Effects of field bean (Vicia faba L. var. minor) dietary supplementation on plasma thyroid hormones, insulin, insulin-like growth factor-1 concentrations and mohair characteristics in growing Angora goat kids

Twenty-two Angora kids were used to study the effect of a dietary supplementation with field bean (Vicia faba L. var. minor) on hair follicle activity, mohair characteristics and plasma total thyroxine (T4), triiodothyronine (T3), insulin (INS) and insulin-like growth factor-1 (IGF-1) concentrations. At birth, their mothers were divided in two groups (S: supplemented, C: control), the S group being supplemented with 300 g/head/day of whole field bean. At weaning, diet of kids from S group was supplemented with 80 g/head/day of whole field bean. At weaning, secondary hair follicle activity (S: 0.91 ± 0.01, C: 0.84 ± 0.02, p < 0.01) and staple length (S: 5.82 ± 0.13 cm, C: 5.16 ± 0.14 cm, p < 0.001) were greater in the S group. At 155 days of age, secondary fibre diameter (S: 16.54 ± 0.35 μm, C: 18.09 ± 0.31 μm, p < 0.01) was higher in the C kids. Concentrations of total plasma T4 and T3 were higher (p < 0.001) in S (120 ± 12 and 4.87 ± 0.92 ng/ml respectively) than in C kids (92 ± 8 and 2.97 ± 0.77 ng/ml respectively). At weaning, T4 values were negatively correlated (p < 0.05) with the secondary fibre diameter and the T3/T4 ratio was positively correlated (p < 0.05) with the secondary to primary hair follicle ratio. At 155 days of age, both T3 and T3/T4 values were positively correlated (p < 0.01) with staple length. Plasma INS (0.11 ± 0.03 ng/ml) and total IGF-1 concentrations (232 ± 13 ng/ml) were not affected by diet. Improvements of diet quality in kids positively affected fibre diameter and length and follicle activity rate. We suggest that increased circulating thyroid hormones concentrations, but not those of INS and IGF-1, may contribute to the beneficial actions of nutritional supplementation on anatomical growth and mohair production of kids.     

Involvement of the ERK1/2 MAPK pathway in insulin-induced S6K1 activation in avian cells

In mammals, insulin regulates S6K1, a key enzyme involved in the control of protein synthesis, via the well-documented phosphoinositide-3'kinase (PI3K) pathway. Conversely, S6K1 is activated by insulin in avian muscle despite the relative insulin insensitivity of the PI3K pathway in this tissue. Mitogen-activated protein kinase (MAPK) cascade is another insulin sensitive pathway. The aim of this study was to explore the potential involvement of the ERK1/2 MAPK pathway in the control of p70 S6 kinase (S6K1) in avian species. Firstly, we characterized ERK1/2 MAPK in various chicken tissues. ERK2 was the only isoform detected in avian species whatever the tissue studied. We also showed that ERK2 is activated in vivo by insulin in chicken muscle. The regulation and the role of ERK2 in insulin signaling were next investigated in chicken hepatoma cells (LMH) and primary myoblasts. Insulin stimulation led to ERK2 and S6K1 phosphorylation, and concomitantly increased kinase activity. U0126, an inhibitor of the ERK MAPK pathway, completely abolished insulin-induced S6K1 phosphorylation and activity in chicken myoblasts, whereas its effect was only partial in LMH cells. In conclusion, these results show that ERK1/2 MAPK is involved in the control of S6K1 by insulin in chicken cells, particularly myoblasts.     

Adipose tissue gene expression in obese dogs after weight loss

Body weight (BW) mainly depends on a balance between fat storage (lipogenesis) and fat mobilization (lipolysis) in adipocytes. BW changes play a role in insulin resistance (IR), the inability of insulin target tissue to respond to physiological levels of insulin. This results in inhibition of lipogenesis and stimulation of lipolysis. Weight gain leads to IR whereas, weight loss improves insulin sensitivity (IS). The aim of this study was to evaluate the effect of weight loss and recovery of IS on the expression of genes involved in lipogenesis and lipolysis in weight losing dogs. Gene expression was studied in both subcutaneous and visceral adipose tissue. Obese dogs received a hypoenergetic low fat high protein diet (0.6 x NRC recommendation). Before and after weight loss, IS was assessed using the euglycaemic hyperinsulinaemic clamp. Gene expression of IRS-2, SREBP, intracellular insulin effectors, ACC, FAS, FABP, ADRP, PEPCK, lipogenesis key proteins, perilipin and HSL, lipolysis key proteins were quantified using real-time RT-PCR in subcutaneous and visceral fat. BW decreased from 15.2 +/- 0.5 to 11.4 +/- 0.4 kg (p < 0.05) over 78 +/- 8 days. When obese, dogs were insulin resistant. After weight loss, IS was improved. In the subcutaneous adipose tissue, the expression of only the IRS-2 was increased. In the visceral adipose tissue, the expression of the genes involved in the lipogenesis was decreased whereas one of the genes implied in the lipolysis did not change. The expression profile of genes involved in lipid metabolism, as measured after weight loss, is indicative for a lower lipogenesis after weight loss than in obese dogs. Our results also confirm dramatic differences in the lipid metabolism of visceral and subcutaneous fat. They should be completed by comparing gene expression during weight losing and normal weight steady state.     

