Myostatin regulates pituitary development and hepatic IGF1.

Circulating myostatin-attenuating agents are being developed to treat muscle-wasting disease despite their potential to produce serious off-target effects, as myostatin/activin receptors are widely distributed among many nonmuscle tissues. Our studies suggest that the myokine not only inhibits striated muscle growth but also regulates pituitary development and growth hormone (GH) action in the liver. Using a novel myostatin-null label-retaining model (Jekyll mice), we determined that the heterogeneous pool of pituitary stem, transit-amplifying, and progenitor cells in Jekyll mice depletes more rapidly after birth than the pool in wild-type mice. This correlated with increased levels of GH, prolactin, and the cells that secrete these hormones, somatotropes and lactotropes, respectively, in Jekyll pituitaries. Recombinant myostatin also stimulated GH release and gene expression in pituitary cell cultures although inhibiting prolactin release. In primary hepatocytes, recombinant myostatin blocked GH-stimulated expression of two key mediators of growth, insulin-like growth factor (IGF)1 and the acid labile subunit and increased expression of an inhibitor, IGF-binding protein-1. The significance of these findings was demonstrated by smaller muscle fiber size in a model lacking myostatin and liver IGF1 expression (LID-o-Mighty mice) compared with that in myostatin-null (Mighty) mice. These data together suggest that myostatin may regulate pituitary development and function and that its inhibitory actions in muscle may be partly mediated by attenuating GH action in the liver. They also suggest that circulating pharmacological inhibitors of myostatin could produce unintended consequences in these and possibly other tissues.

Effects of tibolone and its metabolites on prolactin and insulin-like growth factor binding protein-1 expression in human endometrial stromal cells.

The effects of the postmenopausal replacement steroid tibolone and its 3α-, 3ß-OH and Δ-4 tibolone metabolites were evaluated on progesterone receptor-mediated classic decidualization markers insulin-like growth factor binding protein-1 (IGFBP-1) and prolactin expression in human endometrial stromal cells (HESCs). Supernatants of conditioned medium or erxtracted RNA from experimental cell incubations of confluent HESCs were subjected to ELISAs, Western blot analysis and RT/PCR, and results were statisically assesed. Over 21 days, specific ELISAs observed linear increases in secreted IGFBP-1 and prolactin levels elicited by tibolone and its metabolites. Cultured HESCs were refractory to E2 and dexamethasone, whereas tibolone and each metabolite exceeded medroxyprogesterone acetate in significantly elevating IGFBP-1 and prolactin output. Anti-progestins eliminated IGFBP-1 and prolactin induction by tibolone and its metabolites. Immunoblotting and RT/PCR confirmed ELISA results. These observations of IGFBP-1 and prolactin expression: (a) indicate the relevance of cultured HESCs in evaluating the chronic effects of tibolone administration to women; (b) are consistent with PR-mediated endometrial atrophy and protection against endometrial bleeding despite the persistence of circulating ER-binding, but not PR-binding metabolites following tibolone administration to women.

[Effects of gibberellins on early development and IGF-1 expression in female rats].

OBJECTIVE: To explore the effects of plant growth regulator gibberellin on early development and IGF-1 expression in female rats. METHODS: Forty weaned female SD rats were randomly divided into four groups and fed with basic diet. Gibberellin was administered intragastrically at the levels of 0, 2.0, 100.0 and 200.0 mg/kg respectively for 15 days. Body weight and body length were measured weekly and the time of vaginal opening was observed every day. Liver, uterus and ovary were dissected after exposure for 15 days. Total RNA of liver was extracted and the expression of IGF-1 and IGFBP-1 mRNA was detected by RT-PCR. RESULTS: Compared with the control group, no significant differences of body weight, body length, vaginal opening time, as well as the organ coefficients of liver, uterus and ovary were observed in gibberellin-treated groups. There was no significant change on the expressions of IGF-1 and IGFBP-1 in the liver of gibberellin-treated groups, although the expression of IGFBP-1 was more than IGF-1 in a few samples. Organ coefficient of liver in high dose group was significantly lower than that in the control group (P < 0.05). CONCLUSION: Gibberellin does not cause abnormal change on growth and development as well as the expression of IGF-1 and IGFBP-1 in liver of female SD rats, but at the level of 200.0 mg/kg gibberellin may induce damages in liver.

