Liver Growth Hormone Receptor Research Articles

Modifications of the GH axis reveal unique sexually dimorphic liver signatures for Lcn13, Asns, Hamp2, Hao2, and Pgc1a

Abstract GH modifies liver gene transcription in a sexually dimorphic manner to meet liver metabolic demands related to sex; therefore GH dysregulation leads to sex-biased hepatic disease. We dissected the steps of the GH regulatory cascade modifying GH-dependent genes involved in metabolism, focusing on the male-predominant genes Lcn13, Asns and Cyp7b1, and the female-predominant genes Hao2, Pgc1a, Hamp2, Cyp2a4 and Cyp2b9. We explored mRNA expression in two settings a) intact liver GH receptor, but altered GH and IGF1 levels (NeuroDrd2KO, HiGH, aHepIGF1kd, and STAT5bCA mouse lines), and b) liver loss of GHR, with or without STAT5b reconstitution (aHepGHRkd, and aHepGHRkd + STAT5bCA). Lcn13 was downregulated in males in most models, while Asns and Cyp7b1 were decreased in males by low GH levels or action, or constant GH levels, but unexpectedly upregulated in both sexes by the loss of liver Igf1 or constitutive Stat5b expression. Hao, Cyp2a4 and Cyp2b9 were generally decreased in female mice with low GH levels or action (NeuroDrd2KO and/or aHepGHRkd mice), and increased in HiGH females, while in contrast, Pgc1a was increased in female NeuroDrd2KO but decreased in STAT5bCA and aHepIgf1kd females. Bioinformatic analysis of RNAseq from aHepGHRkd livers stressed the greater impact of GHR loss on wide gene expression in males and highlighted that GH modifies almost completely different gene signatures in each sex. Concordantly, we show that altering different steps of the GH cascade in the liver modified liver expression of Lcn3, Asns, Cyp7b1, Hao2, Hamp2, Pgc1a, Cyp2a4 and Cyp2b9 in a sex and gene specific manner.

Effects of age and seasonal temperatures on cortisol levels and GHR, IGF-I, and IGF-II expressions in rainbow trout (Oncorhynchus mykiss)

The growth hormone (GH)/insulin-like growth factor (IGF) endocrine axis regulates the cellular growth and organ development in related to changing environmental conditions and age. The aim of this study is to determine growth factor genes, which are biological markers of growth in muscle and liver of rainbow trout (Oncorhynchus mykiss) in different seasonal temperatures and age ranges and the reveal of the relationship between serum cortisol (COR) levels from stress parameters. No difference was found in serum COR levels between the groups with respect to temperature and age. Serum GH levels were found to be higher in the summer juvenile trout compared to the winter juvenile and adult trouts. There was no difference in liver growth hormone receptor (GHR) mRNA levels of juvenile and adult trouts in winter while insulin-like growth factor-I (IGF-I) and insulin-like growth factor-II (IGF-II) mRNA levels in liver and muscle tissues were found to be higher in juvenile trout compared to adults. Among trout of different ages, GHR, IGF-I and IGF-II mRNA levels in liver in summer were higher for juvenile trout compared to adults. Muscle IGF-I mRNA levels in summer were higher in adult trout compared to juveniles. IGF-II mRNA levels in liver and muscle tissues of juvenile trout showed an increase in winter compared to in summer. While the GHR and IGF-II mRNA levels in the liver tissue of adult trout were observed to higher in winter compared to summer, IGF-I mRNA levels were found to be higher in summer. GHR, IGF-I and IGF-II mRNA levels in muscle tissue of adult trout were found to be higher in summer than in winter. This study indicated that juvenile and adult rainbow trout (Oncorhynchus mykiss) are adapted to both winter and summer temperature and that GHR, IGF-I and IGF-II genes are highly expressed.

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.