Glycaemic and insulinaemic responses to feeding hay with different non-structural carbohydrate content in control and polysaccharide storage myopathy-affected horses

The aim of this study was to determine whether the glycaemic/insulinaemic responses to hay with non-structural carbohydrate (NSC, soluble carbohydrate) of 17% (HC), 10% (MC) or 4% (LC) differs in control horses and whether these responses differ between control and horses with polysaccharide storage myopathy (PSSM). Five clinically normal control horses and seven PSSM horses, all unfit and of Quarter Horse breeding (age 9.4 ± 3.4 years, body condition score range: 4.5-6). A crossover design compared the HC and LC hay, with horses randomly assigned to hay type for 5 days, and all horses fed the MC hay during washout, after which the diets were switched. Horses were fed 1.5% BW (as fed) divided into 2 feeding per day, no grain. On morning of the fifth day of each block (seventh day for washout), horses were given 0.5% BW in hay, blood was drawn before and every 30 min for 5 h after feeding, and the rate of intake was measured. Whole blood glucose and plasma insulin were measured. The intake rate was significantly higher for HC. In control horses, the insulin area under the curve (6891.7 ± 3524.2 HC vs. 1185.4 ± 530.2 LC) was significantly higher than LC. Polysaccharide storage myopathy horses had significantly higher glycaemic and insulinaemic responses to HC vs. LC, however; the magnitude of insulin response was lower and glucose response higher in PSSM vs. control horses. Results suggest that insulin responses can differ significantly with the NSC content of hay. Feeding hay with 17% NSC produces elevations in insulin that could be detrimental for PSSM horses.     

Effect of regular walking exercise on glucose tolerance and insulin response to i.v. glucose infusion in growing beef steers

The purpose of the present paper was to investigate the effect of regular walking exercise on glucose tolerance and insulin response to i.v. glucose infusion in growing beef steers. Four crossbred beef steers walked on a treadmill during a 6 week exercise period (1.2 km/h, 1 h/day and 5 days/week). The changes in plasma glucose and insulin levels following glucose infusion were analyzed immediately prior to (bodyweight: 260.4 ± 24.2 kg) and after (295.7 ± 30.1 kg) the exercise period. The basal levels of plasma glucose (86.4 vs. 82.0 mg/dL, P = 0.040) and insulin (24.5 vs. 14.3 μU/mL, P = 0.016) were significantly lower after the exercise period. Further, the increase in the levels of plasma glucose (420.4 vs. 280.8 mg/dL, P < 0.001) and insulin (94.5 vs. 73.1 μU/mL, P = 0.028) following the glucose infusion decreased after the exercise period. The area under the curve of plasma glucose (108.8 vs. 62.9 mg/dL per min, P < 0.001) and insulin (53.6 vs. 29.7 μU/mL per min, P = 0.018) indicated more rapid clearance of exogenous glucose and less insulin secretion for glucose clearance after the exercise period. These results suggest that regular exercise improves glucose tolerance, with lower insulin response to glucose infusion in growing steers, as observed in rodents and humans.     

丙谷胺对产蛋鸡摄食行为及内分泌的影响

选用35周龄伊莎蛋鸡8只,分别安装慢性颈静脉血管插管.实验采用自身对照法,对照期饲喂基础日粮,丙谷胺期在喂料前填喂丙谷胺.应用摄食行为计算机监测系统(FIDAS系统)记录各个实验期产蛋鸡喂料后4h内的采食行为数据,并测定有关血液生化指标.结果显示,实验期(填喂丙谷胺后)与对照期相比较,产蛋鸡午前(8:00～12:00)与午后(13:00～17:00)4 h内摄食量分别增加27.69%与30.41%(P＜0.05),摄食时间分别降低15.67%与3.75%,摄食餐数分别增加12.32%与27.2%(P＜0.05);血糖水平分别降低5.44%与18.03%(P＜0.01),瘦素水平分别升高2.59%与7.19%,胰岛素水平分别升高33.09%(P＜0.05)与24.5%(P＜0.05).提示丙谷胺能够促进蛋鸡摄食,并影响有关内分泌激素的水平.     

