IGF-1 and IGFBP-3 in Inflammatory Cachexia.

Inflammation induces a wide response of the neuroendocrine system, which leads to modifications in all the endocrine axes. The hypothalamic-growth hormone (GH)-insulin-like growth factor-1 (IGF-1) axis is deeply affected by inflammation, its response being characterized by GH resistance and a decrease in circulating levels of IGF-1. The endocrine and metabolic responses to inflammation allow the organism to survive. However, in chronic inflammatory conditions, the inhibition of the hypothalamic-GH-IGF-1 axis contributes to the catabolic process, with skeletal muscle atrophy and cachexia. Here, we review the changes in pituitary GH secretion, IGF-1, and IGF-1 binding protein-3 (IGFBP-3), as well as the mechanism that mediated those responses. The contribution of GH and IGF-1 to muscle wasting during inflammation has also been analyzed.

Caenorhabditis elegans as a Useful Model for Studying Aging Mutations.

The Caenorhabditis elegans genome possesses homologs of about two-thirds of all human disease genes. Based on its physiological aging characteristics and superiority, the use of C. elegans as a model system for studies on aging, age-related diseases, mechanisms of longevity, and drug screening has been widely acknowledged in recent decades. Lifespan increasing mutations in C. elegans were found to delay aging by impinging several signaling pathways and related epigenetic modifications, including the insulin/IGF-1 signaling (IIS), AMP-activated protein kinase (AMPK), and mechanistic target of rapamycin (mTOR) pathways. Interestingly, dietary restriction (DR) has been shown to increase the lifespan of numerous metazoans and protect them from multiple age-related pathologies. However, the underlying molecular mechanisms are unclear. In recent decades, C. elegans has been used as a unique model system for high-throughput drug screening. Here, we review C. elegans mutants exhibiting increased in lifespan and age-dependent changes under DR, as well as the utility of C. elegans for drug screening. Thus, we provide evidence for the use of this model organism in research on the prevention of aging.

Nutrition and growth in children.

The well-balanced nourishment during "the first 1000 days," the period between conception (day 18) and the age of two years, is quite important for two main reasons. Firstly, the nutritive requirement is high due to the rapid physiological growth and functional development. Then, this period is characterized by extreme susceptibility to external stimuli such as inadequate maternal and infant nutritional status which they can interfere with the different stages of the development process leading to short and long-term consequences for health. Linear growth and brain development are particularly impaired from not sufficient nutrition. In consideration of the irreversible damage of malnutrition, especially on developing brain, an adequate nutrition during the first 1000 days of life is paramount. The aim of this review was to overview the latest scientific evidences on the relationship between nutrition and growth, focusing on nutritional requirements during the first 1000 days, and the impact of inadequate nutrition on brain development and linear growth.

KMP01D Demonstrates Beneficial Anti-inflammatory Effects on Immune Cells: An ex vivo Preclinical Study of Patients With Colorectal Cancer.

Background: Colorectal cancer (CRC) is frequently associated with dysbiosis of the gut microbiome which, together with a compromised gut barrier, can result in perioperative endotoxin leakage into the circulation. Constant local and systemic inflammatory activity is suggested to facilitate metastases formation. Previous studies have pointed to the capacity of a colostrum preparation to neutralize endotoxins within the gastrointestinal tract which could ameliorate associated inflammatory responses and tumor recurrence in affected patients. This study aimed to examine the effects of the colostrum preparation, KMP01D, on the inflammatory activity of patient-derived immune cells. Methods: The effects of KMP01D on pro-/anti-inflammatory cytokine responses and apoptosis were examined ex vivo using immune cells from CRC patients (stages I-IV, n = 48). The expression of CD14, CD68, Toll-like receptor (TLR)4, and insulin-like growth factor (IGF)-1 was also analyzed. Results: KMP01D increased interleukin (IL)-10 and IL-13 anti-inflammatory cytokine expression in patient-derived peripheral blood mononuclear cells (PBMCs). Interestingly, KMP01D also decreased the secretion of IL-1ß, IL-6, interferon (IFN)-γ, tumor necrosis factor (TNF)-α, IL-12 inflammatory cytokines, and IGF-1 in these cells. Moreover, CD14 and TLR4 expression involved in endotoxin signaling was downregulated in PBMCs and tumor-derived cells. Apoptosis of immune cells and tumor-derived cells was likewise enhanced with KMP01D. Addition of vitamin D3 as a cofactor demonstrated enhanced anti-inflammatory effects. Conclusions: KMP01D demonstrated beneficial ex vivo effects on inflammatory cytokine responses in PBMCs and enhanced apoptosis of immune cells from CRC patients. In line with previous clinical trials, we present new evidence endorsing KMP01D as a treatment strategy to regulate stage-dependent local and systemic inflammation in CRC patients.

