Associations between Bronchopulmonary Dysplasia, Insulin-like Growth Factor I and Nutrition

Insulin-like growth factor I (IGF-I) has been suggested as an important factor in the pathogenesis of bronchopulmonary dysplasia (BPD). In turn, nutrition has been associated with IGF-I levels and could be of importance in the pathogenesis of BPD. This study aimed to explore the association between nutrition, the IGF-I axis and the occurrence of BPD. Eighty-six preterm infants (44 male, mean gestational age: 29.0 weeks (standard deviation: 1.7 weeks)) were enrolled in an observational study. Serum IGF-I (µg/L) and insulin-like growth factor binding protein 3 (IGFBP-3; mg/L) were measured at birth and at 2, 4 and 6 weeks postnatal age. BPD was diagnosed at 36 weeks postmenstrual age. Twenty-nine infants were diagnosed with BPD. For every µg/L per week increase in IGF-I, the odds of BPD decreased (0.68, 95% CI 0.48-0.96, corrected for gestational age). The change in IGF-I in µg/L/week, gestational age in weeks and a week of predominant donor human milk feeding were associated with the occurrence of BPD in the multivariable analysis (respectively, OR 0.63 (0.43-0.92), OR 0.44 (0.26-0.76) and 7.6 (1.2-50.4)). IGFBP-3 was not associated with the occurrence of BPD in the multivariable analysis. In conclusion, a slow increase in IGF-I levels and a lower gestational age increase the odds of BPD. Donor human milk might increase the odds of BPD and should be further explored.

U-Shaped relationship of insulin-like growth factor I and incidence of nonalcoholic fatty liver in patients with pituitary neuroendocrine tumors: a cohort study

Context

Although the role of insulin-like growth factor I (IGF-1) in nonalcoholic fatty liver disease (NAFLD) has garnered attention in recent years, few studies have examined both reduced and elevated levels of IGF-1.

Objective

The aim of this study was to examine the potential relationship between IGF-1 levels and the risk of new-onset NAFLD in patients with pituitary neuroendocrine tumors (PitNET).

Methods

We employed multivariable Cox regression models and two-piecewise regression models to assess the association between IGF-1 and new-onset NAFLD. Hazard ratios (HRs) and their corresponding 95% confidence intervals (CIs) were calculated to quantify this association. Furthermore, a dose-response correlation between lgIGF-1 and the development of NAFLD was plotted. Additionally, we also performed subgroup analysis and a series sensitivity analysis.

Results

A total of 3,291 PitNET patients were enrolled in the present study, and the median duration of follow-up was 65 months. Patients with either reduced or elevated levels of IGF-1 at baseline were found to be at a higher risk of NAFLD compared to PitNET patients with normal IGF-1(log-rank test, P < 0.001). In the adjusted Cox regression analysis model (model IV), compared with participants with normal IGF-1, the HRs of those with elevated and reduced IGF-1 were 2.33 (95% CI 1.75, 3.11) and 2.2 (95% CI 1.78, 2.7). Furthermore, in non-adjusted or adjusted models, our study revealed a U-shaped relationship between lgIGF-1 and the risk of NAFLD. Moreover, the results from subgroup and sensitivity analyses were consistent with the main results.

Conclusions

There was a U-shaped trend between IGF-1 and new-onset NAFLD in patients with PitNET. Further evaluation of our discoveries is warranted.

The Role of Insulin-like Growth Factor I in Mechanisms of Resilience and Vulnerability to Sporadic Alzheimer's Disease

Despite decades of intense research, disease-modifying therapeutic approaches for Alzheimer's disease (AD) are still very much needed. Apart from the extensively analyzed tau and amyloid pathological cascades, two promising avenues of research that may eventually identify new druggable targets for AD are based on a better understanding of the mechanisms of resilience and vulnerability to this condition. We argue that insulin-like growth factor I (IGF-I) activity in the brain provides a common substrate for the mechanisms of resilience and vulnerability to AD. We postulate that preserved brain IGF-I activity contributes to resilience to AD pathology as this growth factor intervenes in all the major pathological cascades considered to be involved in AD, including metabolic impairment, altered proteostasis, and inflammation, to name the three that are considered to be the most important ones. Conversely, disturbed IGF-I activity is found in many AD risk factors, such as old age, type 2 diabetes, imbalanced diet, sedentary life, sociality, stroke, stress, and low education, whereas the Apolipoprotein (Apo) E4 genotype and traumatic brain injury may also be influenced by brain IGF-I activity. Accordingly, IGF-I activity should be taken into consideration when analyzing these processes, while its preservation will predictably help prevent the progress of AD pathology. Thus, we need to define IGF-I activity in all these conditions and develop a means to preserve it. However, defining brain IGF-I activity cannot be solely based on humoral or tissue levels of this neurotrophic factor, and new functionally based assessments need to be developed.

Insulin-like growth factor-1 improves in vitro meiotic resumption of dromedary camel (Camelus Dromedarius) oocytes

Despite relatively high maturation rate of in vitro matured oocytes in the dromedary camel, however, blastocyst production is very low after in vitro fertilization (IVF). Herein, the influences of oocyte collection method (follicular aspiration vs slicing; Experiment I), the addition of Insulin-like growth factor I (IGF-I) to the maturation medium (Experiment II) on in vitro maturation (IVM) of oocyte were investigated. Although the nuclear maturation did not differ regardless of collecting method, follicular aspiration led to lower degeneration rates than those in controls (P < 0.05). The percentages of oocytes at MII were greater in the presence of IGF-1 than in its absence (71.9% vs 48.4%, respectively, P<0.05). Additionally, the percentages of degenerated oocytes were higher in the control group compared to oocytes cultured in the presence of IGF-I (23.6% vs 10.4%, respectively, P<0.05). IGF-I treatment improved the quality of MII matured oocytes as evidenced by the decrease of cathepsin B (CTSB) activity, a marker of poor quality oocytes, when compared to control ones (P < 0.05). In conclusion, follicular aspiration decreased the degeneration rate; however, it had no effect on completion of maturation. IGF-I enhanced the IVM of oocyte and decreased degeneration rate.

Corrigendum: Guidance for the treatment of adult growth hormone deficiency with somapacitan, a long-acting growth hormone preparation

[This corrects the article DOI: 10.3389/fendo.2022.1040046.].

Beyond the method change in clinical practice: evaluation of insulin-like growth factor I assay

Objectives

Insulin-like growth factor I (IGF-I) is the preferred biomarker for diagnosing and monitoring growth-related disorders but its serum quantification presents several difficulties since different IGF-I assays still leads to different IGF-I concentrations, especially when results are either above or below the normal range.

Methods

We conducted a prospective study between November and December 2020 at a tertiary University Hospital with 212 serum samples to determine the analytical performance of the IGF-I assay on the Cobas e411 (Roche Diagnostics) and compare it with that of the Immulite 2000XPi (Siemens).

Results

In this work, we report for the first time the existence of discrepancies between IGF-I levels measured by Immulite 2000XPi and Cobas e411. Deming regression model provided a slope of 1.570 (95% CI: 1.395-1.745) and an intercept of -58.591 (95% CI: -89.151 to -28.030), with R²=0.967 and average bias of +53.061 with overestimation of IGF-I. It was found that Cobas e411 provides abnormally high IGF-I concentrations, but further studies are required to elucidate the cause of the discrepancies.

Conclusions

Our data can alert clinicians and laboratory professionals of this situation and avoid misinterpretation of increased IGF-I levels as a therapeutic failure rather than as a problem associated with this method change.

How insulin-like growth factor I binds to a hybrid insulin receptor type 1 insulin-like growth factor receptor

Monomers of the insulin receptor and type 1 insulin-like growth factor receptor (IGF-1R) can combine stochastically to form heterodimeric hybrid receptors. These hybrid receptors display ligand binding and signaling properties that differ from those of the homodimeric receptors. Here, we describe the cryoelectron microscopy structure of such a hybrid receptor in complex with insulin-like growth factor I (IGF-I). The structure (ca. 3.7 Å resolution) displays a single IGF-I ligand, bound in a similar fashion to that seen for IGFs in complex with IGF-1R. The IGF-I ligand engages the first leucine-rich-repeat domain and cysteine-rich region of the IGF-1R monomer (rather than those of the insulin receptor monomer), consistent with the determinants for IGF binding residing in the IGF-1R cysteine-rich region. The structure broadens our understanding of this receptor family and assists in delineating the key structural motifs involved in binding their respective ligands.

•

A cryo-EM structure of IGF-I bound to a hybrid IR/IGF-1R ectodomain is presented

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The structure is congruent to those of the single-liganded homodimeric receptors

Characteristics and treatment outcomes of micromegaly - acromegaly with apparently normal basal GH: A retrospective study and literature review

Objective. Micromegaly describes a subgroup of patients with clinically evident acromegaly and elevated insulin-like growth factor I (IGF-I) with apparently normal basal growth hormone (bGH) and often a glucose-suppressed growth hormone (GH) of <1 ng/mL at diagnosis. It is controversial whether this condition is a distinct clinical entity or a classic acromegaly in early stages. The aim of the present article was to characterize the prevalence, clinical and biochemical characteristics, and therapeutic outcomes of micromegaly. Methods. A retrospective study of patients with an acromegaly followed ≥1 year at a tertiary center from 1995 to 2019. Patients without IGF-I or GH measurements at diagnosis were excluded. At diagnosis, bGH was considered normal if <2 ng/mL. Results. From 74 patients with acromegaly, 6 (8.1%) had normal bGH levels. There was no difference in the gender distribution, median diagnostic delay, and follow-up time between patients with normal bGH and elevated bGH. Patients with normal bGH were significantly older at time of the first acromegalic manifestation and diagnosis they had significantly lower nadir post-glucose GH and IGF-I levels, and tended to have a higher prevalence of obesity than patients with the elevated bGH. The frequency of acromegalic symptoms, signs, and other comorbidities than obesity was similar between groups. Five patients (83.3%) with normal bGH presented microadenomas. Post-operative remission and outcomes at last visit were comparable between patients with or without normal bGH. Conclusions. Normal bGH acromegaly is relatively uncommon in our patients. These patients showed differentiating characteristics from the classical acromegaly with elevated bGH. Further studies are needed to extend the knowledge about its clinical behavior, therapeutic outcomes, morbidity, and mortality.