The Role of Exogenous Insulin in the Complex of Hepatic Lipidosis and Ketosis Associated with Insulin Resistance Phenomenon in Postpartum Dairy Cattle

As a result of a marked decline in dry matter intake (DMI) prior to parturition and a slow rate of increase in DMI relative to milk production after parturition, dairy cattle experience a negative energy balance. Changes in nutritional and metabolic status during the periparturient period predispose dairy cattle to develop hepatic lipidosis and ketosis. The metabolic profile during early lactation includes low concentrations of serum insulin, plasma glucose, and liver glycogen and high concentrations of serum glucagon, adrenaline, growth hormone, plasma β-hydroxybutyrate and non-esterified fatty acids, and liver triglyceride. Moreover, during late gestation and early lactation, flow of nutrients to fetus and mammary tissues are accorded a high degree of metabolic priority. This priority coincides with lowered responsiveness and sensitivity of extrahepatic tissues to insulin, which presumably plays a key role in development of hepatic lipidosis and ketosis. Hepatic lipidosis and ketosis compromise production, immune function, and fertility. Cows with hepatic lipidosis and ketosis have low tissue responsiveness to insulin owing to ketoacidosis. Insulin has numerous roles in metabolism of carbohydrates, lipids and proteins. Insulin is an anabolic hormone and acts to preserve nutrients as well as being a potent feed intake regulator. In addition to the major replacement therapy to alleviate severity of negative energy balance, administration of insulin with concomitant delivery of dextrose increases efficiency of treatment for hepatic lipidosis and ketosis. However, data on use of insulin to prevent these lipid-related metabolic disorders are limited and it should be investigated.     

蓝塘仔猪IGF-1水平与组织IGF-1、GHR基因的表达

32头不同日龄(出生、3、21、35d)蓝塘仔猪,由前腔静脉采血后剖杀,取肝脏、背最长肌样品。用RIA法测血液、组织中IGF 1浓度,用放射受体法(RBA)检测肝脏、肌肉组织中GHR结合活性,用实时荧光定量PCR法检测IGF 1、GHRmRNA的表达水平。结果表明:(1)血液中IGF 1在出生日显著高于其它时期(P<0 05)。肌肉组织中IGF 1含量高于肝脏组织,肌肉组织IGF 1含量在3、21、35日龄时都显著高于出生日(P<0 05)。(2)肝脏细胞膜GHR结合活性在出生日显著高于3、21日龄(P<0 05),肝脏细胞膜GHR结合活性高于肌肉组织。(3)肝脏组织IGF 1、GHRmRNA的表达量均显著高于肌肉组织(P<0 05)。肝脏IGF 1mRNA的表达在出生日、21日龄时显著高于3、35日龄(P<0 05),GHRmRNA的表达在出生日显著高于其它日龄(P<0 05)。肌肉IGF 1、GHRmRNA的表达在出生日均显著高于其它日龄(P<0 05)。     

赖氨酸采食量对早期断奶仔猪生长发育及胰腺内分泌机能的影响

将55头21日龄断奶的雄性仔猪随机分为5组，各组仔猪饲喂赖氨酸含量为0．60％、0．80％、1．00％、1．20％和1．40％的试验日粮21d。42日龄结束饲养试验时进行葡萄糖灌注试验，观察赖氨酸采食量对早期断奶仔猪生长发育和胰腺内分泌的影响。结果表明：早期断奶仔猪体增重与赖氨酸采食量为强正相关，根椐体增重指标，21～42日龄阶段，仔猪的赖氨酸采食量不应低于3．16g／d，日粮赖氨酸含量不应低于1.40％。赖氨酸严重缺乏(采食量小于1．45g／d)时，胰岛素的分泌量下降，对高血糖应激的反应能力降低。     

Contribution of insulin to the ascorbate recycling system in the chicken liver

The effect of insulin on the ascorbate recycling system in the chicken liver was examined. First, insulin was injected subcutaneously into the chicken, and liver glutathione‐dependent dehydroascorbate reductase (GSH‐DHAR) activity was determined. Insulin increased liver GSH‐DHAR activity, but did not affect plasma and liver ascorbate concentration. Dehydroascorbate increased plasma and liver ascorbate levels, and liver GSH‐DHAR activity. However, distinct changes in plasma insulin level were not observed by dehydroascorbate injection. In addition, reduction of external dehydroascorbate in cultured chicken hepatocytes could not be observed in an insulin‐deprived culture, although the cells reduced external dehydroascorbate in a serum‐free culture with insulin. We concluded that insulin affects the ascorbate recycling system as an essential factor in the chicken liver.