Direct inhibitory effect of flaxseed on porcine ovarian granulosa cell functions.

Flaxseed is useful as a functional food and alternative medicine owing to its beneficial health effects. Its action on ovarian cell functions and interrelationships with the upstream hormonal regulators remain unknown. Our aim was to examine the direct influence of flaxseed extract on basal porcine ovarian functions (proliferation, apoptosis), leptin release, and response to insulin-like growth factor I (IGF-I). First, we examined the effect of flaxseed extract on the accumulation of proliferation (PCNA) and apoptosis (Bax) markers and on leptin release in cultured porcine ovarian granulosa cells. Next, granulosa cells were cultured with IGF-I with and without flaxseed extract and analyzed for PCNA and Bax accumulation by quantitative immunocytochemistry and for leptin release by radioimmunoassay. Flaxseed decreased the accumulation of PCNA and increased that of Bax at all doses and reduced leptin output at 100 µg/mL. In contrast, IGF-I promoted PCNA accumulation and suppressed Bax. Flaxseed did not modify IGF-I action on these parameters. Thus, we showed that flaxseed influences porcine reproductive processes, having a direct effect on the ovary and the ability to affect ovarian cell proliferation, apoptosis, and leptin release. Furthermore, we confirmed the pro-proliferative and antiapoptotic actions of IGF-I but showed that flaxseed action on ovarian cell proliferation and apoptosis is not due to changes in the cell response to IGF-I. The potential direct anti-reproductive action of flaxseed needs to be considered during its application in nutrition, medicine, and animal production.

The role of insulin-like growth factor 1 in ALS cell and mouse models: A mitochondrial protector.

Amyotrophic lateral sclerosis (ALS) is a common neurodegenerative disorder, but little is known about the exact causes and pathophysiology of this disease. In transgenic mouse models of ALS, mitochondrial abnormalities develop during the disease and might contribute to the progression of ALS. Gene therapy was recently shown to induce beneficial effects. For example, the delivery of human insulin-like growth factor-1 (hIGF-1) by self-complementary adeno-associated virus (AAV) vectors has been shown to prolong the lifespan of ALS transgenic mice. However, the function of IGF-1 in mitochondria has not been systematically studied in ALS models. In this study, scAAV9-hIGF-1 was intramuscularly injected into transgenic SOD1G93A mice and administered to cell lines expressing the ∼25-kDa C-terminal fragment of transactive response DNA-binding protein (TDP-25). The mitochondrial electrical transmembrane potential was hyperpolarized, and electron microscopy findings revealed that the abnormal mitochondria were transformed. Moreover, the intrinsic mitochondrial apoptotic process was modified through the upregulation of anti-apoptotic proteins (B-cell lymphoma-extra large (Bcl-xl) and B-cell lymphoma-2 (Bcl-2)), the downregulation of pro-apoptotic proteins (Bcl-2-associated x protein (Bax) and Bcl-2 homologous antagonist killer (Bak)) and a reduction in mitochondrial cytochrome c release. Mitophagy was also increased after scAAV9-hIGF-1 treatment, as evidenced by a decrease in the p62 level and an increase in the LC3-II level. Furthermore, the clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) system was used to delete the IGF-1 gene in SOD1G93A model mice via an intrathecal injection of scAAV9-sgRNA-IGF1-Cas9 to confirm these findings. The protective effect of IGF-1 on the mitochondria decreased after genetic deletion. These novel findings demonstrate that IGF-1 strongly protects mitochondria from apoptosis and upregulates mitophagy in mouse and cell models of ALS. Therefore, therapies that specifically protect mitochondrial function might be promising strategies for treating ALS.