Dietary protein source and protein/carbohydrate ratio affects appetite regulation-related genes expression in gilthead seabream (Sparus aurata)

This study aimed to evaluate the effect of dietary protein source (fishmeal, FM; or plant-feedstuffs, PF) and dietary protein/carbohydrate (P/CH) ratio on gilthead seabream appetite regulation and intermediary metabolism. Additionally, the effect of sampling 5 h after feeding (AF) compared to 24 h AF was also evaluated. Four isolipidic diets were formulated having as major protein sources FM or PF (20% FM and 80% PF), and P/CH ratios of 50/10 or 40/20, being the pregelatinized maize starch the main carbohydrate source (diets FM-P50/CH10; FM-P40/CH20; PF-P50/CH10; PF-P40/CH20). Diets were fed until satiation to 140 g gilthead seabream for 41 days. The expression of appetite regulation genes was assessed at 5 and 24 h AF, while other evaluated parameters were assessed only at 5 h AF. Liver leptin expression was higher at 5 h AF, and brain leptin receptor (lepr) expression was higher at 24 h AF. Brain expression of cocaine- and amphetamine-regulated transcript (cart), leptin and ghrelin receptor (ghrr)-a and liver ghrr-b were also affected by sampling time, but the effects were dependent of the diet provided. FM-based diets promoted the expression of brain cart and leptin (at 24 h AF), and liver growth hormone receptor (ghr)-ii, and increased plasma cholesterol and total lipids levels. Fish fed the PF-based diets had higher liver glycogen content, number and size of adipocytes, and expression of hepatic leptin (at 24 h AF), fatty acid synthase, glucokinase, and target of rapamycin. Regarding dietary P/CH ratio, fish fed the P50/CH10 diets presented higher feed efficiency, plasma triglycerides, and expression of intestine cholecystokinin (at 5 h AF), liver ghrr-b (at 24 h AF), glutamate dehydrogenase and ghr-ii. The protein efficiency ratio, hepatosomatic and visceral indices, plasmatic glucose level, and brain lepr expression (at 5 h AF) were higher in fish fed the P40/CH20 diets. The majority of appetite regulation related-genes were not affected by the use of PF-based diets, while the higher dietary CH seemed to lead to a shorter satiety sensation. PF-based diets promoted liver lipid deposition, hypocholesterolemia, and the activation of glycogenesis pathway, while higher CH content induced an increase in plasma glucose that appeared to be stored as lipids. In conclusion, PF-based diets with up to 20% of CH can be used in gilthead seabream without compromising growth performance and FI, and only slightly modifying appetite and metabolic parameters.

The role of protein restriction and interaction with antibiotics in the regulation of compensatory growth in pigs: growth performance, serum hormone concentrations, and messenger RNA levels in component tissues of the endocrine growth axis

The present study investigated the effects of protein restriction and antibiotics on the hypothalamus–pituitary–liver growth axis during the compensatory growth of growing and finishing pigs. Growth performance, serum hormones, and messenger RNA (mRNA) levels of hormones and their receptors in growth axis tissues were recorded for analyses. A total of 64 piglets (large white × Landrace × Duroc cross) with an initial weight of 10.07 ± 0.14 kg were randomly divided into 4 treatment groups of 16 piglets per group. The dietary treatments consisted of 2 protein levels (14% and 20%) and 2 antibiotic levels (no antibiotics and 20 mg/kg colistin sulfate with 50 mg/kg kitasamycin) in a 2 × 2 factorial arrangement. The study was performed over 30 d for the first stage (S1, restriction phase) and 74 d for the second stage (S2, realimentation phase). The 4 treatment diets were maintained throughout the duration in the restriction phase. The 4 groups were fed the same diet in the realimentation phase. The trial period totaled 104 d. Protein restriction decreased BW, average daily food intake, and ADG in weaning pigs (P < 0.01) and induced compensatory growth after feeding a normal diet during the growth of finishing pigs. Average daily gain increased during the last phase of compensatory growth (P < 0.01). Protein restriction increased serum GH and leptin (LEP) and the mRNA levels of liver IGF-1 receptor (IGF-1-R; P < 0.01) but decreased serum IGF-1 (P < 0.01) and the mRNA levels of liver GH receptor (GH-R; P < 0.01) and IGF-1 (P < 0.05) in weaning piglets. Serum GH was increased, but serum IGF-1 was decreased during the realimentation phase (P < 0.05). Antibiotics increased the mRNA levels of GHRH (P < 0.05) and decreased somatostatin (P < 0.01) in the hypothalamus of weaning pigs. Protein restriction and antibiotics had no interactions across the entire trial. In conclusion, the slowing of growth caused by early protein restriction may be compensated for in the later stages of pig raising, and the mechanism of compensation is related to the regulation of GH, IGF-1, GH-R, and IGF-1-R.

