Recombinant buckwheat trypsin inhibitor decreases fat accumulation via the IIS pathway in Caenorhabditis elegans.

Buckwheat trypsin inhibitor (BTI) is a low molecular weight polypeptide that can help to prevent metabolic diseases such as obesity, hyperglycemia and hyperlipidemia. Herein, the effects of recombinant BTI (rBTI) on fat accumulation in Caenorhabditis elegans were studied. rBTI prevented fat accumulation under normal and high glucose conditions, and led to significantly shorter body widths without affecting C. elegans feeding behavior. Results also indicate that rBTI altered fat breakdown, synthesis, and accumulation by altering the transcription, expression and activity of key enzymes in lipolysis and fat synthesis. In daf-2 and daf-16 mutants, rBTI did not prevent fat accumulation, indicating that rBTI activity relies on the insulin/insulin-like growth factor (IIS) pathway. Overall rBTI may regulate changes in lipolysis and fat synthesis by down-regulating the IIS pathway, which can affect fat accumulation. These findings support the application of rBTI in preventing obesity, hyperglycemia and hyperlipemia.

Proteomic Analysis of RBP4/Vitamin A in Children with Cleft Lip and/or Palate.

Cleft of the lip and/or palate (CLP) is one of the most common congenital craniofacial defects. Non-syndromic CLP (NSCLP) is a multifactorial disease influenced by the interaction of genetic and environmental factors. However, there are few studies reporting on the developmental or metabolic status of babies with NSCLP after birth. In our study, we sought to identify and evaluate the differential expression of serum protein profiles in NSCLP children and unaffected babies. Thus, a 'shotgun proteomics' approach was first used to analyze the plasma proteome of 13 children with NSCLP and 10 control children, aged 2 to 3.5 years. In total, more than 300 proteins were identified in the serum sample. With gene ontology (GO) analysis, we detected many differentially expressed proteins that could be related to NSCLP, including those involved in lipoprotein metabolism, insulin-like growth-factor-related processes, and so on, especially the proteins involved in retinol transport. Retinol binding protein 4 (RBP4), one protein of the retinol transport category, was significantly decreased in the NSCLP group. Thus, serum vitamin A levels were further determined by high-performance liquid chromatography (HPLC). A significant difference (p < .01) was also found in vitamin A concentrations, consistent with the trend of RBP4. Our results indicated that reduced levels of RBP4 and vitamin A were related to newborns with NSCLP and should thus receive more attention. These results also suggest that vitamin A supplementation might be necessary at an early stage.

Myostatin and insulin-like growth factors in uremic sarcopenia: the yin and yang in muscle mass regulation.

Myostatin and the insulin-like growth factors (IGF-I and -II) play inhibitory and stimulatory roles, respectively, in the development and regulation of skeletal muscle mass. The findings of Sun et al. in this issue shed light on the potential regulation and actions of this yin-and-yang system in uremic sarcopenia and the salutary effects of exercise.

Effects of L-carnitine on fetal growth and the IGF system in pigs.

