A preliminary study of growth hormone in the treatment of dilated cardiomyopathy

Ghrelin improves renal function in mice with ischemic acute renal failure

Growth hormone and IGF-1 have been suggested to have tissue-protective effects. Ghrelin is a stomach-derived growth hormone secretagogue. The effects of ghrelin on ischemia/reperfusion-induced renal failure in mice were examined. Ischemic acute renal failure was induced by bilateral renal artery clamping for 45 min and reperfusion for 24 h. Ghrelin (100 microg/kg mouse) or vehicle was injected subcutaneously six times before surgery and three times after surgery every 8 h. Twenty-four hours after reperfusion, the right kidney was isolated and perfused. Acetylcholine (ACh)- and adrenomedullin-induced endothelium-dependent vasorelaxation of renal vessels significantly improved in ghrelin-pretreated mice (%Delta renal perfusion pressure by 10(-7) M ACh -63.5 +/- 3.7 versus -41.2 +/- 5.5%; P < 0.05). This change was associated with significant increases of nitric oxide release in the kidneys of ghrelin-treated mice (10(-7) M ACh 35.5 +/- 5.8 versus 16.9 +/- 3.5 fmol/g kidney per min; P < 0.05). Serum concentration of urea nitrogen (53 +/- 7 versus 87 +/- 15 mg/dl; P < 0.05) and renal injury score were significantly lower in the ghrelin group (2.5 +/- 0.8 versus 5.3 +/- 1.5; P < 0.01). Tubular apoptotic index was significantly lower in the ghrelin group (5 +/- 5 versus 28 +/- 4; P < 0.05). Furthermore, the survival rate after the 60-min ischemic period was higher in the ghrelin group (80 versus 20%; P < 0.05). Ghrelin treatment significantly increased the serum level of IGF-1. However, such renal protective effects of ghrelin on ischemia/reperfusion injury were not observed in insulin receptor substrate-2 knockout mice. These results suggest that ghrelin may protect the kidneys from ischemia/reperfusion injury and that this effect is related to an improvement of endothelial function through an IGF-1-mediated pathway.

Effects of biventricular pacing on interstitial remodelling, tumor necrosis factor-α expression, and apoptotic death in failing human myocardium

AIMS

Recent data from the COMPANION trial have documented that cardiac resynchronization therapy (CRT) with biventricular (BiV) pacing reduces mortality and hospitalization in patients with advanced CHF, but little is known regarding the cellular and molecular mechanisms of CRT. Our aim is to evaluate interstitial remodelling, tumor necrosis factor-alpha (TNF-alpha) expression, and apoptosis in patients with advanced CHF treated with CRT.

METHODS AND RESULTS

We performed endomyocardial biopsies in 10 patients, aged 62, with dilated cardiomyopathy before and 6 months after the implantation of a BiV pacing device. Clinical status and left ventricular (LV) architecture and function were assessed as well as myocardial histology, TNF-alpha expression, and apoptotic index. CRT improved clinical status, as shown by a significant reduction of the Minnesota living with heart failure questionnaire (MLHFQ) score (from 53 to 40) and 6-min walked distance (from 290 to 330 m) (all P<0.05 vs. baseline). This was associated with reverse LV remodelling substantiated by significant reductions of LV volumes and end-systolic circumferential wall stress. Examination of myocardial tissue revealed a significant decrease of collagen volume fraction (CVF) (from 25.16 to 18.0%), TNF-alpha expression (from 9.5 to 3.6 pixel x 10(3)), and apoptotic index (from 2030 to 1408 apoptotic nuclei/10(6)), with increased capillary density (from 1801 to 2011 capillary/mm(2)) after 6 months of CRT (all P<0.05 vs. baseline). Moreover, changes in TNF-alpha expression were positively correlated with both CVF and end-systolic circumferential wall stress (r=0.80 and 0.70, respectively).

CONCLUSION

We provide the first evidence that CRT reduces interstitial remodelling, TNF-alpha expression, and apoptosis. The data may explain the beneficial effects of CRT on CHF progression and survival.

Ghrelin and immunity: a young player in an old field

There is increasing evidence of the coupling of immune status to the metabolic system. The communication between the state of systemic and cellular energy balance to immune compartment is mediated via a complex array of cytokines, hormones and neuropeptides. Ghrelin, a recently described orexigenic peptide hormone, is predominantly produced by the stomach and functions as a positive regulator of the somatotropic axis and a peripheral signal of negative energy balance. Apart from its well-studied metabolic effects, ghrelin also exerts multiple regulatory effects on several other organ systems including the cardiovascular, central nervous and immune systems. Here, we summarize the growing evidence of ghrelin as a significant player in the regulation of inflammation and the immune function and the potential therapeutic targeting of ghrelin or its receptor, the growth hormone secretagogue receptor (GHS-R), in various inflammatory and cachexic disease states.

Cardiovascular risk in aging and obesity: is there a role for GH

GH has significant impact in adults. In fact, patients with the GH deficiency (GHD) syndrome are now recognized as having an increased cardiovascular risk. The effects of human aging on GH secretion have been evaluated by a number of researchers. Studies of 24 h secretion of GH have shown variable reductions in most 24-h GH secretory parameters in middle-aged and in older men and women, resulting in a decrease in plasma levels of its anabolic mediator IGF-I. Obesity is also associated with several endocrine and metabolic abnormalities. These include decreased serum GH concentrations, reduced GH half-life, frequency of GH secretory episodes and daily GH production rate. The mechanism of the low GH in obesity is not completely understood nor is it clear whether its relationship with visceral adiposity is causal. The aim of this article will be to review the available clinical data concerning the potential involvement of "subclinical" or perhaps better "functional" GHD, which is observed in aging and obesity, in the increase in cardiovascular risk which characterizes these two conditions.

The total length of myocytes and capillaries, and total number of myocyte nuclei in the rat heart are time-dependently increased by growth hormone

Growth hormone (GH) can increase size and dimensions of rat hearts. The aim was to study how GH administration influences the growth of cardiac myocytes and capillaries in relation to time. Three-month-old female rats were divided into 10 groups (n=3), and injected with either GH (5mg/kg/day) or vehicle for 5, 10, 20, 40, or 80 days. From the left ventricle (LV) histological sections were made and stereological methods applied. Linear regression showed that GH time-dependently increased: LV volume (r=0.96, P<0.001), total volume of myocytes (r=0.96, P<0.001) and capillaries (r=0.64, P<0.05), total length of myocytes (r=0.90, P<0.001) and capillaries (r=0.78, P<0.001), and total number of myocyte nuclei (r=0.85, P<0.001). In conclusion, during 80 days of GH treatment the total volume and length of myocytes and capillaries, and total number of myocyte nuclei increased in a linear way. The results indicate that GH is a potent mediator of myocardial growth.

Growth hormone therapy in heart failure: a novel therapy worthy of further consideration?

Despite the improvements in survival with angiotensin-converting enzyme inhibitors and beta-blockers, the clinical events for patients with heart failure remain elevated. New therapies for heart failure are required to improve the functional capacity, quality of life and prognosis. Growth hormone exerts both direct and indirect effects on cardiac structure and function. Experimental models of heart failure and small studies have demonstrated significant improvements in cardiac function, haemodynamical parameters, functional capacity and quality of life. The results from randomised controlled studies have been mixed with others showing benefit and some that do not. The randomised studies showing benefit consistently used growth hormone every other day. Further studies are needed to assess the potential role of this adjuvant therapy in patients with heart failure.