Ghrelin and Its Receptors in Gilthead Sea Bream: Nutritional Regulation.

Ghrelin is involved in the regulation of growth in vertebrates through controlling different functions, such as feed intake, metabolism, intestinal activity or growth hormone (Gh) secretion. The aim of this work was to identify the sequences of preproghrelin and Ghrelin receptors (ghsrs), and to study their responses to different nutritional conditions in gilthead sea bream (Sparus aurata) juveniles. The structure and phylogeny of S. aurata preproghrelin was analyzed, and a tissue screening was performed. The effects of 21 days of fasting and 2, 5, 24 h, and 7 days of refeeding on plasma levels of Ghrelin, Gh and Igf-1, and the gene expression of preproghrelin, ghsrs and members of the Gh/Igf-1 system were determined in key tissues. preproghrelin and the receptors are well conserved, being expressed mainly in stomach, and in the pituitary and brain, respectively. Twenty-one days of fasting resulted in a decrease in growth while Ghrelin plasma levels were elevated to decrease at 5 h post-prandial when pituitary ghsrs expression was minimum. Gh in plasma increased during fasting and slowly felt upon refeeding, while plasma Igf-1 showed an inverse profile. Pituitary gh expression augmented during fasting reaching maximum levels at 1 day post-feeding while liver igf-1 expression and that of its splice variants decreased to lowest levels. Liver Gh receptors expression was down-regulated during fasting and recovered after refeeding. This study demonstrates the important role of Ghrelin during fasting, its acute down-regulation in the post-prandial stage and its interaction with pituitary Ghsrs and Gh/Igf-1 axis.

In-ovo green light photostimulation during different embryonic stages affect somatotropic axis.

Previous studies demonstrated that in-ovo photostimulation with monochromatic green light increased the somatotropic axis expression in broilers embryos. The objective of the current study was to detect the critical period for in-ovo GL photostimulation, in order to find the optimal targeted photostimulation period during the incubation process. Three hundred thirty-six fertile broiler eggs were divided into 4 groups. The first group was incubated under dark conditions as a negative control. The second incubated under intermittent monochromatic green light using light-emitting diode (LED) lamps with an intensity of 0.1 W\m2 at shell level from d 0 of the incubation as a positive control. The third group incubated under intermittent monochromatic green light from d 10 of the incubation. The last group incubated under intermittent monochromatic green light from d 15 of the incubation. In-ovo green light photostimulation from embryonic d 0 (ED0) increased plasma growth hormone (GH), as well as hypothalamic growth hormone releasing hormone (GHRH) and liver growth hormone receptor (GHR) and insulin-like growth factor-1 (IGF-1) mRNA levels. In-ovo green light photostimulation from ED10 increased the GH plasma levels compared to the negative control group, without affecting somatotropic axis mRNA genes expressions of GHRH, GHR, and IGF-1. In-ovo green light photostimulation from ED15 caused an increase in both the plasma GH levels and the somatotropic axis mRNA genes expressions of GHRH, GHR, and IGF-1, compared to the negative control group. These results suggest that the critical period of somatotropic axis acceleration by GL photostimulation start at 15 d of incubation.

