Is there a role of ghrelin in preventing catabolism?

Acyl ghrelin improves cardiac function in heart failure and increases fractional shortening in cardiomyocytes without calcium mobilization

BACKGROUND AND AIMS

Ghrelin is an endogenous appetite-stimulating peptide hormone with potential cardiovascular benefits. Effects of acylated (activated) ghrelin were assessed in patients with heart failure and reduced ejection fraction (HFrEF) and in ex vivo mouse cardiomyocytes.

METHODS AND RESULTS

In a randomized placebo-controlled double-blind trial, 31 patients with chronic HFrEF were randomized to synthetic human acyl ghrelin (0.1 µg/kg/min) or placebo intravenously over 120 min. The primary outcome was change in cardiac output (CO). Isolated mouse cardiomyocytes were treated with acyl ghrelin and fractional shortening and calcium transients were assessed. Acyl ghrelin but not placebo increased cardiac output (acyl ghrelin: 4.08 ± 1.15 to 5.23 ± 1.98 L/min; placebo: 4.26 ± 1.23 to 4.11 ± 1.99 L/min, P < 0.001). Acyl ghrelin caused a significant increase in stroke volume and nominal increases in left ventricular ejection fraction and segmental longitudinal strain and tricuspid annular plane systolic excursion. There were no effects on blood pressure, arrhythmias, or ischaemia. Heart rate decreased nominally (acyl ghrelin: 71 ± 11 to 67 ± 11 b.p.m.; placebo 69 ± 8 to 68 ± 10 b.p.m.). In cardiomyocytes, acyl ghrelin increased fractional shortening, did not affect cellular Ca2+ transients, and reduced troponin I phosphorylation. The increase in fractional shortening and reduction in troponin I phosphorylation was blocked by the acyl ghrelin antagonist D-Lys 3.

CONCLUSION

In patients with HFrEF, acyl ghrelin increased cardiac output without causing hypotension, tachycardia, arrhythmia, or ischaemia. In isolated cardiomyocytes, acyl ghrelin increased contractility independently of preload and afterload and without Ca2+ mobilization, which may explain the lack of clinical side effects. Ghrelin treatment should be explored in additional randomized trials.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05277415.

Pre- and postprandial effects on ghrelin signaling in the brain and on the GH/IGF-I axis in the Mozambique tilapia (Oreochromis mossambicus)

The discovery of ghrelin (GRLN) has broadened our understanding of the regulation of energy homeostasis in vertebrates. In addition to stimulating growth hormone release from the pituitary, GRLN has been implicated as a hunger signal stimulating food intake in mammals and goldfish. Indeed, GRLN levels rise preprandial and fall following a meal. The current study investigated pre- and postprandial changes (3 h before and after a meal) in GRLN signaling in the tilapia (Oreochromis mossambicus). Significant elevations in preprandial brain mRNA levels of the GRLN receptor (GHS-R1a) and GRLN were observed; though not significant brain neuropeptide Y (NPY) mRNA levels did increase preprandially. GHS-R1b, and NPY mRNA levels were reduced significantly 3 h after a meal; whereas GHS-R1a levels were unaltered postprandially. Brain ghrelin mRNA levels exhibited a transient significant increase 1 h postprandially. Tilapia that missed the scheduled feeding exhibited no changes in brain GHS-R1a, GRLN and NPY postprandial mRNA levels; whereas GHS-R1b mRNA levels were significantly reduced 1 and 3 h postprandially. Brain GHSR preprocessed RNA (heteronuclear mRNA) levels were significantly elevated 3 h preprandially. GHS-R hnRNA levels were significantly elevated 1h postprandial in fed and fasted tilapia. No preprandial rise in plasma GRLN was observed. Following a meal, plasma GRLN levels were significantly elevated; whereas there was no change in tilapia missing the scheduled feeding. Stomach mRNA levels of GRLN rose preprandially and remained unchanged following a meal. In animals that missed the scheduled feeding stomach GRLN levels dropped significantly 1 h following a meal. There was no change in plasma growth hormone levels in the fed fish, although there was a significant rise in the fasted fish 1h after the scheduled feeding. Postprandial levels of plasma IGF-I were elevated in both fed and fasted tilapia. These results suggest that brain derived GRLN is likely driving day-to-day appetite through GHS-R1a and NPY; while systemic GRLN may play a role in postprandial metabolism.