Guidance for the treatment of adult growth hormone deficiency with somapacitan, a long-acting growth hormone preparation

Adult growth hormone deficiency (AGHD) is a rare endocrine disorder characterized by an abnormal body composition, metabolic abnormalities associated with increased cardiovascular diseases, bone loss, and impaired quality of life. Daily subcutaneous injections with recombinant growth hormone (GH) can alleviate the abnormalities associated with AGHD. Several long-acting GH (LAGH) preparations are currently in development that aim to reduce treatment burden for patients receiving daily GH injections. Somapacitan (Sogroya^®; Novo Nordisk, Denmark) is the first LAGH preparation that has been approved for treatment of AGHD in the United States, Europe, and Japan. The recent approval of somapacitan and anticipated approval of other LAGH molecules presents new questions for physicians planning to treat AGHD with LAGH in the future. Differences in the technologies used to prolong the half-life of recombinant GH are expected to result in variations in pharmacokinetic and pharmacodynamic profiles between preparations. Therefore, it is essential that physicians understand and consider such variations when treating patients with these novel GH replacement therapies. Here, we present a set of treatment recommendations that have been created to guide physicians initiating therapy with somapacitan in patients with AGHD who are eligible for GH replacement. Furthermore, we will review the published data that underlie these recommendations to explain the rationale for the treatment and monitoring advice provided.

Genetically predicted insulin-like growth factor-I in relation to muscle mass and strength

OBJECTIVE

Insulin-like growth factor I (IGF-I) has been associated with muscle status in animal- and population-based studies. We conducted a Mendelian randomisation study to assess the causality of the associations of IGF-I with muscle strength and mass.

DESIGN AND PATIENTS

Genetic variants associated with serum IGF-I at genome-wide significance in the UK Biobank study (358,072 individuals of European descent) were selected as instrumental variables. Summary-level data on the associations of those variants with muscle weakness (low-grip strength) and muscle mass (fat-free body mass) were available from a meta-analysis of 22 genome-wide association studies including 46,596 cases and 209,927 noncases and genome-wide association analysis in 155,961 individuals from the UK Biobank study, respectively. The univariable and multivariable inverse-variance weighted methods were used.

RESULTS

Higher genetically predicted IGF-I levels were associated with a reduced risk of muscle weakness and increased muscle mass. For one standard deviation increase in genetically predicted IGF-I levels, the odds ratio was 0.92 (95% confidence interval [CI], 0.88, 0.97; p = .001) for muscle weakness and the change was 0.53 (95% CI: 0.28, 0.79; p < .001) kg for muscle mass. In the multivariable model with adjustment for genetically predicted height, the associations were attenuated but persisted for both muscle weakness (odds ratio: 0.95, 95% CI: 0.91, 0.99; p = .015) and muscle mass (change: 0.25, 95% CI: 0.10, 0.40; p = .001).

CONCLUSION

This study suggests that high IGF-I levels may decrease the risk of muscle weakness and loss.

Disease-inclusive exercise classes improve physical fitness and reduce depressive symptoms in individuals with and without Parkinson's disease-A feasibility study

BACKGROUND AND PURPOSE

Exercise is an adjunctive treatment in the management of Parkinson's disease (PD), but barriers such as health status, fear of overexertion, and lack of transportation to the location prevent regular exercise participation. Disease-inclusive exercise classes may offer an opportunity to make exercise more accessible for older adults with and without diseases. However, the efficacy of such heterogenous exercise classes is still widely unknown. Therefore, it was the aim of this study to analyze the feasibility of disease-inclusive exercise classes in older adults with and without PD.

METHODS

Twenty-one older adults (healthy older adults (HOA): n = 13; PD: n = 8) completed an 8-week multimodal exercise intervention in supervised group sessions. Exercise classes lasted 60 min with the goal of two participations a week. We assessed physical fitness (timed up and go test [TUG], 6-minute walking test [6MWT], single leg stance), depressive symptoms and cognitive functions, and we determined growth factors (BDNF & IGF-1) before and after the intervention to determine the effects and by that, the feasibility of a disease-inclusive exercise program. Repeated measures ANOVA were used to establish changes.

RESULTS

TUG and 6MWT improved significantly after the training in both HOA (p = .008; p < .001) and individuals with PD (p = .024; p < .001). Furthermore, individuals with PD increased single leg stance left (p = .003). HOA (p = .003) and individuals with PD (p = .001) decreased their depressive symptoms between pre- and post-test significantly. Whereas growth factors tended to improve, no differences in cognitive functions were revealed.

CONCLUSION

Disease-inclusive multicomponent exercise improved physical functions and reduced depressive symptoms independent of health status. This should encourage exercise providers, researchers, and clinicians to further investigate disease-inclusive exercise, because they may have an important social impact and represent a more inclusive society.

Mechanistic Target of Rapamycin Complex 1 Signaling Links Hypoxia to Increased IGFBP-1 Phosphorylation in Primary Human Decidualized Endometrial Stromal Cells

Insulin-like growth factor-1 (IGF-1) bioavailability in pregnancy is governed by IGF binding protein (IGFBP-1) and its phosphorylation, which enhances the affinity of IGFBP-1 for the growth factor. The decidua is the predominant source of maternal IGFBP-1; however, the mechanisms regulating decidual IGFBP-1 secretion/phosphorylation are poorly understood. Using decidualized primary human endometrial stromal cells (HESCs) from first-trimester placenta, we tested the hypothesis that mTORC1 signaling mechanistically links hypoxia to decidual IGFBP-1 secretion/phosphorylation. Hypoxia inhibited mechanistic target of rapamycin (mTORC1) (p-P70-S6K/Thr389, -47%, p = 0.038; p-4E-BP1/Thr70, -55%, p = 0.012) and increased IGFBP-1 (total, +35%, p = 0.005; phosphorylated, Ser101/+82%, p = 0.018; Ser119/+88%, p = 0.039; Ser 169/+157%, p = 0.019). Targeted parallel reaction monitoring-mass spectrometry (PRM-MS) additionally demonstrated markedly increased dual IGFBP-1 phosphorylation (pSer98+Ser101; pSer169+Ser174) in hypoxia. IGFBP-1 hyperphosphorylation inhibited IGF-1 receptor autophosphorylation/ Tyr1135 (-29%, p = 0.002). Furthermore, silencing of tuberous sclerosis complex 2 (TSC2) activated mTORC1 (p-P70-S6K/Thr389, +68%, p = 0.038; p-4E-BP1/Thr70, +30%, p = 0.002) and reduced total/site-specific IGFBP-1 phosphorylation. Importantly, TSC2 siRNA prevented inhibition of mTORC1 and the increase in secretion/site-specific IGFBP-1 phosphorylation in hypoxia. PRM-MS indicated concomitant changes in protein kinase autophosphorylation (CK2/Tyr182; PKC/Thr497; PKC/Ser657). Overall, mTORC1 signaling mechanistically links hypoxia to IGFBP-1 secretion/phosphorylation in primary HESC, implicating decidual mTORC1 inhibition as a novel mechanism linking uteroplacental hypoxia to fetal growth restriction.

Soluble Alpha Klotho in Acromegaly: Comparison With Traditional Markers of Disease Activity

CONTEXT

Soluble alpha klotho (sαKL) has been linked to growth hormone (GH) action, but systematic evaluation and comparisons with traditional biomarkers in acromegaly are lacking.

OBJECTIVE

To evaluate the potential of sαKL to aid classification of disease activity.

METHODS

This retrospective study at 2 academic centers included acromegaly patients before surgery (A, n = 29); after surgery (controlled, discordant, or uncontrolled) without (B1, B2, B3, n = 28, 11, 8); or with somatostatin analogue treatment (C1, C2, C3, n = 17, 11, 5); nonfunctioning pituitary adenomas (n = 20); and healthy controls (n = 31). sαKL was measured by immunoassay and compared with traditional biomarkers (random and nadir GH, insulin-like growth factor I [IGF-I], IGF binding protein 3). Associations with disease activity were assessed.

RESULTS

sαKL was correlated to traditional biomarkers, particularly IGF-I (rs=0.80, P <0.0001). High concentrations before treatment (A, median, interquartile range: 4.04 × upper limit of normal [2.26-8.08]) dropped to normal after treatment in controlled and in most discordant patients. A cutoff of 1548 pg/mL for sαKL discriminated controlled (B1, C1) and uncontrolled (B3, C3) patients with 97.8% (88.4%-99.9%) sensitivity and 100% (77.1%-100%) specificity. sαKL was below the cutoff in 84% of the discordant subjects. In the remaining 16%, elevated sαKL and IGF-I persisted, despite normal random GH. Sex, age, body mass index, and markers of bone and calcium metabolism did not significantly affect sαKL concentrations.

CONCLUSION

Our data support sαKL as a biomarker to assess disease activity in acromegaly. sαKL exhibits close association with GH secretory status, large dynamic range, and robustness toward biological confounders. Its measurement could be helpful particularly when GH and IGF-I provide discrepant information.

