The role of ghrelin and ghrelin analogues in wasting disease

Hexarelin Modulation of MAPK and PI3K/Akt Pathways in Neuro-2A Cells Inhibits Hydrogen Peroxide-Induced Apoptotic Toxicity

Hexarelin, a synthetic hexapeptide, exerts cyto-protective effects at the mitochondrial level in cardiac and skeletal muscles, both in vitro and in vivo, may also have important neuroprotective bioactivities. This study examined the inhibitory effects of hexarelin on hydrogen peroxide (H₂O₂)-induced apoptosis in Neuro-2A cells. Neuro-2A cells were treated for 24 h with various concentrations of H₂O₂ or with the combination of H₂O₂ and hexarelin following which cell viability and nitrite (NO₂⁻) release were measured. Cell morphology was also documented throughout and changes arising were quantified using Image J skeleton and fractal analysis procedures. Apoptotic responses were evaluated by Real-Time PCR (caspase-3, caspase-7, Bax, and Bcl-2 mRNA levels) and Western Blot (cleaved caspase-3, cleaved caspase-7, MAPK, and Akt). Our results indicate that hexarelin effectively antagonized H₂O₂-induced damage to Neuro-2A cells thereby (i) improving cell viability, (ii) reducing NO₂⁻ release and (iii) restoring normal morphologies. Hexarelin treatment also reduced mRNA levels of caspase-3 and its activation, and modulated mRNA levels of the BCL-2 family. Moreover, hexarelin inhibited MAPKs phosphorylation and increased p-Akt protein expression. In conclusion, our results demonstrate neuroprotective and anti-apoptotic effects of hexarelin, suggesting that new analogues could be developed for their neuroprotective effects.

Ghrelin treatment prevents development of activity based anorexia in mice

Stimulation of feeding is necessary for treatment of pathological conditions of chronic malnutrition due to anorexia. Ghrelin, a hunger hormone, is one of the candidate for pharmacological treatments of anorexia, but because of its instability in plasma has limited efficacy. We previously showed that plasmatic IgG protect ghrelin from degradation and that IgG from obese subjects and mice may increase ghrelin׳s orexigenic effect. In this study we tested if ghrelin alone or combined with IgG may improve feeding in chronically food-restricted mice with or without physical activity-based anorexia (ABA) induced by free access to a running wheel. Mice received a single daily intraperitoneal injection of ghrelin (1nM) together or not with total IgG (1nM) from obese ob/ob or lean mice before access to food during 8 days of 3h/day feeding time. We found that both ghrelin and ghrelin combined with IgG from obese, but not lean mice, prevented ABA, however, they were not able to diminish body weight loss. Physical activity was lower during the feeding period and was increased shortly after feeding in mice receiving ghrelin together with IgG from obese mice. In food-restricted mice without ABA, ghrelin treatments did not have significant effects on food intake. Thus, this study supports pharmacological use of ghrelin or ghrelin combined with IgG from obese animals for treatment of anorexia accompanied by elevated physical activity. The utility of combining ghrelin with protective IgG should be further determined in animal models of anorexia with unrestricted access to food.

Ghrelin

BACKGROUND

The gastrointestinal peptide hormone ghrelin was discovered in 1999 as the endogenous ligand of the growth hormone secretagogue receptor. Increasing evidence supports more complicated and nuanced roles for the hormone, which go beyond the regulation of systemic energy metabolism.

SCOPE OF REVIEW

In this review, we discuss the diverse biological functions of ghrelin, the regulation of its secretion, and address questions that still remain 15 years after its discovery.

MAJOR CONCLUSIONS

In recent years, ghrelin has been found to have a plethora of central and peripheral actions in distinct areas including learning and memory, gut motility and gastric acid secretion, sleep/wake rhythm, reward seeking behavior, taste sensation and glucose metabolism.