Human IGF-I propeptide A promotes articular chondrocyte biosynthesis and employs glycosylation-dependent heparin binding.

BACKGROUND: Insulin-like growth factor I (IGF-I) is a key regulator of chondrogenesis, but its therapeutic application to articular cartilage damage is limited by rapid elimination from the repair site. The human IGF-I gene gives rise to three IGF-I propeptides (proIGF-IA, proIGF-IB and proIGF-IC) that are cleaved to create mature IGF-I. In this study, we elucidate the processing of IGF-I precursors by articular chondrocytes, and test the hypotheses that proIGF-I isoforms bind to heparin and regulate articular chondrocyte biosynthesis. METHODS: Human IGF-I propeptides and mutants were overexpressed in bovine articular chondrocytes. IGF-I products were characterized by ELISA, western blot and FPLC using a heparin column. The biosynthetic activity of IGF-I products on articular chondrocytes was assayed for DNA and glycosaminoglycan that the cells produced. RESULTS: Secreted IGF-I propeptides stimulated articular chondrocyte biosynthetic activity to the same degree as mature IGF-I. Of the three IGF-I propeptides, only one, proIGF-IA, strongly bound to heparin. Interestingly, heparin binding of proIGF-IA depended on N-glycosylation at Asn92 in the EA peptide. To our knowledge, this is the first demonstration that N-glycosylation determines the binding of a heparin-binding protein to heparin. CONCLUSION: The biosynthetic and heparin binding abilities of proIGF-IA, coupled with its generation of IGF-I, suggest that proIGF-IA may have therapeutic value for articular cartilage repair. GENERAL SIGNIFICANCE: These data identify human pro-insulin-like growth factor IA as a bifunctional protein. Its combined ability to bind heparin and augment chondrocyte biosynthesis makes it a promising therapeutic agent for cartilage damage due to trauma and osteoarthritis.

Nutrition, infection and stunting: the roles of deficiencies of individual nutrients and foods, and of inflammation, as determinants of reduced linear growth of children.

The regulation of linear growth by nutritional and inflammatory influences is examined in terms of growth-plate endochondral ossification, in order to better understand stunted growth in children. Linear growth is controlled by complex genetic, physiological, and nutrient-sensitive endocrine/paracrine/autocrine mediated molecular signalling mechanisms, possibly including sleep adequacy through its influence on growth hormone secretion. Inflammation, which accompanies most infections and environmental enteric dysfunction, inhibits endochondral ossification through the action of mediators including proinflammatory cytokines, the activin A-follistatin system, glucocorticoids and fibroblast growth factor 21 (FGF21). In animal models linear growth is particularly sensitive to dietary protein as well as Zn intake, which act through insulin, insulin-like growth factor-1 (IGF-1) and its binding proteins, triiodothyronine, amino acids and Zn2+ to stimulate growth-plate protein and proteoglycan synthesis and cell cycle progression, actions which are blocked by corticosteroids and inflammatory cytokines. Observational human studies indicate stunting to be associated with nutritionally poor, mainly plant-based diets. Intervention studies provide some support for deficiencies of energy, protein, Zn and iodine and for multiple micronutrient deficiencies, at least during pregnancy. Of the animal-source foods, only milk has been specifically and repeatedly shown to exert an important influence on linear growth in both undernourished and well-nourished children. However, inflammation, caused by infections, environmental enteric dysfunction, which may be widespread in the absence of clean water, adequate sanitation and hygiene (WASH), and endogenous inflammation associated with excess adiposity, in each case contributes to stunting, and may explain why nutritional interventions are often unsuccessful. Current interventions to reduce stunting are targeting WASH as well as nutrition.

