铬的生物学功能及应用效果

正1铬的生物学功能1.1铬参与糖代谢早在1966年,Mertz就报道铬可以有效改善糖尿病者耐糖量,降低对外源性胰岛素的需求量。Steel等研究发现,铬可以促进肝脏对葡萄糖的吸收。潘庆等在奥尼罗非鱼日粮中添加2毫克/千克有机铬,结果表明,添加吡啶甲酸铬能够促进罗非鱼对葡萄糖的利用。铬参与糖代谢,主要作用于细胞上的胰岛素敏感部位,可提高细胞表面胰岛素数量或激活胰岛素和膜受体之间的二硫键,加强两者之间的协同作用,从而刺激外周组织对葡萄糖的摄取,增加葡萄糖的吸收,加快血清中葡萄糖向外周组织的转运,维持血糖的正常水平,增强动物     

吡啶羧酸铬对猪的作用效果

１概述铬为人和动物正常代谢所必需的微量元素。其作用是作为葡萄糖耐受因子（ＧｌｕｃｏｓｅＴｏｌｅｒａｎｃｅＦａｃｔｏｒ,ＧＴＦ）的重要组成成分。ＧＴＦ是一种能够维持动物血液中葡萄糖正常的物质,其化学结构至今尚未完全弄清,但研究者们相信其中可能含有烟酸、谷氨酸、半脘氨酸、甘氨酸和三价铬（Ｃｒ３ｒ）。没有铬,ＧＴＦ就没有活性。ＧＴＦ的作用是增加动物的葡萄糖耐受量和增强胰岛素活性,促进胰岛素与细胞受体结合,进而刺激动物机体组织对葡萄糖的摄取。铬对脂类代谢的作用是维持血液的正常胆固醇水平,影响脂肪和胆固醇…     

肉鸡铬的营养研究进展

铬是葡萄糖耐受因(GTF)的活性组成部分，GTF调节体内葡萄糖代谢。铬通过强胰岛素在体内的作用，参与碳水化合物、脂肪、蛋白质和核酸的代谢。补铬可提高动物抗应激的能力．铬还能促进机体免疫机能。此外，铬可提高肉鸡的生产性能和抗应激，降低发病率并能改善肉质品质。     

微量元素铬的营养调控及吸收转运模式探讨

铬作为葡萄糖耐受因子的重要活性成分,可以刺激胰岛素与跨膜胰岛素受体结合,增强胰岛素活性,并参与碳水化合物、脂肪、蛋白质和核酸代谢。本文主要综述铬的研究概况、营养调控机制及吸收转运模式。     

肉鸡铬的营养研究进展

铬是葡萄糖耐受因子(GTF)的活性组成部分,GTF可调节体内葡萄糖代谢。铬通过增强胰岛素在体内的作用,参与碳水化合物、脂肪、蛋白质和核酸的代谢,进而影响肉鸡的生长、免疫、繁殖和胴体品质,降低应激,改善机体免疫机能,提高肉鸡的生产性能和繁殖力。肉鸡体内铬的研究已经取得一定的进展,本文综述了铬的来源、铬在肉鸡体内的代谢、分布、含量、缺乏、中毒以及营养机理和铬在肉鸡生产中应用效果,为进一步在肉鸡生产中科学地应用铬提供依据。     

有机铬制剂在饲料中的应用

铬是葡萄糖耐受因子（GTF）的主要组成部分如果缺乏足够的GTF．胰岛素的作用会受到抑制．从而影响葡萄糖和重要氯基酸的运输和血糖的正常水平。此外．铬还参与蛋白质．碳水化合物以及脂肪的代谢等。     