Serum ghrelin and adiponectin levels are increased but serum leptin level is unchanged in low weight Chronic Obstructive Pulmonary Disease patients

BACKGROUND

Weight loss and muscle wasting are common features reported in COPD patients and they are all related with systemic inflammation. In this study, the relationship between pulmonary functions and inflammatory and metabolic parameters in low weight COPD patients were investigated.

METHODS

Fifty male COPD patients were grouped according to the Global Initiative for Chronic Obstructive Lung Disease criteria. Group 1: Mild-moderate COPD patients (n=18; with a mean age of 66.4 ± 9.2 yrs; body mass index (BMI):19.7 ± 1.5 kg/m(2)), group 2: Severe-very severe COPD patients (n=32; with a mean age of 65.9 ± 10.0 yrs; BMI:19.3 ± 1.6 kg/m(2)), group 3: Control group composed of healthy nonsmoking males (n=17; with a mean age of 50.2 ± 8.4 yrs; BMI:21.85 ± 1.5 kg/m(2)). Anthropometric parameters, serum levels of adiponectin (ApN), ghrelin, leptin, hsCRP, IL-6, IL-1β, IL-8, TNF-α and pulmonary functions were compared.

RESULTS

Adiponectin concentration was higher in group 1 (43.3 ± 28.6 ng/mL; p<0.05) and group 2 (59.9 ± 31.8 ng/mL; p<0.001) when compared with the control group (23.5 ± 13.6 ng/mL). Ghrelin concentrations were higher in COPD groups (1281.0 ± 1173.7 and 1840.0 ± 403.6 pg/mL; p<0.05) compared to the control subjects (554.0 ± 281.9 pg/mL). When the groups were compared, no significant difference was found for leptin, IL-1β, TNF-α, and IL-8. Interleukin-6 and hsCRP levels were higher in group 1 than in the control group. ApN was negatively correlated with BMI and FEV1. In all groups, FEV1 showed positive correlation with BMI, skinfold thicknesses, insulin and triglyceride; negative correlation with age, pack/years, HDL-Chol and ApN. Increased SHBG with decreased insulin level and HOMA-IR may indicate increased insulin sensitivity in COPD groups.

CONCLUSION

The anti-inflammatory effect of ApN and ghrelin is more evident in severe-very severe COPD patients.

Growth hormone secretagogues exert differential effects on skeletal muscle calcium homeostasis in male rats depending on the peptidyl/nonpeptidyl structure

The orexigenic and anabolic effects induced by ghrelin and the synthetic GH secretagogues (GHSs) are thought to positively contribute to therapeutic approaches and the adjunct treatment of a number of diseases associated with muscle wasting such as cachexia and sarcopenia. However, many questions about the potential utility and safety of GHSs in both therapy and skeletal muscle function remain unanswered. By using fura-2 cytofluorimetric technique, we determined the acute effects of ghrelin, as well as of peptidyl and nonpeptidyl synthetic GHSs on calcium homeostasis, a critical biomarker of muscle function, in isolated tendon-to-tendon male rat skeletal muscle fibers. The synthetic nonpeptidyl GHSs, but not peptidyl ghrelin and hexarelin, were able to significantly increase resting cytosolic calcium [Ca²⁺]i. The nonpeptidyl GHS-induced [Ca²⁺]i increase was independent of GHS-receptor 1a but was antagonized by both thapsigargin/caffeine and cyclosporine A, indicating the involvement of the sarcoplasmic reticulum and mitochondria. Evaluation of the effects of a pseudopeptidyl GHS and a nonpeptidyl antagonist of the GHS-receptor 1a together with a drug-modeling study suggest the conclusion that the lipophilic nonpeptidyl structure of the tested compounds is the key chemical feature crucial for the GHS-induced calcium alterations in the skeletal muscle. Thus, synthetic GHSs can have different effects on skeletal muscle fibers depending on their molecular structures. The calcium homeostasis dysregulation specifically induced by the nonpeptidyl GHSs used in this study could potentially counteract the beneficial effects associated with these drugs in the treatment of muscle wasting of cachexia- or other age-related disorders.