Hypothalamic neurogenesis persists in the aging brain and is controlled by energy-sensing IGF-I pathway.

Hypothalamic tanycytes are specialized glial cells lining the third ventricle. They are recently identified as adult stem and/or progenitor cells, able to self-renew and give rise to new neurons postnatally. However, the long-term neurogenic potential of tanycytes and the pathways regulating lifelong cell replacement in the adult hypothalamus are largely unexplored. Using inducible nestin-CreER(T2) for conditional mutagenesis, we performed lineage tracing of adult hypothalamic stem and/or progenitor cells (HySC) and demonstrated that new neurons continue to be born throughout adult life. This neurogenesis was targeted to numerous hypothalamic nuclei and produced different types of neurons in the dorsal periventricular regions. Some adult-born neurons integrated the median eminence and arcuate nucleus during aging and produced growth hormone releasing hormone. We showed that adult hypothalamic neurogenesis was tightly controlled by insulin-like growth factors (IGF). Knockout of IGF-1 receptor from hypothalamic stem and/or progenitor cells increased neuronal production and enhanced α-tanycyte self-renewal, preserving this stem cell-like population from age-related attrition. Our data indicate that adult hypothalamus retains the capacity of cell renewal, and thus, a substantial degree of structural plasticity throughout lifespan.

Amelioration of Diabetic Mouse Nephropathy by Catalpol Correlates with Down-Regulation of Grb10 Expression and Activation of Insulin-Like Growth Factor 1 / Insulin-Like Growth Factor 1 Receptor Signaling.

Growth factor receptor-bound protein 10 (Grb10) is an adaptor protein that can negatively regulate the insulin-like growth factor 1 receptor (IGF-1R). The IGF1-1R pathway is critical for cell growth and apoptosis and has been implicated in kidney diseases; however, it is still unknown whether Grb10 expression is up-regulated and plays a role in diabetic nephropathy. Catalpol, a major active ingredient of a traditional Chinese medicine, Rehmannia, has been reported to possess anti-inflammatory and anti-aging activities and then used to treat diabetes. Herein, we aimed to assess the therapeutic effect of catalpol on a mouse model diabetic nephropathy and the potential role of Grb10 in the pathogenesis of this diabetes-associated complication. Our results showed that catalpol treatment improved diabetes-associated impaired renal functions and ameliorated pathological changes in kidneys of diabetic mice. We also found that Grb10 expression was significantly elevated in kidneys of diabetic mice as compared with that in non-diabetic mice, while treatment with catalpol significantly abrogated the elevated Grb10 expression in diabetic kidneys. On the contrary, IGF-1 mRNA levels and IGF-1R phosphorylation were significantly higher in kidneys of catalpol-treated diabetic mice than those in non-treated diabetic mice. Our results suggest that elevated Grb10 expression may play an important role in the pathogenesis of diabetic nephropathy through suppressing IGF-1/IGF-1R signaling pathway, which might be a potential molecular target of catalpol for the treatment of this diabetic complication.

Circulating IGF-1 may mediate improvements in haemoglobin associated with vitamin A status during pregnancy in rural Nepalese women.

Pregnancy exacerbates vitamin A (VA) deficiency and anaemia among women in developing countries. Improving circulating haemoglobin (Hb) requires erythrocyte production and availability of iron. Insulin-like growth factor- 1 (IGF-1) functions in erythropoiesis, but its association with VA status and pregnancy-associated anaemia has not been studied. The aim of this study was to examine the relationship between serum retinol, IGF-1, and Hb among pregnant women in extant samples collected during a placebo-controlled trial of VA and beta-carotene (BC) supplementation in rural Nepal conducted from 1994 to 1997. Mid-pregnancy serum IGF-1 was measured in serum from n=589 randomly selected women of n=1186 in whom anthropometric, VA (retinol) and iron (Hb, erythrocyte zinc protoporphyrin (ZP), and ferritin) status data were available. Associations of IGF-1 with retinol, Hb or anaemia, and iron status were determined using multiple linear and logistic regression. Path analysis was used to explore the role of IGF-1 as a mediator between retinol and Hb, accounting for iron status. A 2.6 g/L increase in IGF-1 was observed per 0.1 mol/L increment in retinol (p<0.0001). Hb increased with each quartile of IGF-1, and odds of anaemia declined 68.8% from the 1st to 4th quartile. Improved iron status indicators explained only 29.1% of the association between IGF-1 and Hb, while IGF-1 explained 25.6% of the association between retinol and Hb. Increasing IGF-1 was likely one mechanism by which retinol improved circulating Hb in pregnant women of rural Nepal, although IGF-1 worked primarily through pathways independent of improved iron status indicators, perhaps by stimulating erythrocyte production.

