Liver Insulin-like Growth Factor Research Articles

Differential Acute Adipogenic Signaling Changes Following Neuromusculoskeletal Injuries

Following traumatic injury, neuromusculoskeletal tissue undergoes extensive plastic modification. Changes can be observed at the local and systemic levels and can involve tissue function, signaling, and local composition. Currently there is limited understanding of early adipogenic changes following some traumatic injuries, which is needed to understand the long-term lack of functional muscle recovery. The objective of this project was to examine plasticity after injury, namely systemic and local adipogenic signaling and fat droplet deposition following volumetric muscle loss (VML) and denervation injuries. We hypothesized there would be differential changes in local and systemic adipogenic signaling, specifically changes in fat droplet accumulation following neuromusculoskeletal injuries. Adult C57B1/6J mice (n=36; 6 male, 6 female/group): posterior compartment VML, tibial nerve denervation, and naïve control. Both injury models target plantarflexor muscles. Mice were euthanized 72-hrs post-injury. In vivo muscle function was assessed, and gastrocnemius, liver, and serum were saved for analysis. Whole gastrocnemius muscles from a subset (n=4/group) were saved for histology, and five standardized sections were systematically obtained 1.5mm apart; muscle sections were stained with H&E and Oil-Red-O to evaluate total fiber number and fat droplet accumulation, respectively. Data were analyzed by two- and three-way ANOVA with Tukey’s HSD post hoc. Maximal torque declined ~81 and 98% following VML and denervation injury, respectively (main effect p<0.001), and VML-injured muscle was more fatigable than injury naïve (main effect p=0.001). Following denervation, liver insulin-like growth factor 1 (IGF-1) was increased ~52% compared to other groups, and was most pronounced in males (main effect injury p<0.001; sex p=0.021). VML injury resulted in a 4-fold higher muscle IGF-1 regardless of sex (interaction p=0.021), and greater muscle interleukin-6 (IL-6), which was more pronounced in females (main effect injury p=0.001; sex p=0.049). Platelet-derived factor growth receptor (PDFGRα) expression was diminished following VML injury in both sexes (interaction p=0.016); suggesting a decrease in fibro-adipogenic progenitors (FAPs) and an alternative origin responsible for increases in IGF-1 and IL-6 rather than FAPs. Serum leptin concentrations were blunted following both VML- and denervation-injury (main effect p=0.002), which may illicit alterations in the regenerative process, specifically the maintenance of muscle quality. Serum IGF-1 and IL-6 concentrations were not affected by injury (p≥0.164). Histological analysis revealed a significant decrease in total fiber number across the middle three sections of the VML-injured muscle (i.e., the section initially injured) compared to other groups (p≤0.034). Findings provide a foundation for characterizing adipocyte development in the muscle remaining after injury and identify therapeutic targets for rehabilitative and nutritional approaches to address contractile and metabolic impairments following injury. Future work should elucidate the time course of adipogenic signaling following these injuries, with particular interest in their relationship to changes in metabolic and contractile impairments. R01-AR078903 (JAC & SMG); University of Minnesota UROP (BAC). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comparison of hyperoxia or normoxia resolution of intermittent hypoxia and intermittent hyperoxia episodes on liver histopathology, IGF-1, IGFBP-3, and GHBP in neonatal rats

ObjectiveExtremely low gestational age neonates requiring oxygen therapy for chronic lung disease experience repeated fluctuations in arterial oxygen saturation, or intermittent hypoxia (IH), during the first few weeks of life. These events are associated with a high risk for reduced growth, hypertension, and insulin resistance in later life. This study tested the hypothesis that IH, or intermittent hyperoxia have similar negative effects on the liver; somatic growth; and liver insulin-like growth factor (IGF)-I, IGF binding protein (BP)-3, and growth hormone binding protein (GHBP), regardless of resolution in normoxia or hyperoxia between episodes. DesignNewborn rats on the first day of life (P0) were exposed to two IH paradigms: 1) hyperoxia (50% O2) with brief hypoxia (12% O2); or 2) normoxia (21% O2) with hypoxia (12% O2); intermittent hypoxia (50% O2/21% O2); hyperoxia only (50% O2); or room air (RA, 21% O2). Pups were euthanized on P14 or placed in RA until P21. Controls remained in RA from P0-P21. Growth, liver histopathology, apoptosis, IGFI, IGFBP-3, and GHBP were assessed. ResultsPathological findings of the liver hepatocytes, including cellular swelling, steatosis, apoptosis, necrosis and focal sinusoid congestion were seen in the IH and intermittent hyperoxia groups, and were particularly severe in the 21–12% O2 group during exposure (P14) with no significant improvements during recovery/reoxygenation (P21). These effects were associated with induction of HIF1α, and reductions in liver IGFI, IGFBP-3, and GHBP. ConclusionsExposure to IH or intermittent hyperoxia during the first few weeks of life regardless of resolution in RA or hyperoxia is detrimental to the immature liver. These findings may suggest that interventions to prevent frequent fluctuations in oxygen saturation during early neonatal life remain a high priority.