Gut hormones, appetite suppression and cachexia in patients with pulmonary TB

Background

Cachexia is a hallmark of pulmonary tuberculosis and is associated with poor prognosis. A better understanding of the mechanisms behind such weight loss could reveal targets for therapeutic intervention. The role of appetite-regulatory hormones in tuberculosis is unknown.

Methods and Findings

41 subjects with newly-diagnosed pulmonary TB (cases) were compared to 82 healthy controls. We measured appetite, body mass index (BMI), % body fat (BF), plasma peptide YY (PYY), leptin, ghrelin, and resistin for all subjects. Measurements were taken at baseline for controls and at treatment days 0, 30, and 60 for cases. Baseline appetite, BMI, and BF were lower in cases than in controls and improved during treatment. PYY, ghrelin, and resistin were significantly elevated in cases and fell during treatment. Leptin was lower in cases and rose with treatment. Appetite was inversely related to PYY in cases. High pre-treatment PYY predicted reduced gains in appetite and BF. PYY was the strongest independent predictor of appetite in cases across all time points.

Conclusions

Appetite-regulatory hormones are altered in TB patients. As hormones normalize during treatment, appetite is restored and nutritional status improves. High baseline PYY is an indicator of poor prognosis for improvement in appetite and nutrition during treatment. Wasting in TB patients may partly be mediated by upregulation of PYY with resulting appetite suppression.

Nutrition therapy issues in esophageal cancer

Esophageal cancer has traditionally been a disease with poor long term outcomes in terms of both survival and quality of life. In combination with surgical and pharmacologic therapy, nutrition support has been demonstrated to improve patient tolerance of treatment, quality of life, and longterm outcomes. An aggressive multi-disciplinary approach is warranted with nutrition support remaining a cornerstone in management. Historically, nutrition support has focused on adequate caloric provision to prevent weight loss and allow for tolerance of treatment regimens. Alterations in metabolism occur in these patients making their use of available calories inefficient and the future of nutritional support may lie in the ability to alter this deranged metabolism. The purpose of this article is to review the current literature surrounding the etiology, treatment, and role of nutrition support in improving outcomes in esophageal cancer.

Pharmacological interventions for geriatric cachexia: a narrative review of the literature

OBJECTIVE

The objective of this review was to investigate the range of pharmacological interventions that have been studied for treatment of geriatric cachexia, and to evaluate their effect on selected clinical outcomes in this population.

METHODS

Databases including Medline and Cochrane Central Register of Controlled Trials were searched up to March 2010 with search terms including "cache*", "intervention", "megestrol acetate" and "cytokine inhibitors". Studies investigating subjects with mean age <60y or disease-related cachexia were excluded. Outcomes assessed were weight or BMI, body composition, appetite and laboratory parameters indicative of cachexia.

RESULTS

Fifteen publications met the selection criteria, reporting on ten studies. Seven studies investigated use of megestrol acetate (MA): two randomised controlled trials, one case control study, two pre-test/post-test studies and two retrospective chart reviews. Weight/BMI was common amongst outcomes and these studies showed an improvement in weight compared with baseline. MA studies which investigated body composition, appetite and/or laboratory parameters provided some evidence for improvement in these outcomes. Three randomised controlled trials investigated the use of other interventions: ghrelin, growth hormone and vitamin supplementations. All demonstrated a significant increase in lean body mass. The only other outcome of interest in these three trials was weight in one study with a significant increase demonstrated.

CONCLUSION

Little investigation has been conducted in this population and the diagnosis of cachexia is problematic however these trials provide preliminary evidence for beneficial outcomes in older adults likely to have cachexia. Further high quality adequately powered prospective studies are necessary to provide effective treatment for geriatric cachexia.

Dietary and pharmacological management of severe catabolic conditions

INTRODUCTION

Nutritional debilitation is among the most devastating and life-threatening complications of cancers and various chronic diseases. It arises from a complex interaction between the illness and the host. This process includes cytokine production, release of lipid-mobilizing and proteolysis-inducing agents and alterations in intermediary metabolism. As a result, many patients develop cachexia with progressive body fat and muscle tissue wasting with associated worsening of their clinical status and a lower quality of life. This review will provide up-to-date information about different pharmacological management of cachexia.