NNZ-2566, a novel analog of (1-3) IGF-1, as a potential therapeutic agent for fragile X syndrome.

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability. Previous studies have implicated mGlu5 in the pathogenesis of the disease, and many agents that target the underlying pathophysiology of FXS have focused on mGluR5 modulation. In the present work, a novel pharmacological approach for FXS is investigated. NNZ-2566, a synthetic analog of a naturally occurring neurotrophic peptide derived from insulin-like growth factor-1 (IGF-1), was administered to fmr1 knockout mice correcting learning and memory deficits, abnormal hyperactivity and social interaction, normalizing aberrant dendritic spine density, overactive ERK and Akt signaling, and macroorchidism. Altogether, our results indicate a unique disease-modifying potential for NNZ-2566 in FXS. Most importantly, the present data implicate the IGF-1 molecular pathway in the pathogenesis of FXS. A clinical trial is under way to ascertain whether these findings translate into clinical effects in FXS patients.

A review on the role of L-carnitine in the management of tamoxifen side effects in treated women with breast cancer.

L-carnitine is an antioxidant and is found to be a protective agent against many diseases including cancer. This review illustrates the possible role of L-carnitine as an add-on therapy to breast cancer patients maintained on tamoxifen. The objectives of carnitine treatment are diverse: improving tamoxifen-related side effects, offering better cancer prognosis by reducing the risk of developing cancer recurrence or metastasis, and modulating the growth factors which may be, in part, a prospective illustration to overcome tamoxifen resistance. So, it could be recommended to supplement L-carnitine to breast cancer patients starting tamoxifen treatment.

Insulin receptor substrate signaling suppresses neonatal autophagy in the heart.

The induction of autophagy in the mammalian heart during the perinatal period is an essential adaptation required to survive early neonatal starvation; however, the mechanisms that mediate autophagy suppression once feeding is established are not known. Insulin signaling in the heart is transduced via insulin and IGF-1 receptors (IGF-1Rs). We disrupted insulin and IGF-1R signaling by generating mice with combined cardiomyocyte-specific deletion of Irs1 and Irs2. Here we show that loss of IRS signaling prevented the physiological suppression of autophagy that normally parallels the postnatal increase in circulating insulin. This resulted in unrestrained autophagy in cardiomyocytes, which contributed to myocyte loss, heart failure, and premature death. This process was ameliorated either by activation of mTOR with aa supplementation or by genetic suppression of autophagic activation. Loss of IRS1 and IRS2 signaling also increased apoptosis and precipitated mitochondrial dysfunction, which were not reduced when autophagic flux was normalized. Together, these data indicate that in addition to prosurvival signaling, insulin action in early life mediates the physiological postnatal suppression of autophagy, thereby linking nutrient sensing to postnatal cardiac development.

Enriched early life experiences reduce adult anxiety-like behavior in rats: a role for insulin-like growth factor 1.