Genetically mimicked effects of ASGR1 inhibitors on all-cause mortality and health outcomes: a drug-target Mendelian randomization study and a phenome-wide association study

BackgroundAsialoglycoprotein receptor 1 (ASGR1) is emerging as a potential drug target to reduce low-density lipoprotein (LDL)-cholesterol and coronary artery disease (CAD) risk. Here, we investigated genetically mimicked ASGR1 inhibitors on all-cause mortality and any possible adverse effects.MethodsWe conducted a drug-target Mendelian randomization study to assess genetically mimicked effects of ASGR1 inhibitors on all-cause mortality and 25 a priori outcomes relevant to lipid traits, CAD, and possible adverse effects, i.e. liver function, cholelithiasis, adiposity and type 2 diabetes. We also performed a phenome-wide association study of 1951 health-related phenotypes to identify any novel effects. Associations found were compared with those for currently used lipid modifiers, assessed using colocalization, and replicated where possible.ResultsGenetically mimicked ASGR1 inhibitors were associated with a longer lifespan (3.31 years per standard deviation reduction in LDL-cholesterol, 95% confidence interval 1.01 to 5.62). Genetically mimicked ASGR1 inhibitors were inversely associated with apolipoprotein B (apoB), triglycerides (TG) and CAD risk. Genetically mimicked ASGR1 inhibitors were positively associated with alkaline phosphatase, gamma glutamyltransferase, erythrocyte traits, insulin-like growth factor 1 (IGF-1) and C-reactive protein (CRP), but were inversely associated with albumin and calcium. Genetically mimicked ASGR1 inhibitors were not associated with cholelithiasis, adiposity or type 2 diabetes. Associations with apoB and TG were stronger for ASGR1 inhibitors compared with currently used lipid modifiers, and most non-lipid effects were specific to ASGR1 inhibitors. The probabilities for colocalization were > 0.80 for most of these associations, but were 0.42 for lifespan and 0.30 for CAD. These associations were replicated using alternative genetic instruments and other publicly available genetic summary statistics.ConclusionsGenetically mimicked ASGR1 inhibitors reduced all-cause mortality. Beyond lipid-lowering, genetically mimicked ASGR1 inhibitors increased liver enzymes, erythrocyte traits, IGF-1 and CRP, but decreased albumin and calcium.

The impact of egg thermal regimes on the response to food deprivation and refeeding in juvenile European Sea bass (Dicentrarchus labrax)

Fish are ectotherms and this means they are highly vulnerable to changes in ambient temperature, particularly during early developmental stages when temperature can induce persistent effects on phenotypic traits. In this study, the effect of egg incubation temperature on the response of juvenile European sea bass (Dicentrarchus labrax) to food deprivation and recovery after refeeding was assessed. Eggs were incubated at 11, 13.5 and 16 °C until hatching and then were reared at a common temperature until 9 months when fish were deprived of food for one week. The recovery from food deprivation was evaluated at 10 h and 2 days post-refeeding. Food deprivation in fish from eggs incubated at the highest temperature (16 °C) compared to 11 and 13.5 °C exhibited the most morphological and metabolic changes in the liver and foregut. Liver metabolism was changed as revealed by the significant reduction in lipid area and the increased number of hepatocyte nuclei. Foregut atrophy was coupled to a significant up-regulation of transcripts associated with gluconeogenesis (pck1) and peptide absorption (pept1). A modified metabolic response to the fast-refeed regime was revealed by the significantly decreased levels of plasma lactate, which may result from up-regulation of transcripts of the thyroid axis, deiodinase 2 (dio2) in the foregut. Fish incubated as eggs at a lower temperature (11 °C) exhibited less changes following the fast-refeed regime. Food deprivation did not significantly modify the morphology of the foregut and the liver parenchyma recovered sooner in fish from the 11 °C egg thermal regime compared to fish from the other thermal regimes following refeeding. The latter group of fish had a temporary stimulation of the GH-IGF axis with significant up-regulation of liver insulin-like growth factor I and II (igf-1 and igf-2) after fasting. The liver parenchyma of fish from the 13.5 °C egg thermal regime (the standard temperature of the hatchery stage) did not recover by the end of the experiment and transcripts of catalase (cat), encoding an antioxidant enzyme, were significantly downregulated compared to fish from the other egg thermal regimes. Our results suggest that thermal imprinting at the egg stage in European sea bass modified the juvenile metabolic response to food deprivation and the recovery response when feeding was resumed.

