Serum Growth Hormone Concentrations Research Articles

Insulin Reverses Growth Hormone-induced Homologous Desensitization

Growth hormone (GH) is secreted in a pulsatile pattern to promote body growth and metabolism. GH exerts its function by activating several signaling pathways, including JAK2/STAT and MEK/ERK. ERK1/2 activation by GH plays important roles in gene expression, cell proliferation, and growth. We previously reported that in rat H4IIE hepatoma cells after an initial GH exposure, a second GH exposure induces STAT5 phosphorylation but not ERK1/2 phosphorylation (Ji, S., Frank, S. J., and Messina, J. L. (2002) J. Biol. Chem. 277, 28384-28393). In this study the mechanisms underlying GH-induced homologous desensitization were investigated. A second GH exposure activated the signaling intermediates upstream of MEK/ERK, including JAK2, Ras, and Raf-1. This correlated with recovery of GH receptor levels, but was insufficient for GH-induced phosphorylation of MEK1/2 and ERK1/2. Insulin restored the ability of a second GH exposure to induce phosphorylation of MEK1/2 and ERK1/2 without altering GH receptor levels or GH-induced phosphorylation/activation of JAK2 and Raf-1. GH and insulin synergized in promoting cell proliferation. Further investigation suggested that insulin increased the amount of MEK bound to KSR (kinase suppressor of Ras) and restored GH-induced tyrosine phosphorylation of KSR. Previous GH exposure also induced desensitization of STAT1 and STAT3 phosphorylation, but this desensitization was not reversed by insulin. Thus, insulin-regulated resensitization of GH signaling may be necessary to reset the complete response to GH after a normal, physiologic pulse of GH.

Effect of ghrelin in dry matter intake and energy metabolism in prepartum sheep: A preliminary study

The objective of this study was to determine the effect of ghrelin on dry matter intake and energy metabolites in ewes during the last 10 d of gestation. Ewes were randomly assigned to either a treatment ( n = 6) or a control group ( n = 6). One hour after feeding (08:00 and 16:00), ewes in the treated group were given ovine ghrelin (3 μg/kg, i.m.) and the control group received an equivalent volume of saline. Treatments were continued until lambing. Daily blood samples were taken starting at assignment. The principal findings were that: (1) ewes treated with ghrelin had a higher dry matter intake only on the first day of treatment; (2) treated ewes had lower serum concentrations of non-esterified fatty acids and insulin but higher serum concentrations of growth hormone; (3) serum concentrations of β-hydroxy butyrate and cortisol were not different between treated and non-treated ewes. In conclusion, treatment with ghrelin affected dry matter intake and energy metabolites of pre-partum ewes during the last 10 d of pregnancy.

Comparative Pharmacokinetics and Pharmacodynamics of a New Sustained-Release Growth Hormone (GH), LB03002,VersusDaily GH in Adults with GH Deficiency

LB03002 is a novel sustained-release GH preparation administered once weekly. Our objective was to examine the pharmacokinetics, pharmacodynamics, and safety of LB03002 vs. daily GH. This open-label, crossover study compared the pharmacokinetics and pharmacodynamics of LB03002 and daily GH. Six male and three female patients with adult GH deficiency participated in the single-center study. Subjects were on stable daily GH treatment before the study. After a 4-wk washout with no GH, five weekly doses of LB03002 were given. GH and IGF-I concentrations were measured during the last dose of daily GH and during the first and fifth weekly doses of LB03002. The observed maximal serum GH concentration was approximately doubled after LB03002 (6.1 +/- 3.2 and 4.5 +/- 2.2 microg/liter at first and fifth doses) compared with daily GH (2.7 +/- 2.2 microg/liter). A sustained increase in GH concentration for more than 48 h was observed with LB03002, such that dose-normalized area under the curve (AUC) was not significantly different between daily GH and LB03002. Mean maximal serum IGF-I concentration was 34-41% greater with LB03002 than with daily GH, and AUC was 7-fold greater. However, normalized to GH dose, AUC for IGF-I was comparable. Adverse events and local reactions were acceptable, and there were no evident safety concerns with LB03002. Multiple weekly doses of LB03002 appeared safe and well tolerated. Comparable GH bioavailability and sustained IGF-I elevations support the use of once-weekly LB03002 to replace daily GH therapy.