Interactions of amino acids and hormones regulate the balance between growth and milk protein synthesis in lactating rats fed diets differing in protein content

Insulin-like growth factor-I (IGF-I), growth hormone (GH), and prolactin (PRL) play important roles in milk protein synthesis, and their plasma concentrations were reported to be affected by dietary protein intake. To investigate the relationship between circulating amino acid (AA) and concentrations of these hormones, 18 Wistar rats aged 14 wk were assigned to a low (LP; 9% protein), standard (SP; 21% protein), or high-protein (HP; 35% protein) diet from parturition through day 15 of lactation. Plasma, liver, pituitary gland, skeletal muscle, and mammary gland samples were collected at the end of treatment. Circulating and hepatic IGF-I concentrations increased linearly with elevated dietary protein concentrations (P < 0.0001). Rats receiving the HP diet had higher circulating GH (P < 0.01) and pituitary PRL concentrations (P < 0.0001) but lower pituitary GH concentration (P < 0.0001) relative to those in rats receiving the LP and SP diets. Pearson correlation test performed on composed data across treatments showed that several circulating AAs were correlated with circulating and tissue concentrations of IGF-I, GH, and PRL. Multiple linear regression analyses identified Leu, Gln, Ala, Gly, and Arg as the main AAs associated with hormone responses (R2 = 0.37 ~ 0.80; P < 0.05). Rats fed the LP and HP diets had greater Igf1 and Ghr gene expression in skeletal muscle than those fed the SP diets (P < 0.01). However, LP treatment decreased Prlr mRNA abundance in mammary glands as compared with the SP and HP treatments (P < 0.05). The HP diets increased AA transporter expression (P < 0.01) but decreased mammalian target of rapamycin (P < 0.05) and 70 kDa ribosomal protein S6 kinase 1 (P < 0.01) phosphorylation in mammary glands as compared with the LP and SP diets. The results of the present study suggested that several circulating AAs mediated the effects of dietary protein supply on concentrations of IGF-I, GH, and PRL, which in turn altered the metabolism status in peripheral tissues including the lactating mammary glands.

Insulin-like growth factor-1 improves postoperative cognitive dysfunction following splenectomy in aged rats

Postoperative cognitive dysfunction (POCD) is a serious complication following anesthesia and operations in aged patients undergoing surgical intervention. It is characterized by temporary or permanent cognitive decline, memory impairment and deterioration in language comprehension and social adaption ability. Therefore, the development of POCD prevention and treatment tools has become an area of interest. The current study assessed the therapeutic effects of insulin-like growth factor-1 (IGF-1) on POCD in aged rats and explored the underlying mechanisms. Model rats underwent splenectomy under 1.5-2% isoflurane and mechanical ventilation. IGF-1 (50 µg/kg) was diluted in normal saline and administered by abdominal hypodermic injection daily from the operation to day 7 post-operation. Following splenectomy, the animals showed marked cognitive impairment as determined by the Morris water maze test. Hippocampal protein levels of amyloid precursor protein (APP), β-site APP-cleaving enzyme-1 (BACE-1), amyloid-β (Aβ), capase3, Bax and Bcl-2 were assessed by immunoblotting. Neuronal apoptosis in the hippocampus was analyzed using a TUNEL assay. The results demonstrated that the levels of APP, BACE-1, Aβ, caspase3 and Bax were increased following splenectomy, while the levels of Bcl2 were reduced at days 1, 3 and 7 post-operation in aged rats. However, IGF-1 downregulated APP, BACE-1, Aβ, capase3 and Bax, and upregulated Bcl2 at these time points following splenectomy. TUNEL staining revealed that administration of IGF-1 significantly reduced neuronal apoptosis in the hippocampal CA1 region following splenectomy. These results indicated that IGF-1 decreased Aβ-protein production and inhibited neuronal apoptosis in the hippocampus following splenectomy, subsequently alleviating POCD.

Frequency of oligosymptomatic gastrointestinal tract diseases and its relation to insulin-like growth factor I in idiopathic (non-GH-deficient) short stature children

INTRODUCTION

There is a discussion about growth hormone therapy in idiopathic short stature (ISS) children. To diagnose ISS, it is necessary to exclude other diseases; gastrointestinal tract diseases (GIDs) are among them. However, GID symptoms may be scarce. The aim of the study was to evaluate the frequency of unexpected oligosymptomatic GIDs in ISS and assess their influence on auxological parameters and insulin-like growth factor I (IGF-I) concentration.

MATERIAL AND METHODS

The analysis included 101 children with ISS and 95 controls. All patients were tested for celiac disease (CD), inflammatory bowel disease (IBD), lactose malabsorption (LM), cystic fibrosis (CF), Helicobacter pylori (HP) and Ascaris sp. (Asc) infections, as well as Candida albicans (Calb) colonization, by applying simple blood and stool tests and gastrofiberoscopy.

RESULTS

In 75.2% of short children, one or more than one GIDs listed above were diagnosed, with the highest frequency of: Calb (46.5%), LM (33.7%), HP (24.7%) and/or Asc (21.8%). The incidence of GIDs was significantly higher than in the control group. The GID frequency increases with the age of children. In most ISS children, the IGF-I SDS was below -1.0 and it was the lowest in children with HP (p < 0.05).

CONCLUSIONS

High frequency of unexpected oligosymptomatic GIDs in children diagnosed with ISS indicates the need to search for gastrointestinal (GI) causes in each case of short stature in children. The pathomechanisms responsible for short stature in these cases may vary, although it seems that reduced production of IGF-I plays an important role.

Association between Serum Insulin-Like Growth Factor-1 and Neurological Severity in Acute Ischemic Stroke

Background and Purpose

Serum insulin-like growth factor-1 (IGF-1) is known to have a neuroprotective effect. This study aimed to determine the effects of serum IGF-1 on the severity and clinical outcome of acute ischemic stroke (AIS).

Methods

This study included 446 patients with AIS who were admitted to Hallym University Sacred Heart Hospital within 7 days of stroke onset from February 2014 to June 2017. Serum IGF-1 levels were measured within 24 hours of admission. Stroke severity was measured using the National Institutes of Health Stroke Scale (NIHSS) score at admission, and the functional outcome at 3 months after symptom onset was assessed using the modified Rankin Scale score. The effects of serum IGF-1 levels on stroke severity and 3-month functional outcomes were analyzed using multivariate logistic regression analysis.

Results

This study evaluated 379 patients with AIS (age 67.2±12.6 years, mean±standard deviation; 59.9% males) after excluding 67 patients who had a history of previous stroke (n=25) or were lost to follow-up at 3 months (n=42). After adjusting for clinically relevant covariates, a higher serum IGF-1 level was associated with a lower NIHSS score at admission (adjusted odds ratio=0.44, 95% confidence interval=0.24–0.80, p=0.01), while there was no significant association at 3 months.

Conclusions

This study showed that a higher serum IGF-1 level is associated with a lower NIHSS score at admission but not at 3 months. Further studies are required to clarify the usefulness of the serum IGF-1 level as a prognostic marker for ischemic stroke.

Regenerative Therapies to Restore Interneuron Disturbances in Experimental Models of Encephalopathy of Prematurity

Encephalopathy of Prematurity (EoP) is a major cause of morbidity in (extreme) preterm neonates. Though the majority of EoP research has focused on failure of oligodendrocyte maturation as an underlying pathophysiological mechanism, recent pioneer work has identified developmental disturbances in inhibitory interneurons to contribute to EoP. Here we investigated interneuron abnormalities in two experimental models of EoP and explored the potential of two promising treatment strategies, namely intranasal mesenchymal stem cells (MSCs) or insulin-like growth factor I (IGF1), to restore interneuron development. In rats, fetal inflammation and postnatal hypoxia led to a transient increase in total cortical interneuron numbers, with a layer-specific deficit in parvalbumin (PV)+ interneurons. Additionally, a transient excess of total cortical cell density was observed, including excitatory neuron numbers. In the hippocampal cornu ammonis (CA) 1 region, long-term deficits in total interneuron numbers and PV+ subtype were observed. In mice subjected to postnatal hypoxia/ischemia and systemic inflammation, total numbers of cortical interneurons remained unaffected; however, subtype analysis revealed a global, transient reduction in PV+ cells and a long-lasting layer-specific increase in vasoactive intestinal polypeptide (VIP)+ cells. In the dentate gyrus, a long-lasting deficit of somatostatin (SST)+ cells was observed. Both intranasal MSC and IGF1 therapy restored the majority of interneuron abnormalities in EoP mice. In line with the histological findings, EoP mice displayed impaired social behavior, which was partly restored by the therapies. In conclusion, induction of experimental EoP is associated with model-specific disturbances in interneuron development. In addition, intranasal MSCs and IGF1 are promising therapeutic strategies to aid interneuron development after EoP.

A Mediterranean Dietary Intervention in Female Carriers of BRCA Mutations: Results from an Italian Prospective Randomized Controlled Trial

Background: Women carriers of BRCA1/2 mutations face a high lifetime risk (penetrance) of developing breast and/or ovarian cancer. Insulin-like growth factor I (IGF-I), body weight and markers of insulin resistance affect BRCA penetrance. We conducted a multicenter prospective two-armed (1:1) randomized controlled trial (NCT03066856) to investigate whether a Mediterranean dietary intervention with moderate protein restriction reduces IGF-I and other metabolic modulators of BRCA penetrance. Methods: BRCA carriers, with or without a previous cancer, aged 18-70 years and without metastases were randomly assigned to an active dietary intervention group (IG) or to a control group (CG). The primary endpoint of the intervention was the IGF-I reduction. Results: 416 women (216 in the IG and 200 in the CG) concluded the six-month dietary intervention. The IG showed significantly lowered serum levels of IGF-I (-11.3 ng/mL versus -1.3 ng/mL, p = 0.02), weight (-1.5 Kg versus -0.5 Kg, p < 0.001), waist circumference (-2 cm versus -0.7 cm, p = 0.01), hip circumference (-1.6 cm versus -0.5 cm, p = 0.01), total cholesterol (-10.2 mg/dL versus -3.6 mg/dL, p = 0.04) and triglycerides (-8.7 mg/dL versus + 5.5 mg/dL, p = 0.01) with respect to the CG. Conclusions: A Mediterranean dietary intervention with moderate protein restriction is effective in reducing IGF-I and other potential modulators of BRCA penetrance.

Ocular findings and growth in 5-year-old preterm children born to mothers with preeclampsia

PURPOSE

To evaluate growth, blood pressure and ophthalmological status in preschool children born preterm to mothers with preeclampsia.

METHODS

In a prospective cohort study, 78 children (34 girls) born preterm without retinopathy of prematurity were examined regarding length/height, weight, head circumference and insulin-like growth factor I (IGF-I) at birth and at 5 years of age. At 5 years, IGF-binding protein 3 and blood pressure were also measured. A detailed ophthalmological examination including ocular dimensions, fundus morphology, visual fields, visual evoked potentials and perceptual visual dysfunction was performed. Children born to preeclamptic mothers (n = 24) were compared to children with non-preeclamptic mothers (n = 54).