Metabolic memory determines gene expression in liver and adipose tissue of undernourished ewes

The aim of this work was to determine the effects of undernutrition on gene expression in liver and adipose tissue, and on the hepatic concentration of insulin like growth factor 1 (IGF1) and insulin, in pregnant ewes with different initial body condition score (iBCS). Thirty-six Rasa Aragonesa ewes were divided into 2 groups with different BCS: BCS > 2.75 (n = 19; high, H) and BCS < 2.25 (n = 17; low, L), and were randomly assigned to two nutritional treatments: 1.5 (control, C) or 0.5 (undernourished, U) times the daily maintenance requirements. Thus, the final four groups were: high-iBCS control (HC, n = 9), high-iBCS undernourished (HU, n = 10), low-iBCS control (LC, n = 9) and low-iBCS undernourished (LU, n = 8). High-iBCS ewes presented greater liver IGF1 mRNA expression (P < 0.05), which is consistent with higher liver IGF1 and insulin concentrations (P = 0.10 and P < 0.05, respectively), and with greater liver growth hormone receptor (GHR) gene expression (P < 0.05). These data, and the trend for more leptin receptor type b (LEPR-b) mRNA in high-iBCS ewes (P = 0.09) suggest a better anabolic status. Furthermore, undernourished ewes presented lower hepatic insulin like growth factor binding protein 3 (IGFBP3) gene expression (P = 0.05), suggesting a shift in the availability of IGFs in plasma and therefore, in their action in target tissues. In the adipose tissue, U ewes presented lower GHR mRNA expression than C animals (P < 0.05), being greatest in the high-iBCS control group. As expected, leptin (LEP) gene expression in adipose tissue was greater in high-iBCS than in low-iBCS ewes (P < 0.05). Nevertheless, the most interesting finding was the organ-specific pattern of LEPR-b gene expression: in contrast to the liver, the greatest adipose tissue LEPR-b gene expression was observed in the low-iBCS undernourished ewes (P < 0.05). In summary, the present study demonstrates that the initial body condition score evokes different, even contrasting, responses in key metabolic organs (i.e., liver and adipose tissue) of control and undernourished ewes.

Effects of the Isolated and Combined Ablation of Growth Hormone and IGF-1 Receptors in Somatostatin Neurons.

Hypophysiotropic somatostatin (SST) neurons in the periventricular hypothalamic area express growth hormone (GH) receptor (GHR) and are frequently considered as the key neuronal population that mediates the negative feedback loop controlling the hypothalamic-GH axis. Additionally, insulin-like growth factor-1 (IGF-1) may also act at the hypothalamic level to control pituitary GH secretion via long-loop negative feedback. However, to the best of our knowledge, no study so far has tested whether GHR or IGF-1 receptor (IGF1R) signaling specifically in SST neurons is required for the homeostatic control of GH secretion. Here we show that GHR ablation in SST neurons did not impact the negative feedback mechanisms that control pulsatile GH secretion or body growth in male and female mice. The sex difference in hepatic gene expression profile was only mildly affected by GHR ablation in SST neurons. Similarly, IGF1R ablation in SST neurons did not affect pulsatile GH secretion, body growth, or hepatic gene expression. In contrast, simultaneous ablation of both GHR and IGF1R in SST-expressing cells increased mean GH levels and pulse amplitude in male and female mice, and partially disrupted the sex differences in hepatic gene expression. Despite the increased GH secretion in double knockout mice, no alterations in body growth and serum or liver IGF-1 levels were observed. In summary, GHR and IGF1R signaling in SST neurons play a redundant role in the control of GH secretion. Furthermore, our results reveal the importance of GH/IGF-1 negative feedback mechanisms on SST neurons for the establishment of sex differences in hepatic gene expression profile.

Improvement of goose embryonic and muscular developments by wider angle egg turning during incubation and the regulatory mechanisms

Egg turning during incubation plays important roles in achieving high hatching performance and gosling quality. The objective of this study was to improve embryonic and muscular developments so to achieve better gosling quality by wider egg turning angles during incubation, and to unravel the associated regulatory molecular mechanisms. In each of three consecutive incubations, 1,728 goose eggs were divided into 3 groups that were set in the same type of commercial incubators with turning angles adjusted differently to 50°, 60°, and 70°, respectively. On average of the 3 tests, incubation with wider 70° turning angle reduced the post-18-day embryo mortality, promoted embryonic growth and development, improved the hatchability and gosling quality. On embryonic day of 29, gene mRNA expression levels of the hypothalamic growth hormone-releasing hormone (GHRH), pituitary growth hormone (GH), and liver insulin-like growth factor 1 (IGF-1) were higher in the 70° turning group than in the 50° or 60° groups. Wider angle turning also increased mRNA expression levels of the muscle development regulatory genes such as MYF5, MyoD, Myogenin (MyoG), and MRF4. Changes in expression of the above genes, together with the upregulation of the Pax3 and Pax7 genes in leg muscles, well explained the enhancement of the muscular growth and development when eggs were incubated by wider turning angles. These results also extended our understanding of the impacts and mechanisms of egg turning during incubation on hatching performance and gosling quality.

