Plasma GH Levels Research Articles

Selection for growth rate and body size have altered the expression profiles of somatotropic axis genes in chickens.

The growth hormone / insulin-like growth factor-1 (GH/IGF-1) pathway of the somatotropic axis is the major controller for growth rate and body size in vertebrates, but the effect of selection on the expression of GH/IGF-1 somatotropic axis genes and their association with body size and growth performance in farm animals is not fully understood. We analyzed a time series of expression profiles of GH/IGF-1 somatotropic axis genes in two chicken breeds, the Daweishan mini chickens and Wuding chickens, and the commercial Avian broilers hybrid exhibiting markedly different body sizes and growth rates. We found that growth rate and feed conversion efficiency in Daweishan mini chickens were significantly lower than those in Wuding chickens and Avian broilers. The Wuding and Daweishan mini chickens showed higher levels of plasma GH, pituitary GH mRNA but lower levels of hepatic growth hormone receptor (GHR) mRNA than in Avian broilers. Daweishan mini chickens showed significantly lower levels of plasma IGF-1, thigh muscle and hepatic IGF-1 mRNA than did Avian broilers and Wuding chickens. These results suggest that the GH part of the somatotropic axis is the main regulator of growth rate, while IGF-1 may regulate both growth rate and body weight. Selection for growth performance and body size have altered the expression profiles of somatotropic axis genes in a breed-, age-, and tissue-specific manner, and manner, and alteration of regulatory mechanisms of these genes might play an important role in the developmental characteristics of chickens.

Influence of strain origin on osmoregulatory and endocrine parameters of two non-native strains of Atlantic salmon (Salmo salar L.)

Non-native strains of Atlantic salmon are used in reinstatement trials where populations are extinct. Environmental cues like photoperiod and temperature are known to influence the smolting process and there is evidence of strain-, stock- or population-specific differences associated with seaward migration or smoltification. The objective of this study was to compare morphological, osmoregulatory and endorcrine features between two strains, one originating from a cold and short river in Ireland (Cong) and another from a long and warm river in France (Loire-Allier), reared under Belgian conditions in order to highlight major differences in restocking adaptability. Comprehensive endocrine profiles, consistent with their interactive role of mediating changes associated with smolting, have been observed. Na+/K+ATPase activity (1.3–10.5 µmol ADP∗mg prot.−1∗h−1) and hormone plasma levels (e.g. 55–122 ng∗mL−1 of cortisol and 4.5–6.4 ng∗mL−1 of GH) were consistent with reported values. We observed strain-related differences of the influence of temperature and daylength on cortisol, GH and sodium plasma levels. These may be related to the respective environmental conditions prevailing in the river of origin, which have impacted the genetic background for smoltification. Using Na+/K+ATPase activity as an indicator, both strains smoltified successfully and simultaneously testifying a prevailing influence of environmental cues over genetic factors for smoltification.

Impact of prenatal cold stress on placental physiology, inflammatory response, and apoptosis in rats.

Prenatal cold stress is one of the earliest factors affecting mammalian health, and is associated with neonatal growth retardation and immune dysfunction, thus increasing disease susceptibility. The mechanisms underlying these observations remain unclear; hence, the objective of this study was to elucidate placental responses to cold stress. 60 maternal rats were randomly allocated to either stressed (n = 30) or non-stressed (control, n = 30) treatment conditions and 30 pubs (n=15) were used for the pups analysis. We found that maternal exposure to cold stress resulted in decreased body temperature, increased food intake without body weight gain, and a high level of plasma corticosterone (CORT) between gestational day (GD) 14 and GD21. In addition, gestation cold stress induced the placental expression of heat shock protein 70 (HSP70), IκBα, glucocorticoid receptor (GR), mineralocorticoid receptor (MR), 11β-hydroxysteroid dehydrogenase 2 (11β-HSD2), interferon (IFN) regulatory factor 3 (IRF3), Caspase-3 proteins and altered the ratio of B-cell lymphoma-extra large (Bcl-xL) to Bcl-associated x (Bax) proteins on gestational GD15, GD17, GD19, and GD21, also resulted in the production of interleukin (IL)-1β. Next, gestational cold stress provoked a decrease in plasma GH levels of 21-day-old offspring, and the body weights of offspring were have no differences from postnatal day (PD) 1–21. Taken together, our results indicate that gestational cold stress induces placental apoptosis and the activation of NF-kB via HSP70/TLR4/NF-κB signaling pathways in the placenta, these changes may affect placental function and fetus development.