Association of body weight gain with muscle, fat, and liver expression levels of growth hormone receptor, insulin-like growth factor I, and beta-adrenergic receptor mRNAs in steers

The physiological basis of feed efficiency is unclear. Administration of GH or beta-adrenergic agonists improves feed efficiency in various animals. The objective of this study was to test the hypothesis that more efficient cattle have greater expression of GH receptor (GHR) or beta-adrenergic receptor (ADRB) mRNA in skeletal muscle, fat, and liver, the major target tissues of GH and beta-adrenergic agonists. Fifty Angus steers were fed a finishing diet for 75 d to determine residual feed intake (RFI). Carcass measures, skeletal muscle, subcutaneous fat, and liver samples were collected from the top 10 high-RFI steers and top 10 low-RFI steers at slaughter. Abundances of GHR, insulin-like growth factor I (IGF1), IGF1 receptor (IGF1R), beta-1 adrenergic receptor (ADRB1), ADRB2, and ADRB3 mRNAs were quantified by real-time reverse transcription-PCR. Low-RFI steers consumed 11% less dry matter intake than high-RFI steers (P = 0.004). Low- and high-RFI steers, however, did not differ in ADG or other growth or carcass measures. Low-RFI steers had a tendency to have smaller birth weights than high-RFI steers (P = 0.089). The expression levels of GHR, IGF1, IGF1R, ADRB1, ADRB2, and ADRB3 mRNAs in muscle, fat, and liver were neither different (P > 0.1) between high- and low-RFI steers nor correlated (P > 0.1) with RFI. These results do not support our original hypothesis. However, the expression levels of GHR, IGF1, and IGF1R mRNAs in muscle and fat were positively correlated with ADG (r = 0.52 to 0.65, P = 0.002 to 0.02), whereas the expression levels of GHR mRNA (r = −0.50, P = 0.03) and IGF1 mRNA (r = −0.47, P = 0.04) in the liver were negatively correlated with ADG. These results suggest that the GHR, IGF1, and IGF1R mRNA expression levels in the muscle and fat have a positive effect, whereas the GHR and IGF1 mRNA expression levels in the liver have a negative effect on postweaning body weight gain in cattle.

Increased fibrosis: A novel means by which GH influences white adipose tissue function

ObjectiveWhite adipose tissue (WAT) fibrosis – the buildup of extracellular matrix (ECM) proteins, primarily collagen – is now a recognized hallmark of tissue dysfunction and is increased with obesity and lipodystrophy. While growth hormone (GH) is known to increase collagen in several tissues, no previous research has addressed its effect on ECM in WAT. Thus, the purpose of this study is to determine if GH influences WAT fibrosis. DesignThis study examined WAT from four distinct strains of GH-altered mice (bGH and GHA transgenic mice as well as two tissue specific GH receptor gene disrupted lines, fat growth hormone receptor knockout or FaGHRKO and liver growth hormone receptor knockout or LiGHRKO mice). Collagen content and adipocyte size were studied in all cohorts and compared to littermate controls. In addition, mRNA expression of fibrosis-associated genes was assessed in one cohort (6month old male bovine GH transgenic and WT mice) and cultured 3T3-L1 adipocytes treated with GH. ResultsCollagen stained area was increased in WAT from bGH mice, was depot-dependent, and increased with age. Furthermore, increased collagen content was associated with decreased adipocyte size in all depots but more dramatic changes in the subcutaneous fat pad. Notably, the increase in collagen was not associated with an increase in collagen gene expression or other genes known to promote fibrosis in WAT, but collagen gene expression was increased with acute GH administration in 3T3-LI cells. In contrast, evaluation of 6month old GH antagonist (GHA) male mice showed significantly decreased collagen in the subcutaneous depot. Lastly, to assess if GH induced collagen deposition directly or indirectly (via IGF-1), fat (Fa) and liver (Li) specific GHRKO mice were evaluated. Decreased fibrosis in FaGHRKO and increased fibrosis in LiGHRKO mice suggest GH is primarily responsible for the alterations in collagen. ConclusionsOur results show that GH action is positively associated with an increase in WAT collagen content as well as a decrease in adipocyte size, particularly in the subcutaneous depot. This effect appears to be due to GH and not IGF-1 and reveals a novel means by which GH regulates WAT accumulation.

