Blood Insulin-like Growth Factor-1 Levels Research Articles

Growth indices and vitamin D content in children with idiopathic short stature depending on the variants of the Taql polymorphism genotype of the VDR gene

Background. The vitamin D receptor (VDR) gene is a key regulator of biological processes, including tissue and cell growth and differentiation, bone metabolism, and modulation of immune responses. Several studies have shown that 1,25(OH)2D increases circulating insulin-like growth factor-1 (IGF-1) levels in vivo and in bone cell cultures. It also increases the expression of IGF-1 receptors in growth plate chondrocytes and several IGF-binding proteins in osteoblasts and bone marrow stromal cell cultures. A vitamin D receptor gene polymorphism is associated with adult height and may affect the growth indicators in children with idiopathic short stature. The purpose was to study the growth indicators and vitamin D levels in children with idiopathic short stature depending on the variants of the Taql polymorphism genotype of the VDR gene. Materials and methods. Determination of the Taql polymorphism of the VDR gene (rs731236) was performed using polymerase chain reaction followed by an analysis of the length of the restriction fragments when detected by agarose gel electrophoresis in 35 children with idiopathic short stature. Results. Most children (68.57 %) were heterozygotes, 17.14 % were homozygotes for T/T alleles, and 14.29 % were homozygotes for C/C alleles. The highest growth retardation has been observed in homozygous T/T carriers. Children carrying homozygotes for C/C alleles had the least growth retardation. Growth hormone levels after clonidine stimulation test and IGF-1 levels in blood were within normal limits in all patients. Vitamin D deficiency was found in T/T homozygotes and vitamin D insufficiency in C/T heterozygotes and C/C homozygotes. Conclusions. Among children with idiopathic short stature, the prevalence of the T/C genotype was 68.57 %. The greatest growth retardation occurred in patients with homozygous T/T alleles (SDS = –2.61 ± 0.31). A decrease in serum vitamin D levels was detected in all children. Vitamin D deficiency (43.83 ± 6.47 nmol/l) was found in children homozygous for the T/T allele, and vitamin D insufficiency — in T/C heterozygotes (58.97 ± 11.78 nmol/l) and C/C homozygotes (56.93 ± 19.54 nmol/l).

Associations Between Hypertension, Angiotensin-Converting Enzyme Inhibitors, and Physical Performance in Very Old Adults: Results from the ilSIRENTE Study

BackgroundResults regarding the associations between hypertension-related parameters and physical performance in older adults are conflicting. A possible explanation for these divergent results is that investigations may not have adjusted their analyses according to the use of angiotensin-converting enzyme inhibitors (ACEIs).ObjectivesTo examine the associations between hypertension-related parameters, ACEI use, and a set of physical performance tests in very old adults.DesignCross-sectional study from the ilSIRENTE database.SettingMountain community of the Sirente geographic area (L’Aquila, Abruzzo, Italy).ParticipantsAll persons born in the Sirente area (13 municipalities) before 1 January 1924 and living in that region at the time of study were identified and invited to participate. The final sample included 364 older adults (mean age: 85.8 ± standard deviation [SD] 4.8).MeasurementsPhysical performance was assessed using isometric handgrip strength (IHG), walking speed (WS) at normal and fast pace, 5-time sit-to-stand test (5STS), and muscle power measures. Blood pressure (BP) was measured after 20 to 40 min of rest, while participants sat in an upright position. Drugs were coded according to the Anatomical Therapeutic and Chemical codes. ACEIs were categorized in centrally (ACEI-c) and peripherally (ACEI-p) acting. Blood inflammatory markers, free insulin-like growth factor 1 (IGF-1), and IGF-binding protein 3 (IGFBP-3) were assayed.ResultsResults indicated that 5STS test was significantly and negatively associated with diastolic BP values. However, significance was lost when results were adjusted for ACEI use. Participants on ACEIs were more likely to have greater specific muscle power and higher blood levels of IGFBP-3 than non-ACEI users. When participants were categorized according to ACEI subtypes, those on ACEI-p had higher blood IGF-1 levels compared with ACEI-c users.ConclusionsThe main findings of the present study indicate that ACEI use might influence the association between hypertension-related parameters and neuromuscular parameters in very old adults. Such results may possibly be linked to the effects of ACEI-p on the IGF-1 pathway.