Effects of 9-cis-retinoic acid on the insulin-like growth factor axis in former smokers

PURPOSE

Insulin-like growth factor (IGF) axis has been associated with the risk of lung cancer. 9-cis-retinoic acid (9-cis-RA) has shown potential chemopreventive activities in former smokers. This study was designed to evaluate the effects of 9-cis-RA on IGF axis in former smokers to identify any benefit the retinoid may have in preventing lung cancer.

PATIENTS AND METHODS

Serum concentrations of IGF-I, IGF binding protein (IGFBP)-3, and their molar ratio (IGF-I/IGFBP-3) were measured with radioimmunoassay kits in stored blood samples from the participants of an original chemoprevention trial. The participants had ceased smoking for at least 12 months and were randomly assigned to receive 3 months of daily oral 9-cis-RA (100 mg) or placebo. All statistical tests were two-sided.

RESULTS

A total of 111 samples from the study's baseline and 84 samples from the 3 months treatment were analyzed. The serum concentrations of IGF-I and IGF-I/IGFBP-3 at baseline were significantly lower in female than in male participants. After 3 months of treatment, the serum level of IGF-I and IGF-I/IGFBP-3 were significantly lower in the 9-cis-RA group than in the placebo group (P = .03 and P < .01, respectively), but the IGFBP-3 level was significantly higher (P = .03).

CONCLUSION

9-cis-RA treatment modulated the IGF axis in former smokers, suggesting that the IGF axis is a potential target for the chemopreventive activities of 9-cis-RA and that the serum concentrations of IGF, IGFBP-3, and IGF-I/IGFBP-3 could serve as surrogate end point biomarkers of 9-cis-RA treatment.

Influence of growth hormone on cardiovascular health and disease

Experimental and clinical studies indicate that growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are involved in heart development. Impaired cardiovascular function, as recently demonstrated, could potentially reduce life expectancy both in GH deficiency (GHD) and excess. Patients with childhood- or adult-onset GHD may have both cardiac structural and functional abnormalities, i.e. reduced cardiac mass, reduced diastolic filling, and impaired left ventricular response to peak exercise. In addition, GHD patients may present with an increase in vascular intima-media thickness and a higher occurrence of atheromatous plaques that can further aggravate the hemodynamic conditions and contribute to the increased cardiovascular and cerebrovascular risk. However, some evidence has been provided to show that cardiovascular abnormalities can be partially reversed after somatropin (recombinant GH) therapy in patients with GHD. Recently, somatropin administration was shown to induce improvement in hemodynamics and clinical status in some patients with heart failure. Although these data need to be confirmed in more extensive studies, such promising results open new perspectives for somatropin therapy. The role of GH secretagogues in heart failure is still unknown.

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.

GH-releasing peptides improve cardiac dysfunction and cachexia and suppress stress-related hormones and cardiomyocyte apoptosis in rats with heart failure

Growth hormone (GH)-releasing peptides (GHRP), a class of synthetic peptidyl GH secretagogues, have been reported to exert a cardioprotective effect on cardiac ischemia. However, whether GHRP have a beneficial effect on chronic heart failure (CHF) is unclear, and the present work aims to clarify this issue. At 9 wk after pressure-overload CHF was created by abdominal aortic banding in rats, one of four variants of GHRP (GHRP-1, -2, and -6 and hexarelin, 100 mug/kg) or saline was injected subcutaneously twice a day for 3 wk. Echocardiography and cardiac catheterization were performed to monitor cardiac function and obtain blood samples for hormone assay. GHRP treatment significantly improved left ventricular (LV) function and remodeling in CHF rats, as indicated by increased LV ejection fraction, LV end-systolic pressure, and diastolic posterior wall thickness and decreased LV end-diastolic pressure and LV end-diastolic dimension. GHRP also significantly alleviated development of cardiac cachexia, as shown by increases in body weight and tibial length in CHF rats. Plasma CA, renin, ANG II, aldosterone, endothelin-1, and atrial natriuretic peptide were significantly elevated in CHF rats but were significantly decreased in GHRP-treated CHF rats. GHRP suppressed cardiomyocyte apoptosis and increased cardiac GH secretagogue receptor mRNA expression in CHF rats. GHRP also decreased myocardial creatine kinase release in hypophysectomized rats subjected to acute myocardial ischemia. We conclude that chronic administration of GHRP alleviates LV dysfunction, pathological remodeling, and cardiac cachexia in CHF rats, at least in part by suppressing stress-induced neurohormonal activations and cardiomyocyte apoptosis.

Cardiac changes associated with growth hormone therapy among children treated with anthracyclines

OBJECTIVE

The objective was to assess the cardiac effects of growth hormone (GH) therapy. Anthracycline-treated childhood cancer survivors frequently have reduced left ventricular (LV) wall thickness and contractility, and GH therapy may affect these factors.

METHODS

We examined serial cardiac findings for 34 anthracycline-treated childhood cancer survivors with several years of GH therapy and baseline cardiac z scores similar to those of a comparison group (86 similar cancer survivors without GH therapy).

RESULTS

LV contractility was decreased among GH-treated patients before, during, and after GH therapy (-1.08 SD below the age-adjusted population mean before therapy and -1.88 SD 4 years after therapy ceased, with each value depressed below normal). Contractility was higher in the control group than in the GH-treated group, with this difference being nearly significant. The GH-treated children had thinner LV walls before GH therapy (-1.38 SD). Wall thickness increased during GH therapy (from -1.38 SD to -1.09 SD after 3 years of GH therapy), but the effect was lost shortly after GH therapy ended and thickness diminished over time (-1.50 SD at 1 year after therapy and -1.96 SD at 4 years). During GH therapy, the wall thickness for the GH-treated group was greater than that for the control group; however, by 4 years after therapy, there was no difference between the GH-treated group and the control group.

CONCLUSIONS

GH therapy among anthracycline-treated survivors of childhood cancer increased LV wall thickness, but the effect was lost after therapy was discontinued. The therapy did not affect the progressive LV dysfunction.

Death begets failure in the heart

Recently, low--but abnormal--rates of cardiomyocyte apoptosis have been observed in failing human hearts. Genetic and pharmacological studies suggest that this cell death is causally linked to heart failure in rodent models. Herein, we review these data and discuss potential therapeutic implications.

Protein kinase cascades in the regulation of cardiac hypertrophy

In broad terms, there are 3 types of cardiac hypertrophy: normal growth, growth induced by physical conditioning (i.e., physiologic hypertrophy), and growth induced by pathologic stimuli. Recent evidence suggests that normal and exercise-induced cardiac growth are regulated in large part by the growth hormone/IGF axis via signaling through the PI3K/Akt pathway. In contrast, pathological or reactive cardiac growth is triggered by autocrine and paracrine neurohormonal factors released during biomechanical stress that signal through the Gq/phospholipase C pathway, leading to an increase in cytosolic calcium and activation of PKC. Here we review recent developments in the area of these cardiotrophic kinases, highlighting the utility of animal models that are helping to identify molecular targets in the human condition.

Effects of protein-rich supplementation and nandrolone in lean elderly women with femoral neck fractures

AIM

To evaluate the effects of a protein-rich liquid supplementation, alone or in combination with the anabolic steroid nandrolone decanoate, on body composition, activities of daily living (ADL) status and the health-related quality of life (HRQoL) after a femoral neck fracture.