In-ovo monochromatic green light photostimulation enhances embryonic somatotropic axis activity

Previous studies demonstrated that in ovo photostimulation with monochromatic green light increases body weight and accelerates muscle development in broilers. The mechanism in which in ovo photostimulation accelerates growth and muscle development is not clearly understood. The objective of the current study was to define development of the somatotropic axis in the broiler embryo associated with in ovo green light photostimulation. Two-hundred-forty fertile broiler eggs were divided into 2 groups. The first group was incubated under intermittent monochromatic green light using light-emitting diode (LED) lamps with an intensity of 0.1 W\m2 at shell level, and the second group was incubated under dark conditions and served as control. In ovo green light photostimulation increased plasma growth hormone (GH) and prolactin (PRL) levels, as well as hypothalamic growth hormone releasing hormone (GHRH), liver growth hormone receptor (GHR), and insulin-like growth factor-1 (IGF-1) mRNA levels. The in ovo photostimulation did not, however, increase embryo's body weight, breast muscle weight, or liver weight. The results of this study suggest that stimulation with monochromatic green light during incubation increases somatotropic axis expression, as well as plasma prolactin levels, during embryonic development.

High dietary energy level stimulates growth hormone receptor and feed utilization in large Atlantic salmon (Salmo salarL.) under hypoxic conditions

This study examines how appetite and growth regulation of Atlantic salmon are affected by low dissolved oxygen (LO) and dietary digestible energy levels (DE: high [HE] vs. low [LE]). Long-term exposure to LO resulted in a reduced feed intake, growth, digestible protein and fat retention efficiencies and increased feed conversation ratio and plasma ghrelin concentrations (p < .05) compared to high dissolved oxygen (HO). Pair-feeding of rations based on the feed intake of the LO groups, but fed at HO, resulted in a 50% growth improvement in HE diet groups. This suggests that the poor growth under LO was not entirely caused by the reduced feed intake. Salmon adapted to LO by increased haemoglobin concentrations, while osmoregulation was affected by increased plasma chloride concentrations (p < .05). Plasma ghrelin concentration was unaffected by DE (p > .05). Growth regulation was affected by the HE diet, with increased liver and muscle growth hormone receptor ghr1 mRNA (p < .05), regardless of oxygen level. The growth depression due to low oxygen appears to be related to higher metabolic costs, while higher DE upregulates the GH-IGF system at the ghr1 level and found to be beneficial for growth, feed intake, oxyregulation and osmoregulation under hypoxia.

Growth Hormone Control of Hepatic Lipid Metabolism.

In humans, low levels of growth hormone (GH) and its mediator, IGF-1, associate with hepatic lipid accumulation. In mice, congenital liver-specific ablation of the GH receptor (GHR) results in reductions in circulating IGF-1 and hepatic steatosis, associated with systemic insulin resistance. Due to the intricate relationship between GH and IGF-1, the relative contribution of each hormone to the development of hepatic steatosis is unclear. Our goal was to dissect the mechanisms by which hepatic GH resistance leads to steatosis and overall insulin resistance, independent of IGF-1. We have generated a combined mouse model with liver-specific ablation of GHR in which we restored liver IGF-1 expression via the hepatic IGF-1 transgene. We found that liver GHR ablation leads to increases in lipid uptake, de novo lipogenesis, hyperinsulinemia, and hyperglycemia accompanied with severe insulin resistance and increased body adiposity and serum lipids. Restoration of IGF-1 improved overall insulin sensitivity and lipid profile in serum and reduced body adiposity, but was insufficient to protect against steatosis-induced hepatic inflammation or oxidative stress. We conclude that the impaired metabolism in states of GH resistance results from direct actions of GH on lipid uptake and de novo lipogenesis, whereas its actions on extrahepatic tissues are mediated by IGF-1.