Role of cord blood IGF-1 and maternal HbA1c levels to predict interventricular septal hypertrophy among infants of diabetic mothers: A case-control study

BackgroundInfants of diabetic mothers (IDMs) develop interventricular septal hypertrophy (ISH) (> 6 mm) [1]. The proportion of IDMs developing ISH varies from country to country. Maternal HbA1c and cord blood Insulin-like growth factor-1 (IGF-1) levels have been found useful to predict ISH. MethodsThis was a case-control study of term neonates of diabetic mothers (cases) and of non-diabetic mothers (controls) to evaluate echocardiographic (ECHO) differences among cases and controls and to find the correlation of interventricular septal thickness (IVS) thickness with maternal HbA1C and cord blood IGF-1 levels. ResultsOf 32 cases and 34 controls (mean gestational age 37.7 ± 0.9 weeks), 15 (46.8 %) cases, no control developed ISH. Septal thickness was more (6 ± 0.15 cm vs 3 ± 0.06 cm; p = 0.027) in cases than controls. Functional ECHO parameters including left ventricle ejection fraction were comparable (p = 0.9) among the two groups. Maternal HbA1C levels were higher (6.5 % ± 1.3 vs 3.6 % ± 0.7; p = 0.001) with a positive correlation with IVS (Pearson's coefficient 0.784, p < 0.001). Cord blood IGF1 levels were too higher in cases (99.1 ± 6.09 ng/ml vs 37.1 ± 2.99 ng/ml; p < 0.001) with moderate correlation with IVS thickness (Pearson's coefficient 0.402; p = 0.00). Receiver operator curve analysis showed, that at a cut-off of 72 ng/ml, cord blood IGF1 predicted ISH with 72 % sensitivity; 88 % specificity and at a cut-off of 7.35 %, maternal HbA1c predicted ISH with sensitivity; specificity of 93.8 % and 72.1 % respectively. ConclusionISH was present in 46.8 % in cases as compared to none in controls. IVS thickness correlated well with maternal HbA1C and moderately with cord blood IGF-1 levels. Functional parameters on ECHO were unaffected by maternal diabetic control. At the cut-off of maternal HbA1c of 7.35 % and cord blood IGF-1 of 72 ng /ml, babies need to be monitored clinically with ECHO to look for ISH.

Association of umbilical cord insulin-like growth factor 1 levels with severe retinopathy in extremely preterm infants.

The association between umbilical cord blood insulin-like growth factor 1 (IGF-1) levels and retinopathy of prematurity (ROP) remains unclear. This study aimed to investigate whether umbilical cord blood IGF-1 levels can predict the development of severe ROP in extremely preterm infants. This hospital-based retrospective cohort study included infants born at <37 weeks gestational age (GA) between 2019 and 2021 and then classified them into the two GA groups: extremely preterm, <28 weeks and preterm infants, 28-36 weeks. Extremely preterm infants were further subclassified into two groups according to the laser treatment as follows: the severe ROP (ROP-Tx) and ROP (No ROP-Tx) groups. Median umbilical cord blood IGF-1 values were compared between the groups. Perinatal risk factors were identified by univariate and multivariate analyses. Finally, umbilical cord IGF-1 cut-off values requiring ROP treatment with laser were determined by receiver operating characteristic (ROC) curve analyses. A total of 205 infants were enrolled, with 32 being extremely preterm (ROP-Tx: n=11; No ROP-Tx: n=21) and 173 being preterm. IGF-1 levels were significantly lower in extremely preterm (13.5ng/mL) than preterm infants (36ng/mL, p<0.001). In extremely preterm infants, IGF-1 levels were significantly lower in the ROP-Tx group than the No ROP-Tx group (10 vs. 19ng/mL, respectively, p=0.024). Only GA, umbilical cord blood IGF-1 levels, birth head circumference, and birth chest circumference were identified as risk factors by univariate analysis (p<0.05). Multivariate analysis showed that only umbilical cord blood IGF-1 was an independent risk factor (odds ratio: 1.26, p=0.021). ROC curves revealed an IGF-1 cut-off value of 14ng/mL. The need of laser treatment for ROP was found to be associated with low umbilical cord blood IGF-1 levels in extremely preterm infants. Umbilical cord blood IGF-1 can be used as a biomarker for the risk of developing severe ROP.

