Mitochondrial protection by low doses of insulin-like growth factor-Ⅰin experimental cirrhosis

AIM： To characterize the mitochondrial dysfunction in experimental cirrhosis and to study whether insulin-like growth factor-Ⅰ （IGF-Ⅰ ） therapy （4 wk） is able to induce beneficial effects on damaged mitochondria leading to cellular protection. METHODS： Wistar rats were divided into three groups： Control group, untreated cirrhotic rats and cirrhotic rats treated with IGF-Ⅰ treatment （2 μg/1O0 g bw/d）. Mitochondrial function was analyzed by flow cytometry in isolated hepatic mitochondria, caspase 3 activation was assessed by Western blot and apoptosis by TUNEL in the three expedmental groups. RESULTS： Untreated cirrhotic rats showed a mitochondrial dysfunction characterized by a significant reduction of mitochondrial membrane potential （in status 4 and 3）; an increase of intramitochondrial reactive oxigen species （ROS） generation and a significant reduction of ATPase activity. IGF-Ⅰ therapy normalized mitochondrial function by increasing the membrane potential and ATPase activity and reducing the intramitochondrial free radical production. Activity of the electron transport complexes Ⅰ and Ⅲ was increased in both cirrhotic groups. In addition, untreated cirrhotic rats showed an increase of caspase 3 activation and apoptosis. IGF- Ⅰ therapy reduced the expression of the active peptide of caspase 3 and resulted in reduced apoptosis. CONCLUSION： These results show that IGF- Ⅰ exerts a mitochondrial protection in experimental cirrhosis leading to reduced apoptosis and increased ATP production.

Effects of ethanol on insulin-like growth factor-Ⅰ system in primary cultured rat hepatocytes: Implications of JNK1/2 and alcoholdehydrogenase

AIM: To evaluate the effects of ethanol on the insulin- like growth factor-Ⅰ (IGF-Ⅰ) system involved in c-Jun N-terminal kinase (JNK1/2) and alcoholdehydrogenase (ADH) activity in primary cultured rat hepatocytes. METHODS: Hepatocytes isolated from male Sprague-Dawley rats were incubated with various concentrations of ethanol for different durations of time. The cells were pretreated with SP600125 (10 μmol/L) and 4-MP (200 μmol/L), and then treated with ethanol (200 mmol/L). We then measured IGF-Ⅰ secretion, IGF-Ⅰ mRNA expression, cell viability and JNK1/2 activity by radioimmunoassay, RT-PCR, MTT assay and Western blot, respectively (n = 6). RESULTS: Ethanol induced the activity of phospho (p)-JNK1/2, reaching a maximum at 60 min and then decreasing at 180 min. The effects of ethanol on the IGF-Ⅰ system were increased at 60 min (secretion: 7.11 ± 0.59 ng/mg protein vs 4.91 ± 0.51 ng/mg, mRNA expression: 150.2% ± 10.2% vs 101.5% ± 11.3%, P = 0.045) and then decreased at 180 min (secretion: 3.89 ± 0.25 ng/mg vs 5.4 ± 0.54 ng/mg protein; mRNA expression: 41.5% ± 10.4% vs 84.7% ± 12.1%, P = 0.04), however cell viability was decreased in a dose- and time-dependent manner. SP600125 blocked the ethanol-induced changes (at 60 min). Additionally, 4-methylpyrazole prevented the ethanol-induced decreases in the IGF-Ⅰ system, cell viability and p-JNK1/2 activity (at 180 min). CONCLUSION: This study suggests that ethanol- induced p-JNK1/2 activation is associated with the IGF-Ⅰ system and cell viability in hepatocytes. Furthermore, alcohol dehydrogenase is involved in the relationship between ethanol-induced inactivation of p-JNK1/2 and the changes of the IGF-Ⅰ system and cell viability.