Is cow's milk harmful to a child's health?

Discussions and debates have recently emerged on the potential positive and negative effects of cow's milk in the paediatric community, also under the pressure of public opinion. The negative effects of cow's-milk consumption seem to be limited to iron status up to 9 to 12 months; then no negative effects are observed, provided that cow's milk, up to a maximum daily intake of 500 mL, is adequately complemented with iron-enriched foods. Lactose intolerance can be easily managed and up to 250 mL/day of milk can be consumed. Allergy to cow's-milk proteins is usually transient. Atopic children may independently be at risk for poor growth, and the contribution of dairy nutrients to their diet should be considered. The connection of cow's milk to autistic spectrum disorders is lacking, and even a cause-effect relation with type 1 diabetes mellitus has not been established because many factors may concur. Although it is true that cow's milk stimulates insulin-like growth factor-1 and may affect linear growth, association with chronic degenerative, noncommunicable diseases has not been established. Finally, fat-reduced milk, if needed, should be considered after 24 to 36 months. Cow's milk represents a major source of high nutritional quality protein as well as of calcium. Moreover, it has growth-promoting effects independent of specific compounds. Its protein and fat composition, together with the micronutrient content, is suggestive of a functional food, whose positive effects are emphasised by regular consumption, particularly under conditions of diets poor in some limiting nutrients, although in industrialised countries cow's milk's optimal daily intake should be around 500 mL, adequately complemented with other relevant nutrients.

Effects of an oral ghrelin mimetic on body composition and clinical outcomes in healthy older adults: a randomized trial.

BACKGROUND: Growth hormone secretion and muscle mass decline from midpuberty throughout life, culminating in sarcopenia, frailty, decreased function, and loss of independence. The decline of growth hormone in the development of sarcopenia is one of many factors, and its etiologic role needs to be demonstrated. OBJECTIVE: To determine whether MK-677, an oral ghrelin mimetic, increases growth hormone secretion into the young-adult range without serious adverse effects, prevents the decline of fat-free mass, and decreases abdominal visceral fat in healthy older adults. DESIGN: 2-year, double-blind, randomized, placebo-controlled, modified-crossover clinical trial. SETTING: General clinical research center study performed at a university hospital. PARTICIPANTS: 65 healthy adults (men, women receiving hormone replacement therapy, and women not receiving hormone replacement therapy) ranging from 60 to 81 years of age. INTERVENTION: Oral administration of MK-677, 25 mg, or placebo once daily. MEASUREMENTS: Growth hormone and insulin-like growth factor I levels. Fat-free mass and abdominal visceral fat were the primary end points after 1 year of treatment. Other end points were body weight, fat mass, insulin sensitivity, lipid and cortisol levels, bone mineral density, limb lean and fat mass, isokinetic strength, function, and quality of life. All end points were assessed at baseline and every 6 months. RESULTS: Daily administration of MK-677 significantly increased growth hormone and insulin-like growth factor I levels to those of healthy young adults without serious adverse effects. Mean fat-free mass decreased in the placebo group but increased in the MK-677 group (change, -0.5 kg [95% CI, -1.1 to 0.2 kg] vs. 1.1 kg [CI, 0.7 to 1.5 kg], respectively; P < 0.001), as did body cell mass, as reflected by intracellular water (change, -1.0 kg [CI, -2.1 to 0.2 kg] vs. 0.8 kg [CI, -0.1 to 1.6 kg], respectively; P = 0.021). No significant differences were observed in abdominal visceral fat or total fat mass; however, the average increase in limb fat was greater in the MK-677 group than the placebo group (1.1 kg vs. 0.24 kg; P = 0.001). Body weight increased 0.8 kg (CI, -0.3 to 1.8 kg) in the placebo group and 2.7 kg (CI, 2.0 to 3.5 kg) in the MK-677 group (P = 0.003). Fasting blood glucose level increased an average of 0.3 mmol/L (5 mg/dL) in the MK-677 group (P = 0.015), and insulin sensitivity decreased. The most frequent side effects were an increase in appetite that subsided in a few months and transient, mild lower-extremity edema and muscle pain. Low-density lipoprotein cholesterol levels decreased in the MK-677 group relative to baseline values (change, -0.14 mmol/L [CI, -0.27 to -0.01 mmol/L]; -5.4 mg/dL [CI, -10.4 to -0.4 mg/dL]; P = 0.026); no differences between groups were observed in total or high-density lipoprotein cholesterol levels. Cortisol levels increased 47 nmol/L (CI, 28 to 71 nmol/L (1.7 microg/dL [CI, 1.0 to 2.6 microg/dL]) in MK-677 recipients (P = 0.020). Changes in bone mineral density consistent with increased bone remodeling occurred in MK-677 recipients. Increased fat-free mass did not result in changes in strength or function. Two-year exploratory analyses confirmed the 1-year results. LIMITATION: Study power (duration and participant number) was insufficient to evaluate functional end points in healthy elderly persons. CONCLUSION: Over 12 months, the ghrelin mimetic MK-677 enhanced pulsatile growth hormone secretion, significantly increased fat-free mass, and was generally well tolerated. Long-term functional and, ultimately, pharmacoeconomic, studies in elderly persons are indicated.