Reference intervals for thyroid hormone, sex hormone, and clinical biochemical tests in cord blood from Taiwanese newborn – TMICS cohort

Background/PurposeThis study aims to establish reference intervals for important biochemical parameters in cord blood of newborn male and female infants in Taiwan and to investigate their sex difference. We also examined the correlation of the same markers between maternal blood levels and neonatal cord blood levels. Methods2,136 pregnant women receiving regular routine prenatal health assessments in their third trimester (weeks 29–40) were recruited from nine hospitals in Taiwan between 2012 and 2015. After exclusion, we were left with 580 cord blood samples to include in this study. ResultsCord blood thyroid-stimulating hormone was higher in males than females (p < 0.05). Males also had significantly higher sex hormone levels (estradiol, follicle-stimulating hormone, and sex hormone-binding globulin), while females had higher levels of luteinizing hormone. Male newborns had higher cord blood immunoglobulin E (IgE), while females had higher insulin-like growth factor-1 (IGF-1) levels. We found a slight positive link between maternal blood and cord blood in thyroid hormones and sex hormones. ConclusionThis study found sex differences in cord blood thyroid hormone, sex hormone, IGF-1, and IgE levels and a link between maternal blood levels of thyroid and sex hormones and those in the cord blood of their infants.

Meta-analysis of peripheral insulin-like growth factor 1 levels in schizophrenia.

We aimed to investigate if there is a significant difference in peripheral insulin-like growth factor 1 (IGF-1) levels between schizophrenia patients and healthy controls and to determine whether a difference exists before and after initiation of antipsychotics. PubMed/MEDLINE, Scopus, and Web of Science were searched up to March 27, 2022. Original clinical studies of any type that reported peripheral blood, serum or plasma IGF-1 levels measured after fasting in schizophrenia patients and/or healthy control group were selected based on inclusion and exclusion criteria. Data were analyzed using Meta-Essentials: Workbooks for meta-analysis and pooled through random-effects meta-analyses. Twelve publications met eligibility criteria. Schizophrenia patients under antipsychotic treatment had significantly lower peripheral IGF-1 levels compared to healthy controls (n=632, Hedges' g -0.42, 95% CI from -0.79 to -0.04, p=.006, I2 =70.38%), while no significant difference was found between schizophrenia patients regardless of the antipsychotic treatment status and healthy controls, as well as between antipsychotic naïve or free schizophrenia patients and healthy controls, and before and after initiation of antipsychotic treatment. However, high heterogeneity was observed and its potential sources in some of the subgroup analyses included sample type and region. Schizophrenia patients under antipsychotic treatment seem to have lower peripheral IGF-1 levels compared to healthy controls. Additional studies with larger and more homogenous samples are needed to confirm these findings.

Percentile-Based Reference Values of Umbilical Cord Blood Insulin-like Growth Factor 1 in Japanese Newborns.

We aimed to create percentile-based reference values of the umbilical cord blood insulin-like growth factor-1 (IGF-1) levels in Japanese newborns, as these values have not yet been established. A total of 259 newborns were classified into four gestational-age-at-birth (GA) groups: extremely preterm (<28 weeks); early preterm (28–33 weeks); late preterm (34–36 weeks); and term (≥37 weeks). They were further subclassified as small-for-gestational-age (SGA) or non-SGA. The 10th, 25th, 50th, 75th, and 90th percentiles of the umbilical cord blood IGF-1 levels were calculated and compared between the groups by using reference values of 9, 18, 33, 52, and 71 ng/mL, respectively. In the extremely preterm group, the IGF-1 levels were significantly lower than those in the early preterm, late preterm, and term groups (13.5, 24.0, 44.5, and 47.5 ng/mL, respectively; p < 0.001). The umbilical cord blood IGF-1 levels in the SGA newborns were significantly lower than those in the non-SGA newborns in all subgroups. In multivariate analyses, the GA and birth weight standard deviation scores were independent determinant factors for the umbilical cord blood IGF-1 levels. Thus, we established percentile-based reference values of umbilical cord blood IGF-1 in Japanese newborns; these reference values can be applied on the basis of the extent of prematurity and the SGA status.