Utility of baseline serum phosphorus levels for predicting remission in acromegaly patients.

High GH and IGF I levels increase tubular phosphate reabsorption in patients with acromegaly. We aimed to investigate the utility of serum phosphorus levels as an indicator for predicting chance of remission in acromegaly patients. Fifty-one patients (n: 51; F: 24, M: 27) with diagnosis of acromegaly were included in the study. Plasma IGF-1, Phosphorus (P) and nadir GH levels on oral glucose tolerance test (OGTT) at the time of diagnosis were analysed retrospectively. Patients were classified into two groups according to their plasma P levels; P ≤ 4.5mg/dl (Group-1, n: 23, 45.1%), P>4.5mg/dl (Group-2, n: 28, 54.9%). Two groups were compared according to remission status; remission (n: 27) and non-remission (n: 24). Remission was defined with absence of clinical symptoms, normal plasma IGF-1 (adjusted for age and gender) and GH levels (<1 mcg/dl) at least 3 months after initial treatment. Serum P levels decreased significantly after treatment in both groups (p < 0.001). There was a significant correlation between baseline phosphorus levels and remission rates, nadir GH in OGTT, pituitary adenoma size and Ki-67 scores (p = 0.001, r: -0.51; p = 0.01, r: 0.44; p = 0.001, r: 0.52; p = 0.02, r: 0.71, respectively). Mean baseline P levels were significantly higher in patients with non-remission (4.8 vs 4.2, P < 0.001). Logistic regression analysis did not reveal an independent effect on remission with any of these risk factors. High serum P levels may be an indicator for a low likelihood of onset of remission in acromegaly patients. Further studies with wider spectrum are needed to make specific suggestions.

Augmented Growth Hormone Secretion and Stat3 Phosphorylation in an Aryl Hydrocarbon Receptor Interacting Protein (AIP)-Disrupted Somatotroph Cell Line.

Aryl hydrocarbon receptor interacting protein (AIP) is thought to be a tumor suppressor gene, as indicated by a mutational analysis of pituitary somatotroph adenomas. However, the physiological significance of AIP inactivation in somatotroph cells remains unclear. Using CRISPR/Cas9, we identified a GH3 cell clone (termed GH3-FTY) in which Aip was genetically disrupted, and subsequently investigated its character with respect to growth hormone (Gh) synthesis and proliferation. Compared with GH3, GH3-FTY cells showed remarkably increased Gh production and a slight increase in cell proliferation. Gh-induced Stat3 phosphorylation is known to be a mechanism of Gh oversecretion in GH3. Interestingly, phosphorylated-Stat3 expression in GH3-FTY cells was increased more compared with GH3 cells, suggesting a stronger drive for this mechanism in GH3-FTY. The phenotypes of GH3-FTY concerning Gh overproduction, cell proliferation, and increased Stat3 phosphorylation were significantly reversed by the exogenous expression of Aip. GH3-FTY cells were less sensitive to somatostatin than GH3 cells in the suppression of cell proliferation, which might be associated with the reduced expression of somatostatin receptor type 2. GH3-FTY xenografts in BALB/c nude mice (GH3-FTY mice) formed more mitotic somatotroph tumors than GH3 xenografts (GH3 mice), as also evidenced by increased Ki67 scores. GH3-FTY mice were also much larger and had significantly higher plasma Gh levels than GH3 mice. Furthermore, GH3-FTY mice showed relative insulin resistance compared with GH3 mice. In conclusion, we established a somatotroph cell line, GH3-FTY, which possessed prominent Gh secretion and mitotic features associated with the disruption of Aip.

"Micromegaly": an update on the prevalence of acromegaly with apparently normal GH secretion in the modern era.