RESULTS

Children exposed to preeclampsia had lower weight (p = 0.0002, mean difference -1.46, 95% CI -2.09; -0.83), length (p = 0.013, -1.10, 95% CI -1.92; -0.23) and IGF-I levels (p = 0.0002, -26.0, 95% CI -36.0; -16.1) at birth compared to non-exposed children. At 5 years of age, the preeclamptic group had larger optic cup areas (p = 0.0006, 0.32, 95% CI 0.15; 0.46, in right eye, p = 0.049, 0.18, 95% CI 0.001; 0.35, in left eye). There was no significant difference between the groups regarding other ophthalmological findings or blood pressure. Children with reduced eye motility had lower neonatal IGF-I levels (p = 0.033, 15.5, 95% CI 1.1; 30.3).

CONCLUSION

Preeclampsia was shown to affect growth and IGF-I levels, confirming previous studies. Children exposed to preeclampsia were shown to have larger optic cup areas. Furthermore, lower neonatal IGF-I levels were seen in preterm children with reduced eye motility at 5 years of age.

The Influence of Gestational Diabetes Mellitus upon the Selected Parameters of the Maternal and Fetal System of Insulin-Like Growth Factors (IGF-1, IGF-2, IGFBP1-3)-A Review and a Clinical Study

BACKGROUND

Gestational diabetes mellitus (GDM), defined as impaired glucose tolerance with onset or first recognition in pregnancy, increases the risk of not only maternal but also fetal and neonatal complications. Given the structural similarity of insulin-like growth factors with insulin and participation of components of the insulin-like growth factor system in glucose homeostasis, we hypothesized that the IGF axis is involved in the development of GDM complications or its pathogenesis. The aim of this study was to evaluate the effect of GDM on the selected parameters of the insulin-like growth factors (IGF-1, IGF-2, IGFBP1-3) in the maternal and fetal blood.

METHODS

The clinical material of this case-control study included 109 pregnant women and their offspring. The study group (n = 120) consisted of 60 patients with diagnosed gestational diabetes and their newborn babies. The control group (n = 98) comprised 49 healthy parturients and their offspring. We measured the concentrations of IGF-1, IGF-2, IGFBP-1, IGFBP-2, IGFBP-3, insulin and glucose made by the ELISA method in peripheral blood serum in patients suffering from GDM and pregnant women without GDM, and in the umbilical cord blood of newborn babies born to them.

RESULTS

The analysis of concentrations of IGF-1, -2 and IGFBP-3 in peripheral blood as well as umbilical cord blood did not demonstrate a statistically significant difference between the study group and the control group. Significantly lower concentration of IGFBP-1, IGFBP-2 in peripheral blood and in umbilical cord blood was detected in the study group in comparison to the control group. A statistically positive correlation between the concentration of IGF-1 in umbilical cord serum of newborn babies born to women with gestational diabetes and the length of a baby after its birth was observed.

CONCLUSIONS

Gestational diabetes mellitus does not significantly affect the concentrations of IGF-1, -2, IGFBP-3 in the peripheral blood and umbilical cord blood, but has the greatest influence on maternal and fetal IGFBP-2 concentrations. A positive correlation between the concentration of IGF-1 in umbilical cord blood and the length of a newborn suggests an influence of IGF-1 on the process of fetal development.

Strong Positive Correlation between TSH and Ghrelin in Euthyroid Non-Growth Hormone-Deficient Children with Short Stature

The growth processes in children depend on the proper functioning of some hormones and growth factors. Recently, a positive correlation between ghrelin and TSH (thyroid stimulating hormone) in patients with hyper- and hypothyroidism was proved. Moreover, in hypothyroid rats with high ghrelin concentration, growth hormone (GH) and insulin-like growth factor I (IGF-I) secretion was suppressed. We analyzed these relationships in euthyroid prepubertal children with idiopathic short stature (ISS). The analysis comprised concentration of ghrelin, GH in stimulating tests and during the night, as well as IGF-I, TSH, free thyroxine (FT4) and free triiodothyronine (FT3) in 85 children with ISS (36 girls, 49 boys) aged 9.65 ± 3.02 years (mean ± SD). A strong positive correlation between ghrelin and TSH was confirmed (r = +0.44, p < 0.05). A higher ghrelin but lower nocturnal GH and lower IGF-I were observed in children with higher normal TSH concentration than those in children with lower normal TSH. Interestingly, alterations of TSH level were without any impact on FT4 and FT3 concentrations. Summing up, in ISS prepubertal euthyroid children, ghrelin and TSH secretion are closely related. On the other hand, the higher the TSH, the lower the nocturnal GH and IGF-I levels. The contribution of the above findings in deterioration of growth processes requires further studies.

Comparison of nocturnal and morning ghrelin concentration in children with growth hormone deficiency and with idiopathic short stature

Ghrelin - a growth hormone (GH) secretagogue - presents a circadian rhythm with higher nocturnal than diurnal concentration (similar to GH). However, daily ghrelin production depends on food intake and nutritional state; it is increased in the fasting state and decreased after a meal. Since most past research concerning short stature children has relied on the morning ghrelin concentration for analyses, we decided to assess ghrelin concentration at the 60^th and 90^th minute after falling asleep and in the morning at 06:00 h, shortly after waking up from nighttime sleep (after 12 h of fasting). We compared these ghrelin concentrations to determine differences between nocturnal and morning ghrelin release in short children, both with idiopathic short stature (ISS) and growth hormone deficiency (GHD). We also analyzed the correlation between the nocturnal and morning ghrelin concentrations with nocturnal GH concentrations, measured at the same time points, as well as with maximal GH concentration, achieved by stimulation tests, and with the insulin-like growth factor I (IGF-I). The ghrelin and GH concentration 60^th and 90^th minute after falling asleep, as well as fasting morning ghrelin and IGF-I concentrations, were measured in 19 (n = 10 ISS and n = 9 GHD) prepubertal short children (7 girls and 12 boys), aged 10.36 ± 3.06 y. Differences between the nocturnal and morning ghrelin concentrations were analyzed by the Wilcoxon matched-pairs signed-rank test. Typical regression and correlation analyses were used to assess relationships among parametric data for other analyses. The Wilcoxon test showed ghrelin concentration is significantly higher in the morning than both at the 60^th and 90^th minute after falling asleep time points (in ISS and GHD). A significant correlation was observed: a) positive - between nocturnal ghrelin (both at the 60^th and 90^th minute) and morning ghrelin concentrations; b) positive - between ghrelin at the 60^th minute and nocturnal GH concentrations (both at the 60^th and 90^th minute); c) negative - between ghrelin at the 60^th minute and IGF-I concentrations; and d) negative - between body mass index and ghrelin concentrations at the 60^th and 90^th minute. We conclude: 1) in short children, both with GHD and with ISS, morning ghrelin level reflects its nocturnal concentration; however, it is significantly higher than the nocturnal ones. There is no significant difference between the measurement of ghrelin concentration at night at the 60^th or 90^th minute after falling asleep; 2) morning ghrelin concentration is affected by the hunger and satiety; therefore, it appears that nocturnal measurements better reflect the pool of hormone responsible for stimulation of GH and IGF-I secretion, especially since positive correlation between nocturnal ghrelin and nocturnal GH secretion was noted; 3) it seems that a higher body mass index is an additional independent factor, associated mainly with lower nocturnal (but not morning) ghrelin secretion.

High-intensity interval training-induced hypertrophy in gastrocnemius muscle via improved IGF-I/Akt/FoxO and myostatin/Smad signaling pathways in rats

Objective

It has been shown that high-intensity interval training (HIIT) leads to skeletal muscle hypertrophy; however, its mechanisms of cellular and molecular regulation are still unclear. The purpose of this study was to investigate the effect of HIIT on muscle hypertrophy and major signal transduction pathways.

Design

12 male rats were randomly divided into two groups: control and HIIT. The exercise group performed 30-min HIIT in each session (5 × 4-min intervals running at 85-95% VO2max separated by 2-min active rest at 55-60% VO2max), 3 days/week for 8 weeks. Muscle fiber cross-sectional area (CSA) and the expression of signal transduction pathway proteins were determined in the gastrocnemius muscle.

Results

In the HIIT group, the expression of IGF-I, IGF-IR Akt, p-Akt, AMPKα, p-AMPKα and follistatin increased significantly, whereas a significant decrease was observed in the expression of FoxO1, p-FoxO1, myostatin, ActRIIB, Smad2/3 and p-Smad2/3 (P < 0.05). However, there were no significant differences between the HIIT and control groups in the expression of mTOR, p-mTOR, P70S6K, and p-P70S6K (P > 0.05). In addition, CSA and gastrocnemius muscle weight increased significantly in the HIIT group (P < 0.05).

Conclusions

HIIT induced muscle hypertrophy by improving IGF-I/Akt/FoxO and myostatin/Smad signal transduction pathways.

How IGF-II Binds to the Human Type 1 Insulin-like Growth Factor Receptor

Human type 1 insulin-like growth factor receptor (IGF-1R) signals chiefly in response to the binding of insulin-like growth factor I. Relatively little is known about the role of insulin-like growth factor II signaling via IGF-1R, despite the affinity of insulin-like growth factor II for IGF-1R being within an order of magnitude of that of insulin-like growth factor I. Here, we describe the cryoelectron microscopy structure of insulin-like growth factor II bound to a leucine-zipper-stabilized IGF-1R ectodomain, determined in two conformations to a maximum average resolution of 3.2 Å. The two conformations differ in the relative separation of their respective points of membrane entry, and comparison with the structure of insulin-like growth factor I bound to IGF-1R reveals long-suspected differences in the way in which the critical C domain of the respective growth factors interact with IGF-1R.