Effects of a blood flow restriction exercise under different pressures on testosterone, growth hormone, and insulin-like growth factor levels.

ObjectiveTo investigate the changes in serum growth hormone (GH), testosterone, and insulin-like growth factor 1 (IGF-1) during low-intensity resistance exercise under different cuff pressures.MethodsWe performed a single-blind, cross-over design study. Twenty-five healthy young men performed three exercise protocols as follows: 1) no blood flow restriction exercise (control group), 2) resistance exercise at 40% of arterial occlusion pressure (AOP) (low group), and 3) resistance exercise at 70% of AOP (high group). Blood lactate, GH, testosterone, and IGF-1 levels were measured at four time points.ResultsThere were no differences in the indices before exercise. The blood flow restriction exercise under different pressures had different effects on each index and there was an interactive effect. GH levels were significantly higher in the high group than in the other groups after exercise. Immediately after exercise, IGF-1 and testosterone levels were significantly higher in the high group than in the other groups. At 15 minutes after exercise, testosterone levels were significantly higher in the high group than in the other groups.ConclusionsLow-intensity resistance exercise combined with blood flow restriction effectively increases GH, IGF-1, and testosterone levels in young men. Increasing the cuff pressure results in greater levels of hormone secretion.

Association between Growth Hormone and Insulin-like Growth Factor-1 (IGF-1) Levels, Liver Function and Short-Term Survival of Paediatric Liver Recipients

The growth hormone/insulin-like growth factor-1 (IGF-1) system is an important humoral mediator of liver function with an inherent potential for assessing liver condition and survival prognosis following liver transplantation (LT). Aim . Analysis of associations between growth hormone and IGF-1 levels in blood and markers of liver function and post-LT survival in children. Materials and methods . We examined 143 children with end-stage liver disease (ESLD) aged 3 to 73 (median 8) months after related LT. The growth hormone and IGF-1 concentrations in plasma were evaluated in ELISA assays. Results . In children with ESLD, concentrations of growth hormone and IGF-1 were significantly higher and lower, respectively, compared to healthy children of the same age ( p <0.01). Compared to the level of growth hormone, the level of IGF-1 was related to the diagnosis ( r = 0.30, p = 0.004). IGF-1 shows lower concentrations in biliary atresia and other cholestatic liver diseases compared to non-cholestatic aetiologies (4.7 (0.0—23.4) and 42.3 (9.0—55.0) ng/mL, respectively, p = 0.03). The growth hormone level directly correlated with the severity of liver fibrosis ( r = 0.47, p = 0.02). It was higher in fibrosis grade 4 (F4) than in F1—F3 (4.7 (2.1—7.2) and 2.1 (1.2—3.3) ng/mL, respectively, p = 0.02). Hormone levels normalised after LT. Unlike IGF-1, the level of growth hormone correlated one month after LT with the 6-months survival rate of recipients ( r = 0.36, p = 0.01) being significantly lower in survivors compared to patients who did not survive this period (1.3 (0.5—1.9) and 2.9 (1.6—12.4) ng/mL, respectively, p = 0.02). Conclusion . Blood levels of growth hormone and IGF-1 were shown to differ significantly between ESLD and healthy children, correlating with fibrosis severity and disease aetiology. The level of growth hormone in the blood of LT recipients associates with a short-term survival rate.

Effect of Transsphenoidal Adenectomy on Glucose Tolerance Status in Patients with Growth Hormone-secreting Pituitary Adenoma.