Approximately 25% of cases of clinically active acromegaly cases treated in our academic center between 1996 and 2000, were diagnosed in patients who had elevated plasma IGF-1 levels, but apparently "normal" 24-h mean plasma GH levels. The current study served to update the data for patients with acromegaly referred to our facility, after increasing awareness of this "normal" GH subpopulation throughout the medical community. A retrospective chart review was conducted on 157 patients with acromegaly who underwent resection of a confirmed somatotroph pituitary adenoma at the University of Michigan Health System between the dates of 1 Jan 2001 to 23 Sept 2015. Overall prevalence of acromegalic patients with "normal" GH levels, defined as GH <4.7ng/mL, was 31%. Over time, the percentage of patients with "normal" GH at diagnosis did not decline: 26% from 2001 to 2005, 19% from 2006 to 2010, and 47% from 2011 to 2015. Mean pituitary tumor size was 1.8±0.1cm for the group with elevated GH, and 1.2±0.1cm for the group with "normal" GH (p<0.001). Percent microadenomas was higher in a group with "normal" GH as compared to those with elevated GH (48 vs. 12%, p<0.001), and tumors >2cm in the maximal diameter were encountered more frequently in the group with elevated GH (43 vs. 14%, p<0.001). Our data show that a substantial percentage of patients with clinical acromegaly have "normal" GH, and therefore strengthens the growing body of evidence which supports the leading role of IGF-1 levels in diagnostic evaluation. At the present time, questions about the natural course of "micromegaly" and treatment benefits compared to the subpopulation with elevated GH levels remain unanswered, but research continues to build on our understanding of the heterogeneous population of individuals.

Incubation temperature alters thermal preference and response to heat stress of broiler chickens along the rearing phase

The current study aimed to investigate whether embryonic temperature manipulation may alter thermal preference throughout the rearing phase of broiler chickens and how this manipulation may affect response to thermal challenge, metabolism, growth rate and feed intake rate. Eggs were exposed to a constant incubation temperature [machine temperatures: 36°C (Low), 37.5°C (Control), and 39°C (High); eggshell temperature of 37.4 ± 0.08°C, 37.8 ± 0.15°C, and 38.8± 0.33°C, respectively] from d 13 till hatching. Low treatment chickens showed lower plasma T3 and GH levels at d 1 of age and lower T3 level at d 42 of age compared to the Control treatment. Preferred ambient, rectal temperature, T4 level, growth rate, food intake rate, and response to thermal challenge were not altered in these chickens. On the other hand, High-treatment chickens exhibited high preferred ambient temperature and rectal temperature during the first 2 wk post-hatch, lower plasma T3 level at d 21 and 42 and a delayed increase in respiratory movement in response to thermal challenge compared to the Control treatment. However, chickens subjected to the Control and High treatments did not differ in T4 and GH level and performance. We conclude that exposure to high temperature during late embryonic development has long-lasting effects on the thermoregulatory system of broiler chickens by affecting the heat tolerance of these chickens. Moreover, the preferred ambient temperature of the chickens from heat-treated eggs correspond to those recommended for the strain under study, whereas for the cold-treated and control-chickens it was 1°C below, indicating that incubation temperature might have consequences on the ambient temperature chickens require during the rearing phase.

Laron Syndrome: Siblings with Extreme Short Stature and Very High Growth Hormone

Primary growth hormone resistance or growth hormone insensitivity syndrome (GHIS), also known as Laron syndrome, is a hereditary disease caused by deletions or different types of mutations in the growth hormone receptor gene or by post-receptor defects. This disorder is characterized by a clinical appearance attributable to severe growth hormone deficiency with high levels of circulating growth hormone in contrast to low serum insulin-like growth factor-1 (IGF-1) and low serum insulin-like growth factor binding protein (IGFBP-3)values. It is an autosomal recessive disorder and to date, more than 70 unique growth hormone receptor (GHR) mutations have been identified in more than 250 GHIS patients. We report the case of an 8-year-old boy and his 12-year-old sister born to first cousin parent that presented with severe short stature who had the classic feature of GH deficiency. Investigations revealed high plasma GH levels in both the cases. Subsequently, IGF-1 and IGFBP-3 assay were done and the levels were found to be very low. These reports along with elevated GH level in the context of typical picture of GH deficiency confirmed the diagnosis of GHIS. Genetic testing could not be done because of unavailability in our context. Regrettably specific therapy in the form of recombinant IGF-1 could not be offered as it is not commercially available in our country.