Effect of Sex and Assay Method on Serum Concentrations of Growth Hormone in Patients with Acromegaly and in Healthy Controls

Diagnosis and follow-up of acromegaly is based on measurements of serum growth hormone (GH) concentrations during an oral glucose tolerance test (OGTT). A nadir value <1 microg/L is commonly used to define a normal response, but some authors suggest lower cutoff values. To compare the results and subsequent patient classification obtained with 3 GH assays, we obtained basal serum samples from 78 apparently healthy adult controls (43 women and 35 men; median age, 32.5 years) and from 71 treated (44 women and 27 men; median age, 55.2 years) and 7 untreated acromegaly patients (4 women and 3 men; median age, 54.6 years), and OGTT was performed on all patients and on 72 of the 78 controls. GH was determined by 2 immunometric assays-a double monoclonal (AutoDELFIA; Wallac) and a monopolyclonal (Immulite 2000; DPC) assay-and in a limited set of samples by an RIA (Spectria RIA; Orion). There was a strong correlation (r = 0.995; P < 0.001) between the 2 immunometric methods, but the results obtained with the Immulite 2000 were, on average, 1.4-fold higher than those obtained with the AutoDELFIA. At concentrations around the cutoff (1 microg/L), however, the difference was approximately 2-fold. Overall, the Orion RIA method also showed a good correlation (r = 0.951-0.959) with the other methods, but it did not measure concentrations <2 microg/L. Women had higher basal and OGTT nadir GH concentrations than men. Reference intervals should be determined separately for each method, and the need for establishing sex-specific reference values should be investigated.

Acromegaly due to a somatroph adenoma in a dog

A 10-year-old uncastrated male Dalmatian dog was referred for gait abnormalities consisting of chronic progressive stiffness and rigidity. Other symptoms were polyphagia associated with weight gain, polyuria and polydipsia, excessive panting, and an inspiratory stridor. The owner had noticed progressive thickening of the skin and enlargement of the tongue over the last 3 years. Physical examination revealed thickening of the skin, redundant skin folds, and enlargement of the tongue. The only remarkable abnormalities found on routine laboratory examination were mild anaemia and an increased serum fructosamine concentration. Circulating concentrations of total thyroxine, free thyroxine, and cTSH, and the results of an ACTH stimulation test were all within reference ranges. The basal serum growth hormone (GH) concentration was markedly elevated (23 μg/l) and did not decrease during a glucose tolerance test or after somatostatin administration. The serum insulin-like growth factor-1 concentration was also markedly elevated (1254 μg/l). Basal serum insulin concentration was high (95 mU/l) and insulin concentrations increased considerably after glucose loading, consistent with insulin resistance. Abdominal ultrasonography showed no abnormalities. Survey radiographs of the vertebral column showed severe spondylosis deformans extending from the cervical to the lumbosacral spine. CT scanning of the skull showed an enlarged pituitary gland with normal enhancement pattern. On post-mortem examination, the entire vertebral column appeared as a single and inflexible structure due to the presence of multiple fused osteophytes. The pituitary gland contained an acidophilic adenoma that immunostained positively for GH (and negatively for ACTH and alpha-MSH). In conclusion, this Dalmatian dog with acromegaly and insulin resistance represents the first case of GH hypersecretion proven to be due to a somatotroph adenoma.