Daily rhythms of the expression of genes from the somatotropic axis: The influence on tilapia (Oreochromis niloticus) of feeding and growth hormone administration at different times

The aim of this research was to investigate the presence of daily rhythms in the somatotropic axis of tilapia fed at two times (mid-light, ML or mid-dark, MD) and the influence of the time of day of growth hormone (GH) administration on the response of this axis. Two different GH injection times were tested: ZT 3 (3h after lights on) and ZT 15 (3h after lights off). In both experiments, the mRNA expression levels of hypothalamic pituitary adenylate cyclase-activating polypeptide (pacap), pituitary growth hormone (gh), liver insulin-like growth factors (igf1 and igf2a), and liver and muscle growth hormone receptors (ghr1 and ghr2) and IGF receptors (igf1ra and igf2r) were evaluated by means of qPCR. Daily rhythms were observed in the liver for ghr1, ghr2 and igf2r but only in fish fed at ML, with the acrophases located in the light phase (ZT 3:30, 3:31 and 7:38h, respectively). In the muscle, ghr1 displayed a significant rhythm in both groups and ghr2 in ML fed fish (acrophases at ZT 5:29, 7:14 and 9:23h). The time of both GH administration and feeding influenced the response to GH injection: ML fed fish injected with GH at ZT 15h showed a significant increase in liver igf1, igf2a and ghr2; and muscle ghr2 expression. This is the first report that describes the existence of daily rhythms in the somatotropic axis of tilapia and its time-dependent responses of GH administration. Our results should be considered when investigating the elements of the somatotropic axis in tilapia and GH administration.

Liver growth hormone receptor signaling in chronic kidney disease related growth retardation: the role of suppressor of cytokine signaling 2

Liver growth hormone receptor signaling in chronic kidney disease related growth retardation: the role of suppressor of cytokine signaling 2

Gene expression of key regulators of mitochondrial biogenesis is sex dependent in mice with growth hormone receptor deletion in liver.

Mitochondrial biogenesis is an essential process for cell viability. Mice with disruption of the growth hormone receptor (GHR) gene (Ghr gene) in the liver (LiGHRKO), in contrast to long-lived mice with global deletion of the Ghr gene (GHRKO), are characterized by lack of improved insulin sensitivity and severe hepatic steatosis. Tissue-specific disruption of the GHR in liver results in a mouse model with dramatically altered GH/IGF1 axis. We have previously shown increased levels of key regulators of mitochondrial biogenesis in insulin-sensitive GHRKO mice. The aim of the present study is to assess, using real-time PCR, the gene expression of key regulators of mitochondrial biogenesis (Pgc1α, Ampk, Sirt1, Nrf2 and Mfn2) and a marker of mitochondrial activity (CoxIV) in brains, kidneys and livers of male and female LiGHRKO and wild-type (WT) mice. There were significant differences between males and females. In the brain, expression of Pgc1α, Ampk, Sirt1, Nrf2 and Mfn2 was lower in pooled females compared to pooled males. In the kidneys, expression of Ampk and Sirt1 was also lower in female mice. In the liver, no differences between males and females were observed. Sexual dimorphism may play an important role in regulating the biogenesis of mitochondria.

Profiles of mRNA expression of related genes in the duck hypothalamus–pituitary growth axis during embryonic and early post-hatch development

In this study, the ontogeny of body and liver weight and the pattern of related gene mRNA expression in the hypothalamus–pituitary growth axis (HPGA) of two different duck breeds (Anas platyrhynchos domestica) were compared during embryonic and post-hatch development. Duck hypothalamic growth hormone release hormone (GHRH), somatostatin (SS), pituitary growth hormone (GH), liver growth hormone receptor (GHR) and insulin-like growth factor-I (IGF-1) mRNA were first detected on the 13th embryonic day. During early duck development, SS maintained a lower expression status, whereas the other four genes exhibited highly significant variations in an age-specific manner. Highly significant breed specificity was observed with respect to hepatic IGF-1 mRNA expression, which showed a significant breed–age interaction effect. Compared with previous studies on chickens, significant species differences were observed regarding the mRNA expression of bird embryonic HPGA-related genes. During early development, highly significant breed and age specificity were observed with respect to developmental changes in body and liver weight, and varying degrees of significant linear correlation were found between these performances and the mRNA expression of HPGA-related genes in the duck HPGA. These results suggest that different genetic backgrounds may lead to differences in duck growth and HPGA-related gene mRNA expression, and the differential mRNA expression of related genes in the duck HPGA may be particularly important in the early growth of ducks. Furthermore, hepatic IGF-1 mRNA expression presented highly significant breed specificity, and evidence suggests the involvement of hepatic IGF-1 in mediating genetic effects on embryo and offspring growth in ducks.