Relationship between Levels of Pre-Stroke Physical Activity and Post-Stroke Serum Insulin-Like Growth Factor I

Physical activity (PA) and insulin-like growth factor I (IGF-I) have beneficial effects for patients who have suffered an ischemic stroke (stroke). However, the relationship between the levels of PA and IGF-I after stroke has not been explored in detail. We investigated the pre-stroke PA level in relation to the post-stroke serum IGF-I (s-IGF-I) level, at baseline and at 3 months after the index stroke, and calculated the change that occurred between these two time-points (ΔIGF-I). Patients (N = 380; 63.4% males; mean age, 54.7 years) with data on 1-year leisure-time pre-stroke PA and post-stroke s-IGF-I levels were included from the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). Stroke severity was assessed using the National Institutes of Health Stroke Scale (NIHSS). Pre-stroke, leisure-time PA was self-reported as PA1–4, with PA1 representing sedentary and PA2–4 indicating progressively higher PA levels. Associations between s-IGF-I and PA were evaluated by multiple linear regressions with PA1 as the reference and adjustments being made for sex, age, history of previous stroke or myocardial infarctions, cardiovascular risk factors, and stroke severity. PA correlated with baseline s-IGF-I and ΔIGF-I, but not with the 3-month s-IGF-I. In the linear regressions, there were corresponding associations that remained as a tendency (baseline s-IGF-I, p = 0.06) or as a significant effect (ΔIGF-I, p = 0.03) after all the adjustments. Specifically, for each unit of PA, ΔIGF-I increased by 9.7 (95% CI 1,1−18.4) ng/mL after full adjustment. This supports the notion that pre-stroke PA is independently related to ΔIGF-I.

Feedlot performance and biological responses to coated and non-coated steroidal implants containing trenbolone acetate and estradiol benzoate in finishing beef steers1,2,3

Predominately Angus steers (n = 24; initial BW = 435 ± 28.3 kg) were used to evaluate non-coated (NC) and coated implants (CI) containing equal amounts of trenbolone acetate (TBA; 200 mg) and estradiol benzoate (EB; 28 mg) in finishing steers on sera metabolite responses, gene expression, and immunohistochemical analyses of the Longissimus muscle (LM). Performance data were analyzed as a randomized complete block design, and all other data were analyzed as repeated measures for a completely randomized design. Treatments were no implant (NI), NC (Synovex-PLUS; Zoetis, Parsippany, NJ), and CI (Synovex-One Feedlot) implant. There were 2 pen replicates per treatment (n = 4 steers/pen). LM biopsies, blood, and BW were collected before feeding on days 0, 14, 28, 56, 84, 112, and 133, with final BW being captured on day 140. Genes of interest were determined by RT-qPCR using two housekeeping genes. Sera was analyzed for estradiol-17β (E2),17β-trenbolone (TbOH), insulin-like growth factor 1 (IGF-I), NEFA, and urea-N (SUN). An α of 0.10 determined significance for performance and sera data; α of 0.05 was used for gene and histology data. No performance differences (P ≥ 0.10) were detected. An implant × day interaction (P ≤ 0.10) for E2, IGF-I, and SUN was detected; implants elevated (P ≤ 0.10) E2, 17β-TbOH, and IGF-I; and decreased SUN across day of the study, meaning sera metabolites are not altered with time on feed. An implant × day interaction was detected for myogenic factor 5 (MYF-5) positive cells and proportions of MHCIIX. In LM, CI had greater (P < 0.10) IGF-I in LM over NI. CI increased (P < 0.05) G protein-coupled estrogen receptor 1 (GPER1) expression, as well as, GPER1 semi-quantitative scores over NI and NC. An implant × day interaction (P ≤ 0.05) for estrogen and androgen receptor-positive nuclei was detected; implants had increased (P ≤ 0.05) estrogen and androgen receptor-positive nuclei compared to NI. CIs increase genes associated with muscle tissue growth.

Growth Hormone and Neuronal Hemoglobin in the Brain-Roles in Neuroprotection and Neurodegenerative Diseases

In recent years, evidence for hemoglobin (Hb) synthesis in both animal and human brains has been accumulating. While circulating Hb originating from cerebral hemorrhage or other conditions is toxic, there is also substantial production of neuronal Hb, which is influenced by conditions such as ischemia and regulated by growth hormone (GH), insulin-like growth factor-I (IGF-I), and other growth factors. In this review, we discuss the possible functions of circulating and brain Hb, mainly the neuronal form, with respect to the neuroprotective activities of GH and IGF-I against ischemia and neurodegenerative diseases. The molecular pathways that link Hb to the GH/IGF-I system are also reviewed, although the limited number of reports on this topic suggests a need for further studies. In summary, GH and/or IGF-I appear to be significant determinants of systemic and local brain Hb concentrations through mediating responses to oxygen and metabolic demand, as part of the neuroprotective effects exerted by GH and IGF-I. The nature and quantity of the latter deserve further exploration in specific experiments.

Idiopathic short stature and growth hormone sensitivity in prepubertal children

OBJECTIVE

We compared growth hormone sensitivity to an insulin-like growth factor I (IGF-I) generation test in children with idiopathic short stature (ISS) and of normal stature (NS) across the birthweight range.

METHODS

Forty-six prepubertal children (~7.1 years) born at term were studied: ISS (n = 23; 74% boys) and NS (n = 23; 57% boys). Children underwent a modified IGF-I generation test with recombinant human growth hormone (rhGH; 0.05 mg/kg/d) over four consecutive days. Hormonal concentrations were measured at baseline and day 5.

RESULTS

Children with idiopathic short stature were 1.90 SDS lighter (P < 0.0001) but had 4.5% more body fat (P = 0.0007) than NS children. Overall, decreasing birthweight SDS across the normal range (-1.9 to +1.5 SDS) was associated with lower percentage IGF-I response to rhGH stimulation in univariable (r = 0.45; P = 0.002) and multivariable models (β = 24.6; P = 0.006). Plasma IGF-I concentrations rose in both groups with rhGH stimulation (P < 0.0001). GHBP levels (P = 0.002) were suppressed in ISS children (-19%; P = 0.029) but increased among NS children (+18%; P = 0.028), with contrasting responses also observed for leptin and IGFBP-1. Further, the increase in insulin concentrations in response to rhGH stimulation was ~3-fold greater in NS children (142% vs 50%; P = 0.006).

CONCLUSIONS

A progressive decrease in birthweight SDS was associated with a reduction in GH sensitivity in both NS and ISS children. Thus, the lower IGF-I response to rhGH stimulation in association with decreasing birthweight indicates that the ISS children at the lower end of the birthweight spectrum may have partial GH resistance, which may contribute to their poorer growth.

Neuron-specific Mafb knockout causes growth retardation accompanied by an impaired growth hormone/insulin-like growth factor I axis

Mammalian postnatal growth is regulated primarily by the growth hormone (GH)/insulin-like growth factor I (IGF-I) axis. MafB is a basic leucine zipper (bZip) transcription factor that has pleiotropic functions. Although MafB plays a critical role in fetal brain development, such as in guidance for hindbrain segmentation, its postnatal role in neurons remains to be elucidated. To investigate this, we used neuron-specific Mafb conditional knockout (cKO) mice. In addition to an approximately 50% neonatal viability, the Mafb cKO mice exhibited growth retardation without apparent signs of low energy intake. Notably, serum IGF-I levels of these mice in the postnatal stage were lower than those of control mice. They seemed to have a neuroendocrine dysregulation, as shown by the upregulation of serum GH levels in the resting state and an inconsistent secretory response of GH upon administration of growth hormone-releasing hormone. These findings reveal that neuronal MafB plays an important role in postnatal development regulated by the GH/IGF-I axis.

Circulating insulin-like growth factor I in relation to melanoma risk in the European prospective investigation into cancer and nutrition

Insulin-like growth factor-I (IGF-I) regulates cell proliferation and apoptosis, and is thought to play a role in tumour development. Previous prospective studies have shown that higher circulating concentrations of IGF-I are associated with a higher risk of cancers at specific sites, including breast and prostate. No prospective study has examined the association between circulating IGF-I concentrations and melanoma risk. A nested case-control study of 1,221 melanoma cases and 1,221 controls was performed in the European Prospective Investigation into Cancer and Nutrition cohort, a prospective cohort of 520,000 participants recruited from 10 European countries. Conditional logistic regression was used to estimate odds ratios (ORs) for incident melanoma in relation to circulating IGF-I concentrations, measured by immunoassay. Analyses were conditioned on the matching factors and further adjusted for age at blood collection, education, height, BMI, smoking status, alcohol intake, marital status, physical activity and in women only, use of menopausal hormone therapy. There was no significant association between circulating IGF-I concentration and melanoma risk (OR for highest vs lowest fifth = 0.93 [95% confidence interval [CI]: 0.71 to 1.22]). There was no significant heterogeneity in the association between IGF-I concentrations and melanoma risk when subdivided by gender, age at blood collection, BMI, height, age at diagnosis, time between blood collection and diagnosis, or by anatomical site or histological subtype of the tumour (Pheterogeneity≥0.078). We found no evidence for an association between circulating concentrations of IGF-I measured in adulthood and the risk of melanoma.

Revisiting the Role of Insulin-Like Growth Factor-I Receptor Stimulating Activity and the Apolipoprotein E in Alzheimer's Disease

Background: Alterations in insulin-like growth factor I (IGF-I) signaling have been associated with dementia and Alzheimer's disease (AD). Studies on the association between IGF-I levels and dementia risk have been inconclusive. We reported earlier that higher levels of IGF-I receptor stimulating activity are associated with a higher prevalence and incidence of dementia. Objective: In the present study, we test the robustness of the association between IGF-I receptor stimulating activity and dementia by extending the follow-up period to 16 years and investigate possible effect modification by apolipoprotein E (ApoE). Methods: At baseline, circulating IGF-I receptor stimulating activity was determined by the IGF-I kinase receptor activation (KIRA) assay in 1,014 elderly from the Rotterdam Study. Dementia was assessed from baseline (1997-1999) to follow-up in January 2015. Associations of IGF-I receptor stimulating activity and incident dementia were assessed with Cox proportional hazards models. Results: During 10,752 person-years of follow-up, 174 people developed dementia. In the extended follow-up we no longer observed a dose-response relationship between IGF-I receptor stimulating activity and risk of dementia [adjusted odds ratio 1.11; 95% confidence interval (CI) 0.97-1.28]. Interestingly, we found evidence of an interaction between ApoE-ε4 and tertiles of IGF-I receptor stimulating activity. IGF-I receptor stimulating activity in the median and top tertiles was related to increased dementia incidence in hetero- and homozygotes of the ApoE-ε4 allele, but did not show any association with dementia risk in people without the ApoE-ε4 allele (adjusted odds ratio medium vs. low IGF-I receptor stimulating activity in ApoE-ε4 carriers: 1.45; 95% CI 1.00-2.12). These findings suggest a threshold effect in ApoE-ε4 carriers. In line with the hypothesis that downregulation of IGF-I signaling is associated with increased dementia risk, ApoE-ε4 homozygotes without prevalent dementia displayed lower levels of IGF-I receptor stimulating activity than heterozygotes and non-carriers. Conclusion: The findings shed new light on the association between IGF-I signaling and the neuropathology of dementia and ask for replication in other cohorts, using measures of IGF-I receptor stimulating activity rather than total serum levels as putative markers of dementia risk.