Adaptive hormetic response of pre-exposure of mouse brain with low-dose 12C 6+ ion or 60Co γ-ray on growth hormone (GH) and body weight induced by subsequent high-dose irradiation

The brain of the Kun-Ming strain mice were irradiated with 0.05 Gy of 12C 6+ ion or 60Co γ-ray as the pre-exposure dose, and were then irradiated with 2 Gy of 12C 6+ ion or 60Co γ-ray as challenging irradiation dose at 4 h after per-exposure. Body weight and serum growth hormone (GH) concentration were measured at 35th day after irradiation. The results showed that irradiation of mouse brain with 2 Gy of 12C 6+ ion or 60Co γ-ray significantly diminished mouse body weight and level of serum GH. The relative biological effectiveness values of a 2 Gy dose of 12C 6+ ion calculated with respect to 60Co γ-ray were 1.47 and 1.34 for body weight and serum GH concentration, respectively. Pre-exposure with a low-dose (0.05 Gy) of 12C 6+ ion or 60Co γ-ray significantly alleviated reductions of mouse body weight and level of serum GH induced by a subsequent high-dose (2 Gy) irradiation. The data suggested that low-dose ionizing irradiation can induce adaptive hormetic responses to the harmful effects of pituitary by subsequent high-dose exposure.

Growth hormone response to graded exercise intensities is attenuated and the gender difference abolished in older adults

We investigated the joint impact of age, gender, and exercise intensity on growth hormone (GH) secretion. At a university center, nine young men, eight young women, seven older men, and six older women were each tested on six randomly ordered occasions [control (C) and 5 exercise conditions (Ex)]. Serum GH concentrations were measured by immunochemiluminometry [10-min samples: 0700-0900 (baseline); 0900-1300 (C or Ex + recovery)]. Integrated GH concentrations (IGHC) were calculated by trapezoidal reconstruction, and GH secretion was modeled by deconvolution analyses. Subjects exercised from 0900 to 0930 at graded intensities [standardized to individual lactate threshold (LT)] of 25 and 75% of the difference between rest and LT, LT, and 25 and 75% of the difference between LT and peak oxygen consumption. Data were analyzed via mixed-effects ANOVA for repeated measures with post hoc contrasts. We found that 1) Ex elevated IGHC above C in all four cohorts, 2) 1.75 LT Ex resulted in maximal IGHC, 3) IGHC differed by gender in young (women > men) but not older adults, 4) older adults secreted 50% less GH during graded exercise, 5) Ex selectively augmented the mass of GH secreted per burst, and 6) higher Ex + recovery IGHC in young women was due to higher baseline IGHC, rather than greater stimulated GH secretion. We conclude that young women manifest a greater absolute and incremental IGHC response to exercise than postmenopausal women and men of any age. Age diminishes the GH response to exercise and abolishes the young-adult gender difference. Attenuation of GH responses to all exercise intensities in older adults has implications for exercise prescription because higher exercise intensities may be required to stimulate GH release in older adults.