The effects of L-carnitine on porcine fetal growth traits and the IGF system were determined. Fourth-parity sows were fed a gestation diet with either a 50-g top dress containing 0 (control, n = 6) or 100 mg of L-carnitine (n = 6). At midgestation, fetuses were removed for growth measurements, and porcine embryonic myoblasts (PEM) were isolated from semitendinosus. Real-time quantitative PCR was used to measure growth factor messenger RNA (mRNA) levels in the uterus, placenta, muscle, hepatic tissue, and cultured PEM. A treatment x day interaction (P = 0.02) was observed for maternal circulating total carnitine. Sows fed L-carnitine had a greater (P = 0.01) concentration of total carnitine at d 57 than control sows. Circulating IGF-I was not affected (P = 0.55) by treatment. Supplementing sows with L-carnitine resulted in larger (P = 0.02) litters (15.5 vs. 10.8 fetuses) without affecting litter weight (P = 0.07; 1,449.6 vs. 989.4 g) or individual fetal weight (P = 0.88) compared with controls. No treatment effect was found for muscle IGF-I (P = 0.36), IGF-II (P = 0.51), IGFBP-3 (P = 0.70), or IGFBP-5 (P = 0.51) mRNA abundance. The abundance of IGF-I (P = 0.72), IGF-II (P = 0.34), and IGFBP-3 (P = 0.99) in hepatic tissue was not influenced by treatment. Uterine IGF-I (P = 0.46), IGF-II (P = 0.40), IGFBP-3 (P = 0.29), and IGFBP-5 (P = 0.35) mRNA abundance did not differ between treatments. Placental IGF-I (P = 0.30), IGF-II (P = 0.18), IGFBP-3 (P = 0.94), and IGFBP-5 (P = 0.42) mRNA abundance did not differ between treatments. There was an effect of side of the uterus for IGF-I (P = 0.04) and IGF-II (P = 0.007) mRNA abundance; IGF-I mRNA abundance was greater in the left uterine horn than in the right uterine horn (0.14 and 0.07 relative units, respectively). Placental IGF-II mRNA abundance was greater (P = 0.007) in the left than in the right uterine horn (483.5 and 219.59, respectively). The abundance of IGFBP-3 was not affected by uterine horns in either uterine (P = 0.66) or placental (P = 0.13) tissue. There was no treatment difference for IGF-I (P = 0.31) or IGFBP-5 (P = 0.13) in PEM. The PEM isolated from sows fed L-carnitine had decreased IGF-II (P = 0.02), IGFBP-3 (P = 0.03), and myogenin (P = 0.04; 61, 59, and 67%, respectively) mRNA abundance compared with controls. These data suggest that L-carnitine supplemented to gestating sows altered the IGF system and may affect fetal growth and development.

Effects of maternal nutrition and porcine growth hormone (pGH) treatment during gestation on endocrine and metabolic factors in sows, fetuses and pigs, skeletal muscle development, and postnatal growth.

Prenatal growth is very complex and a highly integrated process. Both maternal nutrition and the maternal somatotropic axis play a significant role in coordinating nutrient partitioning and utilization between maternal, placental and fetal tissues. Maternal nutrition may alter the nutrient concentrations and in turn the expression of growth regulating factors such as IGFs and IGFBPs in the blood and tissues, while GH acts in parallel via changing IGFs/IGFBPs and nutrient availability. The similarity in the target components implies that maternal nutrition and the somatotropic axis are closely related to each other and may induce similar effects on placental and fetal growth. Severe restriction of nutrients throughout gestation has a permanent negative effect on fetal and postnatal growth, whereas the effects of both temporary restriction and feeding above requirements during gestation seem to be of transitional character. Advantages in fetal growth gained by maternal growth hormone treatment during early to mid-gestation are not maintained to term, whereas treatment during late or greatest part of gestation increases progeny size at birth, which could be of advantage for postnatal growth. This review summarizes the available knowledge on the effects of different maternal feeding strategies and maternal GH administration during pregnancy and their interactions on metabolic and hormonal (especially IGFs/IGFBPs) status in the feto-maternal unit, skeletal muscle development and growth of the offspring in pigs.

Colostral and milk insulin-like growth factors and related substances: mammary gland and neonatal (intestinal and systemic) targets.

The identification of hormones and regulatory factors in colostrum and milk has led to intensive investigations on their roles in the development and maintenance of the mammary and neonatal tissues. Insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs) in transgenic mice influence mammary biology gland towards the end of lactation. In the bovine, IGFBP-3 is the major IGFBP in mammary secretions. In addition to binding IGFs, IGFBP-3 also binds to lactoferrin (Lf). Secreted IGFBP-3 re-enters mammary epithelial cells and with the presence of a nuclear localization sequence, IGFBP-3 and Lf enter the nucleus. Nuclear IGFBP-3 affects apoptotic signaling through the retinoic-x-receptors, while Lf affects apoptotic events through unknown mechanisms. Such interactions likely influence mammary development and involution. Furthermore, ingested colostral bioactive factors can exert regulatory functions in neonates. Intestinal receptors for IGFs and insulin are modified by age and/or diet. Feeding IGF-I had no effect, but colostrum extracts had small intestinal effects (stimulation of proliferation and villus size), suggesting that several factors, rather than one single bioactive factor were responsible. Systemic changes of metabolic and endocrine profiles in neonates depend on composition, amounts, time and duration of feeding colostrum. Early postnatal colostrum intake is not only important for the provision and absorption of immunoglobulins. Thus, in neonatal calves the lack of colostrum intake during the first 24h after birth results in a low immunoglobulin G, beta-carotene and Vitamin A status that persists for weeks and plasma patterns of fatty acids, essential amino acids and the glutamine/glutamate ratios are affected. In calves oral administration of IGF-I had no and feeding of colostrum whey extracts had only minor effects on metabolic and endocrine traits. Thus, mammary secretions influence regulatory functions of mammary and neonatal tissues.