Expression of genes encoding IGFBPs, SNARK, CD36, and PECAM1 in the liver of mice treated with chromium disilicide and titanium nitride nanoparticles.

OBJECTIVE: The aim of the present study was to examine the effect of chromium disilicide and titanium nitride nanoparticles on the expression level of genes encoding important regulatory factors (IGFBP1, IGFBP2, IGFBP3, IGFBP4, IGFBP5, SNARK/NUAK2, CD36, and PECAM1/CD31) in mouse liver for evaluation of possible toxic effects of these nanoparticles. METHODS: Male mice received 20 mg chromium disilicide nanoparticles (45 nm) and titanium nitride nanoparticles (20 nm) with food every working day for 2 months. The expression of IGFBP1, IGFBP2, IGFBP3, IGFBP4, IGFBP5, SNARK, CD36, and PECAM1 genes in mouse liver was studied by quantitative polymerase chain reaction. RESULTS: Treatment of mice with chromium disilicide nanoparticles led to down-regulation of the expression of IGFBP2, IGFBP5, PECAM1, and SNARK genes in the liver in comparison with control mice, with more prominent changes for SNARK gene. At the same time, the expression of IGFBP3 and CD36 genes was increased in mouse liver upon treatment with chromium disilicide nanoparticles. We have also shown that treatment with titanium nitride nanoparticles resulted in down-regulation of the expression of IGFBP2 and SNARK genes in the liver with more prominent changes for SNARK gene. At the same time, the expression of IGFBP3, IGFBP4, and CD36 genes was increased in the liver of mice treated with titanium nitride nanoparticles. Furthermore, the effect of chromium disilicide nanoparticles on IGFBP2 and CD36 genes expression was significantly stronger as compared to titanium nitride nanoparticles. CONCLUSIONS: The results of this study demonstrate that chromium disilicide and titanium nitride nanoparticles have variable effects on the expression of IGFBP2, IGFBP3, IGFBP4, IGFBP5, SNARK, CD36, and PECAM1 genes in mouse liver, which may reflect the genotoxic activities of the studied nanoparticles.

Progesterone receptor (PR) inhibits expression of insulin-like growth factor-binding protein-1 (IGFBP-1) in human endometrial cell line HEC-1B: characterization of the inhibitory effect of PR on the distal promoter region of the IGFBP-1 gene.

Progestin has been shown to have both stimulatory and inhibitory effects on the expression of insulin-like growth factor binding protein-1 (IGFBP-1) in human endometrial cells. In this study, progestin was found to reduce levels of secreted IGFBP-1 and IGFBP-1 messenger RNA and IGFBP-1 promoter activity after stably transfecting a progesterone receptor (PR; B form) expression vector into HEC-1B cells. Deletion analysis of the IGFBP-1 promoter revealed that PR specifically inhibited promoter activity derived from a 59-bp distal BsaHI/RsaI fragment. It was concluded that PR inhibited the promoter activity through protein-protein interactions based on the facts that 1) no progesterone-responsive element was revealed by a series block mutation in the BsaHI/RsaI fragment; 2) PR bound by the antiprogesterone ZK98299 inhibited IGFBP-1 promoter activity; 3) a DNA-binding mutant of PR inhibited the IGFBP-1 promoter activity; and 4) in an in vivo competition assay, the DNA-binding domain of PR did not release the inhibitory effect of intact PR. Analysis of PR deletion mutants indicated that both transcriptional activation domains of PR (TAF-1 and TAF-2) were involved in the inhibition of IGFBP-1 expression. Thus, our data may explain the superinduction of IGFBP-1 in human endometrial cells after progestin withdrawal or progestin replacement with antiprogestin.