一种自发胰岛素抵抗的3T3-L1脂肪细胞模型构建

本研究旨在突变3T3-L1细胞葡萄糖转运蛋白4(GluT4)的基因序列,造成GluT4功能障碍,从而获得一种稳定、自发胰岛素抵抗的脂肪细胞模型。利用CRISPR/Cas9技术对3T3-L1细胞的GluT4编码区进行定向切割,通过流式细胞术和基因测序筛选稳定突变的细胞株;使用CCK-8法检测所筛选细胞株的增殖活力;对细胞进行成脂诱导分化,油红O染色以判断细胞成脂分化能力;以胰岛素刺激下葡萄糖摄入量确定细胞对胰岛素的抵抗程度;qPCR和Western blot检测胰岛素抵抗细胞成脂分化过程中关键基因的表达。结果表明:第九外显子处13 bp的缺失导致3T3-L1细胞GluT4蛋白功能障碍,这一突变不影响细胞的增殖活力;成脂诱导分化过程中,该细胞株表现出严重且稳定的自发胰岛素抵抗,葡萄糖摄取受阻,与成脂分化和脂质合成相关的基因表达显著或极显著下调(P0.05或P0.01)。综上所述,GluT4功能障碍阻碍了脂肪细胞响应胰岛素的葡萄糖摄取,从而造成脂肪细胞产生自发的胰岛素抵抗;本研究从多个角度对该胰岛素抵抗脂肪细胞模型进行检测分析,验证了其稳定性和有效性,为脂肪营养代谢和胰岛素抵抗相关研究提供了新材料。     

有机铬对家禽代谢,胴体组成和禽蛋营养成分的影响

铬是葡萄糖耐受因子(GTF)不可缺少的成分,具有调控动物食欲、维持正常血糖水平和蛋白质摄入的作用,此外,铬还有抗心脏病和糖尿病的作用(Mertz,1993)。GTF的作用是促进胰岛素的生理功能(Mertz等1974)。胰岛素是调节能量、脂肪代谢、蛋白质沉积和胆固醇利用的重要激素。当细胞的胰岛素敏感性下降,细胞利用葡萄糖和氨基酸的能力受到影响,导致脂肪     

苹果酸酶在葡萄糖和胰岛素诱导鹅肝脂肪变性中的作用研究

本研究旨在研究不同浓度葡萄糖和胰岛素诱导鹅肝脂肪变性过程中苹果酸酶(Malic enzyme,ME)的活性及其mRNA表达情况,以探讨ME在鹅肝脂肪变性中的作用。根据鸡ME基因序列保守区设计引物,通过RT-PCR、克隆测序等技术扩增鹅ME基因;分离、培养四川白鹅原代肝细胞,添加不同浓度葡萄糖和胰岛素诱导肝细胞脂肪变性,检测细胞内甘油三酯(TG)含量、ME活性及其mRNA表达情况。结果发现,鹅ME基因跟原鸡同源性最高;与对照组相比,葡萄糖及其与胰岛素协同作用均能显著促进肝细胞内甘油三酯(TG)沉积,且呈现出剂量递增效应,而胰岛素对细胞内TG含量影响不明显;与对照组比较得出:ME的活性和mRNA表达水平随着葡萄糖浓度升高而增加,30mmol.L-1葡萄糖具有明显的促进作用(P<0.05);低浓度(50nmol.L-1)胰岛素显著增加ME的活性和mRNA表达水平(P<0.05),当胰岛素浓度达到200nmol.L-1时,ME的活性和mRNA表达水平受到一定抑制;葡萄糖和低浓度胰岛素(50nmol.L-1)协同能促进ME的活性和mRNA表达水平。本研究扩增获得了鹅ME基因部分序列,且发现葡萄糖和胰岛素协同可以增强ME的活性和mRNA表达水平,从而显著增加肝脏中TG的含量,诱导鹅肝脂肪变性。     