METHODS

Sixty women, aged 83 +/- 5 years (mean +/- SD), BMI < 24 kg/m2 (20.4 +/- 2 kg/m2 ) and capable of co-operating, with a femoral neck fracture treated with internal fixation, were randomised to open treatment during 6 months with a protein-rich liquid formula alone (PR, Fortimel, 200 ml/day, 20 g protein/day) or in combination with nandrolone decanoate (PR/N, Deca-Durabol 25 mg i.m./3 weeks) or to a control group (C). The patients were re-examined after 6 and 12 months regarding body weight (BW), lean body mass (LBM, DXA), ADL status according to Katz, HRQoL according to EQ 5-D and fracture healing.

RESULTS

LBM decreased in the C (-1.2 +/- 2 kg) and PR groups (-1.2 +/- 1 kg) but remained the same in the PR/N group (0.3 +/- 1 kg) (P < 0.05 between groups). ADL remained at a high level in the two intervention groups but declined significantly in the C group (P < 0.005 between groups). The decline in HRQoL was least pronounced in the PR/N group at 6 months (P < 0.05 between groups). Patients with fracture healing complications lost more BW (P < 0.05) and LBM (P < 0.01) than patients with uneventful fracture healing.

CONCLUSION

Protein-rich liquid supplementation in combination with nandrolone given for 6 months to lean elderly women after a femoral neck fracture may positively affect LBM, ADL and HRQoL.

New pharmacological strategies in chronic heart failure

Diuretics, ACE inhibitors and betablockers form the cornerstone of pharmacological treatment of chronic heart failure (CHF), while angiotensin receptor blockers are gaining ground. However, despite optimal treatment CHF remains a syndrome with poor prognosis. For this reason, a large number of new agents have been developed as add-on treatment over the last few years. Vasopeptidase inhibitors, moxonidine, endothelin antagonists, vasopressin antagonists, and selective aldosterone antagonists, are some of the new agents that were designed to interfere with different neurohormonal pathways. Immunomodulating agents, growth hormone, caspase inhibitors, adrenomedullin, and erythropoietin have different modes of action, which in general are less understood. Although most of the agents exhibited efficacy in preclinical trials, the clinical results have not always been similarly positive. The results of trials involving vasopeptidase inhibitors, endothelin antagonists, immunomodulating agents, and growth hormone have been disappointing. Other compounds like caspase inhibitors, adrenomedullin, and vasopressin antagonists are still at the early stages of development. Currently, the two most promising agents seem to be erythropoietin and the selective aldosterone receptor blocker eplerenone. In the present article an overview of new pharmacological developments for CHF is given, and the clinical value of these developments is discussed.

Novel pharmacological treatments for heart failure

Pharmacological therapies remain the primary strategy for treating patients with acute and chronic heart failure. Several novel neurohormonal antagonists, inotropic agents, immune modulators, and metabolic and replacement therapies are currently in development to meet the demands of an increasing number of patients with heart failure. The success in drug development in this field will require a better understanding of the effects of heart failure on drug dosing, better integration of novel and existing drug therapies, the development of more reliable surrogate markers to effectively tailor medical therapy to individual needs and the ability to detect and treat patients at risk before the onset of heart failure.

Early, selective growth hormone administration may ameliorate left ventricular remodeling after myocardial infarction

Left ventricular (LV) remodeling after myocardial infarction (MI) may lead to congestive heart failure, disability and death. It consists of expansion of the infarct zone and dilatation of the non-infarcted myocardium, causing shape distortion and ventricular enlargement. Experimental studies have shown that treatment with growth hormone (GH) stimulates cardiac repair, resulting in increased infarct zone collagen scar formation and possibly enhanced proteinosynthesis. These actions may ameliorate the process of LV remodeling. We hypothesize that these beneficial effects may be more prominent, if GH is delivered selectively in the infarct area, during the early phase of acute MI. Experimental and clinical studies are necessary to validate this hypothesis.

Effects of Ghrelin Administration on Left Ventricular Function, Exercise Capacity, and Muscle Wasting in Patients With Chronic Heart Failure

BACKGROUND

Ghrelin is a novel growth hormone-releasing peptide that also induces vasodilation, inhibits sympathetic nerve activity, and stimulates feeding through growth hormone-independent mechanisms. We investigated the effects of ghrelin on left ventricular (LV) function, exercise capacity, and muscle wasting in patients with chronic heart failure (CHF).

METHODS AND RESULTS

Human synthetic ghrelin (2 microg/kg twice a day) was intravenously administered to 10 patients with CHF for 3 weeks. Echocardiography, cardiopulmonary exercise testing, dual x-ray absorptiometry, and blood sampling were performed before and after ghrelin therapy. A single administration of ghrelin elicited a marked increase in serum GH (25-fold). Three-week administration of ghrelin resulted in a significant decrease in plasma norepinephrine (1132+/-188 to 655+/-134 pg/mL; P<0.001). Ghrelin increased LV ejection fraction (27+/-2% to 31+/-2%; P<0.05) in association with an increase in LV mass and a decrease in LV end-systolic volume. Treatment with ghrelin increased peak workload and peak oxygen consumption during exercise. Ghrelin improved muscle wasting, as indicated by increases in muscle strength and lean body mass. These parameters remained unchanged in 8 patients with CHF who did not receive ghrelin therapy.

CONCLUSIONS

These preliminary results suggest that repeated administration of ghrelin improves LV function, exercise capacity, and muscle wasting in patients with CHF.

Cardiovascular Effects of Growth Hormone Treatment: Potential Risks and Benefits

Growth hormone (GH) and insulin-like growth factor-I are involved in heart development and in maintaining cardiac structure and performance. Cardiovascular disease has been reported to reduce life expectancy both in GH deficiency (GHD) and in GH excess. Patients with GHD suffer from abnormalities of left ventricular performance, i.e. reduced diastolic filling and impaired response to peak exercise. Patients with GHD also have increased intima-media thickness at the common carotid arteries, associated with a higher occurrence of atherosclerotic plaques, which may further aggravate the haemodynamic conditions. This may contribute to increased cardiovascular and cerebrovascular risk. These cardiovascular abnormalities can be reversed, at least partially, with GH replacement therapy. In recent years, GH therapy has been used to increase cardiac mass in ischaemic or dilated cardiomyopathy, but the results have produced contradictory data.

Recombinant human growth hormone treatment for dilated cardiomyopathy in children

OBJECTIVE

Dilated cardiomyopathy (DCM) is one of the most common causes of heart failure among children and is often progressive despite maximal medical therapy. Heart failure is characterized by a number of neurohormonal abnormalities, including derangements in the growth hormone (GH)/insulin-like growth factor-1 (IGF-1) signaling axis. Decreased serum levels of GH, which acts on cardiac myocytes primarily through IGF-1, are associated with impaired myocardial growth and function, which can be improved with restoration of GH/IGF-1 homeostasis. In animal models and among human adults with heart failure attributable to DCM, treatment with GH results in acquisition of left ventricular (LV) mass and improved LV function, through a combination of mechanisms. We undertook this study to determine the effects of recombinant human GH on LV function and mass among children with stable LV dysfunction attributable to DCM.