Effects of antioxidant system on coronary artery lesions in patients with abnormal glucose metabolism.

To evaluate the effects of catalase (CAT), superoxide dismutase (SOD), and glutathione (GSH) system on the range and severity of coronary artery lesions in patients with abnormal glucose metabolism. This study included 766 patients with abnormal glucose metabolism. Levels of fasting blood lipids, blood glucose, CAT, SOD, GSH, glutathione reductase (GR), and glutathione peroxidase (GSH-Px) were measured in all the patients. Coronarography was performed, and the degree of the lesions in each coronary artery was quantitatively analyzed using the Gensini scoring system. In patients with impaired glucose regulation and diabetes, the number of coronary artery branches with stenosis and the Gensini scores were inversely correlated with the plasma levels of CAT, SOD, GSH, GH, and GSH-Px (P<0.001). Patients were grouped according to the Gensini scores. As the scores increased, the levels of CAT, SOD, GSH, GSH-Px, and GR gradually decreased. Logistic gradual regression analysis showed that GSH-Px and CAT were independent risk factors associated with the coronary artery lesions in three or more branches. Decreased plasma levels of CAT, SOD, GSH, GR, and GSH-Px were inversely correlated, at least to some extent, with the extent of coronary artery lesions. Particularly, GSH-Px and CAT were independent risk factors associated with coronary artery lesions involving three or more branches. This suggests that long-term hyperglycemia leads to enhancement of oxidative stress.

Long-lived hypopituitary Ames dwarf mice are resistant to the detrimental effects of high-fat diet on metabolic function and energy expenditure.

SummaryGrowth hormone (GH) signaling stimulates the production of IGF‐1; however, increased GH signaling may induce insulin resistance and can reduce life expectancy in both mice and humans. Interestingly, disruption of GH signaling by reducing plasma GH levels significantly improves health span and extends lifespan in mice, as observed in Ames dwarf mice. In addition, these mice have increased adiposity, yet are more insulin sensitive compared to control mice. Metabolic stressors such as high‐fat diet (HFD) promote obesity and may alter longevity through the GH signaling pathway. Therefore, our objective was to investigate the effects of a HFD (metabolic stressor) on genetic mechanisms that regulate metabolism during aging. We show that Ames dwarf mice fed HFD for 12 weeks had an increase in subcutaneous and visceral adiposity as a result of diet‐induced obesity, yet are more insulin sensitive and have higher levels of adiponectin compared to control mice fed HFD. Furthermore, energy expenditure was higher in Ames dwarf mice fed HFD than in control mice fed HFD. Additionally, we show that transplant of epididymal white adipose tissue (eWAT) from Ames dwarf mice fed HFD into control mice fed HFD improves their insulin sensitivity. We conclude that Ames dwarf mice are resistant to the detrimental metabolic effects of HFD and that visceral adipose tissue of Ames dwarf mice improves insulin sensitivity in control mice fed HFD.

Effects of dietary genistein on GH/IGF-I axis of Nile tilapia Oreochromis niloticus

There is considerable concern that isoflavones, such as genistein in fish feed composed of soybean protein, aff ects somatic growth in fish. Our previous works demonstrated that 30 and 300 μg/g dietary genistein had no significant eff ect on growth performance in Nile tilapia (Oreochromis niloticus), but the higher level of genistein (3 000 μg/g) significantly depressed growth. This study was conducted to further examine the eff ects of dietary genistein on the endocrine disruption on growth hormone/insulin-like growth factor-I (GH/IGF-I) axis in Nile tilapia (O. niloticus). Juvenile fish were fed by hand twice daily to satiation with one of four isonitrogenous and isoenergetic diets, each containing either 0, 30, 300 or 3 000 μg/g genistein. Following an 8-week feeding period, plasma GH and IGF-I levels were investigated by radioimmunoassay and gene expression levels of gh, ghrelin, gnrhs, ghr, npy, npyrs, pacap, ghrs, igf-I, igf-Ir, and igfbp3 were examined by real-time PCR. The results show that no significant change in plasma GH and IGF-I levels in fish fed with diets containing 30 μg/g and 300 μg/g genistein. mRNA expression of genes along the GH/IGF-I axis remained unaff ected, except for igf-Ir, which was stimulated by the 300 μg/g genistein diet. While in fish fed the 3 000 μg/g genistein diet, the plasma GH and IGF-I levels decreased, and mRNA expression of gh, ghr2, npyr1, igf-I, and igf-Ir were also significantly depressed. In contrast, npy and igfbp3 mRNA expression were enhanced. This study provides convincing evidence for growth impediment by genistein by disturbing the GH/IGF-I axis in Nile tilapia O. niloticus.