The Potent Humanin Analogue (HNG) Protects Germ Cells and Leucocytes While Enhancing Chemotherapy-Induced Suppression of Cancer Metastases in Male Mice.

Humanin is a peptide that is cytoprotective against stresses in many cell types. We investigated whether a potent humanin analogue S14G-humanin (HNG) would protect against chemotherapy-induced damage to normal cells without interfering with the chemotherapy-induced suppression of cancer cells. Young adult male mice were inoculated iv with murine melanoma cells. After 1 week, cancer-bearing mice were randomized to receive either: no treatment, daily ip injection of HNG, a single ip injection of cyclophosphamide (CP), or CP+HNG and killed at the end of 3 weeks. HNG rescued the CP-induced suppression of leucocytes and protected germ cell from CP-induced apoptosis. Lung metastases were suppressed by HNG or CP alone, and further suppressed by CP+HNG treatment. Plasma IGF-1 levels were suppressed by HNG with or without CP treatment. To investigate whether HNG maintains its protective effects on spermatogonial stem cells, sperm output, and peripheral leucocytes after repeated doses of CP, normal adult male mice received: no treatment, daily sc injection of HNG, 6 ip injections of CP at 5-day intervals, and the same regimens of CP+HNG and killed at the end of 4 weeks of treatment. Cauda epididymal sperm counts were elevated by HNG and suppressed by CP. HNG rescued the CP-induced suppression of spermatogonial stem cells, sperm count and peripheral leucocytes. We conclude that HNG 1) protects CP-induced loss of male germ cells and leucocytes, 2) enhances CP-induced suppression of cancer metastases, and 3) acts as a caloric-restriction mimetic by suppressing IGF-1 levels. Our findings suggest that humanin analogues may be promising adjuvants to chemotherapy.

Insulin-like growth factor binding protein-1 (IGFBP-1) and IGF-I during oral and transdermal estrogen replacement therapy: relation to lipoprotein(a) levels.

Low levels of insulin-like growth factor binding protein-1 (IGFBP-1) have recently been associated with several risk factors for cardiovascular disease. The effects of estrogen replacement therapy (ERT) on plasma IGFBP-1 levels are, however, unclear. A double-blind, placebo-controlled study for 6 months was conducted in 73 hysterectomized postmenopausal women randomized into two groups: oral estradiol (E2) valerate, 2 mg/day (n = 35) and transdermal E2 gel, 1 mg/day (n=38). Plasma IGFBP-1, insulin-like growth factor-I (IGF-I) and lipoprotein(a) (Lp(a)) were determined at baseline, 3 and 6 months. The groups were similar for age and BMI. The baseline levels of estrone (E1), E2, IGFBP-1, IGF-I and Lp(a) did not differ between the groups. During treatment, serum estradiol concentrations increased in both groups. During oral ERT, IGFBP-1 levels increased by 104% (P<0.001), whereas IGF-I levels decreased by 13% (mean, P<0.05). IGF-I and IGFBP-1 levels remained unchanged in the transdermal group. Lp(a) levels decreased by 23% (median, P<0.001) in the oral group, but were unaffected by transdermal therapy. The change in IGFBP-1 concentrations during oral ERT showed an inverse correlation to that in Lp(a) (r = -0.40, P<0.05, Spearman correlation). In conclusion, oral ERT seems to enhance plasma levels of IGFBP-1, which may be one reason for the reduced Lp(a) levels.

Tissue availability of insulin-like growth factor I is inversely related to insulin resistance in essential hypertension: effects of angiotensin converting enzyme inhibition.