Early life experiences can affect brain development, contributing to shape interindividual differences in stress vulnerability and anxiety-like behavior. In rodents, high levels of maternal care have long-lasting positive effects on the behavior of the offspring and stress response; post-weaning rearing in an enriched environment (EE) or massage counteract the negative effects of maternal separation or prenatal stressors. We recently found that insulin-like growth factor 1 (IGF-1) is a key mediator of early EE or massage on brain development. Whether early enrichment of experience can induce long-lasting effects on anxiety-like behavior and whether IGF-1 is involved in these effects is not known. We assessed anxiety-like behavior by means of the elevated plus maze in control adult rats and in adult rats subjected to early EE or to massage. We found that both EE and massage reduced adult anxiety-like behavior. Early IGF-1 systemic injections in rat pups reared in standard condition mimic the effects of EE and massage, reducing anxiety-like behavior in the adult; blocking early IGF-1 action in massaged and EE animals prevents massage and EE effects. In EE and IGF-1-treated animals, we assessed the hippocampal expression of glucocorticoid receptors (GRs) at postnatal day 12 (P12) and P60, finding a significantly higher GR expression at P60 for both treatments. These results suggest that IGF-1 could be involved in mediating the long-lasting effects of early life experiences on vulnerability/resilience to stress in adults.

Hypothalamic IGF-I gene therapy prolongs estrous cyclicity and protects ovarian structure in middle-aged female rats.

There is substantial evidence that age-related ovarian failure in rats is preceded by abnormal responsiveness of the neuroendocrine axis to estrogen positive feedback. Because IGF-I seems to act as a permissive factor for proper GnRH neuronal response to estrogen positive feedback and considering that the hypothalamic content of IGF-I declines in middle-aged (M-A) rats, we assessed the effectiveness of long-term IGF-I gene therapy in the mediobasal hypothalamus (MBH) of M-A female rats to extend regular cyclicity and preserve ovarian structure. We used 3 groups of M-A rats: 1 group of intact animals and 2 groups injected, at 36.2 weeks of age, in the MBH with either a bicistronic recombinant adeno-associated virus (rAAV) harboring the genes for IGF-I and the red fluorescent protein DsRed2, or a control rAAV expressing only DsRed2. Daily vaginal smears were taken throughout the study, which ended at 49.5 weeks of age. We measured serum levels of reproductive hormones and assessed ovarian histology at the end of the study. Although most of the rats injected with the IGF-I rAAV had, on the average, well-preserved estrous cyclicity as well as a generally normal ovarian histology, the intact and control rAAV groups showed a high percentage of acyclic rats at the end of the study and ovaries with numerous enlarged cysts and scarce corpora lutea. Serum LH was higher and hyperprolactinemia lower in the treated animals. These results suggest that overexpression of IGF-I in the MBH prolongs normal ovarian function in M-A female rats.

Acute effects of blood transfusion on pituitary gonadal axis and sperm parameters in adolescents and young men with thalassemia major: a pilot study.

OBJECTIVE: To evaluate semen parameters and measure serum FSH, LH, T, and insulin-like growth factor (IGF) 1 concentrations before and 7 days after packed red cell transfusion (PCTx) in young adults with thalassemia major (TM). DESIGN: Prospective study. SETTING: Tertiary care hospital. PATIENT(S): This study investigated 10 young adults with TM, aged 17-32 years, with full pubertal development (Tanner stage 5, eugonadal) and capacity to ejaculate. They had been regularly transfused since early childhood and underwent chelation therapy with the use of desferrioxamine replaced by deferasirox for the past 4-5 years. At the time of the study their serum ferritin levels ranged from 500 to 5,922 ng/mL (mean 2,686 ng/mL). Basal serum concentrations of FSH, LH, T, and IGF-1 were evaluated before and 7 days after PCTx. INTERVENTION(S): We studied the effect of PCTx on semen parameters and the endocrine functions in these 10 patients with TM. MAIN OUTCOME MEASURE(S): After PCTx, a significant increase of hemoglobin from 8.7 ± 0.86 g/dL to 11.1 ± 0.82 g/dL was associated with increased T (from 16.5 ± 8 nmol/L to 20 ± 8.8 nmol/L), IGF-1 (from 173 ± 46 ng/mL to 214 ± 61 ng/mL), and gonadotropin concentrations. RESULT(S): Total sperm count increased significantly from 57.8 ± 38.3 million/mL to 166 ± 132 million/mL, and rapid progressive sperm motility progressive motility increased from 20.6 ± 16.6% to 79.7 ± 67.4%. After PCTx, LH concentrations were correlated significantly with T concentrations and sperm volume and count. The increase of IGF-1 concentration was correlated significantly with hemoglobin level after PCTx and negatively with ferritin concentration. Significant correlations were found before and after PCTx between serum T concentrations and semen parameters, including sperm count, rapid progressive motility, and the number of sperm with normal morphology, and between IGF-1 levels and seminal parameters. No correlations were found between serum FSH and IGF-1 concentrations and seminal parameters. CONCLUSION(S): This study suggests that in thalassemic men, blood transfusion is associated with significant acute enhancement of sperm parameters and increased concentrations of serum T, LH, FSH, and IGF-1. These "acute" effects on spermiogenesis are reached by an unknown mechanism and suggest a number of pathways that need further human and/or experimental studies.