Effects of nonylphenol on key hormonal balances and histopathology of the endangered Caspian brown trout (Salmo trutta caspius)

Endocrine disruptor chemicals (EDCs) potentially pose a hazard to endangered species. Evaluation of the sensitivity of these species to EDCs could be helpful for protecting their populations. So, the present study investigated the adverse effects of nonylphenol, an EDC, on the endocrine hormones and histopathology of male and female juvenile Caspian brown trout (Salmo trutta caspius) following 21days of exposure to nominal concentrations of 1, 10 and 100μg/l. The results showed that the HSI and plasma total calcium of male and female fishes exposed to 100μg/l nonylphenol were significantly increased compared with the control groups (P<0.001). The male plasma T3 level was significantly decreased in 10 (P<0.01) and 100 (P<0.001) μg/l nonylphenol. The female T3 level increased in 1μg/l nonylphenol concentration (P<0.05). The plasma T4 of males showed significant elevation in fishes exposed to 100μg/l nonylphenol (P<0.05), but no change for females in any of treatment groups relative to controls (P>0.05). No significant effect of nonylphenol exposure was observed on male plasma TSH levels (P>0.05), whereas, in females, nonylphenol at all concentrations significantly reduced TSH levels. A bell-shaped response was observed in male and female plasma GH levels. Moreover, various histopathological lesions were observed in gill and intestine tissues of fishes exposed to different nonylphenol concentrations. These results demonstrate the high sensitivity of this endangered species to even environmentally relevant concentrations of nonylphenol. Furthermore, Caspian brown trout could be used as bioindicators reflecting the toxicity of nonylphenol.

Intensive rearing of male calves during the first three weeks of life has long-term effects on number of islets of Langerhans and insulin stained area in the pancreas.

Permanent effects of early postnatal nutrition on the development and function of tissues and organs have been previously demonstrated primarily in humans and rodents. The objective of this study in calves was to analyze the impact of rearing conditions during the first 3 wk of life on morphology of insulin-producing pancreatic β-cells. Forty-two male Holstein calves were raised during the first 3 wk of life either intensively (intensively reared [INT]; ad libitum milk feeding and individual hutches; = 21) or according to an established restrictive rearing protocol (4 L milk/d) during wk 1 in hutches and 720 g/d milk replacer (MR) from d 8 to 21 in group pens (restrictively reared [CON]; = 21). Thereafter, all calves were housed and fed under comparable conditions. Birth weight and weekly BW up to wk 10 were recorded. Plasma glucose, insulin, IGF-1, and GH levels were assessed in wk 1, 2, 3, and 10 of life. Slaughtering took place after 8 mo and pancreatic tissue from the medium body (corpus pancreatic) was removed. The number of islets of Langerhans and the insulin stained area were examined histologically. Total milk intake of INT calves was nearly double the intake in CON calves in the first 3 wk of life ( < 0.01). Daily starter intake during wk 4 to 10 of life did not differ between groups ( = 0.24). During the first 3 wk, the ADG were up to 9 times higher in INT calves compared to CON calves ( < 0.01), yet BW at time of slaughter did not differ ( = 0.18). Intensive rearing led to increased plasma glucose, insulin, and IGF-1 concentrations after 3 wk of life compared with rearing to the established standard protocol (all < 0.05), whereas GH was lower in INT calves during the second week of life. At time of slaughter, the mean number of islets of Langerhans was higher in INT calves compared to CON calves (9.1 ± 0.3 vs. 7.8 ± 0.3; < 0.01). Also, the total insulin stained area per photograph was higher in INT calves compared to CON calves (107,180 ± 4,987 vs. 84,249 ± 4,962 μm; < 0.01). Number of islets of Langerhans was negatively associated with birth weight but positively correlated with insulin and in trend with IGF-1 plasma levels during the second week of life. Insulin stained area tended to be linked with IGF-1 concentration during the third week of life. In conclusion, differences in the morphology of pancreatic islets of Langerhans indicate that calves can be programmed metabolically by an altered postnatal rearing intensity.