The effect of polymorphism in gene of insulin-like growth factor-Ⅰ on the serum periparturient concentration in Holstein dairy cows

Objective:To investigate the relationship between polymorphism within the 5'-untranslated region(5'-UTR)of IGF-I gene and its periparturient concentration in Iranian Holstein dairy cows.Methods:Blood samples(5 mL,n=37)were collected by caudal venipuncture from each animal into sample lubes containing the EDTA and DNA was extracted from blood.In order to measure ICF-I concentration the collection of blood samples(n=111)was also done at 14 d before calving(prepartum),25 and 45 d postpartum.Results:We found evidence for a significant effect of C to T mutation in position 512 of IGF-I gene on its serum concentration in dairy cows in Iran.Cows with CC genotype had significantly higher concentration(Mean-SD)of IGF-I at 14 d prepartum(91.8±18.1)μg/L compared to those with TT genotype(73.3±14.4)μg/L(P=0.04).A significant trend(quadratic)was found for IGF-I concentration,as higher in CC cows compared to ones with TT genotype,during the 14 d before calving to 45 d postpartum(P=0.01).Conclusions:We concluded that C/T transition in the promoter region of IGF-I gene can influence the serum concentration of ICF-I in periparturient dairy cows.

Reactivation of the insulin-like growth factor-Ⅱsignaling pathway in human hepatocellular carcinoma

Constitutive activation of the insulin-like growth factor (IGF)-signaling axis is frequently observed in human hepatocellular carcinoma(HCC).Especially the over- expression of the fetal growth factor IGF-Ⅱ,IGF-Ⅰ receptor(IGF-IR),and cytoplasmic downstream effectors such as insulin-receptor substrates(IRS)contribute to proliferation,anti-apoptosis,and invasive behavior. This review focuses on the relevant alterations in this signaling pathway and independent in vivo models that support the central role IGF-Ⅱsignaling during HCC development and progression.Since this pathway has become the center of interest as a target for potential anti-cancer therapy in many types of malignancies,various experimental strategies have been developed,including neutralizing antibodies and selective receptor kinase inhibitors,with respect to the specific and efficient reduction of oncogenic IGF-Ⅱ/IGF-IR-signaling.

羊乳中类胰岛素生长因子Ⅰ的特性

采用双抗体夹心酶联免疫法研究了温度、p H、紫外线以及金属离子等因素对羊乳中类胰岛素生长因子Ⅰ(insulin-like grouth factor-Ⅰ,IGF-Ⅰ)浓度的影响。研究表明:羊乳中IGF-Ⅰ在20℃时浓度最高,达到(29.91±0.91)ng/m L(P<0.05),在40℃时具有较高的热稳定性;IGF-Ⅰ在p H=4时浓度最高,达到(28.53±1.11)ng/m L(P<0.05),在p H值为6~8时稳定性较高;紫外线照射会造成IGF-Ⅰ的浓度显著降低(P<0.05)。Na^+、Ca^(2+)、Al^(3+)、Zn^(2+)等金属离子对IGF-Ⅰ的浓度具有抑制作用,而Mg^(2+)、Fe^(2+)对IGF-Ⅰ无明显影响,低浓度的Fe^(3+)、Cu^(2+)对IGF-Ⅰ的浓度具有抑制作用,而高浓度的Fe^(3+)、Cu^(2+)对IGF-Ⅰ具有激活作用。通过研究,评估温度、p H、紫外线以及金属离子对羊乳中IGF-Ⅰ浓度的影响,为生产具有更高IGF-Ⅰ浓度的功能活性羊乳产品提供依据和指导。