FINDINGS

Until recently, the 2 major options for pharmacological therapy have been either progestational agents or corticosteroids. However, knowledge of the mechanisms of cachexia has led to newer therapeutic interventions for treating several aspects of the syndrome. These include antiserotonergic agents, branched-chain amino acids, eicosapentanoic acid, melanocortin antagonists and antimyostatin agents-all of which act on the feeding-regulatory circuitry to increase appetite and inhibit illness-derived catabolic elements.

CONCLUSIONS

Information from this review will guide health care providers in limiting weight loss and improve performance status of the cachectic patients through dietary and pharmacological therapy, with the hope that such approach would extend patients survival and improve their quality of life.

Ghrelin, appetite and gastric electrical stimulation

Ghrelin is a peptide hormone produced mainly by the stomach and has widespread physiological functions including increase in appetite. The stimulation of the ghrelin system represents a potential therapeutic approach in various disorders characterized by deficient ghrelin signaling or by low appetite. This stimulation may be achieved via pharmacological targeting of the ghrelin receptor with synthetic ghrelin or ghrelin mimetics or via increased endogenous ghrelin production. Recently, it was demonstrated that gastric electrical stimulation (GES) with Enterra parameters results in increased ghrelin production in rats. Furthermore, recent data revealed putative role of ghrelin-reactive immunoglobulins in the modulation of the ghrelin signaling which can be also stimulated by GES. Here, we review the links between GES and ghrelin in existing GES experimental and clinical applications for treatment of gastroparesis, functional dyspepsia or obesity and discuss if GES can be proposed as a non-pharmacological approach to improve ghrelin secretion in several pathological conditions characterized by low appetite, such as anorexia nervosa or anorexia-cachexia syndrome.

Cancer cachexia therapy: a key weapon in the fight against cancer

PURPOSE OF REVIEW

Cachexia affects millions of cancer patients around the world. Though its causes are poorly understood, its devastating impact on the patient and their loved ones underscore the urgency of this unmet medical need. Recent research efforts suggest multiple body systems are dysregulated in cachexia, not only increasing the challenge in effectively treating the disease but also expanding the opportunities for intervention.

RECENT FINDINGS

Agents as diverse as anti-inflammatory monoclonal antibodies and novel anabolic small molecules are under clinical evaluation for their ability to prevent and treat wasting. The therapies evaluated to date range in their ability to improve appetite, mitigate weight loss and reverse undesirable changes in body composition and physical function.

SUMMARY

An increased understanding of cancer cachexia, both mechanistically and its impact on cancer patients' struggle with their disease, has resulted in diverse therapeutic concepts. Recent clinical efforts demonstrate progress with novel therapies but fall short of effectively treating most cachectic patients and highlight a clear need for further research. Given the inherent heterogeneity of cancer patients and the significant impact of muscle wasting on morbidity and mortality, continued research efforts are critical in developing effective therapies to prevent and treat cancer cachexia.

Nutritional interventions for cancer-induced cachexia

Cancer-induced cachexia remains a significant cause of morbidity and mortality in cancer treatment. Cancer research and development continues at an aggressive pace and yet a degree of cancer-induced cachexia is experienced by up to 80% of advanced stage cancer patients. Unfortunately, there are no established treatment regimens for this condition. Weight loss and fatigue consistently appear in patient oncologic histories and progress notes. However, few oncologists fully understand the pathologic mechanisms causing cachexia resulting in well-meaning advice to increase caloric intake with minimal results. Our goal is to describe the pathologic basis of cancer-induced cachexia and to detail accompanying metabolic derangements. Understanding the causes of cachexia sheds light on the subsequent need for multi-modality therapy including clinical intervention with specialized nutrition support, drug therapy, lifestyle and diet changes. In addition to nutrition support modalities, practicing oncologists may prescribe medical therapies designed to increase body weight and lean body mass, including megestrol acetate, tetrahydrocannibinol, oxandrolone, and non-steroidal anti-inflammatory drugs. A variety of experimental therapies are also being investigated for cancer-induced cachexia including tumor necrosis factor-alpha inhibitors and ghrelin infusions. We review the available data to support nutrition-oriented interventions in cancer-induced cachexia, including omega-3 fatty acids, amino-acid loading/protein supplementation, parenteral and enteral nutrition support, and food-derived compounds such as curcumin, reservatrol, and pomegranate.