Endocrine and metabolic aspects in milk-fed calves.

In neonatal calves besides adaptations in organ function there are marked metabolic and endocrine changes. The growth hormone (GH)-insulin-like growth factor (IGF) axis is basically functioning, but needs maturation. Various metabolic and endocrine traits do not exhibit marked ontogenetic changes after the first week of life, but others remain different from the adult stage. Thus, plasma oxytocin or an oxytocin-like substance and nitrate concentrations are elevated for months. The ability to digest colostrum (C) and milk involves great alterations in structure and function of the gastrointestinal (GI) tract. C intake is important for passive immunity, provision of nutrients, minerals and vitamins, and contains biologically active substances. IGF-I, present in C in high amounts, appears to enhance GI tract development and function. For sufficient absorption not only of immunoglobulins, but also of fatty acids and fat-soluble vitamins, C should be ingested immediately after birth. The amino acid pattern and the glutamine/glutamate ratio depends greatly on whether C is fed or not. Effects on insulin, IGF-I, and IGF binding proteins depend on time-point and amounts of C fed. After the colostral period calves are almost exclusively fed milk and milk substitutes or weaned. Low iron intake, required for the production of pale meat, besides anemia causes metabolic and endocrine adaptations, such as enhanced insulin-dependent glucose utilization and appears to reduce IGF-I responses to GH. Metabolic and endocrine changes, such as insulin resistance and disturbed glucose metabolism, can be observed in part in association with high feeding intensity in veal calves.

Milk intake and bone mineral acquisition in adolescent girls: randomised, controlled intervention trial.

OBJECTIVES: To investigate the effect of milk supplementation on total body bone mineral acquisition in adolescent girls. DESIGN: 18 month, open randomised intervention trial. SUBJECTS: 82 white girls aged 12.2 (SD 0.3) years, recruited from four secondary schools in Sheffield. INTERVENTION: 568 ml (one pint) of whole or reduced fat milk per day for 18 months. MAIN OUTCOME MEASURES: Total body bone mineral content and bone mineral density measured by dual energy x ray absorptiometry. Outcome measures to evaluate mechanism included biochemical markers of bone turnover (osteocalcin, bone alkaline phosphatase, deoxypyridinoline, N-telopeptide of type I collagen), and hormones important to skeletal growth (parathyroid hormone, oestradiol, insulin-like growth factor I). RESULTS: 80 subjects completed the trial. Daily milk intake at baseline averaged 150 ml in both groups. The intervention group consumed, on average, an additional 300 ml a day throughout the trial. Compared with the control group, the intervention group had greater increases of bone mineral density (9.6% v 8.5%, P = 0.017; repeated measures analysis of variance) and bone mineral content (27.0% v 24.1%, P = 0.009). No significant differences in increments in height, weight, lean body mass, and fat mass were observed between the groups. Bone turnover was not affected by milk supplementation. Serum concentrations of insulin-like growth factor I increased in the milk group compared with the control group (35% v 25%, P = 0.02). CONCLUSION: Increased milk consumption significantly enhances bone mineral acquisition in adolescent girls and could favourably modify attainment of peak bone mass.

Evolution of insulin-like growth factor (IGF) function: production and characterization of recombinant hagfish IGF.