滋阴泻火方对性早熟大鼠血清类胰岛素样生长因子-Ⅰ水平的影响

目的探讨滋阴泻火方对性早熟模型大鼠血清类胰岛素样生长因子-Ⅰ(IGF-Ⅰ)水平的影响。方法26日龄雌性SD大鼠36只,随机分成6组,即正常对照组、性早熟模型组、亮丙瑞林组及中药大、中、小剂量组。除正常对照组外,其余各组均采用N-甲基-DL-天冬氨酸(NMA)40 mg.kg-1皮下注射建立性早熟模型,其中亮丙瑞林组用亮丙瑞林干预,中药各组用不同剂量的滋阴泻火方干预,观察不同干预措施对性早熟模型大鼠卵巢指数、子宫指数及血清IGF-Ⅰ水平的影响。结果性早熟模型组和中药小剂量组的卵巢指数[分别为(6.37±1.61)×10-4、(5.10±2.59)×10-4]和子宫指数[分别为(8.91±2.32)×10-4、(7.86±1.98)×10-4]均显著高于其他各组(P<0.05);亮丙瑞林组、中药大剂量组和中药中剂量组卵巢指数和子宫指数与正常对照组相比均无统计学差异(P>0.05)。与正常对照组比较,性早熟模型组的血清IGF-Ⅰ水平显著升高[(327.08±46.15)vs(239.40±61.92)m IU.m l-1,P<0.05],而4个干预组均无显著性差异(P>0.05);与性早熟模型组比较,中药大剂量组[(218.83±77.06)m IU.m l-1]和中剂量组[(207.09±53.00)m IU.m l-1]的血清IGF-Ⅰ水平显著降低(P<0.05),中药小剂量组无显著性差异(P>0.05);中药各剂量组与亮丙瑞林组比较无显著性差异(P>0.05)。结论滋阴泻火方大、中剂量能降低性早熟模型大鼠的血清IGF-Ⅰ的水平。

The expression of insulin-like growth factor-Ⅰ mRNA and polypeptide in rat osteoblasts with exposure to parathyroid hormone

Objective To investigate the insulin-like growth factor-Ⅰ (IGF-Ⅰ) gene and polypeptide expression in cultured rat osteoblast (ROB) and the role of IGF-Ⅰ in mediating the cell-to-cell communication by mimicking the pharmacokinetics of parathyroid hormone (PTH). Methods The ROB was cultured with three kinds of treatment: (1) Control (Ctr), the cells were cultured without PTH during the first 6 hours and the subsequent 42 hours in a 48-hour cycle; (2) Intermittent exposure to PTH (Itm), the cells were cultured with PTH during the first 6 hours, but without PTH in the subsequent 42 hours; and (3) Continuous exposure to PTH (Ctu), the cells were cultured with PTH during the first 6 hours and the subsequent 42 hours. Results The bone-forming activities of ROB were increased in Itm and inhibited in Ctu. The IGF-Ⅰ mRNA content in Itm cells was elevated only during the first 6 hours and that in Ctu cells was elevated at any time during an incubation cycle. The free IGF-Ⅰ concentration in the medium of Itm cells was generally higher and that of the Ctu cells was generally lower compared with those of the Ctr cells. The IGF-Ⅰ antibody significantly reduced the alkaline phosphatase activity within the cells of Ctr and Itm. Conclusions PTH rapidly and constantly stimulates the IGF-Ⅰ gene transcription of osteoblast. There was an obvious discrepancy between the IGF-Ⅰ mRNA content within the osteoblast and the free IGF-Ⅰ level around the osteoblast in either mode of PTH action. The IGF-Ⅰ might be important for osteoblast-osteoblast communication and bone-forming activity, not only in intermittent PTH administration, but also in the physiological functioning of osteoblasts.