BACKGROUND: The insulin-like growth factor I possesses biologic actions that resemble those of insulin. Tissue access of the factor depends on the distribution of the circulating bound factor between its binding protein 3 that remains within the intravascular space and its binding protein I that is able to cross the endothelium. Preliminary results have shown that tissue availability of insulin-like growth factor I is a determinant of glucose regulation in essential hypertension OBJECTIVE: To investigate whether the tissue availability of circulating insulin-like growth factor I in patients with essential hypertension is related to insulin resistance and whether chronic angiotensin converting enzyme inhibition influences tissue availability of the factor and insulin resistance in these patients. DESIGN AND METHODS: We studied 29 patients with essential hypertension and 20 age-matched and sex-matched normotensive subjects. The measurements were repeated for 25 patients after 12 months of treatment with lisinopril. Tissue availability of circulating insulin-like growth factor I was assessed by analyzing its distribution between its binding proteins 3 and 1. An insulin resistance index was estimated using the homeostasis model analysis of fasting insulin-glucose interactions. Levels of serum insulin-like growth factor I binding proteins 3 and 1, plasma insulin-like growth factor I, and insulin were determined by specific radioimmunoassays. RESULTS: Baseline insulin resistance index was significantly higher in the hypertensive patients than it was in the normotensive controls. With the upper 100% confidence limit of the normotensive population as the cutoff point, a subgroup of 12 hypertensives had an abnormally high insulin resistance index. Compared with patients with normal insulin resistance indexes, patients with greater than normal indexes were characterized by lower binding protein 1 levels, similar binding protein 3 levels, lower binding protein 1 : binding protein 3 ratio and similar insulin-like growth factor I levels. The serum binding protein 1 level and the binding protein 1 : binding protein 3 ratio were inversely correlated to the insulin resistance index for the whole group of hypertensives. After treatment with lisinopril hypertensive patients with higher than normal insulin resistance indexes at baseline exhibited normalization of this parameter and significant increases of binding protein 1 levels and binding protein 1 : binding protein 3 ratio, with no significant changes in insulin-like growth factor I levels. These parameters remained unchanged for the remaining patients. CONCLUSIONS: These results suggest that tissue availability of circulating insulin-like growth factor I is a determinant of insulin sensitivity in patients with essential hypertension. Whereas the patients with normal insulin sensitivity exhibit greater than normal tissue access of circulating insulin-like growth factor I, patients with insulin resistance present normal tissue access of the factor. Our findings suggest that the ability of angiotensin converting enzyme inhibitors to restore insulin sensitivity in essential hypertensives may be related to their ability to facilitate the tissue availability of circulating insulin-like growth factor I.

Lithium chloride inhibits the expression and secretion of insulin-like growth factor-binding protein-1.

Insulin-like growth factor-binding protein-1 (IGFBP-1) regulates IGF availability for glucose homeostasis. The IGFBP-1 promoter shares common regulatory response elements with phosphoenol pyruvate carboxykinase (PEPCK), the expression and activity of which is inhibited by lithium chloride, associated with an inhibition of glycogen synthase kinase (GSK)-3 activity, in the rat hepatoma cell line H4-II-E. We therefore determined the effect of lithium chloride on IGFBP-1 expression and secretion in H4-II-E cells. Lithium chloride inhibited IGFBP-1 secretion in a dose response and reversible manner by approx 80% during 5-h and 16-h incubations. An inhibitory effect on IGFBP-1 mRNA expression was observed at 2 h. The inhibitory effect of lithium and insulin were not additive when used alone, but inhibition by lithium occurred when insulin action was blocked by activating AMP-activated protein kinase with 5-aminoimidazole-4-carboxamide-riboside (AICAR). These findings suggest that GSK-3 inhibition, or another pathway activated by lithium, may be involved in a pathway controlling IGFBP-1, inhibiting synthesis when insulin activity is absent or impaired.

Free and total insulin-like growth factors and insulin-like growth factor binding proteins during 14 days of growth hormone administration in healthy adults.

The objective was to investigate the effect of growth hormone (GH) administration on circulating levels of free insulin-like growth factors (IGFs) in healthy adults. Eight healthy male subjects were given placebo and two doses of GH (3 and 6 IU/m2 per day) for 14 days in a double-blind crossover study. Fasting blood samples were obtained every second day. Free IGF-I and IGF-II were determined by ultrafiltration of serum. Total IGF-I and IGF-II were measured after acid-ethanol extraction. In addition, GH, insulin, IGF binding protein 1 (IGFBP-1) and IGFBP-3 were measured. Serum-free and total IGF-I increased in a dose-dependent manner during the 14 days of GH administration. After 14 days, serum-free IGF-I values were 610 +/- 100 ng/l (mean +/- SEM) (placebo), 2760 +/- 190 ng/l (3 IU/ m2) and 3720 +/- 240 ng/l (6 IU/m2) (p = 0.0001 for 3 and 6 IU/m2 vs placebo; p = 0.004 for 3 IU/m2 vs 6 IU/m2). Total IGF-I values were 190 +/- 10 micrograms/l (placebo), 525 +/- 10 (3 IU/m2), and 655 +/- 40 micrograms/l (6 IU/m2) (p < 0.0001 for 3 and 6 IU/m2 vs placebo; p = 0.04 for 3 IU/m2). There were no differences in the levels of free or total IGF-II during the three study periods. Insulin-like growth factor binding protein 1 was decreased during GH administration (p = 0.04 for placebo vs 3 IU/m2; p = 0.006 for placebo vs 6 IU/m2). In conclusion, fasting serum free IGF-I increased dose dependently during GH administration and free IGF-I increased relatively more than total IGF-I. This may partly be due to the decrease in IGFBP-1.