METHODS

We performed a prospective, single-center, randomized, partially blinded, crossover trial among children 1 to 19 years of age with DCM and cardiac dysfunction of > or =6-month duration. After enrollment, patients were randomly assigned to receive treatment for 6 months with either conventional therapy (determined by the patient's primary cardiologist) plus recombinant human GH (0.025-0.04 mg/kg per day), administered as daily subcutaneous injections, or conventional therapy alone. Patients were then crossed over to the other treatment strategy for 6 months. The primary outcome measure was change in LV shortening fraction (SF). Other echocardiographic indices of LV function, somatic growth, and somatotropic/thyroid hormone levels were also monitored.

RESULTS

Only 8 of an intended 15 patients were enrolled, because of a combination of factors. Two patients withdrew during the study as a result of declining LV function requiring transplantation. LV SF did not change significantly during GH treatment, although both LV SF and LV SF z score were higher 6 months after cessation of GH treatment than at baseline. LV ejection fraction increased during GH therapy to a degree that approached significance. Height and weight percentiles for age increased significantly during GH therapy and remained higher 6 months after treatment. Annualized height velocity during GH treatment (13.7 +/- 3.3 cm/year, >97th percentile for all patients) was significantly higher than that after GH discontinuation (3.2 +/- 3.5 cm/year). Serum levels of IGF-1 and IGF-binding protein-3 were significantly higher after 6 months of GH treatment and 6 months after discontinuation of GH treatment than at baseline. There were no adverse events related to GH treatment.

DISCUSSION

In this prospective, single-center, randomized, partially blinded, crossover trial, recombinant human GH was administered to 8 pediatric patients with stable chronic heart failure secondary to DCM. Because of unanticipated difficulty enrolling eligible patients, the study was underpowered to detect changes in our primary outcome measure of the magnitude we projected. Nevertheless, we did observe several notable cardiovascular effects of GH treatment, including a trend toward improved LV ejection fraction during the course of GH treatment and significantly improved LV SF, SF z score, and LV end systolic stress z score 6 months after discontinuation of GH treatment (relative to baseline values). Given the fact that levels of IGF-1, the primary myocardial effector of GH signaling, remained significantly higher 6 months after GH treatment than at baseline, the improvement in LV functional indices 6 months after discontinuation of therapy may represent progression or perpetuation of a GH treatment effect. In addition to its cardiovascular effects, GH therapy was associated with significant acceleration of somatic growth. The benefits of GH were not associated with significant attributable side effects, although 2 patients developed progressive LV dysfunction during the study and underwent cardiac transplantation.

Acute effects of beta-endorphin on cardiovascular function in patients with mild to moderate chronic heart failure

BACKGROUND

Cardiomyocytes produce opioid peptides and receptors. beta-Endorphin is increased in the plasma of patients with congestive heart failure (CHF). We evaluated whether an intravenous infusion of beta-endorphin exerted any effect on cardiovascular function and on the neurohormonal milieu in patients with mild to moderate CHF.

METHODS

According to a double-blind, placebo-controlled design, 10 patients (5 men, age 46.9 +/- 8.2 years [mean +/- SD]) with CHF and New York Heart Association functional class II to III received, in random order, 1-hour intravenous infusion of beta-endorphin (500 microg/h) and, on a separate occasion, received placebo and underwent echocardiographic and laboratory measurements at baseline and during infusions.

RESULTS

beta-Endorphin significantly increased left ventricular ejection fraction (LVEF) (P =.0001) and stroke volume (P =.0001), and reduced systemic vascular resistance (P =.031) in patients with CHF. These changes were paralleled by a significant increase in plasma levels of glucagon (P =.0001), GH (P =.0001), and IGF-1 (P =.0001), and a significant decrease in plasma levels of endothelin (P =.0001) and catecholamines (P =.01). No hemodynamic and neurohormonal changes were observed during the placebo study in any patient.

CONCLUSIONS

We conclude that a short-term, high dose infusion of beta-endorphin improves LVEF, reduces systemic vascular resistance, blunts the neurohormonal activation, and stimulates the GH/IGF-1 axis in patients with mild to moderate CHF.

Endogenous production of ghrelin and beneficial effects of its exogenous administration in monocrotaline-induced pulmonary hypertension

We investigated the endogenous production of ghrelin as well as cardiac and pulmonary vascular effects of its administration in a rat model of monocrotaline (MCT)-induced pulmonary hypertension (PH). Adult Wistar rats randomly received a subcutaneous injection of MCT (60 mg/kg) or an equal volume of vehicle. One week later, animals were randomly assigned to receive a subcutaneous injection of ghrelin (100 mug/kg bid for 2 wk) or saline. Four groups were analyzed: normal rats treated with ghrelin (n=7), normal rats injected with saline (n=7), MCT rats treated with ghrelin (n=9), and MCT rats injected with saline (n=9). At 22-25 days, right (RV) and left ventricular (LV) pressures were measured, heart and lungs were weighted, and samples were collected for histological and molecular analysis. Endogenous production of ghrelin was almost abolished in normal rats treated with ghrelin. In MCT-treated animals, pulmonary expression of ghrelin was preserved, and RV myocardial expression was increased more than 20 times. In these animals, exogenous administration of ghrelin attenuated PH, RV hypertrophy, wall thickening of peripheral pulmonary arteries, and RV diastolic disturbances and ameliorated LV dysfunction, without affecting its endogenous production. In conclusion, decreased tissular expression of ghrelin in healthy animals but not in PH animals suggests a negative feedback in the former that is lost in the latter. A selective increase of ghrelin mRNA levels in the RV of animals with PH might indicate distinct regulation of its cardiac expression. Finally, ghrelin administration attenuated MCT-induced PH, pulmonary vascular remodeling, and RV hypertrophy, indicating that it may modulate PH.

Local myocardial overexpression of growth hormone attenuates postinfarction remodeling and preserves cardiac function

BACKGROUND

Ventricular remodeling with chamber dilation and wall thinning is seen in postinfarction heart failure. Growth hormone induces myocardial hypertrophy when oversecreted. We hypothesized that localized myocardial hypertrophy induced by gene transfer of growth hormone could inhibit remodeling and preserve cardiac function after myocardial infarction.

METHODS

Rats underwent direct intramyocardial injection of adenovirus encoding either human growth hormone (n = 9) or empty null vector as control (n = 9) 3 weeks after ligation of the left anterior descending coronary artery. Analysis of the following was performed 3 weeks after delivery: hemodynamics, ventricular geometry, cardiomyocyte fiber size, and serum growth hormone levels.

RESULTS

The growth hormone group had significantly better systolic cardiac function as measured by maximum left ventricular pressure (73.6 +/- 6.9 mm Hg versus control 63.7 +/- 7.8 mm Hg, p < 0.05) and maximum dP/dt (2845 +/- 453 mm Hg/s versus 1949 +/- 605 mm Hg/s, p < 0.005), and diastolic function as measured by minimum dP/dt (-2520 +/- 402 mm Hg/s versus -1500 +/- 774 mm Hg/s, p < 0.01). Ventricular geometry was preserved in the growth hormone group (ventricular diameter 12.2 +/- 0.7 mm versus control 13.1 +/- 0.4 mm, p < 0.05; borderzone wall thickness 2.0 +/- 0.2 mm versus 1.5 +/- 0.1 mm, p < 0.001), and was associated with cardiomyocyte hypertrophy (6.09 +/- 0.63 microm versus 4.66 +/- 0.55 microm, p < 0.005). Local myocardial expression of growth hormone was confirmed, whereas serum levels were undetectable after 3 weeks.

CONCLUSIONS

Local myocardial overexpression of growth hormone after myocardial infarction resulted in cardiomyocyte hypertrophy, attenuated ventricular remodeling, and improved systolic and diastolic cardiac function. The induction of localized myocardial hypertrophy presents a novel therapeutic approach for the treatment of ischemic heart failure.