Pituitary hormones and systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is known for its predominant occurrence in women and for its peak incidence during the reproductive years. The increased ratio of female to male SLE patients implies that sex-associated genetic and/or endocrine factors modulate disease proclivity and development. While chromosome differences or sex-associated metabolic or environmental factors may underlie the predominant occurrence of SLE in women, no relationship with the disease has proven stronger than those of female sex and female/male differences in sex hormones. This concept has been supported not only by epidemiologic studies, but also by substantial evidence of the immunoregulatory actions of 17 -estradiol (estradiol), testosterone, progesterone, dehydroepiandrosterone (DHEA)/ DHEA sulfate, and prolactin (1–4). A recent review and meta-analysis of data examining sex hormone abnormalities in SLE patients revealed that female SLE patients had significantly depressed concentrations of androgens and elevated concentrations of estradiol compared not only with their male counterparts with SLE but also with healthy controls (5). In addition, both female and male SLE patients had abnormally elevated serum prolactin concentrations, and in male SLE patients, elevation of serum prolactin concentrations was the only sex hormone aberration clearly identified in meta-analyses (5). Elevated prolactin concentrations in SLE patients (4,5), regulation of sex steroids by pituitary gonadotropins (6,7), interdependence of neuroendocrine and immune systems (8), and effects of inflammatory cytokines on pituitary function (9,10) evoke the possibility that pituitary hormone abnormalities contribute to or synergize with the altered sex steroids contributing to SLE disease expression. Investigations of pituitary hormones in SLE have been relatively uniform in their enrollment of patients and appropriately matched healthy controls. However, small numbers of study participants, variability in interand intrastudy results, long time intervals over which comparisons have been reported, and absence of sufficient statistical power to test respective hypotheses have limited the conclusions and possibly obscured the identification of important relationships between SLE and pituitary hormonal immunomodulation. Furthermore, peptide hormone/steroid/cytokine feedback loops, hormonal interconversions (e.g., DHEA to testosterone and/or estradiol), and the superimposed hourly, daily, and monthly chronobiologic variations of menses, pregnancy, and/or hormone administration complicate a simple interpretation of these cause-and-effect relationships as well as successful application of hormonal immunotherapy. We review herein the investigations of adenohypophyseal hormones—follicle-stimulating hormone (FSH), luteinizing hormone (LH), adrenocorticotropic hormone (ACTH), thyroid-stimulating hormone (TSH), growth hormone (GH), and prolactin—in patients with SLE. These anterior pituitary hormones are peptides of various molecular weights that bind to surface receptors and stimulate a variety of actions (6,7). They can affect the immune system directly (11) or indirectly through their effects on the synthesis of sex steroids with immunomodulatory capacity (1–4). Moreover, manipulation of serum pituitary hormones has been shown to be immunoregulatory, especially in animal models (11–15). In order to better understand the associations between SLE, sex, and pituitary hormones, clinical studies measuring serum concentrations of FSH, LH, ACTH, TSH, and GH (as well as prolactin) in nonpregnant adult women and men with SLE were identified by a computSupported by the Mississippi Lupus Association. Jing Li, MD, Warren May, PhD, Robert W. McMurray, MD: University of Mississippi Medical Center, Jackson. Address correspondence and reprint requests to Robert W. McMurray, MD, Division of Rheumatology and Molecular Immunology, L525 Clinical Sciences Building, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216. E-mail: Robert.McMurray@medicine.umsmed.edu. Submitted for publication March 9, 2005; accepted in revised form August 25, 2005.

Growth hormone releasing hormone test for infertile men with spermatogenetic maturation arrest.

Growth hormone has an important role in the function of the male reproductive system. We investigated infertile men with impaired growth hormone secretion. Growth hormone status was studied in 8 fertile men and 9 infertile men with azoospermia due to spermatogenetic maturation arrest. Growth hormone releasing hormone, the specific stimulatory neurohormone, was used in the growth hormone stimulation test. A dose of 100 microg. of growth hormone releasing hormone was infused intravenously and serum growth hormone concentrations were measured at 0, 15, 30, 60, 90 and 120 minutes. Serum follicle-stimulating hormone, luteinizing hormone, prolactin, testosterone and estradiol were also measured before the test. Serum follicle-stimulating hormone concentrations were significantly increased in the azoospermic group and basal levels of growth hormone were similar to those in the control group. Serum growth hormone concentrations increased after injection of growth hormone releasing hormone and the levels of growth hormone peaked after 30 minutes in both groups. At time 30 minutes growth hormone levels had decreased significantly more in the azoospermic group than in the controls. Men with azoospermia due to spermatogenetic maturation arrest had a low response to the growth hormone releasing hormone test. Relative growth hormone insufficiency, which may be caused by reduced reactivity to growth hormone releasing hormone in pituitary growth hormone secretory cells, is strongly related to spermatogenic dysfunction.