Evaluation of the Efficacy and Safety of Switching to Pasireotide in Patients With Acromegaly Inadequately Controlled With First-Generation Somatostatin Analogs

Introduction: Acromegaly is a rare, serious endocrine disorder characterized by excess growth hormone (GH) secretion by a pituitary adenoma and overproduction of insulin-like growth factor I (IGF-I). Transsphenoidal surgery is the treatment of choice, although many patients require additional interventions. First-generation somatostatin analogs (SSAs) are the current standard of medical therapy; however, not all patients achieve control of GH and IGF-I. Outcomes from a Phase IIIb open-label study of patients with uncontrolled acromegaly on first-generation SSAs switching to pasireotide are reported. Methods: Adults with uncontrolled acromegaly (mean GH [mGH] ≥1 μg/L from a five-point profile over 2 h, and IGF-I >1.3× upper limit of normal [ULN]) despite ≥3 months' treatment with maximal approved doses of long-acting octreotide/lanreotide received open-label long-acting pasireotide 40 mg/28 days. Pasireotide dose could be increased (maximum: 60 mg/28 days) after week 12 if biochemical control was not achieved, or decreased (minimum: 10 mg/28 days) for tolerability. Patients who completed 36 weeks' treatment could continue receiving pasireotide during an extension (weeks 36-72) when concomitant medication for acromegaly was permitted. Primary endpoint was proportion of patients with mGH <1 μg/L and IGF-I <ULN at week 36. Biochemical control was also assessed during the extension. Safety was assessed throughout. Results: One hundred and twenty-three patients were enrolled and received pasireotide; 88 patients continued into the extension. Overall, 18 [14.6% (95% CI: 8.9-22.1)] patients achieved mGH <1 μg/L and IGF-I <ULN at week 36; biochemical control was achieved in 42.9% with screening mGH 1.0-2.5 μg/L and 6.4% with screening mGH >2.5 μg/L. For patients who entered the extension, 14.8% (95% CI: 8.1-23.9), 12.5% (95% CI: 6.4-21.3), 14.8% (95% CI: 8.1-23.9) and 11.4% (95% CI: 5.6-19.9) had mGH <1 μg/L and IGF-I <ULN at weeks 36, 48, 60, and 72, respectively. During the overall study period, most frequent investigator-reported drug-related adverse events were hyperglycemia (41.5%), diabetes mellitus (23.6%), and diarrhea (11.4%). Conclusions: Switching to long-acting pasireotide provided biochemical control in some patients, which was sustained with continued treatment. Long-term safety and tolerability of long-acting pasireotide was consistent with the known safety profile. These data support long-acting pasireotide for some patients with acromegaly who are uncontrolled on first generation SSAs. Clinical Trial Registration: clinicaltrials.gov, identifier: NCT02354508.

Systemic arterial hypertension but not IGF-I treatment stimulates cardiomyocyte enlargement in neonatal lambs

Although cardiomyocyte terminal differentiation is nearly complete at birth in sheep, as in humans, very limited postnatal expansion of myocyte number may occur. The capacity of newborn cardiomyocytes to respond to growth stimulation by proliferation is poorly understood. Our objective was to test this growth response in newborn lambs with two stimuli shown to be potent inducers of cardiomyocyte growth in fetuses and adults: increased systolic load (Load) and insulin-like growth factor I (IGF-I). Vascular catheters and an inflatable aortic occluder were implanted in lambs. Hearts were collected for analysis at 18 days of age after a 7-day experiment and compared with control hearts. Load hearts, but not IGF-I hearts, were heavier ( P = 0.001) because of increased mass of the left ventricle (LV), septum, and left atrium (40-50%, P = 0.004). Terminal differentiation and cell cycle activity were not different between groups. Myocyte length was 7% greater in Load lamb hearts ( P < 0.05), and binucleated myocytes, which comprise ~90% of LV cells, were 25% larger in volume ( P = 0.03). Myocyte number per gram of myocardium was decreased in all ventricles of Load lambs ( P = 0.01). Cells from the IGF-I group were not different by any comparison. These results suggest that the newborn sheep LV responds to systolic stress with cardiomyocyte hypertrophy, not proliferation. Furthermore, IGF-I is ineffective at stimulating cardiomyocyte proliferation at this age (despite effectiveness when administered before birth). Thus, to expand cardiomyocyte number in the newborn heart, therapies other than systolic pressure load and IGF-I treatment need to be developed.

Phase 2 Randomized, Placebo-Controlled Clinical Trial of Recombinant Human Growth Hormone (rhGH) During Rehabilitation From Traumatic Brain Injury

Traumatic brain injury (TBI) is a major cause of death and disability, but there are currently no therapies with proven efficacy for optimizing regeneration of repair during rehabilitation. Using standard stimulation tests, as many as 40-50% of survivors of severe TBI have deficiency of one or more pituitary hormones. Of these, the somatotropic axis is the most commonly affected, with Growth Hormone (GH) deficiency affecting ~20% of persons with severe TBI. Treatment with recombinant human Growth Hormone (rhGH) is generally effective in reversing the effects of acquired GH deficiency, but there is no evidence documenting functional or neurocognitive improvement after GH replacement in TBI patients. As a consequence, screening for GH deficiency and GH replacement when deficiency is found is not routinely performed as part of the rehabilitation of TBI survivors. Given that most of the recovery after TBI occurs within the first 6-12 months after injury and IGF-1 and GH are part of a coordinated restorative neurotrophic system, we hypothesized that patients will optimally benefit from GH therapy during the window of maximal neuroregenerative activity. We performed a Phase IIa, randomized, double-blind, placebo-controlled feasibility trial of recombinant human Growth Hormone (rhGH), starting at discharge from an inpatient rehabilitation unit, with follow up at 6 and 12 months. Our primary hypothesis was that treatment with rhGH in the subacute period would result in improved functional outcomes 6 months after injury. Our secondary hypothesis proposed that treatment with rhGH would increase IGF-1 levels and be well tolerated. Sixty-three subjects were randomized, and 40 completed the trial. At baseline, there was no correlation between IGF-1 levels and peak GH levels after L-arginine stimulation. IGF-1 levels increased after rhGH treatment, but it took longer than 1 month for levels to be higher than for placebo-treated patients. rhGH therapy was well-tolerated. The rhGH group was no different from placebo in the Disability Rating Scale, Glasgow Outcome Scale-Extended, or neuropsychological function. However, a trend toward greater improvement from baseline in Functional Independence Measure (FIM) was noted in the rhGH treated group. Future studies should include longer treatment periods, faster titration of rhGH, and larger sample sizes.

DA Negatively Regulates IGF-I Actions Implicated in Cognitive Function via Interaction of PSD95 and nNOS in Minimal Hepatic Encephalopathy

Insulin-like growth factor I (IGF-I) has been positively correlated with cognitive ability. Cognitive decline in minimal hepatic encephalopathy (MHE) was shown to be induced by elevated intracranial dopamine (DA). The beneficial effect of IGF-I signaling in MHE remains unknown. In this study, we found that IGF-I content was reduced in MHE rats and that IGF-I administration mitigated cognitive decline of MHE rats. A protective effect of IGF-I on the DA-induced interaction between postsynaptic density protein 95 (PSD95) and neuronal nitric oxide synthase (nNOS) was found in neurons. Ribosomal S6 protein kinase (RSK) phosphorylated nNOS in response to IGF-I by recruiting extracellular signal-regulated kinase (ERK1/2). In turn, DA inactivated the ERK1/2/RSK pathway and stimulated the PSD95–nNOS interaction by downregulating IGF-I. Inhibition of the interaction between PSD95 and nNOS ameliorated DA-induced memory impairment. As DA induced deficits in the ERK1/2/RSK pathway and the interaction between PSD95 and nNOS in MHE brains, IGF-I administration exerted a protective effect via interruption of the interaction between PSD95 and nNOS. These results suggest that IGF-I antagonizes DA-induced cognitive loss by disrupting PSD95–nNOS interactions in MHE.

Granulomatous hypophysitis caused by Rathke's cleft cyst mimicking a growth hormone-secreting pituitary adenoma

We report a case of granulomatous hypophysitis caused by Rathke's cleft cyst (RCC) mimicking a growth hormone (GH)-secreting pituitary adenoma. Neuroradiological and endocrinological evaluations showed abnormal findings consistent with acromegaly: Magnetic resonance imaging demonstrated a pituitary mass lesion, and GH and insulin-like growth factor I levels were markedly elevated, and GH levels were not suppressed in oral glucose tolerance test. Transsphenoidal surgery was performed, but no adenomatous tissue could be detected. Histological examination revealed RCC and concurrent granulomatous giant cell inflammatory reaction of the anterior hypophysis. To the authors’ knowledge, this is the first documented case of granulomatous hypophysitis caused by RCC mimicking a GH-secreting pituitary adenoma.

IGFBP2 Produces Rapid-Acting and Long-Lasting Effects in Rat Models of Posttraumatic Stress Disorder via a Novel Mechanism Associated with Structural Plasticity

BACKGROUND

Posttraumatic stress disorder is an anxiety disorder characterized by deficits in the extinction of aversive memories. Insulin-like growth factor 1 (IGF1) is the only growth factor that has shown anxiolytic and antidepressant properties in human clinical trials. In animal studies, insulin-like growth factor binding protein 2 (IGFBP2) shows both IGF1-dependent and IGF1-independent pharmacological effects, and IGFBP2 expression is upregulated by rough-and-tumble play that induces resilience to stress.