Intra- and inter-specific variability of IGF-I expression in farmed cold and warm-water species in Iran

Changes in the expression of liver insulin-like growth factor IGF-I mRNA in two growing cold-water fish species Oncorhynchusmykiss(one from locally produced and one from imported broodstock) and in two warm-water species, Hypophthalmichthysnobilis and Hypophthalmichthysmolitrix were analyzed. Gene expression analysis in liver tissues by using real-time PCR revealed a significant difference in expression level of IGF-I between native and non-native rainbow trout (P bighead carp> silver carp> native rainbow trout. Local strains of rainbow trout, bighead carp and silver carp exhibited stable IGF-I mRNA levels, at different stages of growth. The imported broodstock of rainbow trout exhibited increased IGF-I levels during the entire period studied, with a peak in the IGF-I mRNA levels of fingerlings. The results indicate intra- and inter-specific variability of IGF-I expression in farmed fish.

A Body Weight Sensor Regulates Prepubertal Growth via the Somatotropic Axis in Male Rats.

In healthy conditions, prepubertal growth follows an individual specific growth channel. Growth hormone (GH) is undoubtedly the major regulator of growth. However, the homeostatic regulation to maintain the individual specific growth channel during growth is unclear. We recently hypothesized a body weight sensing homeostatic regulation of body weight during adulthood, the gravitostat. We now investigated if sensing of body weight also contributes to the strict homeostatic regulation to maintain the individual specific growth channel during prepubertal growth. To evaluate the effect of increased artificial loading on prepubertal growth, we implanted heavy (20% of body weight) or light (2% of the body weight) capsules into the abdomen of 26-day-old male rats. The body growth, as determined by change in biological body weight and growth of the long bones and the axial skeleton, was reduced in rats bearing a heavy load compared with light load. Removal of the increased load resulted in a catch-up growth and a normalization of body weight. Loading decreased hypothalamic growth hormone releasing hormone mRNA, liver insulin-like growth factor (IGF)-1 mRNA, and serum IGF-1, suggesting that the reduced body growth was caused by a negative feedback regulation on the somatotropic axis and this notion was supported by the fact that increased loading did not reduce body growth in GH-treated rats. Based on these data, we propose the gravitostat hypothesis for the regulation of prepubertal growth. This states that there is a homeostatic regulation to maintain the individual specific growth channel via body weight sensing, regulating the somatotropic axis and explaining catch-up growth.

GR-C/EBPα-IGF1 axis mediated azithromycin-induced liver developmental toxicity in fetal mice

Azithromycin is considered an effective drug to treat the perinatal mycoplasma infection. However, there is a lack of studies on developmental toxicity of azithromycin. In this study, we observed the developmental toxicity of fetal liver induced by prenatal azithromycin exposure (PAE) in mice and explored the potential mechanism. Pregnant Kunming mice were intraperitoneally injected with azithromycin (37.5 and 150 mg/kg·d) from gestational day (GD) 9 to 18. After PAE, the bodyweight gain rates of pregnant mice and the birthweights of the offspring were decreased, and the liver morphology, development indexes and metabolic function were all altered in different degree in the PAE fetuses. Meanwhile, PAE decreased the fetal serum insulin-like growth factor 1 (IGF1) levels and liver IGF1 signal pathway expression, accompanied by glucocorticoid receptor-CCAAT enhancer-binding protein α (GR-C/EBPα) signal enhancement. Furthermore, azithromycin disturbed hepatocyte differentiation, maturation and metabolic function via upregulating GR-C/EBPα signal and reducing the expression and secretion levels of IGF1 in HepG2 cells. These changes could be reversed by GR siRNA or exogenous IGF1. These results indicated that PAE could cause fetal liver developmental toxicity in mice, and one of the main mechanisms was that azithromycin activated the GR-C/EBPα signal, inhibited the IGF1 signal pathway, and then disturbed the hepatic proliferation, apoptosis, differentiation, and glycose and lipid metabolism.