Role of hormonal levels on hospital mortality for male patients with severe traumatic brain injury

Introduction: Changes in hormone blood levels during the acute phase of traumatic brain injury (TBI) have been described in the literature. The objective was to investigate the association among several hormones plasma levels in the acute phase of severe TBI and the hospital mortality rate of male patients.Methods: The independent association among plasma levels of TSH, LH, FSH, GH, free T4, cortisol, IGF-1 and total testosterone was measured 10 hours and 30 hours after severe TBI and the hospital mortality of 60 consecutive male patients was evaluated.Results: At least one hormonal level abnormality was demonstrated in 3.6–73.1% of patients. The multiple logistic regressions showed a trend for an independent association among hospital mortality and normal or elevated LH levels measured at 10 hours (OR = 3.7, 95% CI = 0.8–16.3, p = 0.08) and 30 hours (OR = 3.9, 95% CI = 0.9–16.7, p = 0.06). Admission with abnormal pupils and a lower Glasgow Coma Score also were independently associated with hospital mortality.Conclusion: The hormonal changes are frequent in the acute phase of severe TBI. The hormones plasma levels, excepting the LH, are not highly consistent with the hospital mortality of male patients.

Growth and endocrine effect of growth hormone transgene dosage in diploid and triploid coho salmon

Growth-hormone transgene dosage, polyploidy, and parental effects on growth and endocrine responses have been assessed in coho salmon. Diploid fry with one or two transgene doses grew equally, whereas later-stage juvenile homozygotes grew faster than hemizygotes. In contrast, homozygotes and hemizygotes grew equally after smoltification, both in sea water and fresh water. Triploid transgenic salmon showed impaired growth which could not be fully overcome with additional transgene copies. Levels of muscle GH mRNA were elevated in two vs. one transgene dose diploids, but in triploids, a dosage effect was observed in muscle but not for animals carrying three transgene doses. IGF-I mRNA levels were elevated in transgenic vs. non-transgenic animals, but a dosage effect was not observed. Diploids and triploids with two transgenes had higher plasma GH levels than one-dose animals, but three-dose triploids showed no further elevation. Circulating IGF-I levels also showed a dosage effect in diploids, but not among any transgene doses in triploids. The present study reveals complex interactions among transgene dosage, maternal effects, developmental stage, and ploidy on growth and endocrine parameters in GH transgenic coho salmon. Specifically, GH transgenes do not always express nor have effects on growth that are directly correlated with the number of transgenes. Further, the reduced growth rate seen in triploid transgenic animals could not be fully overcome by increasing transgene dosage. The findings have relevance for understanding growth physiology, transgene function, and for environmental risk assessments that require understanding phenotypes of hemizygous vs. homozygous transgenic animals in populations.