To explore the effect of transsphenoidal adenectomy on glucose tolerance status in patients with growth hormone (GH)-secreting pituitary adenoma. The clinical data of 105 patients with GH-secreting pituitary adenoma who underwent transsphenoidal adenectomy in our department in 2013 were retrospectively analyzed. The glucose tolerance status, GH level, and insulin-like growth factor-1 (IGF-1) level before and after surgery were compared. Among these 105 patients, the blood glucose tolerance status included normal glucose tolerance (NGT) in 47 cases (44.8%), early carbohydrate metabolism disorders (ECMDs) in 26 cases (24.8%), and diabetes mellitus (DM) in 32 cases (30.5%) before surgery. After the surgery, the fasting blood glucose (P=0.006, P=0.017) and postprandial blood glucose (P=0.000, P=0.000) in the ECMDs and DM groups were significantly improved. Also, the random GH (P=0.001, P=0.004, P=0.001), nadir GH (P=0.000, P=0.001, P=0.001), and IGF-1 (P=0.005, P=0.000, P=0.000) significantly decreased during the follow-up period in NGT, ECMDs and DM groups. Compared with ECMDs and DM groups, the decrease in fasting blood glucose (P=0.029, P=0.000), postprandial blood glucose (P=0.003, P=0.000), and serum IGF-1 (P=0.048, P=0.000) were more significant in DM group. Transsphenoidal adenectomy can improve the blood glucose, GH, and IGF-1 levels in patients with growth hormone-secreting pituitary adenoma. Meanwhile,the surgery has a better effect in improving the glucose tolerance status and IGF-1 in patients with preoperatively confirmed DM.

иЗМенения В Оси «инсУЛинОпОДОбнЫЙ ФАкт ОР РОст А-1— сОМА тОтРОпнЫЙ гОРМОн» и инсУЛинОВОЙ ЧУВстВитеЛьнОсти ткАнеЙ У ДетеЙ, РОДиВШихся с ЗАДеРжкОЙ ВнУтРиУтРОбнОгО РАЗВития

Aim. To study the changes in the axis of the «growth hormone (GH) — insulin-like growth factor-1 (IGF-1)» and the insulin sensitivity of tissues in children born with IUGR, depending on the mass-height dynamics. Material and methods. 49 children born with IUGR and 30 control children born without IUGR were prospectively examined. Levels of GH and IGF-1 levels were determined in cord blood and estimation of the insulin sensitivity of tissues was carried out using the homeostatic model (HOMA-IR) at the age of 3 months. Results and discussion. Demanstrated that IGF-1 levels in cord blood in children with IUGR in comparison with the control group was significantly lower, 52,20 (11,61—99,40) and 103,50 (46,17—181,99) ng/ml, respectively (p <0,05). There were no significant differences of growth hormone level in the umbilical cord blood between the groups. There were no significant differences of the level of IGF-1 and GH at the age of 3 months between the study and control groups. The values of basal insulin resistance of tissues (HOMA- IR) were significantly higher in children of study group: 1,12 (0,36—3,99) and 0,88 (0,21—1,64) ng/ml respectively (p<0,05). 16 of 23 children born with IUGR (69,5%) had «growth leap» in the first 3 months of life assessed by weight, and/or an increase of 2 or more centile corridor (CC). Accelerating the pace of growth was associated with significantly higher levels of IGF-1 and GH levels in 3 months of life. Conclusion. Revealed features of «GH-IGF-1» axis and insulin sensitivity of tissues in children with IUGR aimed to stimulation of postnatal growth and can predispose the development of carbohydrate metabolism disorders in later life.

ОсОбеннОсти пОстнА тАЛьнОгО РОст А У ДетеЙ, РОДиВШихся с ЗАДеРжкОЙ ВнУтРиУтРОбнОгО РАЗВития

Aim. To identify the relationship between the levels of insulin-like growth factor-1 (IGF-1) and growth hormone (GH) in the blood and the postnatal growth rate in children born with IUGR in the first 6 months of life. Material and methods. We prospectively examined 65 children: 33-term infants born with IUGR and 32 healthy full-term infants in the control group. Results and discussion. IGF-1 levels in cord blood in children with IUGR were reduced comparative to the control group. At 3-month age blood IGF-1 of children born with IUGR increases, which is higher than the control group, but in reference values. At 3-month age the level of growth hormone in children with symmetrical IUGR was significantly reduced compared with level at birth, in contrast to the group of children with asymmetric IUGR, in which GH persists on the same level. Children with «growth leap» mass had lower concentration of IGF-1 in the umbilical cord blood which is, on average, almost 2-times lower than children without a «growth leap». At 3-month age IGF-1 level dramatically increased in children with «growth leap» in children without it, on the contrast, IGF-1 level is significantly reduced. There were no differences of growth hormone levels between children with «growth leap» and without it. At 3-month age the level of growth hormone is reduced in comparison with the level of umbilical cord blood. Conclusion. Most children born with IUGR (over 87%) demonstrate accelerated growth rates after birth, the maximum increase in growth rates occur during the first 3 months of life. All groups examined at birth and at 3 months showed a large data spread of IGF-1 and GH.