Effect of central hypothyroidism on Doppler-derived myocardial performance index

BACKGROUND

Myocardial performance index (MPI) has been used to assess global ventricular function in different types of cardiac disease. Thyroid hormones influence cardiac performance directly and indirectly by changes in peripheral circulation. The aim of this study was to evaluate the possible effect of central hypothyroidism (CH) on MPI.

METHODS

The study included 28 control subjects and 7 patients with CH without cardiac disease. MPI was defined as the sum of isovolumetric contraction time (ICT) and isovolumetric relaxation time divided by ejection time. Patients were submitted to hormonal therapy with thyroxin and the study was repeated after 35 to 42 days.

RESULTS

MPI was significantly higher in patients with CH (0.54 +/- 0.08) than in control subjects (0.40 +/- 0.05) (P =.002). The increase in MPI was caused by the prolongation of ICT without a significant variation of isovolumetric relaxation time and ejection time. After hormonal therapy there was a significant reduction of MPI (0.54 +/- 0.08 vs 0.42 +/- 0.07; P =.028) and ICT.

CONCLUSION

MPI was increased in patients with untreated CH. The increase was related to prolongation of ICT and reverted by hormonal therapy.

Cardiac IGF-I manipulation by growth hormone following myocardial infarction

Evidence of a role for growth hormone (GH) in cardiac structure and function has been derived from studies of patients suffering either GH excess or deficiency, both of which may lead to reduced life expectancy. The role of GH in the ischaemic heart, however, is less than clear. We therefore investigated the effect of 30 days GH treatment in sheep with myocardial infarction. GH treatment significantly increased circulating IGF-I levels (P<0.01), heart weight (P<0.01), and cardiomyocyte cross-sectional area (P<0.001). IGF-I mRNA in peri-infarct cardiac tissue also increased significantly (P<0.05). We conclude that post-infarct GH treatment increases circulating and cardiac IGF-I levels, resulting in significant cardiomyocyte hypertrophy. This increase in cardiomyocyte size appears to correlate with local IGF-I expression rather than plasma IGF-I levels.

Nutritional strategy in the management of heart failure in adults

The incidence of congestive heart failure (CHF) is increasing in Westernized countries, and patients with CHF experience poor quality of life (functional impairment, high hospitalization rate and high mortality). Malnutrition occurring during the course of CHF is referred to as cardiac cachexia and is associated with higher mortality independent of the severity of CHF. Cardiac cachexia involving a loss of more than 10% of lean body mass can clinically be defined as a bodyweight loss of 7.5% of previous dry bodyweight in a period longer than 6 months. The energy requirements of patients with CHF, whether cachectic or not, are not noticeably modified since the increase in resting energy expenditure is compensated by a decrease in physical activity energy expenditure. Malnutrition in CHF has been ascribed to neurohormonal alterations, i.e. anabolic/catabolic imbalance and increased cytokine release. Anorexia may occur, particularly during acute decompensation of CHF. Function is impaired in CHF, because of exertional dyspnea and changes in skeletal muscle. Decreased exercise endurance seems to be related to decreased mitochondrial oxidative capacities and atrophy of type 1 fibers, which are attributed to alteration in muscle perfusion and are partially reversible by training. Malnutrition could also impair muscle function, because of decreased muscle mass and strength associated with decreased glycolytic capacities and atrophy of type 2a and 2b fibres. With respect to the putative mechanisms of cardiac cachexia, anabolic therapy (hormones or nutrients) and anticytokine therapy have been proposed, but trials are scarce and often inconclusive. In surgical patients with CHF, perioperative (pre- and postoperative) nutritional support has been shown to be effective in reducing the mortality rate. Long term nutritional supplementation trials in patients with CHF and cachexia are thus required to establish recommendations for the nutritional management of patients with CHF.

GH suppresses TGF-beta-mediated fibrosis and retains cardiac diastolic function

The aims of this study were to elucidate the molecular mechanism by which growth hormone (GH) excess is anti-fibrotic in vitro and in vivo model. The in vivo model GH excess showed a significant increase of relative wall thickness with no concomitant disturbance of cardiac diastolic function. Western blot for extracellular matrix (ECM) structural proteins showed minimal change in the GH treatment group, compared to an Angiotensin II (Ang II) subpressor dose group. In cultured cardiac fibroblasts, we investigated the abundance of ECM proteins, phosphorylation of p38 mitogen-activated protein kinase (MAPK), and transforming growth factor-beta (TGF-beta)-specific transcriptional activity. GH down-regulated the expression of PAI-1 and fibronectin proteins activated by TGF-beta. In reporter assays, GH, but not insulin-like growth factor-1 (IGF-1), reduced TGF-beta-specific transcriptional activity. Moreover, GH markedly down-regulated TGF-beta-induced phosphorylation of p38 MAPK. These results demonstrated that a chronic excess of GH have an anti-fibrotic effect on cardiac remodeling, probably through a down-regulation of TGF-beta signaling via de-phosphorylation of p38 MAPK.

Ghrelin: integrative neuroendocrine peptide in health and disease

OBJECTIVE

Ghrelin is a novel gastric hormone recognized in 1999 as a mediator of growth hormone release. Since growth hormone is anabolic, an important function of ghrelin may be to coordinate energy needs with the growth process. Newly discovered biologic roles of ghrelin imply that it may have other important physiological functions as well. This is a review of recent clinically relevant, yet less well-known, physiologic actions of ghrelin.

SUMMARY BACKGROUND DATA

Ghrelin has profound orexigenic, adipogenic, and somatotrophic properties, increasing food intake and body weight. Secreted predominantly from the stomach, ghrelin is the natural ligand for the growth hormone secretagogue receptor in the pituitary gland, thus fulfilling criteria of a brain-gut peptide. The brain-gut axis is the effector of anabolism by regulating growth, feeding, and metabolism via vagal afferents mediating ghrelin signaling. However, the wide tissue distribution of ghrelin suggests that it may have other functions as well.

METHODS

Systematic literature review of all PubMed citations between 1999 and August 2003 focusing on clinically relevant biochemical and physiological characteristics of ghrelin.

RESULTS

Ghrelin is an important component of an integrated regulatory system of growth and metabolism acting via the vagus nerve, and is implicated in a variety of altered energy states such as obesity, eating disorders, neoplasia, and cachexia. It also enhances immune responses and potentially down-regulates anti-inflammatory molecules. Ghrelin's role as a brain-gut peptide emphasizes the significance of afferent vagal fibers as a major pathway to the brain, serving the purpose of maintaining physiologic homeostasis.

CONCLUSIONS

The discovery of ghrelin has increased our understanding of feeding regulation, nutritional homeostasis, and metabolic processes. Further characterization of ghrelin's functions will likely generate new pharmacological approaches to diagnose and treat different disease entities including those related to the over-nutrition of obesity and the catabolic response to surgical trauma.