The effect of clozapine on factors controlling glucose homeostasis.

BACKGROUND: This prospective study examines the effect of clozapine on factors determining glucose homeostasis. METHOD: The sample consisted of all patients meeting DSM-IV criteria for schizophrenia who commenced clozapine treatment within the South London and Maudsley hospitals during 1 year (2000-2001). Growth hormone (GH), insulin-like growth factor-1 (IGF-1), and IGF binding protein-1 (IGFBP-1) were measured in 19 patients (10 female; mean age = 31.1 years [SD = 5.8]; 9 black British/African, 10 white British) before and after a mean of 2.5 (SD = 0.9) months of clozapine treatment. RESULTS: Baseline IGFBP-1 was low. IGFBP-1, GH, and IGF-1 were not significantly changed by clozapine treatment. CONCLUSIONS: Clozapine does not alter GH, IGF-1, or IGFBP-1 within 3 months of commencing treatment, indicating that alteration in glucose tolerance associated with clozapine treatment involves other mechanisms yet to be elucidated. Baseline abnormalities in IGFBP-1 indicate a preexisting susceptibility to glucoregulatory dysfunction.

Different influences of classical antipsychotics and clozapine on glucose-insulin homeostasis in patients with schizophrenia or related psychoses.

BACKGROUND: The aim of this study was to investigate the influence of classical antipsychotics and the atypical antipsychotic agent clozapine on glucose-insulin homeostasis to explain possible mechanisms behind weight gain associated with antipsychotic treatment. METHOD: Twenty-eight patients on therapy with classical antipsychotics and 13 patients treated with clozapine (all meeting DSM-III-R criteria for schizophrenia or related psychoses) were studied. Fasting blood samples for glucose and insulin, as well as for 2 markers of the glucose-insulin homeostasis, i.e., the growth hormone (GH)-dependent insulin-like growth factor I (IGF-I) and the insulin-dependent insulin-like growth factor binding protein-1, were analyzed. Body mass index (BMI) was calculated and serum concentrations of the different antipsychotic drugs were measured. In addition, the relationship between the endocrine parameters and drug serum concentrations was examined. RESULTS: The insulin levels were positively correlated to the serum concentration of clozapine, whereas no correlations were found between insulin and the serum concentrations of perphenazine (N = 12) or zuclopenthixol (N = 9). Insulin elevation was seen in the patients receiving clozapine more frequently than in the patients receiving classical antipsychotics. In addition, the median level of IGF-I was significantly lower in the patients receiving clozapine than in the patients receiving classical antipsychotics. No significant difference in BMI was found between the 2 patient groups, and all patients but 1 were normoglycemic. CONCLUSION: The correlation between insulin and the clozapine concentration indicates a probable influence of clozapine on insulin secretion. The normal blood glucose levels in the clozapine group support the theory that clozapine induces concentration-dependent insulin resistance with secondary increased insulin secretion. In addition, lower median level of IGF-I in patients receiving clozapine compared with patients receiving classical antipsychotics points to a lower GH secretion in the clozapine group. This impaired GH secretion together with the clozapine-induced insulin resistance might be mechanisms behind weight gain during clozapine therapy.

Modulation of inflammation-induced changes in insulin-like growth factor (IGF)-I and IGF binding protein-1 by anti-TNF antibody.