Delayed Leukocytosis and Cytokine Response to High-Force Eccentric Exercise

Delayed leukocytosis after strenuous exercise is well documented, but the underlying mechanisms are not clear. In this study, we investigated the relationship between exercise-induced muscle damage and delayed leukocytosis, by utilizing an extreme eccentric exercise protocol. We obtained blood samples from 11 healthy men before and after 300 maximal eccentric actions with m. quadriceps. Maximal force-generating capacity was tested before and regularly during the 7 d after exercise. Blood was analyzed for leukocytes, growth hormone (GH), cortisol, granulocyte colony-stimulating factor (G-CSF), macrophage colony-stimulating factor (M-CSF), interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), macrophage inflammatory protein-1beta (MIP-1beta), creatine kinase (CK), C-reactive protein (CRP), complement activation products (C3bc and the terminal complement complex (TCC)), and chemotactic activity in plasma. The force-generating capacity was reduced by 47 +/- 5% (mean +/- SEM) immediately after exercise. Blood concentration of neutrophils and monocytes and the plasma concentration of G-CSF, IL-6, and MCP-1 peaked 6 h after exercise, whereas M-CSF peaked immediately after exercise. Serum concentration of GH and cortisol also peaked immediately after exercise, whereas the serum concentration of CRP and CK peaked after 2 and 4 d, respectively. At 1 h after exercise, chemotactic activity in plasma was increased; at the same time, concentration of C3bc and TCC were decreased. A positive correlation was found between the acute loss of force and the delayed leukocytosis (r = 0.66; P < 0.05), between peak G-CSF and the delayed neutrophilia (r = 0.65, P < 0.05), between acute loss of force and changes in CK (r = 0.65, P < 0.05), between acute loss of force and changes in CRP (r = 0.65, P < 0.05), and between changes in GH and monocyte blood concentrations (r = 0.68, P < 0.05). The degree of exercise-induced muscle damage seems to be reflected by the magnitude of the subsequent delayed leukocytosis. The signal between the exercised muscle and bone marrow must be investigated further, but G-CSF and GH are putative mobilizing factors.

Pubertal alterations in growth and body composition: IX. Altered spontaneous secretion and metabolic clearance of growth hormone in overweight youth

Deconvolution analysis was used to determine 12-hour spontaneous nocturnal growth hormone (GH) secretion and GH half-life in lean (body mass index, <85th percentile; n = 39) and overweight (body mass index, ≥85th percentile; n = 18) youth. The integrated GH concentration, GH burst mass, and half-life were lower ( P < .05) in overweight than in lean youth. For each unit increase in percentage of body fat, integrated serum GH concentrations, secretory burst mass, and half-life declined by 83.6 μg/L per minute ( r = −0.39, P < .01), 0.22 μg/L ( r = −0.28, P < .05), and 0.2 minute ( r = −0.38, P < .01), respectively. The effect of overweight on GH secretion was independent of pubertal status. Hierarchical regression models tested the hypothesis that altered GH secretion in youth is more related to total adiposity than abdominal visceral fat. When age, sex, fat-free mass, testosterone, and estradiol were held constant, the sequential addition of abdominal visceral fat did not increase R 2 for any GH secretion variable. Sequential addition of percentage of body fat increased R 2 ( P < .05) for integrated GH concentration, total secretory rate, secretory burst mass, and pulsatile production rate. We conclude that serum GH concentrations are reduced in overweight youth primarily because of reduced GH burst mass with no change in the number of secretory events and secondarily to reduced GH half-life. Based on the model that GH-releasing hormone predominantly increases GH pulse amplitude whereas somatostatin primarily controls GH pulse frequency, these results suggest that overweight in youth diminishes GH-releasing hormone stimulation resulting in truncated GH bursts but does not alter the number of somatostatin withdrawal intervals so that GH burst frequency is conserved.