Up-regulation of mitochondrial transcription factor 1 mRNA levels by GH in VSMC

It is well known that growth hormone (GH) is involved in the development of arteriosclerosis in which vascular smooth muscle cells (VSMC) play an important role. In this study, we attempted to specify the genes up- or down-regulated by recombinant human GH (rhGH) in VSMC using a differential display method. We found that rhGH increased cytochrome oxidase subunit II/III mRNA in VSMC. Furthermore, the mRNA for mitochondrial transcription factor 1 (mtTF1), which stimulates the expression of cytochrome oxidase subunit II/III, was found to be up-regulated by rhGH in a dose dependent manner using a quantitative PCR method. On the other hand, IGF-I alone did not change mtTF1 mRNA levels. In rat L6 myoblasts and rat H4-II-E hepatocytes, rhGH did not change mtTF1 mRNA levels. Pretreatment with a JAK2 inhibitor AG490 (10 nM) and a MEK inhibitor PD98059 (10 microM) suppressed rhGH-induced rise in mtTF1 mRNA levels of VSMC to the control levels. Pretreatment with a PI-3kinase inhibitor wortomannin (1 nM) did not suppress rhGH-induced rise in mtTF1 mRNA levels. These findings suggest that GH up-regulates mtTF1 mRNA levels through JAK2 and MEK signaling in VSMC.

Growth hormone and exercise tolerance in patients with cystic fibrosis

Cystic fibrosis (CF) is a life-limiting inherited disorder characterised by pulmonary disease, pancreatic dysfunction and symptoms of malnutrition that are all interrelated with low exercise capacity and poor survival rate. Therapy with growth hormone (GH) may improve the reduced dimensional and functional capacity associated with poor nutritional status and catabolism and therefore improve exercise tolerance, quality of life and survival rate in patients with CF. The literature about GH treatment and its effect on exercise tolerance are rather limited, not always consistent and methodological concerns restrict further analysis. GH treatment may have beneficial effects on both growth and exercise tolerance without serious complications in prepubertal children with CF. The observed dimensional changes of the muscular, cardiovascular and pulmonary system seem to improve aerobic exercise capacity and respiratory and peripheral muscle strength. The physiological background of the observed changes is not yet fully understood, therefore, larger-scale studies with an optimised design are required.

Growth hormone, acromegaly, and heart failure: an intricate triangulation

Short-term GH or IGF-I excess provides a model of physiological cardiac growth associated with functional advantage. The physiological nature of cardiac growth is accounted for by the following: (i) the increment in cardiomyocyte size occurs prevalently at expense of the short axis. This is the basis for the concentric pattern of left ventricular (LV) hypertrophy, with consequent fall in LV wall stress and functional improvement; (ii) cardiomyocyte growth is associated with improved contractility and relaxation, and a favourable energetic setting; (iii) the capillary density of the myocardial tissue is not affected; (iv) there is a balanced growth of cardiomyocytes and nonmyocyte elements, which accounts for the lack of interstitial fibrosis; (v) myocardial energetics and mechanics are not perturbed; and (vi) the growth response is not associated with the gene re-programming that characterizes pathologic cardiac hypertrophy and heart failure. Overall, the mechanisms activated by GH or IGF-I appear to be entirely different from those of chronic heart failure. Not to be neglected is also the fact that GH, through its nitric oxide (NO)-releasing action, contributes to the maintenance of normal vascular reactivity and peripheral vascular resistance. This particular kind of interaction of GH with the cardiovascular system accounts for: (i) the lack of cardiac impairment in short-term acromegaly; (ii) the beneficial effects of GH and IGF-I in various models of heart failure; (iii) the protective effect of GH and IGF-I against post-infarction ventricular remodelling; (iv) the reversal of endothelial dysfunction in patients with heart failure treated with GH; and (v) the cardiac abnormalities associated with GH deficiency and their correction after GH therapy. If it is clear that GH and IGF-I exert favourable effects on the heart in the short term, it is equally undeniable that GH excess with time causes pathologic cardiac hypertrophy and, if it is not corrected, eventually leads to cardiac failure. Why then, at one point in time in the natural history of acromegaly, does physiological cardiac growth become maladaptive and translate into heart failure? Before this transition takes places, the acromegalic heart shares very few features with other models of chronic heart failure. None of the mechanisms involved in the progression of heart failure is clearly operative in acromegaly, save for the presence of insulin-resistance and mild alterations of lipoproteins and clot factors. Is this enough to account for the development of heart failure? Probably not. On the other hand, it must be stressed that GH and IGF-I activate several mechanisms that play a protective role against the development of heart failure. These include ventricular unloading, deactivation of neurohormonal components, antiapoptotic effect and enhanced vascular reactivity. Ultimately, all data available concur to hypothesize that acromegalic cardiomyopathy represents a progressive model of cardiac hypertrophy in which the cardiotoxic and pro-remodelling effect is intrinsic to the excessive and unrestrained myocardial growth.

Ghrelin for the gastroenterologist: history and potential

Ghrelin, a novel 28-amino acid orexigenic peptide discovered in 1999, has given us further insights into the control of energy homeostasis and growth hormone secretion. As a natural endogenous ligand of the growth hormone secretagogue receptor, it potently stimulates growth hormone release but is also implicated in many other homeostatic mechanisms. Released from the stomach, it stimulates lactotroph and corticotroph secretion, increases appetite and adiposity, has beneficial hemodynamic effects, has prokinetic and gastric acid secretory functions in the stomach, and may even be implicated in sleep. As advances in the understanding of appetite and obesity are made, it is timely to review the possibly central role of ghrelin in these physiological and pathophysiological states. This review will discuss the recent literature concerning this exciting novel neuropeptide and discuss the possible therapeutic possibilities it may open up to us.

Growth hormone induces myocardial expression of creatine transporter and decreases plasma levels of IL-1beta in rats during early postinfarct cardiac remodeling

Growth hormone has been proposed as a potential new therapeutic agent for treatment of myocardial infarction (MI) and congestive heart failure (CHF). The purpose of this study was to evaluate the effects of GH on: (a) myocardial expression of creatine transporter (CreaT) during early postinfarct remodeling, (b) myocardial levels of total creatine (TCr) and adenine pool (TAN) and (c) plasma levels of inflammatory cytokines interleukin-1beta (IL-1beta), tumor-necrosis-factor-alpha (TNF-alpha) and interleukin-6 (IL-6) in rat model of postinfarct cardiac remodeling. Myocardial infarction (MI) was induced by ligation of the left coronary artery in male Sprague-Dawley rats (200-250 g). Three different groups were studied: MI rats treated with GH (n=11) (3 mg/kg/day), MI rats treated with saline (n=10), and sham operated rats (n=7). In the myocardium from GH treated rats the level of mRNA CreaT expression was significantly increased (p<0.01). There was no difference in TCr between the rats with MI and sham-operated rats. Treatment with GH had no effect on TCr. GH had no effect on TAN in left ventricle. All three groups had similar levels of IL-6 and TNF-alpha in plasma. In the rats with MI, treatment with GH normalized the levels of IL-1beta (p<0.05). In conclusion GH increased the expression of CreaT and decreased levels of plasma IL-1beta during postinfarct remodeling in rats. These mechanisms may be responsible for the previously reported beneficial effects of GH on myocardial energy metabolism and preservation of cardiac function in the settings of postinfarct remodeling and CHF.