Current and potential roles of ghrelin in clinical practice

Ghrelin is a novel GH-releasing peptide, which has been identified as an endogenous ligand for GH-secretagogue receptor. Ghrelin is mainly secreted by the stomach and plays a critical role in a variety of physiological processes including endocrine, metabolic, cardiovascular, immunological, and other actions. Ghrelin stimulates food intake via hypothalamic neurons and causes a positive energy balance and body weight gain by decreasing fat utilization and promoting adiposity. Given the multiple effects of ghrelin, its potential clinical applications have been evaluated in various conditions. Preliminary trials have shown that it may prove valuable in the management of disease-induced cachexia. Ghrelin may improve the wasting syndrome through GH-dependent or GH-independent effects. Moreover, ghrelin may play a role in the management of disorders of gut motility and obesity. Finally, other potential clinical applications of ghrelin include the treatment of patients with diabetes mellitus, infections, rheumatological diseases or GH deficiency and the diagnosis of this hormonal disorder.

Gastric electrical stimulation increases ghrelin production and inhibits catecholaminergic brainstem neurons in rats

Gastric electrical stimulation (GES) is a new therapeutic option for functional dyspepsia and gastroparesis. In addition to ameliorating nausea and vomiting, GES results in improved appetite which is not always associated with accelerated gastric emptying. To explore the central and peripheral factors underlying GES-associated improvement of appetite we developed a GES model in anaesthetized Wistar rats. During laparotomy, two electrodes were implanted into the stomach and high-frequency low-energy GES (14 Hz, 5 mA) was applied. The effects of 1 h GES were compared with sham stimulation. After GES, c-Fos expression was increased in the mucosal and submucosal layers of the stimulated area (174%). In the stomach, GES increased ghrelin mRNA (178%) and doubled the number of ghrelin-positive cells, resulting in elevated plasma levels of ghrelin (2.3 ± 0.2 vs. 1.6 ± 0.2 ng/mL). In the arcuate nucleus of the hypothalamus, GES increased c-Fos (277%) and agouti-related protein (AgRP) mRNA expression (135%). GES reduced the number of c-Fos-positive cells throughout the nucleus of the solitary tract (between 93 and 75% from rostral to caudal levels) including catecholaminergic neurons (81% at caudal level). Gastric emptying, plasma glucose and heart rate variability were not affected by GES. This study shows that GES may improve appetite via stimulation of main orexigenic pathways, including ghrelin production in the stomach and AgRP in the hypothalamus, as well as by reducing the activity of catecholaminergic brainstem neurons.

Ghrelin improves disturbed myocardial energy metabolism in rats with heart failure induced by isoproterenol

To explore the effects of ghrelin on disturbed myocardial energy metabolism during chronic heart failure (CHF). Rats were subcutaneously injected with isoproterenol (ISO) for 10 days with or without ghrelin for another 10 days. Enzyme immunoassay was to measure ghrelin concentrations. Compared with the control group, ISO-treated rats showed suppressed cardiac function with high ghrelin/GHS-R expressions. These rats also showed the decreases in food consumption and weight. The decreased levels of plasma glucose and myocardial glucogen, but the high lactate in blood and myocardium showed myocardial metabolic disturbance. Compared with the group given ISO alone, the rats with ghrelin (20 and 100 microg/kg/day) improved cardiac dysfunction and increased food intake by 13.5 and 14.2% (both P < 0.01), and rate of weight gain by 95% (P < 0.05) and 1.71-fold (P < 0.01), respectively. The plasma glucose were increased by 49.7 and 50.8% (both P < 0.01), and myocardial glucogen, by 40.5 and 51.7% (both P < 0.01), but blood lactate decreased by 1.56- and 1.96-fold (both P < 0.01), and myocardial lactate by 32.1 and 48.7% (both P < 0.05), respectively. Their MCT1 mRNA and protein expressions increased. The myocardial ghrelin/GHS-R pathway can be upregulated during CHF. The ghrelin can attenuate cardiac dysfunction and energy metabolic disturbance in CHF rats.