不同营养方式早产儿血清IGF-I及GH水平的变化研究

目的探讨不同营养方式早产儿血清胰岛素样生长因子(IGF-I)与生长激素(GH)水平的变化及其与生长发育的关系。方法采用放射免疫法测定观察组(42例)与对照组(48例)早产儿出生时及生后第7d、第14d血清IGF-I、GH水平,同时测量两组早产儿相应日龄体质量、身长、头围,计算Rohrer指数(RI),并进行对比分析。结果 (1)两组早产儿生后第14d血清IGF-I水平与脐血及第7d组内比较差异均有统计学意义(P<0.05)。观察组早产儿生后第7d及第14d血清IGF-I水平与对照组相比,差异有统计学意义(P<0.05)。(2)两组早产儿生后第14d血清GH水平差异有统计学意义(P<0.05)。(3)两组早产儿脐血及生后第7d、第14d血清IGF-I水与体质量、RI及GH分别呈正相关,生后第14d血清GH水平与RI呈正相关(P<0.05)。结论 IGF-I及GH在早产儿营养与生长调控的过程中发挥着一定的作用,与早产儿的营养状况密切相关。

IGF-Ⅰ基因多态性与大于胎龄儿及脐血IGF-Ⅰ血清水平关系分析

目的探讨IGF-Ⅰ基因多态性与大于胎龄儿及脐血IGF-Ⅰ血清水平的关系,为降低大于胎龄儿的发生率提供理论依据。方法采用病例对照的研究方法,在南京地区收集大于胎龄儿（LGA）和适于胎龄儿（AGA）各96名,应用聚合酶链反应—限制性片段长度多态性方法（PCR-RFLP）检测IGF-Ⅰrs6214及rs35767的多态性,采用单因素Logistic回归分析计算LGA的相对危险度,比较2组间不同基因型出生时体格指标和脐血IGF-Ⅰ水平的差异。结果在LGA组和AGA组中,IGF-Ⅰrs35767 TT基因型可能会降低大于胎龄儿的风险（OR=0.235,95%CI=0.081~0.682）,携带TT基因型个体的体重、头围和孕周均低于CC及CT基因型携带者;IGF-Ⅰrs6214 AG/GG基因型可能会增加大于胎龄儿的风险（OR=2.117,95%CI=1.151~3.894）。未发现2个多态性位点的改变与脐血IGF-Ⅰ血清水平相关。结论 IGF-Ⅰrs6214和rs35767多态性均与大于胎龄儿的发生相关。

Branched-chain amino acids partially recover the reduced growth of pigs fed with protein-restricted diets through both central and peripheral factors

The objective of this study was to assess the growth efficiency of pigs fed with protein-restricted diets supplemented with branched-chain amino acids(BCAA)and limiting amino acids(LAA)above the rec-ommended levels.Following 2 weeks of adaptation,48 young barrows were weight matched and randomly assigned to 6 treatments(8 pigs/treatment)for 4 weeks:positive control(PC)with standard protein,negative control(NC)with very low protein containing LAA(i.e.,Lys,Met,Thr and Trp)at rec-ommended levels,and NC containing LAA 25%(L25),LAA 50%(L50),LAA+BCAA(i.e.,Leu,Ile and Val)25%(LB25)and LAA+BCAA 50%(LB50)more than recommendations.Feed intake(FI)and body weight(BW)were measured daily and weekly,respectively.At week 6,blood samples were collected,all pigs euthanized and tissue samples collected.The data were analyzed by univariate GLM or mixed procedure(SPSS)and the means were separated using paired Student's t-test followed by Benjamini-Hochberg correction.Relative to PC,NC had decreased FI,BW,unsupplemented plasma essential amino acids,serum insulin-like growth factor-I(IGF-I)and hypothalamic neuropeptide Y(NPY)(P<0.01).Compared to NC,L25 or L50,LB50 had increased BW and serum IGF-I and decreased plasma serotonin and both LB25 and LB50 had higher FI,plasma BCAA,hypothalamic 5-hydroxytryptamine-receptor 2A and NPY and jejunal 5-hydroxytryptamine-receptor 7(P<0.01).Overall,supplementation of protein-restricted diets with increased levels of dietary BCAA partially recovered the negative effects of these diets on growth through improved IGF-I concentration and FI,which was associated with changed expression of serotonin receptors,blood AA and hypothalamic NPY.