Potassium diformate influences gene expression of GH/IGF-I axis and glucose homeostasis in weaning piglets

The objective of this study was to determine the effects of potassium diformate (KDF) on growth performance of weaning piglets and genes expression related with growth axis and hepatic gluconeogenesis. A total of 180 piglets weaned at 28d of age were allocated randomly into two groups, with 6 pens in each group and 15 piglets in each pen. Piglets in the control group were fed basal diet, whereas the KDF-treated group was fed basal diet supplemented with 10g/kg KDF. After 5 weeks feeding, KDF-treated piglets showed higher average daily feed intake (ADFI) and average daily bodyweight gain (ADG) than those of the control (P<0.05), whereas the feed conversion ratio (FCR) was lower than that of the control (P=0.02). The apparent digestibility of dry matter and crude protein of the KDF-treated group were higher than those of the control group (P<0.01). KDF treatment did not change the blood indices level of insulin-like growth factor-I (IGF-I), high density lipoprotein (HDL), low density lipoprotein (LDL), total cholesterol (TC), triglyceride (TG) and blood glucose (BG) in plasma. KDF treatment did not influence the mRNA expression of growth hormone releasing hormone (GHRH) and somatostatin (SS) in hypothalamus, and the levels of growth hormone receptor (GHR) and IGF-I receptor (IGF-IR) mRNA in pituitary. Whereas, it increased the abundance of GH mRNA in pituitary, and the mRNA of GHR, IGF-I, IGF-IR, glucose-6-phosphatase (G6PC), fructose-1,6-bisphosphatase (FBP) and phosphoenolpyruvate carboxykinase (PCK) in liver (P<0.05). Furthermore, KDF treatment increased the concentration of IGF-I peptide in liver (P=0.000). These results suggest that, the beneficial effect of KDF on the growth performance may relate to the regulation of the GH axis and glucose homeostasis in piglets.

Acute heat stress and dietary methionine effects on IGF-I, GHR, and UCP mRNA expression in liver and muscle of quails

This study evaluated the expression of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), and uncoupling protein (UCP) mRNA in muscle and liver of quails that were in thermal comfort or exposed to heat stress and that were fed diets with or without methionine supplementation. Meat quails were fed a diet that either met the nutritional demands for methionine (MS) or did not meet this demand (methionine-deficient diet, MD). The animals were either kept at a thermal comfort temperature (25°C) or exposed to heat stress (38°C for 24 h starting on the 6th day). RNA was extracted from liver and breast muscle, and cDNA was synthesized and amplified using quantitative reverse transcription-polymerase chain reaction. Animals that were fed the MS diet and remained at the thermal comfort temperature exhibited increased IGF-I mRNA expression in the liver (0.56 AU). The GHR mRNA expression in the liver and muscle was influenced by both the study variables. Animals receiving the MS diet showed higher GHR expression, while increased expression was observed in animals at the thermal comfort temperature. The UCP mRNA expression in the muscle was influenced by both methionine supplementation and heat stress. Higher expression was observed in animals that received the MD diet (2.29 vs 3.77 AU) and in animals kept in thermal comfort. Our results suggest that heat stress negatively affects the expression of growth-related genes and that methionine supplementation is necessary to appropriately maintain the levels of IGF-I, GHR, and UCP transcripts for animal metabolism.