While there is considerable structural evidence that insulin-like growth factors (IGFs) share a long evolutionary history, little is known about the conservation of IGF function. In order to address this, we have made recombinant hagfish IGF, hence allowing characterization of an IGF from a representative of the primitive vertebrate class, Agnatha. The production of recombinant hagfish IGF has been complicated by a number of factors including the requirement of a longer leader peptide for fusion protein expression, reduced solubility of the protein, as well as problems in the refolding procedure. However, we were able to produce a small quantity of hagfish IGF with an N-terminal glycine addition which is biologically active. Furthermore, N-terminal amino acid sequencing and mass spectrometry confirm that we have produced hagfish IGF. In vitro assessment of recombinant hagfish IGF in cultured cells indicates that hagfish IGF indeed shares functional properties with mammalian IGFs. Thus, hagfish IGF stimulates protein synthesis in rat myoblasts, but 20- and 5-fold more peptide, respectively, is required to achieve the same half-maximal responses as with human IGF-I (hIGF-I) or IGF-II (hIGF-II). Hagfish IGF also competes for binding to the type-1 IGF receptor present both on rat myoblasts and on salmon embryo fibroblasts, though with somewhat lower affinity than either hIGF-I or hIGF-II. However, studies investigating binding to the IGF-II-specific type-2 receptor suggest that hagfish IGF may in fact be more closely related to IGF-I than to IGF-II. These results indicate that motifs important for functions associated with mammalian IGFs appear to have evolved prior to the Agnathans diverging from the main line of vertebrate evolution 550 million years ago. Accordingly, we now have functional as well as structural evidence that the IGFs have a long evolutionary history.

[Zinc and the growth hormone system]. / Zinco e sistema dell'ormone dell'accrescimento.

Chronic zinc nutritional deficiency constantly causes delay in pondero-statural growth. The mineral controls GH synthesis and secretion, but its administration acts on physical growth also after hypophysectomy: zinc supplementation causes a significant increase in liver synthesis of IGF-I (somatomedin C), which, in chronic mineral nutritional deficiency, is remarkably reduced. In men, in this condition, GH response to its releasing factor (GRF) is normal: a demonstration of the less important role of the pituitary gland in this situation. Therefore, in chronic zinc deficiency, reduced liver production of IGF-I is responsible for reduced physical growth; moreover in this situation receptor resistance to IGF-I (in addition to GH), that fades away after dietetic supplementation of the mineral, has been demonstrated. Therefore zinc play an important role at receptor level, throughout various mechanisms (including a proven increase in receptor number, due to its aggregating membrane direct induced effect).

Cell culture as a tool for identifying nutritional disease therapies.

Cell culture methodologies can be used to help develop therapies for the treatment of polytrauma. An overview is presented of research with the L6 myoblast cell line that led to the discovery of the truncated insulin-like growth factor (IGF) variant, des(1-3)IGF-I and that gave an explanation of the enhanced potency of this growth factor. Subsequent efforts to develop an even more potent variant also utilized cultured cells as indicator bioassays. Such experiments not only provided mechanistic information on IGF action but also directed attention towards IGF variants that were later shown to be more potent in vivo at reversing catabolic conditions.

Insulinlike growth factors. Their regulation of glucose and amino acid transport in placental trophoblasts isolated from first-trimester chorionic villi.

The transport of glucose and amino acids from the maternal to fetal circulation through the placenta is critical to the delivery of fuel for normal fetal growth and development. Little information indicates that transplacental glucose or amino acid transport is influenced by hormones or polypeptide growth factors. We developed a continuous cell line of cytotrophoblastlike cells derived from first-trimester human chorionic villi as a model system to study the regulation of glucose and amino acid transport by insulinlike growth factors (IGFs). Using immunocytochemical and biochemical criteria, the cells were shown to manifest a trophoblastlike phenotype. The cells were maintained in serum-supplemented medium until confluent, at which time they were shifted to serum-free medium for one day. Experiments were initiated by transferring the cells to glucose-free assay buffer and incubating them with IGF-I, IGF-II or insulin. Glucose uptake was measured by the transport of 2-deoxy-D-[1,2-3H]glucose (2[3H]DG) in the presence or absence of cytochalasin B, which has been shown to competitively inhibit glucose uptake. IGF-I, IGF-II and insulin each enhanced 2[3H]DG transport in a dose-dependent fashion. Amino acid transport was measured by incubation of the cells with IGF-I for 60 minutes, followed by a 5-minute challenge with alpha-[methyl-3H]aminoisobutyric acid. IGF-I caused a dose-dependent increase in uptake of the amino acid analog. Radioreceptor assays using [125I]insulinlike growth factor I ([125I]IGF-I) demonstrated that the trophoblast-derived cells contained high-affinity, saturable receptors for IGF-I that also bound IGF-II.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth factors in milk.