Baseline nutritional evaluation in metastatic lung cancer patients: Mini Nutritional Assessment versus weight loss history

BACKGROUND

Cancer cachexia adversely affects survival and quality of life but its timely recognition is problematic. Nutritional questionnaires, like the Mini Nutritional Assessment (MNA), could identify early those patients at risk. The aim of the study was to compare MNA with 5% weight loss, a common criterion used in oncologic evaluation.

PATIENTS AND METHODS

The nutritional status of 171 chemotherapy-naive patients with metastatic lung cancer was evaluated by both methods. The results were compared and correlated with clinical and laboratory values and with clinical outcome.

RESULTS

The incidence of malnourished or patients at risk was higher according to the MNA (P<0.001). Both methods correlated with the performance status (P<0.001) but MNA was further correlated with the number of metastatic sites (P=0.007) and the presence of brain metastasis (P=0.022). Of 14 laboratory values studied, 9 were correlated with MNA and 5 with the weight loss history. Both methods were correlated with response to first-line therapy, time to progression and survival but MNA had a better predictive (P<0.001) and prognostic (P < 0.001) value.

CONCLUSIONS

MNA outperforms weight loss history as a baseline nutritional screening method in patients with metastatic lung cancer and could further refine prognostication.

Effects by daily long term provision of ghrelin to unselected weight-losing cancer patients: a randomized double-blind study

BACKGROUND

The short-term provision of ghrelin to patients with cancer indicates that there may be benefits from long-term provision of ghrelin for the palliative treatment of weight-losing cancer patients. This hypothesis was evaluated in a randomized, double-blind, phase 2 study.

METHODS

Weight-losing cancer patients with solid gastrointestinal tumors were randomized to receive either high-dose ghrelin treatment (13 microg/kg daily; n = 17 patients) or low-dose ghrelin treatment (0.7 microg/kg daily; n = 14 patients) for 8 weeks as a once-daily, subcutaneous injections. Appetite was scored on a visual analog scale; and food intake, resting energy expenditure, and body composition (dual x-ray absorpitometry) were measured before the start of treatment and during follow-up. Serum levels of ghrelin, insulin, insulin-like growth factor 1, growth hormone (GH), triglycerides, free fatty acids, and glucose were measured. Health-related quality of life, anxiety, and depression were assessed by using standardized methods (the 36-item Short Form Health Survey and the Hospital Anxiety and Depression Scale). Physical activity, rest, and sleep were measured by using a multisensor body monitor.

RESULTS

Treatment groups were comparable at inclusion. Appetite scores were increased significantly by high-dose ghrelin analyzed both on an intent-to-treat basis and according to the protocol. High-dose ghrelin reduced the loss of whole body fat (P < .04) and serum GH (P < .05). There was a trend for high-dose ghrelin to improve energy balance (P < .07; per protocol). Otherwise, no statistically significant differences in outcome variables were observed between the high-dose and low-dose groups. Adverse effects were not observed by high-dose ghrelin, such as serum levels of tumor markers (cancer antigen 125 [CA 125], carcinoembryonic antigen, and CA 19-9).

CONCLUSIONS

The current results suggested that daily, long-term provision of ghrelin to weight-losing cancer patients with solid tumors supports host metabolism, improves appetite, and attenuates catabolism.