Growth performance, physiological responses to hypoxia and flesh quality of Chilean croaker (Cilus gilberti) stocked at different densities

The croaker Cilus gilberti is an important coastal food fish in Chile and Peru, and is being considered as a target marine species for diversification of Chilean aquaculture. In order to optimize culture, responses to density and potential environmental rearing conditions must be examined. Stocking density (SD) is an important factor for cultivation-related economic viability, because inappropriate SD is frequently associated with an increase of size heterogeneity, modification of social interactions and reduction of flesh quality. In addition, drastic decreases in dissolved oxygen are one of the major recurrent environmental stress factors in the area of choice for C. gilberti farming in the north of Chile, thus studies on responses to hypoxia and their associations with SD are required. Therefore, in this study, C. gilberti juveniles prior to stocking into grow-out pens were maintained for 120 days at three different stocking densities: 15 kg/m3 (LSD), 25 kg/m3 (MSD) and 35 kg/m3 (HSD), and then exposed to an acute hypoxia event. Biometric parameters, flesh quality, blood and liver biochemical parameters, and molecular markers of growth performance and stress responses were analyzed. Surprisingly, the highest body weight gain occurred in fish held at the highest density. In terms of growth-related genes, levels of growth hormone mRNA were not different between stocking densities, but liver insulin-like growth factor 1 (IGF-1) mRNA levels increased with SD and were the highest in the HSD group. There were no differences in flesh proximate composition. Similarly, glucose, lactate and HSP70 levels measured to assess chronic stress were not different among densities. There was a notable increase in lactate levels of fish in the HSD group in response to acute hypoxia, which suggests a greater reliance on anaerobic glycolysis by this group. In conclusion, results suggest that C. gilberti juveniles tolerate high stocking densities (at least 35 kg/m3) without generating chronic stress or decreasing their capacity to respond to acute hypoxia; and high SD would be preferable due to better growth. Although present results are promising, further research is needed to continue with the standardization of the SD that will allow the best productive yield of this new fish species for Chilean aquaculture.

Dietary clenbuterol modifies the expression of genes involved in the regulation of lipid metabolism and growth in the liver, skeletal muscle, and adipose tissue of Nile tilapia (Oreochromis niloticus)

The current study aimed to evaluate whether clenbuterol, a β2-adrenergic agonist, supplementation in Nile tilapia (Oreochromis niloticus) diets can influence growth and blood parameters. Besides, assessment of adipogenic genes as fatty acid synthase (FAS) and lipoprotein lipase (LPL) which is a key enzyme in the regulation of the flux of fatty acids in liver, muscle, and adipose tissue as well as muscle growth-regulating genes as myostatin (MYO) in muscle and insulin-like growth factor-1 (IGF-1) in liver. The fish were allocated into three equal groups; control group that fed basal diet only and the other two groups fed a basal diet containing clenbuterol at two doses 5 ppm and 10 ppm/kg diet for 30 consecutive days. Results revealed that clenbuterol supplementation significantly increased body weight, decreased liver, spleen and abdominal fat weights, and decreased total circulatory cholesterol and triacylglycerol levels. Moreover, clenbuterol inhibits lipogenesis by downregulation of FAS gene expression by dose and time-dependent manner in the liver while enhanced lipolysis in both the liver and in the adipose tissue. Moreover, lipolysis was reduced in muscle by dose 10 ppm on day 30. Furthermore, clenbuterol presented higher gene expression of MYO and IGF-1 in muscle and liver respectively by dose 5 ppm at day 15 on the other hand, these findings were reversed by day 30 compared with control. In conclusion, clenbuterol efficacy was apparent in a dose and time response pattern to boost growth and reduce fat deposition rates, indicating for the first time that clenbuterol has a profitable growth impact on Nile tilapia.

GH and GHR gene cloning, expression and their associations with growth-related traits of the barbel chub (Squaliobarbus curriculus).

Growth hormone (ScGH) and growth hormone receptor (ScGHR) genes from the barbel chub (Squaliobarbus curriculus), in addition to their cDNAs, were cloned. The associations between their mRNA expression levels and growth-related traits were analysed, and the differences in the levels of expression of growth regulation-related genes between the largest and smallest individuals were compared. The full-length 1182-bp cDNA of ScGH contained a 633-bp open reading frame (ORF), and the length of the gene had 2492bp. The full-length 2825-bp cDNA of ScGHRa contained a 1818-bp ORF, and the gene had 6970bp. The full-length 2822-bp cDNA of ScGHRb contained a 1737-bp ORF, and the gene had 8149bp. Quantitative real-time PCR revealed that ScGH was only expressed in the pituitary. ScGHRa was expressed predominantly in muscle, and the expression level of ScGHRb was the highest in the liver. The ScGHRa mRNA levels in the muscle were significantly negatively correlated with the caudal peduncle length. However, no correlation between growth-related traits and ScGH and ScGHRb expression levels were found. Pituitary ScGH, liver GHRb and liver insulin-like growth factor I (igf-1) expression levels were significantly higher in the largest individuals than those in the smallest S. curriculus individuals. Contrarily, the largest individuals had significantly lower expression levels of muscle igf-1 and liver myog than the smallest individuals. Overall, our results provide novel molecular information for growth-regulation study of S. curriculus.

Prenatal caffeine exposure induces liver developmental dysfunction in offspring rats.