Pharmacokinetics and population pharmacodynamic analysis of lanreotide Autogel

Somatostatin analogs are the first-line medical therapy for acromegaly, and the treatment of this disease has been simplified by the development of extended-release formulations of these analogs. Lanreotide is a somatostatin analog that is available either as the microparticle formulation, requiring 7- to 14-day dosing, or as the aqueous Autogel formulation, requiring 28-day dosing. This study investigated the pharmacokinetics and pharmacodynamics of lanreotide. Patients with acromegaly were given 5 injections of lanreotide microparticles, 30 mg, followed by 3 injections of lanreotide Autogel, at doses of 60, 90, or 120 mg every 28 days. The study was extended to a further 12 injections of lanreotide Autogel with dose titration. A total of 144 patients were recruited; 130 received 3 injections of lanreotide Autogel, and 130 completed the extension phase. Average minimum lanreotide concentrations ( C min) at steady state were 1.949 ± 0.619, 2.685 ± 0.783, and 3.575 ± 1.271 ng/mL for 60, 90, and 120 mg of lanreotide Autogel, respectively, showing a dose-proportional increase. Population pharmacodynamic analysis showed that the relationship between either formulation of lanreotide and serum growth hormone (GH) concentrations was best described using an inhibitory maximum response ( E max) model that allowed for the possibility of an incomplete inhibition of GH. Lanreotide elicited a maximum reduction in GH of 82%. Because patients were already being treated, baseline GH ( E 0) was estimated, and the value of 8.63 ng/mL was in agreement with the inclusion criteria of GH 10 ng/mL or less. The effectiveness of treatment was demonstrated by the median serum concentration of lanreotide, 1.13 ng/mL, required to lower GH to 2.5 ng/mL or less. The serum concentration that elicited half of the E max (EC 50) was estimated as 0.206 ng/mL, showing a high sensitivity to lanreotide, with a predictably high interpatient variability of 200.75% reflecting the range of dosing regimens needed to control GH.

No effect of growth hormone administration on substrate oxidation during exercise in young, lean men

The purpose of this study was to examine the effects of increased fat availability induced by growth hormone (GH) administration on the oxidative metabolism during exercise. Seven well-trained males (age 25 +/- 2 years (mean +/- S.E.M.); peak oxygen consumption : 62 +/- 1 ml min(-1) kg(-1) (completed four randomised trials: 120 min bicycling at 55% 4 h after receiving either 7.5 IU (2.5 mg) GH or placebo (Plc), and during rest after receiving either GH or Plc. In all studies a standardized meal was given 2 h after GH or Plc injection. GH administration resulted in an approximately 60-fold increase in serum GH concentration at rest (P < 0.0001) and during exercise (P < 0.0001). The increase in serum GH was followed by an increase in circulating glycerol at rest (8%, P < 0.0001). When combined with exercise the increase in plasma glycerol was more pronounced (GH: 716% of baseline versus Plc: 328%, P < 0.0001). However, this increase in fat mobilization did not increase fat oxidation during exercise (indirect calorimetry). In conclusion, GH administration combined with aerobic exercise increased lipolytic parameters substantially more than exercise alone, but did not further augment whole body fat oxidation.

Feline Acromegaly: A Review of the Syndrome

Acromegaly is characterized by chronic excessive growth hormone (GH) secretion by the pituitary gland. Feline acromegaly is most commonly caused by a functional pituitary tumor. Definitive diagnosis can be difficult because of the gradual disease onset, subtle clinical signs, unavailability of relevant laboratory tests, and client financial investment. The most significant clinical finding of acromegaly is the presence of insulin-resistant diabetes mellitus. Diagnosis is currently based upon brain imaging and measurement of serum GH and/or insulin-like growth factor-1 concentrations. Definitive treatment in cats is not well described, but radiation therapy appears promising.

Hemodynamic and hormonal responses to a short-term low-intensity resistance exercise with the reduction of muscle blood flow