METHODS

IGFBP2 was evaluated in Porsolt, contextual fear conditioning, and chronic unpredictable stress models of posttraumatic stress disorder. The dependence of IGFBP2 effects on IGF1- and AMPA-receptor activation was tested using selective receptor antagonists. Dendritic spine morphology was measured in the dentate gyrus and the medial prefrontal cortex 24 hours after in vivo dosing.

RESULTS

IGFBP2 was 100 times more potent than IGF1 in the Porsolt test. Unlike IGF1, effects of IGFBP2 were not blocked by the IGF1-receptor antagonist JB1, or by the AMPA-receptor antagonist 2,3-Dioxo-6-nitro-1,2,3,4 tetrahydrobenzo[f]quinoxaline-7-sulfonamide (NBQX) in the Porsolt test. IGFBP2 (1 µg/kg) and IGF1 (100 µg/kg i.v.) each facilitated contextual fear extinction and consolidation. Using a chronic unpredictable stress paradigm, IGFBP2 reversed stress-induced effects in the Porsolt, novelty-induced hypophagia, sucrose preference, and ultrasonic vocalization assays. IGFBP2 also increased mature dendritic spine densities in the medial prefrontal cortex and hippocampus 24 hours postdosing.

CONCLUSIONS

These data suggest that IGFBP2 has therapeutic-like effects in multiple rat models of posttraumatic stress disorder via a novel IGF1 receptor-independent mechanism. These data also suggest that the long-lasting effects of IGFBP2 may be due to facilitation of structural plasticity at the dendritic spine level. IGFBP2 and mimetics may have therapeutic potential for the treatment of posttraumatic stress disorder.

The Plasma Proteome Is Associated with Anthropometric Status of Undernourished Nepalese School-Aged Children

Background: Malnutrition affects body growth, size, and composition of children. Yet, few functional biomarkers are known to be associated with childhood morphology.

Objective: This cross-sectional study examined associations of anthropometric indicators of height, musculature, and fat mass with plasma proteins by using proteomics in a population cohort of school-aged Nepalese children.

Methods: Height, weight, midupper arm circumference (MUAC), triceps and subscapular skinfolds, upper arm muscle area (AMA), and arm fat area (AFA) were assessed in 500 children 6–8 y of age. Height-for-age z scores (HAZs), weight-for-age z scores (WAZs), and body mass index–for-age z scores (BAZs) were derived from the WHO growth reference. Relative protein abundance was quantified by using tandem mass spectrometry. Protein-anthropometry associations were evaluated by linear mixed-effects models and identified as having a false discovery rate (q) <5%.

Results: Among 982 proteins, 1, 10, 14, and 17 proteins were associated with BAZ, HAZ, MUAC, and AMA, respectively (q < 0.05). Insulin-like growth factor (IGF)-I, 2 IGF-binding proteins, and carnosinase-1 were associated with both HAZ and AMA. Proteins involved in nutrient transport, activation of innate immunity, and bone mineralization were associated with HAZ. Several extracellular matrix proteins were positively associated with AMA alone. The proteomes of MUAC and AMA substantially overlapped, whereas no proteins were associated with AFA or triceps and subscapular skinfolds. Myosin light-chain kinase, possibly reflecting leakage from muscle, was inversely associated with BAZ. The proteome of WAZ was the largest (n = 33) and most comprehensive, including proteins involved in neural development and oxidative stress response, among others.

Conclusions: Plasma proteomics confirmed known biomarkers of childhood growth and revealed novel proteins associated with lean mass in chronically undernourished children. Identified proteins may serve as candidates for assessing growth and nutritional status of children in similar undernourished settings. The antenatal micronutrient supplementation trial yielding the study cohort of children was registered at clinicaltrials.gov as NCT00115271.

Girls with a History of Premature Adrenarche Have Advanced Growth and Pubertal Development at the Age of 12 Years

BACKGROUND

Premature adrenarche (PA) has been linked to early thelarche and menarche, but longitudinal data on growth and pubertal development after PA are insufficient.

METHODS

Growth and pubertal development of mostly full-term and appropriate for gestational age-born 43 PA (36 girls) and 63 control children (52 girls) were analyzed prospectively. Children examined first at the mean age of 7.6 years were reexamined at the mean age of 12.0 years.

RESULTS

The PA girls but not the boys were taller and had higher body mass index (BMI) than the controls. A higher proportion of the PA than control girls had reached menarche, while the same percentage of the PA and control boys were at Tanner genital stage ≥2. The PA girls with premature pubarche (PP) were taller but not heavier and had more often reached menarche by the age of 12 years than the PA girls without PP. The PA girls with menarche had lower birth length (BL) and higher prepubertal insulin-like growth factor 1 (IGF-1) concentrations compared with non-menarcheal PA girls. In logistic regression analyses for all girls, lower BL standard deviation score, earlier maternal menarche, and higher prepubertal IGF-1 were independently associated with menarche.

CONCLUSION

At 12 years of age, the PA girls had higher BMI, advanced linear growth, and accelerated pubertal development with earlier menarche than the control girls. The PA girls with PP were taller and had earlier menarche than the PA girls without PP. Lower BL and higher prepubertal IGF-1 concentration were predictive factors for menarche by the age of 12 years.

Potential Mechanisms underlying the Protective Effect of Pregnancy against Breast Cancer: A Focus on the IGF Pathway

A first full-term birth at an early age protects women against breast cancer by reducing lifetime risk by up to 50%. The underlying mechanism resulting in this protective effect remains unclear, but many avenues have been investigated, including lobular differentiation, cell fate, and stromal composition. A single pregnancy at an early age protects women for 30-40 years, and this long-term protection is likely regulated by a relatively stable yet still modifiable method, such as epigenetic reprograming. Long-lasting epigenetic modifications have been shown to be induced by pregnancy and to target the IGF pathway. Understanding how an early first full-term pregnancy protects against breast cancer and the role of epigenetic reprograming of the IGF system may aid in developing new preventative strategies for young healthy women in the future.

Defining human insulin-like growth factor I gene regulation

Growth hormone (GH) plays an essential role in controlling somatic growth and in regulating multiple physiological processes in humans and other species. Insulin-like growth factor I (IGF-I), a conserved, secreted 70-amino acid peptide, is a critical mediator of many of the biological effects of GH. Previous studies have demonstrated that GH rapidly and potently promotes IGF-I gene expression in rodents and in some other mammals through the transcription factor STAT5b, leading to accumulation of IGF-I mRNAs and production of IGF-I. Despite this progress, very little is known about how GH or other trophic factors control human IGF1 gene expression, in large part because of the absence of any cellular model systems that robustly express IGF-I. Here, we have addressed mechanisms of regulation of human IGF-I by GH after generating cells in which the IGF1 chromosomal locus has been incorporated into a mouse cell line. Using this model, we found that physiological levels of GH rapidly stimulate human IGF1 gene transcription and identify several potential transcriptional enhancers in chromatin that bind STAT5b in a GH-regulated way. Each of the putative enhancers also activates a human IGF1 gene promoter in reconstitution experiments in the presence of the GH receptor, STAT5b, and GH. Thus we have developed a novel experimental platform that now may be used to determine how human IGF1 gene expression is controlled under different physiological and pathological conditions.

Estimated Prestroke Peak VO2 Is Related to Circulating IGF-1 Levels During Acute Stroke

Background Insulin-like growth factor-1 (IGF-1) is neuroprotective after stroke and is regulated by insulin-like binding protein-3 (IGFBP-3). In healthy individuals, exercise and improved aerobic fitness (peak oxygen uptake; peak VO₂) increases IGF-1 in circulation. Understanding the relationship between estimated prestroke aerobic fitness and IGF-1 and IGFBP-3 after stroke may provide insight into the benefits of exercise and aerobic fitness on stroke recovery. Objective The purpose of this study was to determine the relationship of IGF-1 and IGFBP-3 to estimated prestroke peak VO₂ in individuals with acute stroke. We hypothesized that (1) estimated prestroke peak VO₂ would be related to IGF-1 and IGFBP-3 and (2) individuals with higher than median IGF-1 levels will have higher estimated prestroke peak VO₂ compared to those with lower than median levels. Methods Fifteen individuals with acute stroke had blood sampled within 72 hours of hospital admission. Prestroke peak VO₂ was estimated using a nonexercise prediction equation. IGF-1 and IGFBP-3 levels were quantified using enzyme-linked immunoassay. Results Estimated prestroke peak VO₂ was significantly related to circulating IGF-1 levels (r = .60; P = .02) but not IGFBP-3. Individuals with higher than median IGF-1 (117.9 ng/mL) had significantly better estimated aerobic fitness (32.4 ± 6.9 mL kg^-1 min^-1) than those with lower than median IGF-1 (20.7 ± 7.8 mL kg^-1 min^-1; P = .03). Conclusions Improving aerobic fitness prior to stroke may be beneficial by increasing baseline IGF-1 levels. These results set the groundwork for future clinical trials to determine whether high IGF-1 and aerobic fitness are beneficial to stroke recovery by providing neuroprotection and improving function.

The Impact of Adipose Tissue on Insulin Resistance in Acromegaly

Adipose tissue (AT) is recognized as key contributor to the systemic insulin resistance and overt diabetes seen in metabolic syndrome. Acromegaly is a disease characterized by excessive secretion of growth hormone (GH) and insulin-like growth factor I (IGF-I). GH is known both for its action on AT and for its detrimental effect on glucose metabolism and insulin signaling. In active acromegaly, while body fat deports are diminished, insulin resistance is increased. Early studies have demonstrated defects in insulin action, both at the hepatic and extrahepatic (i.e., muscle and fat) levels, in active disease. This review discusses recent data suggesting that AT inflammation, altered AT distribution, and impaired adipogenesis are potential mechanisms contributing to systemic insulin resistance in acromegaly.

Whey protein, amino acids, and vitamin D supplementation with physical activity increases fat-free mass and strength, functionality, and quality of life and decreases inflammation in sarcopenic elderly

BACKGROUND

Interventions to attenuate the adverse effects of age-related loss of skeletal muscle and function include increased physical activity and nutritional supplementation.