Expression profiles of growth hormone receptor and insulin-like growth factor I in cattle and yak tissues revealed by quantitative real-time PCR

Abstract. The goals of this study were to compare the mRNA expression profiles of growth hormone recep tor (GHR) and insulin-like growth factor I (IGF-I) in various tissues of cattle and the semi-wild yak (Datong yak) and to find out whether the mRNA levels of the two genes are correlated. The mRNA levels of GHR and IGF-I in heart, lung, liver, spleen, pancreas, kidney, muscle, mammary gland and ovary of cattle and yak were investigated by using quantitative real-time po ly mer ase chain reaction (PCR). The experiments showed that the transcript levels of the two genes were signif icantly higher in liver (P&lt;0.05) than in the other tissues for both species and that IGF-I levels varied more among tissues (P&lt;0.01) than did GHR levels. The GHR tran script level in pancreas was higher in yak (P&lt;0.05) than in cattle. There was no statistically sig nif i cant difference in IGF-I tran script levels among all the tissues of both bovine groups. Growth hormone receptor and IGF-I transcript levels were positively correlated in mammary gland (P&lt;0.01), lung (P&lt;0.05) and muscle (P&lt;0.05) in yak, negatively correlated in cattle heart (P&lt;0.05) and not correlated in the other tissues. The results indicate that the two genes are reg u lated differently in various tissues under normal physiological conditions in these two bovine species.

Abstract 2444: Anticancer effects of antimaia in a highly metastatic, orthotopic, immunologically competent model of breast cancer.

Abstract Traditional testing of candidate therapeutics has examined the ability of drugs to shrink pre-formed, primary xenografts in immunocompromised animals. While shrinkage of primary tumors can be crucial for inoperable tumors, the vast majority of primary tumors are surgically excised. Moreover, patient death results from cells that escaped the primary tumor. In new environments, these metastatic escapees may respond entirely differently to the drug, especially in the presence of an intact immune system. To test a novel anti-breast cancer drug, we have therefore used a highly metastatic, syngeneic model (4T1) that develops in an immunologically and endocrinologically normal animal. The drug, for brevity named Antimaia, is ∼10kDa, readily synthesized, and designed to inhibit expression of the long form (LF) of the prolactin receptor (PRLR). Studies in vivo demonstrated inhibited expression of LF PRLR without any effect on expression of the short forms of the PRLR or the growth hormone receptor in normal liver and ovary and the primary tumor. Treatment of 4T1 cells in vitro inhibited the ability of cells within the population to form mammospheres (100/well in controls and 0/well in Antimaia-treated, when defining a mammosphere as a colony &amp;gt;50μm) indicative of an effect on stem-like cells within the population. This anti-stem cell effect was duplicated when stem cells were identified on the basis of cell markers (Lin-CD29hiCD24+ AldH+), but stem cell elimination was still ongoing at 15 days. With the 4T1 model, orthotopic injection of 1x106 cells produces multiple, grossly-visible metastases in the lung and liver by 14 days. Antimaia treatment (100 pmoles/h/mouse via Alzet minipump) at the time of orthotopic injection reduced both gross and microscopic metastases without effect on primary tumor weight. However, histological examination of the primary tumors nevertheless showed only a rim of viable cells in the Antimaia-treated group. Morphometric analysis quantified the area of central tumor death as 3 fold that seen in the two control groups. Since in vitro stem cell death was still ongoing at 15 days, the next goal was to examine the effect of longer term treatment in vivo. To do this, it was necessary to initiate primary tumors with fewer cells to be compliant with standards of animal care. When 1x 103 cells were orthotopically injected and treatment continued for 29 days, 4 of 6 primary tumors in the Antimaia group (and 0 of 6 in the control group) showed a flattened growth curve after initial tumor formation. Micrometastasis histological analyses are ongoing, but ex vivo analysis of immune cells from the livers has shown an increase in tumor-specific IFNγ+ CD4+ cells that correlates with effects of treatment on final tumor weight. Analysis of liver enzymes at 14 and 29 days showed no evidence of toxicity. We conclude that Antimaia holds great promise as a breast cancer therapeutic. CBCRP 171B-0053. Citation Format: Tomohiro Yonezawa, KaunHui E. Chen, David Duong, Lisa Ma, Mrinal Ghosh, Mitsumori Kawaminami, Ameae M. Walker. Anticancer effects of antimaia in a highly metastatic, orthotopic, immunologically competent model of breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2444. doi:10.1158/1538-7445.AM2013-2444