We previously showed that prenatal caffeine exposure (PCE) induces intrauterine growth retardation (IUGR) and high susceptibility to nonalcoholic fatty liver disease in offspring rats, and the underlying mechanisms are associated with fetal overexposure to maternal glucocorticoids. Herein, we aimed to verify whether PCE disrupts liver development before and after birth and explore its possible programming mechanism. In vivo, reduced fetal weights and increased IUGR rates were accompanied by fetal liver developmental dysfunction in PCE rats. Increased fetal serum corticosterone and decreased insulin-like growth factor 1 (IGF1) levels were observed. Both male and female fetal livers exhibited increased glucocorticoid function-related gene (GR/C/EBPα) expression and inhibited IGF1 signaling pathway (IGF1/IGF1R/Akt2) expression. At PW6, the levels of serum corticosterone and glucocorticoid function-related genes in PCE offspring livers were decreased, while serum IGF1 and liver IGF1 signaling pathway expression were increased, accompanied by obvious catch-up growth and enhanced liver function. Furthermore, in PCE adult offspring under chronic stress, serum corticosterone and liver GR/C/EBPα expression levels were elevated, while the serum IGF1 and liver IGF1 signaling pathway levels were decreased. In vitro, cortisol (not caffeine) upregulated GR and C/EBPα expression and downregulated IGF1R expression. The IGF1R expression downregulated by cortisol was partially reversed by GR or C/EBPα knockdown. In conclusion, PCE induced liver developmental dysfunction in fetal rats and catch-up growth in IUGR offspring. The mechanisms may be closely associated with GR/C/EBPα upregulation and IGF1/IGF1R signaling pathway downregulation in the fetal liver, caused by intrauterine programming of the liver glucocorticoid-IGF1 axis induced by glucocorticoid overexposure.

Heat exposure alters the mRNA expression of growth- and stress-related genes in chicks

High ambient temperature, a major stressor, impairs the growth of chickens. In this study, we examined the effect of heat exposure on the mRNA expression of various growth related genes, such as growth hormone (GH), insulin-like growth factor-1 (IGF1), GH-releasing hormone (GHRH), thyrotropin-releasing hormone (TRH), and somatostatin (SST) in layer-type chickens (Gallus gallus domesticus) at an early age. In addition, we examined the reactivity of the corticotrophin-releasing hormone (CRH) system, one of the stress-regulating pathways, to heat exposure and its role in altering the growth related genes. Four-day heat exposure reduced the body weight gain, feed intake, and feeding efficiency and increased the rectal temperature of chicks (P<0.05). The mRNA expression levels of pituitary GH, liver IGF1, and diencephalic GHRH decreased with heat exposure (P<0.05) whereas the levels of TRH or SST did not change. Heat exposure also reduced the diencephalic mRNA expression level of CRH and increased pituitary CRH receptor-2 mRNA and the plasma corticosterone (CORT) concentration (P<0.05), suggesting that heat exposure affected the hypothamic-pituitary adrenal gland (HPA) axis. Similar to the heat-exposure study, subcutaneous injection of CORT for 4 days decreased body weight, and the mRNA expression of pituitary GH and liver IGF1 (P<0.05). The present study demonstrated that heat exposure reduced the mRNA expressions of pituitary GH and liver IGF1, and suggested that the change in mRNA expression may have been partly caused by CORT.

Effects of high-fat feeding on growth and expression of IGF-1 and IRS-1 in adolescent rats

Objective To observe the effects of high-fat feeding on growth and the expression of insulin-like growth factor 1(IGF-1), insulin receptor substrate 1(IRS-1) in adolescent rats' liver with non-alcoholic fatty liver disease, and to elucidate the relationship between growth failure in adolescent rats with non-alcoholic fatty liver disease and IGF-1, IRS-1 turbulence. Methods Thirty-six Sprague-Dawley (SD) young rats of 21 days were randomly divided into normal control group(NC group, n=18) and high-fat feeding group(HF group, n=18). Non-alcoholic fatty liver disease(NAFLD) model was induced by feeding the SD rats with high-fat food.Immunohistochemistry was applied to detect the expression levels of IGF-1 and IRS-1 in liver tissue.The expressions of mRNA of IGF-1 and IRS-1 were measured by RT-PCR. Results Compared with NC group, the serum alanine amino transferase(ALT), total cholesterol(TC), triglyceride(TG) of HF group in the 6th, 8th, 12th week were gradually increased.The serum ALT[(194.67±11.15)U/L], TC[(1.81±0.09)mmol/L], TG[(0.34±0.05)mmol/L]contents of HF group at 8th week were higher than those at 6th week[(166.00±22.01)U/L, (1.52±0.22)mmol/L, (0.41±0.12)mmol/L, respectively], and the serum ALT[(213.0±27.67)U/L], TC[(2.15±0.37)mmol/L], TG[(0.38±0.15)mmol/L]contents of the 12th week were significantly increased compared with 6th week and 8th week.The constitution and body length of the HF group were lower than those of the normal control group.With time extended, the liver tissue steatosis, inflammation, the balloon like change of the liver tissue pathology of HF group in 6, 8, 12th week gradually increased.Immunohistochemistry results showed that HF group IRS-1[(1.46±0.23), (0.74±0.17), (0.85±0.31)], IGF-1[(0.92±0.02), (0.83±0.02), (0.77±0.03)]expression gradually decreased, the difference was statistically significant(F=36.024, P<0.05). IGF-1 and IRS-1 mRNA expressions in HF group were consistent. Conclusion The liver tissue IGF-1 and IRS-1 are correlated with the weight and body length.The growth failure of young rats induced by high-fat feeding may be related to the decreased expression of IGF-1 and IRS-1. Key words: Fatty liver; Dietary fats, unsaturated; Insulin-like growth factor 1; Insulin receptor substrate proteins