烟酸铬及左旋肉碱在动物营养中的作用

烟酸铬及左旋肉碱在动物营养中的作用,越来越受到人们的关注。下面就近年来对其研究进展作一简述,供同行参考。 一、烟酸铬 1、概述 自从1955年Mertz和Schwarz的第一篇论文发表以来,人们普遍认为铬是人类与动物不可缺少的微量元素。这是基于铬的文献中涉足到葡萄糖容限效因(Glucose Tolerance Factor,GTF),GTF在动物营养中的作用在于它加强了胰岛素与其特殊受体的结合。胰岛素与膜受体的结合刺激了燃料物质的储藏,并影响葡萄糖、脂肪及蛋白质的新陈代谢等。胰岛素增加了肌肉和肝脏细胞,并活化肝糖的合成。而且,胰岛素通过改变参     

Oral chromium picolinate and control of glycemia in insulin-treated diabetic dogs

Chromium is an essential dietary trace mineral involved in carbohydrate and lipid metabolism. Chromium is required for cellular uptake of glucose, and chromium deficiency causes insulin resistance. Chromium supplementation may improve insulin sensitivity and has been used as adjunct treatment of diabetes mellitus in humans. In this study, 13 dogs with naturally acquired diabetes mellitus were treated with insulin for 3 months, then with insulin and chromium picolinate for 3 months. Dogs weighing <15 kg (33 lb: n = 9) were administered 200 microg of chromium picolinate PO once daily for I month, then 200 microg of chromium picolinate twice daily for 2 months. Dogs weighing >15 kg (n = 4) received 200 microg of chromium picolinate once daily for 2 weeks, then 200 microg twice daily for 2 weeks, then 400 microg twice daily for 2 months. Type of insulin, frequency of insulin administration, and diet were kept constant, and insulin dosage was adjusted, as needed, to maintain optimal control of glycemia. Mean body weight, daily insulin dosage, daily caloric intake, 10-hour mean blood glucose concentration, blood glycated hemoglobin concentration, and serum fructosamine concentration were not markedly different when dogs were treated with insulin and chromium picolinate, compared with insulin alone. Adverse effects were not identified with chromium picolinate administration. Results of this study suggest that, at a dosage range of 20-60 microg/kg/d, chromium picolinate caused no beneficial or harmful effects in insulin-treated diabetic dogs.     

Dietary chromium tripicolinate supplementation reduces glucose concentrations and improves glucose tolerance in normal-weight cats

The effect of dietary chromium supplementation on glucose and insulin metabolism in healthy, non-obese cats was evaluated. Thirty-two cats were randomly divided into four groups and fed experimental diets consisting of a standard diet with 0 ppb (control), 150 ppb, 300 ppb, or 600 ppb added chromium as chromium tripicolinate. Intravenous glucose tolerance, insulin tolerance and insulin sensitivity tests with minimal model analysis were performed before and after 6 weeks of feeding the test diets.During the glucose tolerance test, glucose concentrations, area under the glucose concentration-time curve, and glucose half-life (300 ppb only), were significantly lower after the trial in cats supplemented with 300 ppb and 600 ppb chromium, compared with values before the trial. Fasting glucose concentrations measured on a different day in the biochemistry profile were also significantly lower after supplementation with 600 ppb chromium. There were no significant differences in insulin concentrations or indices in either the glucose or insulin tolerance tests following chromium supplementation, nor were there any differences between groups before or after the dietary trial.Importantly, this study has shown a small but significant, dose-dependent improvement in glucose tolerance in healthy, non-obese cats supplemented with dietary chromium. Further long-term studies are warranted to determine if the addition of chromium to feline diets is advantageous. Cats most likely to benefit are those with glucose intolerance and insulin resistance from lack of exercise, obesity and old age. Healthy cats at risk of glucose intolerance and diabetes from underlying low insulin sensitivity or genetic factors may also benefit from long-term chromium supplementation.     

