，载PCI Ghrelin 28aa质粒微球具有缓释作用，并有增强质粒吸收及表达的趋势。     

生长素及其在动物生产中的应用

本文概括了生长素及其受体的结构及分布,对生长素的生物学效应、分泌调节及其在动物生产中的应用进行了综述。     

Combined administration of ghrelin and GHRH synergistically stimulates GH release in Holstein preweaning calves

Ghrelin is a gut peptide which participates in growth regulation through its somatotropic, lipogenic and orexigenic effects. Synergism of ghrelin and growth hormone-releasing hormone (GHRH) on growth hormone (GH) secretion has been reported in humans and rats, but not in domestic animals in vivo. In this study, effects of a combination of ghrelin and GHRH on plasma GH and other metabolic parameters, and changes in plasma active and total ghrelin levels were studied in Holstein bull calves before and after weaning. Six calves were intravenously injected with vehicle (0.1% BSA-saline), ghrelin (1 microg/kg BW), GHRH (0.25 microg/kg BW) or a combination of ghrelin plus GHRH at the age of 5 weeks and 10 weeks (weaning at 6 weeks of age). Ghrelin stimulated GH release with similar potency as GHRH and their combined administration synergistically stimulated GH release in preweaning calves. After weaning, GH responses to ghrelin and GHRH became greater compared with the values of preweaning calves, but a synergistic effect of ghrelin and GHRH was not observed. The GH areas under the concentration curves for 2h post-injection were greater in weaned than in preweaning calves (P<0.05) if ghrelin or GHRH were injected alone, but were similar if ghrelin and GHRH were injected together. Basal plasma active and total ghrelin levels did not change around weaning, but transiently increased after ghrelin injection. Basal plasma insulin, glucose and non-esterified fatty acid levels were reduced after weaning, but no changes by treatments were observed. In conclusion, ghrelin and GHRH synergistically stimulated GH release in preweaning calves, but this effect was lost after weaning.     

The effect of pentaghrelin on amylase release from the rat and porcine dispersed pancreatic acinar cells in vitro

Ghrelin-28 was found to inhibit the pancreatic enzyme output in rats, although the effect of pentaghrelin has not been studied. The effect of ghrelin on pig exocrine pancreas remains largely unknown. The aim of the present study was: (1) to establish a model of porcine dispersed pancreatic acinar cells in vitro and compare it with an existing rat model, and (2) to investigate the effect of pentaghrelin on amylase release from the rat and pig pancreatic acini. The rat and porcine acinar cell preparations released amylase in response to cholecystokinin octapeptide (CCK-8) stimulation in a dose-related manner. Pentaghrelin hardly inhibited the amylase release in rat preparations (maximum inhibition with 10^− 9 M pentaghrelin). It stimulated amylase release in porcine preparations, however, no dose response was found in a range of doses between 10^− 10 and 10^− 7 M. Concluding, pentaghrelin may stimulate amylase release from porcine acinar cells through as yet unknown mechanisms.     

RNA干扰沉默Ghrelin基因对仔猪胃酸分泌的调节作用

[目的]研究生长素(Ghrelin)基因沉默对仔猪胃酸分泌的调节作用,为防治仔猪断奶后某些消化系统功能障碍或分泌异常研究提供新靶点,进而阐明Ghrelin对胃酸分泌的调节作用机制.[方法]采用脂质体将RNA干扰沉默的shGhrelin转染体外培养的猪胃黏膜上皮细胞,优化确立最佳转染条件,并通过荧光定量RT-PCR检测shGrelin转染对胃黏膜上皮细胞中Ghreli基因mRNA表达及H+-K+-ATPase(质子泵)活性的影响.[结果]质粒(shGhrelin)与脂质体(Lipofectamine 2000)的最佳转染比例为1:3,最佳转染时间24h.与正常对照组相比,以shGhrelin转染胃黏膜上皮细胞后,其Ghrelin基因mRNA的表达显著降低(P<0.05,下同),H+-K+-ATPase活性也显著下降.[结论]采用RNA干扰技术能沉默胃黏膜上皮细胞Ghrelin基因表达和抑制H+-K+-ATPase活性,表明Ghrelin对胃酸分泌具有重要的调节作用.     

巢湖鸭Ghrelin基因外显子3的SNP检测及其与体尺性状的关联分析

[目的]分析巢湖鸭Ghrelin基因多态性及其与巢湖鸭体尺性状的关系。[方法]以巢湖鸭为试验材料,采用PCR-SSCP分析检测巢湖鸭Ghrelin基因外显子3的单核苷酸多态性,并将其与巢湖鸭体重、体斜长、胸深、胸宽和龙骨长等体尺性状进行关联分析。[结果]检测到3种基因型AA、BB和AB。巢湖鸭外显子3第54位发生了G→A的突变,该突变位点对巢湖鸭体重、胸深和龙骨长的影响达到极显著水平（P〈0.01）,对体斜长、胸宽和半潜水长的影响达到显著水平（P〈0.05）,对胫长和胫围的影响不显著（P〉0.05）。BB基因型的体重、体斜长、胸深、胸宽、龙骨长和半潜水长显著高于AA型和AB型。[结论]Ghrelin基因多态性与鸭的部分体尺性状存在显著相关性,且对B等位基因进行选择将有利于提高巢湖鸭的体尺指标。     

Effects of feeding pattern on ghrelin and insulin secretion in pigs

Ghrelin is a peptide hormone that has been implicated in the regulation of feed intake, but little is known about its secretion in pigs. Hence, the effect of feeding pattern on the regulation of ghrelin secretion was tested. In experiment 1, barrows were allotted randomly into 1 of 2 groups, (1) ad libitum fed (CONT) and (2) limited access to feed (once per day, MEAL). Blood samples were taken through jugular catheters every 15 min for 6 h after 7 d on the experimental feeding regimen. Plasma concentrations of ghrelin and insulin were determined by radioimmunoassay. Ghrelin concentrations in the MEAL pigs were elevated before feeding and declined after feeding (P < 0.01). No pattern in plasma ghrelin concentrations was observed in the CONT pigs, but ghrelin concentrations were lower than in the MEAL group. Insulin concentrations were greater in CONT pigs (P < 0.01) during most of the sampling and increased after feeding in the MEAL pigs (P < 0.01). In experiment 2, the treatments were the same as in experiment 1; however, the amount of feed was increased in the MEAL group so that their daily intake was similar to the CONT pigs. Ghrelin concentrations in the MEAL group were again elevated before the meal and declined afterward (P < 0.01). Insulin but not glucose concentrations were negatively correlated with ghrelin. Once-per-day feeding resulted in increased plasma concentrations of ghrelin, which decreased after feeding. Ghrelin may be involved in the regulation of feed intake in pigs.