Beneficial effects of GH/IGF-1 on skeletal muscle atrophy and function in experimental heart failure

Muscle atrophy is a determinant of exercise capacity in heart failure (CHF). Myocyte apoptosis, triggered by tumor necrosis factor-alpha (TNF-alpha) or its second messenger sphingosine (SPH), is one of the causes of atrophy. Growth hormone (GH) improves hemodynamic and cardiac trophism in several experimental models of CHF, but its effect on skeletal muscle in CHF is not yet clear. We tested the hypothesis that GH can prevent skeletal muscle apoptosis in rats with CHF. CHF was induced by injecting monocrotaline. After 2 wk, 2 groups of rats were treated with GH (0.2 mg.kg(-1).day(-1) and 1.0 mg.kg(-1).day(-1)) subcutaneously. A third group of controls had saline. After 2 additional weeks, rats were killed. Tibialis anterior cross-sectional area, myosin heavy chain (MHC) composition, and a study on myocyte apoptosis and serum levels of TNF-alpha and SPH were carried out. The number of apoptotic nuclei, muscle atrophy, and serum levels of TNF-alpha and SPH were decreased with GH at high but not at low doses compared with CHF rats. Bcl-2 was increased, whereas activated caspases and bax were decreased. The MHC pattern in GH-treated animals was similar to that of controls. Monocrotaline slowed down both contraction and relaxation but did not affect specific tetanic force, whereas absolute force was decreased. GH treatment restored contraction and relaxation to control values and brought muscle mass and absolute twitch and tetanic tension to normal levels. These findings may provide an insight into the therapeutic strategy of GH given to patients with CHF to improve exercise capacity.

Novel Pharmacologic Therapy of Heart Failure

The prevalence of congestive heart failure is progressively increasing and despite recent advances in therapeutics, there is a continuing need for novel effective therapies. New, investigational treatment strategies include inotropic drugs, neurohormonal antagonists, anticytokine and anti-inflammatory strategies, hormonal therapies, and nutritional supplements. Current positive inotropes (eg, dobutamine and phosphodiesterase inhibitors) provide symptomatic relief, but newer agents may have a better adverse effect profile. Angiotensin-converting enzyme (ACE) inhibitors should remain first-line treatment with angiotensin receptor blockers used in ACE inhibitor-intolerant patients. Many new neurohormonal antagonists have recently been investigated and eplerenone has demonstrated clinical benefit. New hormonal, anticytokine, and anti-inflammatory therapies have shown benefit in small trials, but results in larger trials have been disappointing. Other approaches are currently being tested in large trials that will clarify their role. Nutritional supplements need to be tested in a large prospective trial before they can be recommended.

Ghrelin, a novel growth hormone-releasing peptide, in the treatment of chronic heart failure

Ghrelin is a novel growth hormone (GH)-releasing peptide, isolated from the stomach, which has been identified as an endogenous ligand for growth-hormone secretagogues receptor (GHS-R). This peptide also causes a positive energy balance by stimulating food intake and inducing adiposity through growth hormone-independent mechanisms. In addition, ghrelin has some cardiovascular effects, as indicated by the presence of its receptor in blood vessels and the cardiac ventricles. In vitro, ghrelin inhibits apoptosis of cardiomyocytes and endothelial cells. In humans, infusion of ghrelin decreases systemic vascular resistance and increases cardiac output in patients with heart failure. Repeated administration of ghrelin improves cardiac structure and function and attenuates the development of cardiac cachexia in rats with heart failure. These results suggest that ghrelin has cardiovascular effects and regulates energy metabolism through GH-dependent and -independent mechanisms. Thus, administration of ghrelin may be a new therapeutic strategy for the treatment of severe chronic heart failure (CHF).

Growth hormone prolongs survival in experimental postinfarction heart failure

OBJECTIVES

We evaluated the effects of growth hormone (GH) on survival in experimental heart failure (HF).

BACKGROUND

Growth hormone has been beneficial in various models of experimental HF. Whether GH also affects HF progression and survival is not known.

METHODS

A total of 119 rats with moderate myocardial infarction were randomized to receive either GH (3.5 mg/kg every other day) or placebo for 28 days. Treatment was initiated one month after coronary ligation; the follow-up lasted 13 months. In the surviving animals, Doppler echocardiography and closed-chest Millar left ventricular (LV) catheterization were performed. Apoptosis, collagen volume fraction, and capillary density in the LV zone remote from infarction were measured. The early effects of GH on apoptosis were also assessed in a subgroup of eight infarcted rats, treated as specified earlier and euthanized at one month.

RESULTS

Survival rate was 68% in GH-treated rats and 48% in the placebo group (p = 0.0377). Growth hormone had no effect on myocardial architecture, systolic function, and sarcoplasmatic reticulum calcium ATPase-2 messenger ribonucleic acid. Growth hormone improved LV relaxation; this was associated with a 50% reduction in collagen volume fraction and a 27% increase in capillary density. Growth hormone reduced the apoptotic index by 50% at one month and by 33% at 13 months.

CONCLUSIONS

Growth hormone prolonged survival of rats with postinfarction HF. This effect was associated with marked attenuation of cardiomyocyte apoptosis and pathologic interstitial remodeling in the surviving myocardium and enhanced LV relaxation.

Growth hormone resistance in chronic heart failure and its therapeutic implications

BACKGROUND

In recent years the administration of recombinant human growth hormone (GH) has received great attention. This review compares the potential of this therapeutic intervention in heart failure with that in other diseases where wasting is commonly seen. The pathophysiologic importance of GH and insulin-like growth factor (IGF)-I in these conditions will be discussed.

METHODS AND RESULTS

Abnormalities of the GH-IGF-I axis play an important role in the development of cachexia in chronic illnesses. GH resistance is a major determinant of the wasting process, acting through several different mechanisms: increased catabolism, impaired anabolism, and enhanced apoptosis in peripheral tissues. GH therapy has been evaluated in chronic heart failure (CHF); acquired GH resistance may explain the general lack of therapeutic success in the majority of studies. The assessment of plasma levels of GH, IGF-I, and, in particular, GH binding protein may help to guide dosing of GH for CHF patients.

CONCLUSIONS

GH resistance might be overcome by use of intermittent or higher doses of GH, or alternatively by combining GH with IGF-I. Randomized studies of GH therapy in catabolic states, with targeted dosing and longer duration of treatment are required to fully assess the safety and efficacy of this treatment approach.

Upregulation of cardiac insulin-like growth factor-I receptor by ACE inhibition after myocardial infarction: potential role in remodeling

This study evaluated the effects of angiotensin-converting enzyme (ACE) inhibition after myocardial infarction (MI) on cardiac remodeling and gene expression and localization of components (ligands, receptors, and binding proteins) of the cardiac insulin-like growth factor (IGF) system. After ligation of the coronary artery, rats were randomized to vehicle or ACE inhibitor (Captopril, 50 mg/kg/day) for 4 weeks. Blood pressure, cardiac remodeling, and components of the IGF system were localized in the heart using in situ hybridization (ISH) and immunohistochemistry (IHC). The average infarct size was 42%. There were regional differences in the expression of the IGF system after MI, with increased IGF-I mRNA abundance in the border (24-fold) and infarct (12-fold) and increased IGF-binding protein (IGFBP)-3 mRNA in all areas of the failing left ventricle (threefold). Captopril reduced blood pressure, attenuated cardiac remodeling, and caused a threefold increase in IGF-I receptor mRNA and protein in infarct, border zone, and viable myocardium (p<0.01). Captopril had no effect on IGF-I mRNA but further increased IGFBP-3 mRNA and protein in the border zone, (p<0.05). The changes in the cardiac IGF system following MI are highly localized, persist for at least 4 weeks, and can be modulated by ACE inhibition. These data suggest that the benefits of ACE inhibitors in attenuation of cardiac remodeling may be mediated in part through increased expression of the IGF-I receptor sensitizing the myocardium to the positive effects of endogenous IGF-I.