Effects of exercise and poor indoor air quality on learning, memory and blood IGF-1 in adolescent mice

It is known that regular aerobic exercise enhances cognitive functions and increases blood insulin-like growth factor 1 (IGF-1) levels. People living in urban areas spend most of their time indoors and indoor air quality can affect health. We investigated the effects of aerobic exercise in poor and good air quality environments on hippocampus and prefrontal cortex (PFC) neurons, anxiety, and spatial learning and memory in adolescent mice. Poor air quality impaired spatial learning and memory; exercise did not affect learning or memory impairment. Exercise in a good air quality environment improved spatial learning and memory. Poor air quality increased apoptosis in the hippocampus and PFC. Both exercised and sedentary groups living in a poor air quality environment had lower serum IGF-1 levels than those living in a good air quality environment. Living in a poor air quality environment has negative effects on the hippocampus, PFC and blood IGF-1 levels in adolescent mice, but exercise did not alter the negative effects of poor air quality.

Effects of administration of subtoxic doses of acetaminophen on liver and blood levels of insulin-like growth factor-1 in rats

Acetaminophen (APAP) is widely used in the treatment of pain. Toxic doses of APAP cause acute liver failure, but therapeutic doses are believed to be safe. The purpose of this study is to investigate the effects of administration of subtoxic doses of APAP on liver and blood levels of insulin-like growth factor-1 (IGF-1) in rats. Low dose (100 mg/kg) and high dose (250 mg/kg) of APAP were intraperitoneally injected into Wistar albino rats. Following administration of therapeutic doses of APAP, there were no significant changes in serum transaminases and liver glutathione levels. Both doses of APAP induced a decrease in liver and blood levels of IGF-1 when compared with the controls. There was no significant difference in liver IGF-1 levels between the high-dose and low-dose APAP groups; however, there was a significant difference in blood IGF-1 levels between both the groups. The histological examination showed that low dose of APAP induced mild degree of structural change, while high dose of APAP induced severe structural damage. In conclusion, these results suggest that blood IGF-1 levels may have a value in predicting hepatic damage resulting from therapeutic doses of APAP.

Anxiety correlates to decreased blood and prefrontal cortex IGF-1 levels in streptozotocin induced diabetes

It is well known that diabetes mellitus may cause neuropsychiatric disorders such as anxiety disorders. Diabetes may also cause reduced IGF-1 (insulin like growth factor-1) levels in brain and blood. The purpose of the present study was to investigate the relationship between diabetes induced anxiety and IGF-1 levels in diabetic rats. The anxiety levels of rats were assessed 2 weeks after intraperitoneal injection of streptozotocin. Diabetic rats had higher levels of anxiety, as they spent more time in closed branches in elevated-plus-maze-test and less time in the center cells of open-field-arena. Prefrontal cortex (PFC) IGF-1 levels and neuron numbers were decreased and apoptosis was increased in diabetic rats. Blood IGF-1 levels decreased in a time dependent fashion following streptozotocin injection while blood corticosterone levels increased. They had higher malondialdehyde levels and lower superoxide dismutase enzyme activity. Oxidative stress may negatively affect blood and PFC tissue IGF-1 levels. Reduction in IGF-1 may cause PFC damage, which may eventually trigger anxiety in diabetic rats. Therapeutic strategies that increase blood and brain tissue IGF-1 levels may be promising to prevent psychiatric sequelae of diabetes mellitus.