The aim of the present study was to characterize changes in the insulin-like growth factor (IGF) system produced by the nonbacterial nonendotoxic inflammatory agent zymosan and to determine whether these changes were mediated by enhanced production of tumor necrosis factor (TNF). Rats were injected intraperitoneally with either zymosan or saline and studied 18 h later. Animals were pretreated with either nonimmune IgG or neutralizing anti-TNF antibody 2 h before zymosan injection. Zymosan increased the plasma concentration of TNF alpha, and this was associated with a decrease (approximately 40%) in the IGF-I concentration in plasma, liver, heart, and brain. The IGF-I content was not altered in skeletal muscle and kidney. Zymosan also increased the concentration of IGF binding protein (BP)-1 in plasma (120%), liver (90%), and muscle (470%). Circulating TNF alpha was not detectable in rats injected with anti-TNF antibody before zymosan. The neutralizing antibody prevented the zymosan-induced reduction in IGF-I in plasma and blunted the decreased observed in liver, but did not alter the decrease in heart or brain. Anti-TNF antibody also attenuated (40-60%) the increased IGFBP-1 in plasma, liver, and muscle observed in zymosan-treated rats. We conclude that zymosan-induced inflammation not only decreases IGF-I in plasma and selected tissues, but also increases IGFBP-1 in plasma, liver, and muscle, and that these alterations are due in large part to the enhanced production of TNF alpha.

Plasma insulin-like growth factor-I and its binding proteins 1 and 3 during continuous nonoral and oral combined hormone replacement therapy.

OBJECTIVE: We determined the effects of continuous combined nonoral and oral estrogen-progestin therapy on plasma levels of insulin-like growth factor-I (IGF-I) and its binding proteins 1 (IGFBP-1) and 3 (IGFBP-3). DESIGN: Forty women complaining of climacteric symptoms were randomized to receive either transdermal estradiol patches (50 microg daily) in combination with an intrauterine system releasing 20 microg of levonorgestrel daily or an established regimen of an oral dose of 2 mg of estradiol and 1 mg of norethisterone acetate daily for 1 year. Fifteen women in the nonoral therapy group and 17 in the oral therapy group completed the 1-year prospective study. RESULTS: Plasma levels of IGF-I decreased significantly in the oral therapy group, but no changes were observed in the plasma levels of its binding proteins. Transdermal estrogen in combination with intrauterine levonorgestrel did not induce any change in plasma IGF-I, whereas the plasma levels of IGFBP-3 decreased. IGFBP-1 concentrations increased, which may be related to the induction of this protein into the endometrium by the intrauterine levonorgestrel delivery. CONCLUSIONS: Both the nonoral and oral continuous combined estrogen-progestin therapies used in this study produced only minor changes in the circulating concentrations of IGF-I and its binding proteins.

High levels of 150-kDa insulin-like growth factor binding protein three ternary complex in patients with acromegaly and the effect of pegvisomant-induced serum IGF-I normalization.

OBJECTIVE: To assess the effect of pegvisomant-induced serum insulin-like growth factor 1 (IGF-1) normalization on IGF binding proteins 1, 2, 3 (IGFBP-1, IGFBP-2 and IGFBP-3), total, non-bound (45 kDa) and 150-kDa ternary complex-associated IGFBP-3, and in vivo IGFBP-3 proteolysis in patients with active acromegaly. DESIGN: The above parameters were measured in 16 patients (median age 57 (range 27-78)) with active acromegaly (serum IGF-I at least 30% above the upper limit of an age-related reference range after washout) in a paired manner on samples obtained after washout and the first occurrence of serum IGF-I normalization during pegvisomant therapy (median dose 15 mg/day (10-40 mg)). RESULTS: Total IGFBP-3 and 150-kDa ternary complex-associated IGFBP-3 were significantly elevated in patients at baseline compared to controls ((mean+/-SEM) 4345+/-194 vs. 3456+/-159 microg/L, P<0.01 and 3908+/-160 va. 3042+/-149 microg/L, P<0.01, respectively), but no significant difference in 45-kDa IGFBP-3 or in vivo IGFBP-3 proteolysis was observed. Serum IGF-I normalization (699+/-76 to 242+/-28 microg/L, P<0.0001) was associated with a fall in total IGFBP-3 (4345+/-194 to 3283+/-160 microg/L, P<0.001) due to a reduction in 150-kDa ternary complex-associated IGFBP-3 (3908+/-160 to 3008+/-140 microg/L, P<0.0001). 45 kDa IGFBP-3 and in vivo IGFBP-3 proteolysis were unaffected by GH receptor blockade (326+/-13 to 330+/-18 microg/L, P=0.86; 30+/-3.5 to 30+/-3.9%, P=0.75, respectively). CONCLUSIONS: GH receptor blockade in patients with acromegaly lowers IGF-I and 150-kDa IGFBP-3 ternary complex formation. 50 kDa ternary complex formation (not in vivo IGFBP-3 proteolysis) is GH dependent and measurement of 150-kDa ternary complex-associated IGFBP-3 may provide useful information regarding treatment efficacy in patients with acromegaly.