The positive effects of growth hormone-releasing peptide-6 on weight gain and fat mass accrual depend on the insulin/glucose status

Ghrelin and GH secretagogues, including GH-releasing peptide (GHRP)-6, stimulate food intake and adiposity. Because insulin modulates the hypothalamic response to GH secretagogues and acts synergistically with ghrelin on lipogenesis in vitro, we analyzed whether insulin plays a role in the metabolic effects of GHRP-6 in vivo. Streptozotocin-induced diabetic rats received saline, GHRP-6, insulin, or insulin plus GHRP-6 once daily for 8 wk. Rats receiving saline suffered hyperglycemia, hyperphagia, polydipsia, and weight loss. Insulin, but not GHRP-6, improved these parameters (P < 0.001 for all), as well as the diabetes-induced increase in hypothalamic mRNA levels of neuropeptide Y and agouti-related peptide and decrease in proopiomelanocortin. Cocaine amphetamine-related transcript mRNA levels were also reduced in diabetic rats, with GHRP-6 inducing a further decrease (P < 0.03) and insulin an increase. Diabetic rats receiving insulin plus GHRP-6 gained more weight and had increased epididymal fat mass and serum leptin levels compared with all other groups (P < 0.001). In epididymal adipose tissue, diabetic rats injected with saline had smaller adipocytes (P < 0.001), decreased fatty acid synthase (FAS; P < 0.001), and glucose transporter-4 (P < 0.001) and increased hormone sensitive lipase (P < 0.001) and proliferator-activated receptor-gamma mRNA levels (P < 0.01). Insulin normalized these parameters to control values. GHRP-6 treatment increased FAS and glucose transporter-4 gene expression and potentiated insulin's effect on epididymal fat mass, adipocyte size (P < 0.001), FAS (P < 0.001), and glucose transporter-4 (P < 0.05). In conclusion, GHRP-6 and insulin exert an additive effect on weight gain and visceral fat mass accrual in diabetic rats, indicating that some of GHRP-6's metabolic effects depend on the insulin/glucose status.

Update on clinical trials of growth factors and anabolic steroids in cachexia and wasting

This article and others that focused on the clinical features, mechanisms, and epidemiology of skeletal muscle loss and wasting in chronic diseases, which include chronic kidney disease, cancer, and AIDS, were presented at a symposium entitled "Cachexia and Wasting: Recent Breakthroughs in Understanding and Opportunities for Intervention," held at Experimental Biology 2009. The clinical and anabolic efficacy of specific growth factors and anabolic steroids (eg, growth hormone, testosterone, megestrol acetate) in malnutrition and other catabolic states has been the subject of considerable research during the past several decades. Research on the effects of these agents in cachexia or wasting conditions, characterized by progressive loss of skeletal muscle and adipose tissue, focused on patients with AIDS in the early 1990s, when the devastating effects of the loss of body weight, lean body mass, and adipose tissue were recognized as contributors to these patients' mortality. These same agents have also been studied as methods to attenuate the catabolic responses observed in cancer-induced cachexia and in wasting induced by chronic obstructive pulmonary disease, congestive heart failure, renal failure, and other conditions. This article provides an updated review of recent clinical trials that specifically examined the potential therapeutic roles of growth hormone, testosterone, oxandrolone, and megestrol acetate and emerging data on the orexigenic peptide ghrelin, in human cachexia and wasting.

Diabetes mellitus, inflammation, obesity: proposed treatment pathways for current and future therapies

OBJECTIVE

To review the pathophysiology, pharmacology, and current or future therapies under study for use in treating diabetes mellitus, inflammation associated with diabetes mellitus, and/or obesity related to diabetes mellitus, through 1 of 4 investigational pathways: adiponectin, ghrelin, resveratrol, or leptin.

DATA SOURCES

A literature search using MEDLINE (1966-December 12, 2009), PubMed (1950-December 12, 2009), Science Direct (1994-December 12, 2009), and International Pharmaceutical Abstracts (1970-December 12, 2009) was performed using the terms adiponectin, ghrelin, resveratrol, leptin, inflammation, obesity, and diabetes mellitus. English-language, original research, and review articles were examined, and citations from these articles were assessed as well.