OBJECTIVE

This study tested the hypothesis that nutritional supplementation with whey protein (22 g), essential amino acids (10.9 g, including 4 g leucine), and vitamin D [2.5 μg (100 IU)] concurrent with regular, controlled physical activity would increase fat-free mass, strength, physical function, and quality of life, and reduce the risk of malnutrition in sarcopenic elderly persons.

DESIGN

A total of 130 sarcopenic elderly people (53 men and 77 women; mean age: 80.3 y) participated in a 12-wk randomized, double-blind, placebo-controlled supplementation trial. All participants concurrently took part in a controlled physical activity program. We examined body composition with dual-energy X-ray absorptiometry, muscle strength with a handgrip dynamometer, and blood biochemical indexes of nutritional and health status, and evaluated global nutritional status, physical function, and quality of life before and after the 12 wk of intervention.

RESULTS

Compared with physical activity and placebo, supplementation plus physical activity increased fat-free mass (1.7-kg gain, P < 0.001), relative skeletal muscle mass (P = 0.009), android distribution of fat (P = 0.021), handgrip strength (P = 0.001), standardized summary scores for physical components (P = 0.030), activities of daily living (P = 0.001), mini nutritional assessment (P = 0.003), and insulin-like growth factor I (P = 0.002), and lowered C-reactive protein (P = 0.038).

CONCLUSION

Supplementation with whey protein, essential amino acids, and vitamin D, in conjunction with age-appropriate exercise, not only boosts fat-free mass and strength but also enhances other aspects that contribute to well-being in sarcopenic elderly. This trial was registered at clinicaltrials.gov as NCT02402608.

IGF-1 as an Important Endogenous Growth Factor for Recovery from Impaired Urethral Continence Function in Rats with Simulated Childbirth Injury

PURPOSE

We examined the functional role of endogenous IGF-1 (insulin-like growth factor-1) in the recovery phase of stress urinary incontinence induced by simulated childbirth trauma using an IGF-1 receptor inhibitor.

MATERIALS AND METHODS

Simulated birth trauma was induced by vaginal distension in female Sprague Dawley® rats. The IGF-1 receptor antagonist JB-1 (10 and 100 μg/kg per day) or vehicle was continuously delivered from 1 day before vaginal distension for 7 days using subcutaneous osmotic pumps. Seven, 14 and 21 days after vaginal distension the effect of JB-1 treatment was examined by functional analyses, including leak point and urethral baseline pressure, and urethral responses during passive increments in intravesical pressure, as well as molecular analyses in urethral tissues, including phosphorylation of Akt, apoptotic changes and peripheral nerve density using Western blot and immunohistochemistry.

RESULTS

On functional analyses vehicle treated rats with vaginal distension had significantly decreased leak point and urethral baseline pressure, and urethral responses at 7 days, which recovered to the normal level 14 and 21 days after vaginal distension. In the JB-1 treated vaginal distension group leak point and urethral baseline pressure, and urethral responses were still significantly reduced 21 days after vaginal distension. On molecular analyses JB-1 treatment increased apoptotic cells, induced a significant decrease in phosphorylated Akt and prolonged the decrease of peripheral nerve density in urethral tissues.

CONCLUSIONS

Suppression of endogenous IGF-1 activity delayed recovery from stress urinary incontinence induced by simulated childbirth trauma in rats. Thus, IGF-1 is likely to be an important endogenous mediator for functional recovery from childbirth related stress urinary incontinence. This suggests that IGF-1 could be an effective target for treating stress urinary incontinence in women.

Regulation of Insulin and Insulin-Like Activity in Malnourished Patients with Carcinoma Ventriculi Subjected to Total Gastrectomy and Personalized Nutritional Support

BACKGROUND

Insulin and insulin-like growth factor (IGF) activities are disturbed during critical illness. Time-course changes in the concentrations of insulin, IGF-I and IGF-binding proteins (IGFBPs) were monitored in this study and their correlation with interleukin (IL)-6 was assessed in patients subjected to total gastrectomy and specific nutritional regime.

METHODS

Patients were fed post-operatively according to the following scheme: parenteral nutrition on day 1, enteral nutrition combined with parenteral form from day 2 to 7, peroral nutrition from day 8 and full oral nutrition from day 14. Blood samples were taken periodically and the levels of IL-6, insulin, IGF-I and IGFBP-1 to -4 were determined.

RESULTS

On day 1 post-operatively, the concentration of IL-6 reached its maximum and decreased afterwards. The concentration of insulin increased until day 3 and then started to fall. The concentration of IGF-I, already low preoperatively, continued to decrease. The concentration of IGFBP-1 peaked on day 1 post-operatively, whereas the concentration of IGFBP-3 decreased on that day. The concentration of IL-6 correlated positively with the concentration of IGFBP-1 and negatively with IGFBP-3. On day 14, the concentrations of IL-6, insulin and IGFBP-1 returned to or were close to their basal levels, whereas the concentrations of IGF-I and IGFBP-3 remained reduced.

CONCLUSIONS

A 14-day post-operative recovery, which included specific nutritional support, was suitable to restore insulin concentration and re-establish IGFBP-1 regulation primarily by nutrition. Very low IGF-I level on day 14 after surgery and IGFBP-3 concentration still lower than before surgery indicated that the catabolic condition was not compensated.

Insulin-Like Growth Factor I Produces an Antidepressant-Like Effect and Elicits N-Methyl-D-Aspartate Receptor Independent Long-Term Potentiation of Synaptic Transmission in Medial Prefrontal Cortex and Hippocampus

BACKGROUND

Growth factors play an important role in regulating neurogenesis and synapse formation and may be involved in regulating the antidepressant response to conventional antidepressants. To date, Insulin-like growth factor I (IGFI) is the only growth factor that has shown antidepressant properties in human clinical trials. However, its mechanism of action remains unclear.

METHODS

The antidepressant-like effect of a single IV dose of IGFI was determined using a chronic unpredictable stress paradigm in the rat Porsolt, sucrose preference, novelty-induced hypophagia, and ultrasonic vocalization models. The dependence of the medial prefrontal cortex for these effects was determined by direct medial prefrontal cortex injection followed by Porsolt testing as well as IGFI receptor activation in the medial prefrontal cortex following an optimal IV antidepressant-like dose of IGFI. The effect of IGFI on synaptic transmission and long-term potentiation (LTP) of synaptic strength was assessed in the hippocampus and medial prefrontal cortex. The dependence of these effects on IGFI and AMPA receptor activation and protein synthesis were also determined.

RESULTS

IGFI produced a rapid-acting and long-lasting antidepressant-like effect in each of the depression models. These effects were blocked by IGFI and AMPA receptor antagonists, and medial prefrontal cortex was localized. IGFI robustly increased synaptic strength in the hippocampus and medial prefrontal cortex and these effects were IGFI receptor and protein synthesis-dependent but N-methyl-d-aspartate receptor independent. IGFI also robustly facilitated hippocampal metaplasticity 24 hours postdosing.

CONCLUSIONS

These data support the conclusion that the antidepressant-like effects of IGFI are mediated by a persistent, LTP-like enhancement of synaptic strength requiring both IGFIR activation and ongoing protein synthesis.

Insulin-independent reversal of type 1 diabetes in nonobese diabetic mice with brown adipose tissue transplant

Traditional therapies for type 1 diabetes (T1D) involve insulin replacement or islet/pancreas transplantation and have numerous limitations. Our previous work demonstrated the ability of embryonic brown adipose tissue (BAT) transplants to establish normoglycemia without insulin in chemically induced models of insulin-deficient diabetes. The current study sought to extend the technique to an autoimmune-mediated T1D model and document the underlying mechanisms. In nonobese diabetic (NOD) mice, BAT transplants result in complete reversal of T1D associated with rapid and long-lasting euglycemia. In addition, BAT transplants placed prior to the onset of diabetes on NOD mice can prevent or significantly delay the onset of diabetes. As with streptozotocin (STZ)-diabetic models, euglycemia is independent of insulin and strongly correlates with decrease of inflammation and increase of adipokines. Plasma insulin-like growth factor-I (IGF-I) is the first hormone to increase following BAT transplants. Adipose tissue of transplant recipients consistently express IGF-I compared with little or no expression in controls, and plasma IGF-I levels show a direct negative correlation with glucose, glucagon, and inflammatory cytokines. Adipogenic and anti-inflammatory properties of IGF-I may stimulate regeneration of new healthy white adipose tissue, which in turn secretes hypoglycemic adipokines that substitute for insulin. IGF-I can also directly decrease blood glucose through activating insulin receptor. These data demonstrate the potential for insulin-independent reversal of autoimmune-induced T1D with BAT transplants and implicate IGF-I as a likely mediator in the resulting equilibrium.

Altered metabolism and resistance to obesity in long-lived mice producing reduced levels of IGF-I

The extension of lifespan due to reduced insulin-like growth factor 1 (IGF-I) signaling in mice has been proposed to be mediated through alterations in metabolism. Previously, we showed that mice homozygous for an insertion in the Igf1 allele have reduced levels of IGF-I, are smaller, and have an extension of maximum lifespan. Here, we tested whether this specific reduction of IGF-I alters glucose metabolism both on normal rodent chow and in response to high-fat feeding. We found that female IGF-I-deficient mice were lean on a standard rodent diet but paradoxically displayed an insulin-resistant phenotype. However, these mice gained significantly less weight than normal controls when placed on a high-fat diet. In control animals, insulin response was significantly impaired by high-fat feeding, whereas IGF-I-deficient mice showed a much smaller shift in insulin response after high-fat feeding. Gluconeogenesis was also elevated in the IGF-I-deficient mice relative to controls on both normal and high-fat diet. An analysis of metabolism and respiratory quotient over 24 h indicated that the IGF-I-deficient mice preferentially utilized fatty acids as an energy source when placed on a high-fat diet. These results indicate that reduction in the circulating and tissue IGF-I levels can produce a metabolic phenotype in female mice that increases peripheral insulin resistance but renders animals resistant to the deleterious effects of high-fat feeding.