Growth hormone therapy in heart failure: where are we now?

Despite improvement in survival with angiotensin-converting enzyme inhibitors and beta blockers, clinical events for patients with heart failure remain elevated. New therapies for heart failure are needed to improve functional capacity, quality of life, and prognosis. Growth hormone exerts direct and indirect effects on cardiac structure and function. Experimental models of heart failure and small studies have demonstrated significant improvements in cardiac function, hemodynamic parameters, functional capacity, and quality of life. Despite the lack of benefit demonstrated in small, short-term, randomized clinical trials, further studies are needed to assess the potential role of this adjuvant therapy in heart failure patients.

Insulin-like growth factor-1 exerts Ca2+-dependent positive inotropic effects in failing human myocardium

Myocardial generation of insulin-like growth factor-1 (IGF-1) is altered in hypertrophy and heart failure, but there are no reports on acute functional effects of IGF-1 in human cardiac muscle. We examined inotropic responses and signal transduction mechanisms of IGF-1 in human myocardium. Experiments were performed in isolated trabeculae or cardiomyocytes from 46 end-stage failing hearts. The effect of IGF-1 (0.001 to 0.2 micromol/L) on isometric twitch force (37 degrees C, 1 Hz), intracellular Ca2+ transients (aequorin method), sarcoplasmic reticulum (SR) Ca2+ content (rapid cooling contractures), L-type Ca2+ current (whole-cell voltage clamp), and cAMP concentrations was assessed. In addition, the effects of blocking IGF-1 receptors, phosphoinositide 3-kinase (PI3-kinase), protein kinase C (PKC), or transsarcolemmal Ca2+ entry were tested. IGF-1 exerted concentration-dependent positive inotropic effects (twitch force increased to maximally 133+/-4% of baseline values at 0.1 micromol/L; P<0.05). The IGF-1 receptor antibody alphaIR3 or the PI3-kinase inhibitor wortmannin prevented the functional effects. The inotropic response was paralleled by increases in Ca2+ transients and SR Ca2+ content. IGF-1 (0.1 micromol/L) increased L-type Ca2+ current amplitude by 24+/-7% (P<0.05). Blockade of SR function did not affect the inotropic response to IGF-1. In contrast, L-type Ca2+ channel blockade with diltiazem partially prevented ( approximately 50%) the inotropic response to IGF-1. Inhibition of PKC (GF109203X), Na+-H+ exchange (HOE642), or reverse-mode Na+-Ca2+ exchange (KB-R7943) reduced the response to IGF-1 by approximately 60% to 70%. IGF-1 exerts Ca2+-dependent positive inotropic effects through activation of IGF-1 receptors and a PI3-kinase-dependent pathway in failing human myocardium. The increased [Ca2+]i with IGF-1 originates from both enhanced L-type Ca2+ currents and enhanced Na+-H+ exchange-dependent reverse-mode Na+-Ca2+ exchange. These nongenomic functional effects of IGF-1 may be of clinical relevance.

Administration of growth hormone to patients with advanced cardiac heart failure: effects upon left ventricular function, exercise capacity, and neurohormonal status

Experimental and clinical studies have shown that the administration of recombinant human growth hormone can improve deteriorated left ventricular function and hemodynamics in patients with heart failure. Herein, we compared the effects of growth hormone versus placebo upon resting left ventricular ejection fraction, exercise capacity and neurohormonal status in patients with advanced heart failure. Nineteen patients with advanced cardiac heart failure (ejection fraction <30%) were studied at baseline and after 8 weeks of treatment with growth hormone (0.03 U/kg per day) or placebo. Primary end points were resting left ventricular ejection fraction, peak oxygen consumption and neurohormonal status, including plasma norepinephrine levels and insulin like growth factor-1 and its binding protein-3. Results are presented as median and interquartile ranges. Patients receiving growth hormone had a significant increase in insulin growth factor-1 plasma levels (median difference growth hormone=83 ng/ml [57-170] versus placebo=-6 ng/ml [-23-6], P<0.05) and its binding protein-3. However, no significant increase in left ventricular ejection fraction after growth hormone treatment (ejection fraction pre=16% [13-18] and post=17% [14-27]) was noticed when compared to placebo (ejection fraction pre=20% [15-24] and post=20% [15-26]). Also, no significant effect of growth hormone treatment was seen on peak oxygen consumption or norepinephrine plasma levels. Although the administration of growth hormone to patients with advanced cardiac heart failure was associated with a significant increase in insulin growth factor-1, there were no significant changes in ejection fraction, exercise capacity and/or neurohormonal status.

A 24-hour comparison of serum growth hormone concentrations in patients with heart failure versus healthy controls

STUDY OBJECTIVE

To compare endogenous serum growth hormone concentrations over a 24-hour period in patients with chronic heart failure (CHF) and matched controls.

DESIGN

Prospective, 24-hour, endogenous concentration comparison.

SETTING

Hospital research center.

PATIENTS

Eight evaluable patients with nonischemic dilated cardiomyopathy and 10 healthy control subjects, matched for age and sex.

INTERVENTION

Over a 24-hour period, blood was drawn from the study participants every 20 minutes for determination of growth hormone.

MEASUREMENTS AND MAIN RESULTS

For each patient, the area under the concentration-time curve from time 0-24 hours (AUC0-24), maximum concentration (Cmax), and minimum concentration (Cnadir) of growth hormone were determined. The AUC0-24 and Cmax were 74% (p < 0.05) and 62% (p < 0.05) lower in patients with CHF than in controls, respectively. The Cnadir for all participants was 0 microg/L. Variability in growth hormone concentrations over the 24 hours was considerable for all study participants.

CONCLUSIONS

Growth hormone concentrations are suppressed over a 24-hour period in patients with CHF versus healthy controls. Variability in levels throughout the day suggests that a single point evaluation cannot be used to determine deficiency or abundance of growth hormone.

Hormonal profile in patients with congestive heart failure

BACKGROUND

Recent progress has been made in the understanding of the cellular and molecular mechanisms of growth hormone action and of its effects on cardiac tissue. The aim of this study was to measure growth hormone concentrations, along with various other hormones, in patients with stable chronic congestive heart failure due to idiopathic dilated cardiomyopathy.

METHODS

The study included 23 ambulatory men, 51.2+/-9.3 years of age, on standard medical therapy for heart failure due to idiopathic dilated cardiomyopathy. All patients underwent clinical and laboratory evaluations, including echocardiogram, radionuclide ventriculography, right heart catheterization, coronary angiography, and right ventricular endomyocardial biopsy. Serum or plasma concentrations of growth, thyroid, sex and adrenal hormones were measured in all patients and compared with those found in 20 age-matched healthy men.

RESULTS

Growth hormone, insulin-like growth factor I, and free testosterone values in patients with idiopathic dilated cardiomyopathy and heart failure were 0.37+/-0.2 ng/ml, 123.7+/-50 ng/ml and 48.6+/-23.8 pmol/l, respectively, versus 0.5+/-0.4 ng/ml (P<0.01), 236.3+/-66.4 ng/ml (P<0.001) and 105+/-17 pmol/l (P<0.01), respectively, in the healthy age-matched individuals. All other hormone concentrations were comparable in both groups.

CONCLUSIONS

Chronic heart failure due to idiopathic dilated cardiomyopathy is associated with a significant decrease in growth hormone, insulin-like growth factor I, and testosterone concentrations, probably due to chronic disease.