Inhibition of GHRH aggravated acetaminophen-induced acute mice liver injury through GH/IGF-I axis.

The aim of the current study is to investigate the effects of growth hormone releasing hormone (GHRH) antagonist on acetaminophen (APAP)-induced acute liver injury in mice. Healthy C57/B6L mice were orally treated with 200 mg/kg APAP with or without a 30-min pre-treatment with 300 µg/kg GHRH antagonist MZ-5-156. After 12 hours, serum, plasma, and liver samples from each mouse were collected for analyses. Our results showed that twelve-hour treatment with APAP caused obvious liver injury, elevated serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, increased oxidative stress, reduced expressions of antioxidant enzymes, accumulated expression of pro-inflammatory cytokines, and increased circulating levels of growth hormone (GH) and insulin-like growth factor-I (IGF-I). Pre-treatment with MZ-5-156 aggravated liver injury, further increased serum ALT and AST levels, exacerbated oxidative stress and inflammation induced by APAP. Treatment of MZ-5-156 also blocked the phosphorylation form and total form of Janus kinase 2 (JAK2) and signal transducer and activator of transcription 5 (STAT5). Treatment of GHRH super-agonist JI-38 immediately after MZ-5-156 treatment partly reversed the liver injury caused by APAP and MZ-5-156. In conclusion, GHRH plays essential protective role in APAP-induced acute liver injury in vivo. The protective properties of GHRH are partially through GH/IGF-I axis and JAK/STAT pathway.

Insulin/IGF-I regulation of necdin and brown adipocyte differentiation via CREB- and FoxO1-associated pathways.

Brown adipose tissue plays an important role in obesity, insulin resistance, and diabetes. We have previously shown that the transition from brown preadipocytes to mature adipocytes is mediated in part by insulin receptor substrate (IRS)-1 and the cell cycle regulator protein necdin. In this study, we used pharmacological inhibitors and adenoviral dominant negative constructs to demonstrate that this transition involves IRS-1 activation of Ras and ERK1/2, resulting in phosphorylation of cAMP response element-binding protein (CREB) and suppression of necdin expression. This signaling did not include an elevation of intracellular calcium. A constitutively active form of CREB expressed in IRS-1 knockout cells decreased necdin promoter activity, necdin mRNA, and necdin protein levels, leading to a partial restoration of differentiation. By contrast, forkhead box protein (Fox)O1, which is regulated by the phosphoinositide 3 kinase-Akt pathway, increased necdin promoter activity. Based on reporter gene assays using truncations of the necdin promoter and chromatin immunoprecipitation studies, we demonstrated that CREB and FoxO1 are recruited to the necdin promoter, likely interacting with specific consensus sequences in the proximal region. Based on these results, we propose that insulin/IGF-I act through IRS-1 phosphorylation to stimulate differentiation of brown preadipocytes via two complementary pathways: 1) the Ras-ERK1/2 pathway to activate CREB and 2) the phosphoinositide 3 kinase-Akt pathway to deactivate FoxO1. These two pathways combine to decrease necdin levels and permit the clonal expansion and coordinated gene expression necessary to complete brown adipocyte differentiation.