Glucose transport in the equine hoof

Reasons for performing study: Several conditions associated with laminitis in horses are also associated with insulin resistance, which represents the failure of glucose uptake via the insulin‐responsive glucose transport proteins in certain tissues. Glucose starvation is a possible mechanism of laminitis, but glucose uptake mechanisms in the hoof are not well understood. Objectives: To determine whether glucose uptake in equine lamellae is dependent on insulin, to characterise the glucose transport mechanism in lamellae from healthy horses and ponies, and to compare this with ponies with laminitis. Methods: Study 1 investigated the effects of insulin (300 µU/ml; acute and 24 h) and various concentrations of glucose up to 24 mmol/l, on 2‐deoxy‐D‐[2,6‐³H]glucose uptake in hoof lamellar explants in vitro. Study 2 measured the mRNA expression of GLUT1 and GLUT4 transport proteins by PCR analysis in coronary band and lamellar tissue from healthy horses and ponies, ponies with insulin‐induced laminitis, and ponies suffering from chronic laminitis as a result of equine Cushing's syndrome. Results: Glucose uptake was not affected by insulin. Furthermore, the relationship between glucose concentration and glucose uptake was consistent with an insulin‐independent glucose transport system. GLUT1 mRNA expression was strong in brain, coronary band and lamellar tissue, but was weak in skeletal muscle. Expression of GLUT4 mRNA was strong in skeletal muscle, but was either absent or barely detectable in coronary band and lamellar tissue. Conclusions: The results do not support a glucose deprivation model for laminitis, in which glucose uptake in the hoof is impaired by reduced insulin sensitivity. Hoof lamellae rely on a GLUT1‐mediated glucose transport system, and it is unlikely that GLUT4 proteins play a substantial role in this tissue. Potential relevance: Laminitis associated with insulin resistance is unlikely to be due to impaired glucose uptake and subsequent glucose deprivation in lamellae.     

微量元素铬的吸收和代谢研究进展

铬是动物机体必需微量元素之一，它可作为葡萄糖耐受因子的组成成分，协助胰岛素发挥生理功能。本文主要综述铬的理化特性、吸收、排泄和代谢。     

有机铬的研究进展

铬是动物体必需的微量元素.Cr3+作为葡萄糖耐量因子(GTF)的活性成分强化胰岛素的生理功能,调节三大营养物质的代谢.与无机铬相比,有机铬易被动物体吸收,生物利用率高.大量研究结果表明有机铬在减少动物应激、改善胴体品质、提高母猪繁殖性能等方面有明显作用.     

Supplemental Chromium Picolinate Promotes Growth of Broiler Chickens by Enhancing Insulin Receptor Gene Expression

Chromium has been recognized for decades as a nutritional factor that promotes the growth of broiler chickens,but the molecular mechanism is still not clearly understood.The present study was designed to investigate the physiological and molecular mechanisms of the effects of supplemental chromium picolinate on the growth of broiler chickens.A total of 144 21-day-old Arbor Acres male broiler chicks were randomly divided into a control and an experimental group.The control group was fed a basal diet,and the experimental group was fed the same basal diet supplemented with 200 μg/kg chromium picolinate.The experiment lasted for three weeks from day 28 to 42 of the birds..Supplementation with 200 μg/kg chromium picolinate significantly increased body weight (P 0.05).Serum insulin levels in chickens of the experimental group were increased significantly (P 0.05),whereas serum glucose concentrations were decreased (P 0.05).No significant changes were observed in serum lipid profiles in chickens fed the diet supplemented with chromium picolinate.Gene expression levels of the insulin receptor (IR) and insulin receptor substrate 1 (IRS-1),two pivotal components of the insulin signaling pathway,were also investigated using Real-time quantitative PCR.IR expression was significantly (P 0.05) increased following chromium supplementation.Therefore,supplemental chromium picolinate had a beneficial effect on the growth of broilers.In agreement with observations in mammals,chromium might exert its effect via potentiating insulin action,and ultimately by stimulating anabolism without altering body composition in chickens.     