STUDY SELECTION AND DATA EXTRACTION

Clinical studies and in vitro studies were included in addition to any Phase 1, 2, or 3 clinical trials.

DATA SYNTHESIS

Mechanistic pathways regarding adiponectin, ghrelin, resveratrol, and leptin are of interest as future treatment options for diabetes mellitus. Each of these pathways has produced significant in vitro and in vivo clinical data warranting further research as a possible treatment pathway for diabetes-related inflammation and/or obesity reduction. While research is still underway to determine the exact effects these pathways have on metabolic function, current data suggest that each of these compounds may be of interest for future therapies.

CONCLUSIONS

While several pathways under investigation may offer additional benefits in the treatment of diabetes mellitus and associated impairments, further investigation is necessary for both investigational and approved therapies to ensure that the impact in new pathways does not increase risks to patient safety and outcomes.

New insights into the role of anabolic interventions in dialysis patients with protein energy wasting

PURPOSE OF REVIEW

Patients on maintenance dialysis commonly develop protein-energy wasting (PEW), which is associated with poor survival. There have been several advances in anabolic interventions aimed at improving PEW in these patients in recent years.

RECENT FINDINGS

Oral or parenteral nutritional supplementation, especially if administered during dialysis, improves net protein anabolism in chronic hemodialysis patients. These beneficial effects have been extended to long-term benefits in recent clinical trials. Resistance exercise, alone or combined with intradialytic oral nutrition supplementation, also improves net protein balance in the acute setting although recent studies indicated a limited beneficial effect of long-term exercise alone on muscle protein accretion in chronic hemodialysis patients. Anabolic agents such as growth hormone and androgens have been shown to exert significant benefits on visceral protein stores, muscle mass and strength. Ghrelin, a hormone with combined orexigenic and anti-inflammatory effects, is a potential new nutritional intervention in maintenance dialysis patients.

SUMMARY

Existing anabolic therapeutic strategies have proven to be effective in improving PEW in maintenance dialysis patients. Combined anabolic interventions and several new and established anabolic hormones represent further promising nutritional interventions. Large-scale randomized controlled trials examining the effects of anabolic interventions on mortality and morbidity are still lacking.

Are ghrelin and leptin involved in food intake and body mass index in maintenance hemodialysis?

OBJECTIVES

Both leptin and ghrelin (in the forms of acyl ghrelin and des-acyl ghrelin) are involved in food intake, and appear to be dysregulated in chronic kidney disease. This study describes plasma leptin, acyl, and des-acyl ghrelin concentrations in relation to protein intake and body mass index (BMI) in hemodialysis (HD) patients.

DESIGN

This was a cross-sectional study.

SETTING

This study was conducted during the baseline phase of the French multicenter Influence of a High-Flux Dialyzer on Long-Term Leptin Levels Study.

PATIENTS

We studied 125 HD patients (aged 72.5+/-11.7 years; 59% males).

MAIN OUTCOME MEASURE

Blood samples were collected during fasting, and before a regular HD session. Plasma ghrelin and leptin were evaluated. The protein equivalents of total nitrogen appearance and BMI were calculated.

RESULTS

Patients demonstrated elevated serum leptin (48.0+/-49.0 ng/mL) and des-acyl ghrelin (646.6+/-489.5 pg/mL) levels, and low acyl ghrelin levels (29.8+/-58.5 pg/mL), according to normal values. Acyl ghrelin was negatively correlated with C-reactive protein (r=-0.34, P < .001). The des-acyl to acyl ghrelin ratio was negatively correlated with protein intake, as estimated by normalized Protein Nitrogen Appearance (r=-0.22, P=.01). Serum leptin exhibited its well-described positive correlation with BMI and waist circumference, but the other hormones did not.

CONCLUSIONS

This study reports high des-acyl ghrelin and leptin levels and low acyl ghrelin levels in HD patients, a finding potentially associated with inflammation and food intake.