We investigated the hemodynamic and hormonal responses to a short-term low-intensity resistance exercise (STLIRE) with the reduction of muscle blood flow. Eleven untrained men performed bilateral leg extension exercise under the reduction of muscle blood flow of the proximal end of both legs pressure-applied by a specially designed belt (a banding pressure of 1.3 times higher than resting systolic blood pressure, 160-180 mmHg), named as Kaatsu. The intensity of STLIRE was 20% of one repetition maximum. The subjects performed 30 repetitions, and after a 20-seconds rest, they performed three sets again until exhaustion. The superficial femoral arterial blood flow and hemodynamic parameters were measured by using the ultrasound and impedance cardiography. Serum concentrations of growth hormone (GH), vascular endothelial growth factor (VEGF), noradrenaline (NE), insulin-like growth factor (IGF)-1, ghrelin, and lactate were also measured. Under the conditions with Kaatsu, the arterial flow was reduced to about 30% of the control. STLIRE with Kaatsu significantly increased GH (0.11+/-0.03 to 8.6+/-1.1 ng/ml, P < 0.01), IGF-1 (210+/-40 to 236+/-56 ng/ml, P < 0.01), and VEGF (41+/-13 to 103+/-38 pg/ml, P < 0.05). The increase in GH was related to neither NE nor lactate, but the increase in VEGF was related to that in lactate (r = 0.57, P < 0.05). Ghrelin did not change during the exercise. The maximal heart rate (HR) and blood pressure (BP) in STLIRE with Kaatsu were higher than that without Kaatsu. Stroke volume (SV) was lower due to the decrease of the venous return by Kaatsu, but, total peripheral resistance (TPR) did not change significantly. These results suggest that STLIRE with Kaatsu significantly stimulates the exercise-induced GH, IGF, and VEGF responses with the reduction of cardiac preload during exercise, which may become a unique method for rehabilitation in patients with cardiovascular diseases.

Alterations in the lipid content of pituitary gland and serum prolactin and growth hormone in cadmium treated rats

The present study was undertaken to assess whether chronic exposition to cadmium (Cd, 0.133 mM per liter for 2 months) through drinking water may affect the lipid contents in the pituitary anterior lobe (PAL) of adult male Wistar rats. As compared to metal non-exposed controls, PALs exposed to cadmium showed an increase in total phospholipid contents, which was associated to an increase of the incorporation of [1-14C]-methyl choline into phosphatidylcholine and of [U-14C]-glucose into total phospholipids. The incorporation of [1-14C]-methyl choline into sphingomyelin was not changed. Incorporation of [1-14C]-acetate into total fatty acids also increased but incorporation of [1-14C]-acetate into cholesterol did not change. The activity of phospholipase D decreased both in PALs from Cd exposed rats and in PAL dispersed cells treated with Cd in the culture medium from Cd non-exposed rats. In PALS from Cd exposed rats, a decrease of serum prolactin and growth hormone concentrations was determined. The results shown that cadmium modifies the lipid contents of pituitary gland and directly or indirectly the levels of prolactin and growth hormone in serum.

Acute Hormonal Responses To Restriction Of Leg Muscle Blood Flow During Walking

Low-intensity resistance exercise (20% of one-repetition maximal) combined with restriction of muscle blood flow (namely KAATSU) increases plasma growth hormone (GH) concentration. In general, walking slowly has no effect on acute GH response. PURPOSE To examine the acute responses of serum GH, free testosterone, and cortisol to slow walking combined with KAATSU. METHODS 11 male college students performed walking (50 m/min for five 2 min bouts; 1 min rest between bouts) with and without KAATSU (the proximal end of their thigh compressed at 130% of resting systolic blood pressure throughout the walking session) on separate days. Venous blood samples were obtained prior to the start of exercise (Pre), and immediately (IP), 15- (15P) and 60-min (60P) after exercise. RESULTS Serum GH concentration was elevated (P<0.01) from Pre [1.72 (0.83) ng/ml] to IP [12.4 (3.2) ng/ml] and 15P [13.1 (2.4) ng/ml] in the walking with KAATSU. Free testosterone was also elevated (P<0.05) from Pre [12.7 (1.2) pg/ml] to IP [16.0 (1.3) pg/ml] in the walking with KAATSU. Neither GH [Pre, 1.67 (0.97) ng/ml; IP, 1.39 (0.91), 15P, 1.26 (0.92)] nor free testosterone [Pre, 14.3 (1.3) pg/ml; IP, 14.1 (1.2)] increased during the walking without KAATSU. Cortisol concentration showed a gradual decrease (P<0.05) during the experiments in both walking with and without KAATSU. CONCLUSIONS The results of the present investigation with young male students indicated that slow walking with KAATSU caused greater responses in serum GH and free testosterone compared to normal slow walking.