Study on IGF-1 and IGFBP-3 gene expression in liver of young rats with intermittent hypoxia

Objective:Using the model of young rats with intermittent hypoxia, to study the expression of insulin-like growth factor-1 (IGF-1) and insulin-like growth factor binding protein-3 (IGFBP-3) in liver, and to provide objective evidence for the possible existence of growth retardation in children with OSAHS. Method:Divided 24 rats randomly into three groups, as control group and the mild and severe hypoxia group. Normally fed control group, without treatment, the other two groups were kept in the cabin has been simulated mild and severe intermittent hypoxia conditions of OSAHS in children. 8-hour day cycle of intermittent hypoxia, a total of 35 days. To the last day, animals were sacrificed and fresh liver tissues were fixed in liquid nitrogen, stored in the -80°C refrigerator, then took the molecular biology experiment of IGF-1 and IGFBP-3 in the liver. Result:The expression of IGF-1 mRNA in liver, semi-quantitative analysis showed that the difference of mRNA expression of IGF-1 among the three groups was statistically significant (P<0.05), pairwise comparison, mild hypoxia group was higher than control and severe group, there were significant differences (P<0.05), the control group and severe hypoxia had no significant difference (P>0.05). The expression of IGFBP-3 mRNA in liver showed that, differences between the three groups was not significant (P>0.05). IGF-1 expression in liver tissue analysis showed that, differences between the three groups was statistically significant (P<0.05), pairwise comparisons, its expression in the control group was lower than mild hypoxia group and severe group, there were significant differences (P<0.05), mild hypoxia and severe hypoxia group had no significant difference (P>0.05). IGFBP-3 expression in liver tissue analysis showed that, differences between the three groups was statistically significant (P<0.05), pairwise comparisons, the control group was higher than mild and severe hypoxic group, there were significant differences (P<0.05), mild hypoxia and severe hypoxia group had no significant difference (P>0.05). Conclusion:IGF-1 and IGFBP-3 in the liver of mild hypoxia group, severe hypoxic group and control group showed that their transcription levels and the severity of hypoxia had no significant correlation.

Surgical castration but not immuncastration is associated with reduced hypothalamic GnIH and GHRH/GH/IGF-I axis function in male rats

Gonadotropin-inhibitory hormone (GnIH) is a potent positive regulator of the growth axis. The present study was aimed to comparatively investigate the effects of surgical and immunologic castration on hypothalamic GnIH expression and endocrine function of the growth axis. Thirty-six prepubertal male rats were randomly allocated into three groups (n = 12): control, surgically castrated or immunized against 100-μg D-Lys6-GnRH-tandem peptide conjugated to ovalbumin in Specol adjuvant at 6 weeks of age (with a booster 8 weeks later). Blood samples were collected (for hormone and urea nitrogen concentrations) at 2-week intervals, and growth performance was evaluated. Compared to intact controls, surgical castration reduced (P < 0.05) messenger RNA (mRNA) expressions of hypothalamic GnIH and growth hormone–releasing hormone (GHRH), pituitary growth hormone (GH), and liver insulin-like growth factor-1 (IGF-1), reduced (P < 0.05) serum concentrations of GH and IGF-1 and increased (P < 0.05) serum concentrations of urea nitrogen. In contrast, immunocastration did not alter messenger RNA expressions of hypothalamic GnIH, GHRH and pituitary GH, and the serum concentrations of GH (P > 0.05). Moreover, serum concentrations of IGF-1 and urea nitrogen in immunocastrates were substantially higher and lower than those in surgical castrates, respectively (P < 0.05). Compared to surgical castrates, immuncastrates had superior feed conversion efficiency and faster daily weight gain (P < 0.05). We concluded that surgical castration but not immunocastration is associated with reduced hypothalamic GnIH and GHRH/GH/IGF-I axis function in male rats.