微量元素铬的营养概况

铬是动物机体必需微量元素之一,它可以作为葡萄糖耐受因子的组成成分,协助胰岛素发挥生理功能。作者主要综述了铬的理化性质、形式和代谢、营养生理作用及缺乏和毒性。     

Supplemental Chromium Picolinate Promotes Growth of Broiler Chickens by Enhancing Insulin Receptor Gene Expression

Chromium has been recognized for decades as a nutritional factor that promotes the growth of broiler chickens, but the molecular mechanism is still not clearly understood. The present study was designed to investigate the physiological and molecular mechanisms of the effects of supplemental chromium picolinate on the growth of broiler chickens. A total of 144 21-day-old Arbor Acres male broiler chicks were randomly divided into a control and an experimental group. The control group was fed a basal diet, and the experimental group was fed the same basal diet supplemented with 200 μg/kg chromium picolinate. The experiment lasted for three weeks from day 28 to 42 of the birds.. Supplementation with 200 μg/kg chromium picolinate significantly increased body weight (P < 0.05). Serum insulin levels in chickens of the experimental group were increased significantly (P < 0.05), whereas serum their glucose concentrations were decreased (P < 0.05). No significant changes were observed in serum lipid profiles in chickens fed the diet supplemented with chromium picolinate. Gene expression levels of the insulin receptor (IR) and insulin receptor substrate 1 (IRS-1), two pivotal components of the insulin signaling pathway, were also investigated using Real-time quantitative PCR. IR expression was significantly (P < 0.05) increased following chromium supplementation. Therefore, supplemental chromium picolinate had a beneficial effect on the growth of broilers. In agreement with observations in mammals, chromium might exert its effect via potentiating insulin action, and ultimately by stimulating anabolism without altering body composition in chickens.     

支链氨基酸调控机体糖代谢的研究进展

支链氨基酸是体内最丰富的必需氨基酸,包括亮氨酸﹑异亮氨酸和缬氨酸。支链氨基酸具有促进蛋白质合成、提高机体免疫力和促进胚胎发育等生理功能。支链氨基酸在机体糖代谢调节中发挥着重要作用,其可以通过调控机体胰岛素的分泌﹑胰岛素的敏感性以及葡萄糖转运载体的表达和易位等方式调控糖代谢。本文对支链氨基酸在体内的代谢途径及其调控机体糖代谢的途径进行综述。     

Effects of a supplement containing chromium and magnesium on morphometric measurements, resting glucose, insulin concentrations and insulin sensitivity in laminitic obese horses

Reasons for performing study: Obesity and insulin resistance are risk factors for laminitis in equids and supplements containing chromium and magnesium might improve insulin sensitivity. Hypothesis: A supplement containing chromium, magnesium and other nutraceuticals would alter morphometric measurements, blood variables, and insulin sensitivity in laminitic obese horses. Methods: Twelve previously laminitic obese (body condition score ≥ 7/9) horses were randomly allocated to treatment (n = 6) and control (n = 6) groups and 2 obese horses with clinical laminitis were included in the treatment group. Treated animals received 56 g supplement with 0.25 kg oats once daily for 16 weeks. The supplement contained chromium (5 mg/day as yeast), magnesium (8.8 g/day as oxide/proteinate), and other nutraceuticals. Insulin‐modified frequently sampled i.v. glucose tolerance tests were performed with hay provided at 0, 8 and 16 weeks, and insulin sensitivity was estimated by minimal model analysis. Physical measurements were collected at the same points. Horses were not exercised. Results: Hyperinsulinaemia (>30 µu/ml) was detected in 12 of 14 horses prior to treatment. Glucose and insulin data from one mare with clinical laminitis were excluded because of persistent pain. Mean ± s.d. insulin sensitivity was 0.64 ± 0.62 × 10^?4 l/min/mu prior to treatment for the remaining 13 horses. Time and treatment × time effects were not significant for any of the variables examined, with the exception of resting insulin concentrations, which significantly increased over time (P = 0.018). Health status remained the same. Conclusions: The supplement containing chromium and magnesium evaluated in this study did not alter morphometric measurements, blood variables, resting insulin concentrations or insulin sensitivity in laminitic obese horses. Potential relevance: Additional research is required to determine the appropriate use of chromium and magnesium supplements in horses.