The paper outlines well recognized growth factors in milk (colostrum and during lactation) like the IGF-family; epidermal growth factor; transforming growth factors a, beta; tumor necrosis factor; basic fibroblast growth factor and platelet derived growth factor The origin of these factors is discussed. The IGF-family may be of greater benefit to the newborn calf in contrast to other species where EGF seems to be the dominating and important factor. However, the primary role of the measured growth factors may be related more to the proliferation and maintenance of the lactating gland itself.

Nutritional regulation of the insulin-like growth factors.

Nutrition is one of the main regulators of circulating IGF-I. In humans, serum IGF-I concentrations are markedly lowered by energy and/or protein deprivation. Both energy and proteins are critical in the regulation of serum IGF-I concentrations. Indeed, after fasting, optimal intake of both energy and protein is necessary for the rapid restoration of circulating IGF-I. We believe, however, that in adult humans energy may be somewhat more important than protein in this regard. While the lowest protein intake is able to increase IGF-I in the presence of adequate energy, there is a threshold energy requirement below which optimal protein intake fails to raise IGF-I after fasting. When energy intake is severely reduced, the carbohydrate content of the diet is a major determinant of responsiveness of IGF-I to GH. The essential amino acid content of the diet is also critical for the optimal restoration of IGF-I after fasting, when protein intake is reduced. The exquisite sensitivity of circulating IGF-I to nutrients, the nycthemeral stability of its concentrations and its relative short half-life constitute the basis for its use as a marker of both nutritional status and adequacy of nutritional rehabilitation. For these indications, IGF-I measurement is more sensitive and more specific than measurement of the other nutrient-related serum proteins (albumin, prealbumin, transferrin, retinol-binding protein). Animal models have been developed to investigate the mechanisms responsible for the nutritional regulation of IGF-I. There is no doubt that many mechanisms are involved (Fig. 12). Decline of serum IGF-I in dietary restriction is independent of the diet-induced alterations in pituitary GH secretion. The role of the liver GH receptors is dependent on the severity of the nutritional insult. In severe dietary restriction (fasting), a marked decrease of the number of somatogenic receptors supports the role of a receptor defect in the decline of circulating IGF-I. In contrast, in less severe forms of dietary restriction (protein restriction), the decline of IGF-I results from a postreceptor defect in the GH action at the hepatic level. Nutritional deprivation decreases hepatic IGF-I production by diminishing IGF-I gene expression. Decline in IGF-I gene expression is mainly caused by nutrient deficiency and less importantly by the nutritionally induced hormonal changes (insulin and T3). Diet restriction also increases the clearance and degradation of serum IGF-I through changes in the levels of circulating IGFBPs.(ABSTRACT TRUNCATED AT 400 WORDS)

Anabolic steroid therapies for growth disorders.

Until recently, human growth hormone was the only endocrine therapy available for promotion of growth and development. Dramatic progress in understanding the secretory and regulatory pathways pertinent to the anabolic steroids has led to multiple pharmacologic approaches. Growth hormone dynamics and its impact on therapy are discussed.

Nutrition, somatomedins, and the brain.

Conditions of decreased nutrient supply (malnutrition) and/or decreased nutrient utilization (diabetes) are attended by impairment of growth despite an increase in circulating levels of growth hormone (GH). Growth involves the actions of somatomedins, circulating insulinlike polypeptides with anabolic effects on cartilage, fat, and muscle. In malnutrition and diabetes, mechanisms of growth impairment appear to include a decrease in GH-induced generation of somatomedins, together with an increase in somatomedin inhibitors, factors which antagonize somatomedin action. Brain mediation of these alterations involves a rise in GH secretion due to decreased negative feedback from somatomedins, perhaps accentuated by blunting of feedback via actions of somatomedin inhibitors. In combination these processes lead to shunting of metabolic fuels toward vital processes and away from growth (via decreased somatomedin action) and to protein-sparing and increase in alternate metabolic fuels (via direct GH actions on muscle and fat). Further study of involved hypothalamic and pituitary mechanisms should yield additional insights into the role of the brain in metabolic homeostasis.