Hypothalamic and Pituitary Clusterin Modulates Neurohormonal Responses to Stress

Clusterin is a sulfated glycoprotein abundantly expressed in the pituitary gland and hypothalamus of mammals. However, its physiological role in neuroendocrine function is largely unknown. In the present study, we investigated the effects of intracerebroventricular (ICV) administration of clusterin on plasma pituitary hormone levels in normal rats. Single ICV injection of clusterin provoked neurohormonal changes seen under acute stress condition: increased plasma adrenocorticotropic hormone (ACTH), corticosterone, GH and prolactin levels and decreased LH and FSH levels. Consistently, hypothalamic and pituitary clusterin expression levels were upregulated following a restraint stress, suggesting an involvement of endogenous clusterin in stress-induced neurohormonal changes. In the pituitary intermediate lobe, clusterin was coexpressed with proopiomelanocortin (POMC), a precursor of ACTH. Treatment of clusterin in POMC expressing AtT-20 pituitary cells increased basal and corticotropin-releasing hormone (CRH)-stimulated POMC promoter activities and intracellular cAMP levels. Furthermore, clusterin treatment triggered ACTH secretion from AtT-20 cells in a CRH-dependent manner, indicating that increased clusterin under stressful conditions may augment CRH-stimulated ACTH production and release. In summary, hypothalamic and pituitary clusterin may function as a modulator of neurohormonal responses under stressful conditions.

Tumors, IGF-2, and Hypoglycemia: Insights From the Clinic, the Laboratory, and the Historical Archive

Tumors of mesenchymal and epithelial origin produce IGF-2, which activates pathways in the tumors. In a minority of patients, the tumors (hepatomas, fibromas, and fibrosarcomas are the most common among many) release into the circulation enough IGF-2-related peptides to mimic the fasting hypoglycemia characteristic of patients with insulin-producing islet-cell tumors. Rarely, markedly elevated IGF-2 levels produce somatic changes suggestive of acromegaly. Typically, the elevated IGF-2 levels are associated with suppressed plasma levels of insulin, IGF-1, and GH. Complicating the pathophysiology are the IGF binding proteins (IGFBPs) that can bind IGF-2 and IGF-1, modifying hormone metabolism and action. IGFBP concentrations are often altered in the presence of these tumors. At the cellular level, the 3 hormone-related ligands, IGF-2, IGF-1, and insulin, all bind to 4 (or more) types of IGF-1 receptor (IGF-1R) and insulin receptor (IR). Each receptor has its own characteristic affinity for each ligand, a tyrosine kinase, and overlapping profiles of action in the target cells. The IGF-2R, in addition to binding mannose-6-phosphate-containing proteins, provides an IGF-2 degradation pathway. Recent evidence suggests IGF-2R involvement also in signal transduction. Surgery, the treatment of choice, can produce a cure. For patients not cured by surgery, multiple therapies exist, for the tumor and for hypoglycemia. Potential future therapeutic approaches are sketched. From 1910 to 1930, hypoglycemia, insulin, insulinomas, and non-islet-cell tumors were recognized. The latter third of the century witnessed the emergence of the immunoassay for insulin; the IGFs, their binding proteins, and assays to measure them; and receptors for the insulin-related peptides as well as the intracellular pathways beyond the receptor. In closing, we replace non-islet-cell tumor hypoglycemia, an outdated and misleading label, with IGF-2-oma, self-explanatory and consistent with names of other hormone-secreting tumors.

Submaximal cycling exercise stimulates mTOR signaling pathway in human skeletal muscle

It is known that eccentric muscle contraction promotes muscle protein synthesis. However, effects of concentric contraction on muscle protein synthesis are not clear. We determined whether high repetition of concentric contraction by cycling exercise stimulates mTOR signaling pathway in human skeletal muscle. Six young subjects (21±1 years) performed 90% VO2max cycling exercise at 90rpm for 5 minutes on bicycle ergometer. Muscle biopsies (vastus lateralis) were obtained before exercise and, at 1 and 3 h post‐exercise. mTOR signaling and markers of autophagy (LC3BI and LC3BII protein) were analyzed by using western blotting. Plasma GH, IGF‐1 and insulin levels significantly increased in post‐exercise period (p&lt;0.05). Akt phosphorylation, upstream of mTOR, significantly increased at 1 h post‐exercise (p&lt;0.05). S6K1 phosphorylation, a marker of mTOR activity, significantly increased at 3 h post‐exercise (p&lt;0.05). At the same time point, LC3BII to I ratio were significantly decreased (p&lt;0.05). These data suggest that high repetition of concentric contraction such as cycling exercise can stimulate mTOR signaling in human skeletal muscle, which might leads to promotion of protein synthesis and attenuation of autophagic protein degradation.This study was partly supported by the Sasakawa Scientific Research Grant from the Japan Science Society, and a Grant‐in‐Aid for Young Scientists (B) No. 24700703.