IGF-1 protects against diabetic features in an in vivo model of Huntington's disease

Huntington's disease (HD) is the most prevalent polyglutamine expansion disorder. HD is caused by an expansion of CAG triplet in the huntingtin (HTT) gene, associated with striatal and cortical neuronal loss. Central and peripheral metabolic abnormalities and altered insulin-like growth factor-1 (IGF-1) levels have been described in HD. Thus, we hypothesized that restoration of IGF-1-mediated signaling pathways could rescue R6/2 mice from metabolic stress and behavioral changes induced by polyglutamine expansion. We analyzed the in vivo effect of continuous peripheral IGF-1 administration on diabetic parameters, body weight and motor behavior in the hemizygous R6/2 mouse model of HD. We used 9 week-old and age-matched wild-type mice, subjected to continuously infused recombinant IGF-I or vehicle, for 14 days. IGF-1 treatment prevented the age-related decrease in body weight in R6/2 mice. Although blood glucose levels were higher in R6/2 mice, they did not reach a diabetic state. Even though, IGF-1 ameliorated poor glycemic control in HD mice. This seemed to be associated with a decrease in blood insulin levels in R6/2 mice, which was increased following IGF-1 infusion. Similarly, blood IGF-1 levels decreased during aging in both wild-type and R6/2 mice, being significantly improved upon its continuous infusion. Although no significant differences were found in motor function in R6/2-treated mice, IGF-1 treatment highly improved paw clasping scores. In summary, these results suggest that IGF-1 has a protective role against HD-associated impaired glucose tolerance, by enhancing blood insulin levels.

Quantification of insulin-like growth factor-1 (IGF-1) mRNA: modulation of growth intensity by feeding results in inter- and intra-tissue-specific differences of IGF-1 mRNA expression in steers.

The effect of constant and compensating body growth velocities on IGF-1 mRNA expression was studied in various tissues of growing steers. Twenty-six steers were allocated to three groups in which the average daily gains were kept either constantly high on intensive feeding, low on pasture feeding or were accelerated to compensatory growth after feed restriction. All animals were slaughtered at 570+/-2.6 kg and samples were collected from liver, heart, kidney and from 4 different muscles (m. splenius, m. soleus, m. cutaneus truncii and m. semispinalis capitis), which were selected in order to include maximal differences in fibre composition as well as in growth impetus. IGF-1 mRNA was quantified by a validated internally standardised RT-PCR method. The amount of RNA extracted from the various tissues investigated was constant within each type of tissue and showed no differences between treatment groups. As indicated by a constant ratio between the amount of RNA extracted and the DNA concentrations, there was no effect of the feeding on total transcriptional activity. The order of IGF-1 mRNA abundance per g tissue was liver > > kidney > heart > skeletal muscle. The different feeding regimen resulted in significant differences of IGF-1 mRNA expression rates in all organs showing different patterns between organs. IGF-1 mRNA concentrations showed muscle specific differences and also divergent reactions in response to the differing growth rates. These results support that the liver is the main IGF-1 producing tissue; above that they indicate that skeletal muscle, in particular when taking its absolute mass into account, might considerably contribute to the IGF-1 levels in blood. Our findings demonstrate that IGF-1 mRNA expression is regulated tissue specifically not only between different organs but also within musculature.

Slow Postoperative Decline in Blood Concentration of Insulin-like Growth Factor-1 (IGF-1) in Acromegalic Patients

Recent criteria for cure of acromegaly require normalization of the insulin-like growth factor (IGF-1) level. A retrospective study was conducted to assess postoperative sequential changes in the blood IGF-1 level and to determine the appropriate timing for endocrinologic assessment of the effect of surgery. Blood IGF-1 levels were measured at least 3 times (4.9 +/- 2.0, mean +/- SD) during the first postoperative year in 36 acromegalic patients whose glucose tolerance test results, obtained 3 months after surgery, showed the growth hormone level to be suppressed to under 1 ng/mL. Postoperative IGF-1 parameters, i.e. the actual IGF level and %IGF-1 compared to the nadir during the first postoperative year, rapidly decreased during the first 2 postoperative weeks and then slowly declined over the next 2 weeks. They reached a plateau (stable nadir) during the 2nd postoperative month. Assessment of the postoperative endocrinologic status should be delayed at least one month after surgery in acromegalic patients.