Insulin-like growth factor-binding protein-1: a biochemical marker of endometrial response to progestin during hormone replacement therapy.

OBJECTIVES: To compare immunohistochemical localization of insulin-like growth factor binding protein-1 (IGFBP-1) in endometrial stromal cells with endometrial morphology during three regimens of continuous combined hormone replacement therapy. METHODS: Endometrial samples for morphological examination and immunohistochemical staining with monoclonal antibody against IGFBP-1 were obtained from 30 menopausal women before treatment and after 12 and 24 months of continuous combined hormone replacement therapy. All women received percutaneous estradiolgel releasing 1.5 mg estradiol daily. Regarding progestins, patients were divided into three groups: one group (n = 15) had a 20 micrograms/24 h levonorgestrel-releasing intrauterine device (LNG-IUD); the women in the other two groups received micronised natural progesterone either 100 mg orally (n = 7) or 100-200 mg vaginally (n = 8) daily, 25 days per calendar month. RESULTS: Before treatment the endometrium of all women was atrophic or subatrophic and no IGFBP-1 could be detected in any of the samples which contained enough stromal cells for evaluation. After 12 and 24 months of treatment, epithelial atrophy with decidual transformation in stroma was detected in all specimens in the LNG-IUD group, and IGFBP-1 was localized in decidualized stromal cells in all samples. In the other two groups, no signs of progestin effect were detected by microscopic examination in any of the endometrial samples and IGFBP-1 staining was completely negative in all of them. CONCLUSION: A striking difference occurred in both morphological and biochemical response in the endometrium of women treated with LNG-IUD compared with those receiving oral or vaginal micronised progesterone during continuous combined HRT. Micronised progesterone at doses used in this study turned out to be ineffective to prevent the proliferative effect of estrogen. Immunohistochemical localization of IGFBP-1 in endometrial stromal cells strongly correlated with decidual reaction in all endometrial specimens exposed to LNG-IUD, suggesting that the immunostaining of IGFBP-1 can be used as a means of assessing the strength of progestin effect in the endometrium during HRT.

Modification of serum IGF-I, IGFBPs and SHBG levels by different HRT regimens.

UNLABELLED: During the menopause, levels of SHBG, IGF-I and IGFBPs are significantly modified by the use of different HRT regimens. OBJECTIVE: The aim of this study is to evaluate the influence of three different HRT regimens on serum levels of SHBG, IGF-I, IGFBP-1 and IGFBP-3 in postmenopausal women. METHODS: 41 postmenopausal women requesting HRT were enrolled in the study. Subjects were divided in three groups according to the therapy assigned; Group A: estradiol 2 mg/day+cyproterone acetate 1 mg/day in a cyclic sequential regimen; Group B: estradiol hemihydrate 2 mg/day plus norethisterone acetate (NETA) 1 mg/day in a continuous combined regimen; Group C: estradiol hemihydrate 1 mg/day plus NETA 0.5 mg/day in a continuous combined regimen. Blood samples were drawn before the start of hormonal treatment and after 6 months of HRT. Levels of SHBG, IGF-I, IGFBP-1 and IGFBP-3 in the serum were measured by means of a specific immunoassay. RESULTS: In group A, a significant increase of SHBG, no change of IGFBPs and a significant decrease of IGF-I were observed; in group B and in group C, no significant variations for any of the parameters were recorded. CONCLUSIONS: The association of cyproterone acetate to oral estradiol determines a significant reduction of IGF-I levels and an increase of SHBG; nevertheless, it does not seem to influence the serum levels of the IGF-I binding proteins. The treatment with oral continuous combined estrogens plus androgenic progestins, at low doses, produces minor, not significant, changes in the circulating levels of IGF-I, SHBG and IGFBPs.