The Effect of a Short Sprint on Postexercise Whole-Body Glucose Production and Utilization Rates in Individuals with Type 1 Diabetes Mellitus

Recently we showed that a 10-sec maximal sprint effort performed before or after moderate intensity exercise can prevent early hypoglycemia during recovery in individuals with type 1 diabetes mellitus (T1DM). However, the mechanisms underlying this protective effect of sprinting are still unknown. The objective of the study was to test the hypothesis that short duration sprinting increases blood glucose levels via a disproportionate increase in glucose rate of appearance (Ra) relative to glucose rate of disappearance (Rd). SUBJECTS AND EXPERIMENTAL DESIGN: Eight T1DM participants were subjected to a euglycemic-euinsulinemic clamp and, together with nondiabetic participants, were infused with [6,6-(2)H]glucose before sprinting for 10 sec and allowed to recover for 2 h. In response to sprinting, blood glucose levels increased by 1.2 ± 0.2 mmol/liter (P < 0.05) within 30 min of recovery in T1DM participants and remained stable afterward, whereas glycemia rose by only 0.40 ± 0.05 mmol/liter in the nondiabetic group. During recovery, glucose Ra did not change in both groups (P > 0.05), but glucose Rd in the nondiabetic and diabetic participants fell rapidly after exercise before returning within 30 min to preexercise levels. After sprinting, the levels of plasma epinephrine, norepinephrine, and GH rose transiently in both experimental groups (P < 0.05). A sprint as short as 10 sec can increase plasma glucose levels in nondiabetic and T1DM individuals, with this rise resulting from a transient decline in glucose Rd rather than from a disproportionate rise in glucose Ra relative to glucose Rd as reported with intense aerobic exercise.

465P - The Preclinical Pharmacological Profile of Anamorelin/Ono-7643, A New Ghrelin Receptor Agonist for the Treatment of Cancer Cachexia

ABSTRACT Introduction Ghrelin is the only known circulating orexigenic hormone which acts as the endogenous ligand for the ghrelin receptor (GRLN), and is considered a potential agent to treat cancer cachexia/anorexia. The aim of this study was to evaluate the in vitro and in vivo pharmacological activities of Anamorelin/ONO-7643 (ANA), a new synthetic ghrelin receptor agonist, on food intake (FI), body weight (BW) and GH in rats. Material and methods HEK293 cells expressing human recombinant ghrelin receptor were utilized in a Fluorescent Imaging Plate Reader (FLIPR), along with Fluo-8 dye to signal intracellular calcium. Ghrelin and ANA were incubated (0.001-1000 nM) to generate a concentration-response increase of Ca++. Binding experiments were also performed by using [125I]Ghrelin. In vivo experiments were performed on male SD rats after oral treatment of ANA or vehicle. FI and BW were measured daily from Day 1 up to Day 7 of once-daily treatment. In other experiments, blood samples were collected at different time interval up to 6 hours post single dose for GH measurements. Results Ghrelin and ANA showed a significant agonist activity on the ghrelin receptor in the FLIPR assay, with EC50 values of 0.67 nM and 0.74 nM, respectively. No significant antagonist activity was observed with ANA up to 1000 nM. In binding experiments, the affinity of ghrelin and ANA for ghrelin receptors were evaluated and resulted in a Ki of0.58 nM and 0.70 nM, respectively. In the in vivo experiments, ANA (3, 10, 30 mg/kg p.o.) significantly (p Conclusions Anamorelin is a potent ghrelin agonist endowed with significant orexigenic activity demonstrating both an increase of FI and BW after subchronic treatment in rats. Plasma GH levels were increased after a single administration of ANA. These results support the continued investigation of Anamorelin as a potential treatment of cancer cachexia/anorexia. Disclosure C. Pietra: Employee of Helsinn SA. Y. Takeda: Ono employee. N. Tazawa-Ogata: ONO employee. M. Minami: ONO Employee. E. Duus: Helsinn Therapeutics employee. R. Northrup: Helsinntheraputics employee. All other authors have declared no conflicts of interest.