Abstract A27: Analyses of the level of liver borne growth factors, IGF-1 and HGF in metastatic and non-metastatic uveal melanoma patient serum: Correlation with outcome

Abstract Background: Uveal melanoma arises from melanocytes in the uveal tract of the eye and is biologically different from cutaneous melanoma due to different genetic alterations and a propensity to metastasize to the liver. We hypothesize that growth factors synthesized in liver can play a significant role in this preferential homing of uveal melanoma metastasis. It is critical to explore the factors that can contribute to liver metastasis and identify targets. Further exploring the means to blocking them in a timely fashion is of high therapeutic value. IGF-1 (insulin like growth factor -1) and HGF (hepatocyte growth factor) are two major growth factors secreted from liver. The corresponding receptors, c-Met and IGF-1R have been detected in uveal melanoma tumors and also high protein expression was shown to be associated with poor survival. Therefore we initiated a study to determine the level of serum IGF-1 and HGF at sequential time points for primary and metastatic uveal melanoma patients, with the aim to test for correlation with clinical outcomes. Methods: Commercially available ELISA kits (Quantikine ELISA kits from R&amp;D) were used to measure the levels of IGF-1 and HGF in the serum of 12 uveal melanoma patients at different time points of their treatment and follow up at MD Anderson Cancer Center as a discovery cohort. Blood was drawn at first visit and then at surgery (if relevant) and post-surgery check up, followed by every six month visits or sooner. Serum was isolated from each blood draw and stored at -80 degrees until analysis. At the time of analysis, the serum samples were thawed overnight and used directly in ELISA for HGF and for the IGF-1 with pre-treatment to release the active IGF-1. Patients with detection of metastasis were followed after the diagnosis of metastasis. We compared six patients with metastasis with six others that were free of metastasis at last contact. The serum levels of IGF-1 and HGF were tabulated for each patient and each blood draw, and analyses initiated to test if the levels of IGF-1 or HGF in patients vary at baseline or over time relative to the outcome. Results: We observed a significantly higher level of serum HGF in all 12 patients in this study as compared to the reported normal levels in healthy individuals. Preliminary analyses do not point to an obvious pattern of IGF-1 or HGF serum levels or changes in levels that vary between the metastatic and non-metastatic patients over time. A drawback of the study is the small sample size. Another concern is the dynamic nature of the protein expression, which are being currently investigated. These studies would support additional analysis, and possibly more sensitive and selected marker tests. Supported by the MD Anderson Cancer Center SPORE in Melanoma P50 CA093459, the MD Anderson's Cancer Center Support Grant P30- CA016672, the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation, and funds from the Polo on the Prairie event. Citation Format: Chandrani Chattopadhyay, Junna Oba, Bita Esmaeli, Julie A. Ellerhorst, Elizabeth A. Grimm. Analyses of the level of liver borne growth factors, IGF-1 and HGF in metastatic and non-metastatic uveal melanoma patient serum: Correlation with outcome. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Melanoma: From Biology to Therapy; Sep 20-23, 2014; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(14 Suppl):Abstract nr A27.

Intrauterine Growth Restriction Disrupts Nucleosome Positioning at a Growth Hormone Response Element in the Insulin‐like Growth Factor 1 Gene

Intrauterine growth restriction (IUGR) increases the risk of adult onset diseases such as obesity and type II diabetes. Persistent downregulation of insulin‐like growth factor 1 (IGF1) has been implicated in these diseases. IUGR downregulates liver IGF1 expression in newborn and in day 21 (d21) mice. IGF1 expression at d21 is dependent on growth hormone (GH)‐mediated upregulation at multiple GH response elements (GHRE) including one containing tandem STAT5b binding sites within intron 2 (i2). We hypothesized that IUGR would disrupt prenatal epigenetic programming of the i2 GHRE and prevent postnatal i2 GHRE activation. IUGR mice were generated by thromboxane A2 analog infusion from gestation day 12.5 to term to elicit maternal hypertension. The GHRE chromatin state at the i2 GHRE was assessed by Na‐bisulfite sequencing for DNA methylation and GpC methyltransferase mapping for nucleosome positioning. In normal mice, the GHRE remains hypermethylated throughout gestation and begins to demethylate at d17. By d21 a single nucleosome is displaced. IUGR animals undergo similar DNA demethylation. However, we found two distinct nucleosome patterns at the d21 hepatic i2 GHRE. Some IUGR animals showed no nucleosome displacement, while in others, the nucleosome free region (NFR) was expanded on the 3′ side suggesting the NFR was misaligned. Evidence suggests different GHRE in IGF1 have unique functions and when tandem STAT5b sites are used, both must be functional for the enhancer to work. We speculate the altered NFR spacing could disrupt proper enhanceosome assembly and result in loss/altered GHRE activity.