Acute Hormonal Responses To Restriction Of Leg Muscle Blood Flow During Walking

Low-intensity resistance exercise (20% of one-repetition maximal) combined with restriction of muscle blood flow (namely KAATSU) increases plasma growth hormone (GH) concentration. In general, walking slowly has no effect on acute GH response. PURPOSE To examine the acute responses of serum GH, free testosterone, and cortisol to slow walking combined with KAATSU. METHODS 11 male college students performed walking (50 m/min for five 2 min bouts; 1 min rest between bouts) with and without KAATSU (the proximal end of their thigh compressed at 130% of resting systolic blood pressure throughout the walking session) on separate days. Venous blood samples were obtained prior to the start of exercise (Pre), and immediately (IP), 15- (15P) and 60-min (60P) after exercise. RESULTS Serum GH concentration was elevated (P<0.01) from Pre [1.72 (0.83) ng/ml] to IP [12.4 (3.2) ng/ml] and 15P [13.1 (2.4) ng/ml] in the walking with KAATSU. Free testosterone was also elevated (P<0.05) from Pre [12.7 (1.2) pg/ml] to IP [16.0 (1.3) pg/ml] in the walking with KAATSU. Neither GH [Pre, 1.67 (0.97) ng/ml; IP, 1.39 (0.91), 15P, 1.26 (0.92)] nor free testosterone [Pre, 14.3 (1.3) pg/ml; IP, 14.1 (1.2)] increased during the walking without KAATSU. Cortisol concentration showed a gradual decrease (P<0.05) during the experiments in both walking with and without KAATSU. CONCLUSIONS The results of the present investigation with young male students indicated that slow walking with KAATSU caused greater responses in serum GH and free testosterone compared to normal slow walking.

Pediatric reference intervals for FSH, LH, estradiol, T3, free T3, cortisol, and growth hormone on the DPC IMMULITE 1000

Background We studied serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol (E2), triiodothyronine (T3), free T3 (FT3), cortisol and growth hormone (GH) concentrations in a population of pediatric patients. The reference intervals were determined separately for females and males stratified by age groups to assess age- and sex-related differences. Our objective was to obtain reference intervals for the 7 serum analytes for our pediatric population using the IMMULITE 1000 system. Methods Serum samples of 800 in- and out-patients, newborn to 19 years old were analyzed using the DPC IMMULITE 1000 chemiluminescent immunoassay system. Results and conclusions We report pediatric reference intervals for FSH, LH, E2, T3, FT3, cortisol, and GH. These reference intervals provide the basis for clinical interpretation of laboratory results using the IMMULITE 1000 system and the assessment of child development.

Body mass index and blood glucose: correlations with serum insulin, growth hormone, and insulin-like growth factor-1 levels in patients with diffuse idiopathic skeletal hyperostosis (DISH)

Obesity is a frequent co-morbid condition associated with diffuse idiopathic skeletal hyperostosis (DISH). Serum growth hormone (GH), insulin-like growth factor (IGF-1) and insulin are significantly elevated in patients with DISH. In this study, we examined the relationship between body mass index (BMI) and basal serum GH, IGF-1, and insulin concentration in a group of 36 DISH patients. Basal serum insulin levels were significantly elevated (P<0.001) in DISH patients with a BMI>28 kg m(-2), classified as obese, compared with DISH patients with BMI ranging from 23 to 28 kg m(-2). In addition, BMI strongly positively correlated with serum insulin concentration in DISH patients (adjusted r2 = 0.348, P<0.001). However, BMI did not correlate with either basal serum GH (adjusted r2 = -0.013) or IGF-1 levels (adjusted r2 = -0.010) in DISH. We conclude that BMI does not seem to contribute to elevated serum GH and IGF-1 levels in symptomatic DISH.