Absence of effects of short-term fasting on plasma ghrelin and brain expression of ghrelin receptors in the tilapia, Oreochromis mossambicus

Ghrelin is an important endocrine peptide that links the gastrointestinal system and brain in the regulation of food intake and energy expenditure. In human, rat, and goldfish plasma levels of ghrelin and GH are elevated in fasted animals, suggesting that ghrelin is an orexigenic signal and a driving force behind the elevated plasma levels of GH during fasting. Ghrelin's orexigenic action is mediated by the ghrelin receptor (GHS-R1a and GHS-R1b) which is localized on neuropeptide Y (NPY) neurons in the brain. Studies were undertaken to investigate the effect of short-term fasting on plasma ghrelin and brain expression of GHS-R1a, GHS-R1b, and NPY in the tilapia. Fasting for 7 days had no effect on plasma ghrelin concentrations, whereas significant increases in plasma levels of GH were observed on day 3. Fasting significantly reduced plasma levels of IGF-I on days 3 and 7, and of glucose on days 3, 5, and 7. Brain expression of ghrelin and GHS-R1b were significantly elevated in fasted fish on day 3, but were significantly reduced on day 5. This reduction was likely due to a significant increase in the expression in the fed controls on day 5 compared to day 0. No change was detected in the expression of GHS-R1a or NPY in the brain. These results indicate that ghrelin is not acting as a hunger signal in short-term fasted tilapia and is not responsible for the elevated levels of plasma GH.

Pharmacological Treatment of Geriatric Cachexia: Evidence and Safety in Perspective

Anticachexic or antisarcopenic medications are prescribed worldwide for geriatric patients with poor appetite and associated weight loss. They represent a valuable treatment option for managing cachexia. However, the well-publicized adverse reports about these medications in acquired immunodeficiency syndrome (AIDS) and in the cancer population has led to some concern and much subsequent discussion over the safety of these medications being used in geriatric population. This review looks at the evidence in relation to the benefits and risks of these medications and discusses what we know about their use in the geriatric population.

Plasma ghrelin levels in various stages of development of iron deficiency anemia

OBJECTIVES

Ghrelin stimulates food intake and induces metabolic changes leading to an increase in body weight and body fat mass. Iron-deficiency anemia (IDA) is the most frequently seen cause of nutritional anemia, that is a type of starvation. There is no available study related to levels of ghrelin in IDA. The aim of this study is to show an association with ghrelin levels and iron deficiency and to demonstrate whether changes seen in iron deficiency (ID) are explained by ghrelin, as opposed to whether ghrelin levels correlate with ID.

MATERIALS AND METHODS

The study group was consisted of children who were admitted in the outpatient clinic of pediatrics. Control group (C) was defined as cases with normal hemoglobin (Hb), serum iron (SI), transferrin saturation (TS), and ferritin (F) (>12 ng/mL) values; group hypoferritinemia (IDec) Hb: N, SI: N, TS: N, F<12 ng/mL; group iron deficiency (IDef), Hb: N, SI: decreased, TS<or=16%, F<12 ng/mL, and group IDA, Hb and SI decreased, TS<or=16%, F<12 ng/mL. The patients were categorized into 4 groups [group 1 (C), n=25, age=82.4+/-16.56 mo, F=40.87+/-6.17 ng/mL; group 2 (IDec), n=30, age=57.5+/-20.71 mo, F=29.95+/-3.77 ng/mL; group 3 (IDef), n=28, age=50.21+/-19.87 mo, F=14.82+/-3.41 ng/mL; group 4 (IDA), n=25, age=31.55+/-13.21 mo, F=11.75+/-4.01 ng/mL].

RESULTS

Mean value of ghrelin was detected to be 396.53+/-85.56 pg/mL, 332.26+/-74.35 pg/mL, 309.66+/-68.62 pg/mL, and 177.66+/-27.81 pg/mL in control, groups IDec, IDef, and IDA, respectively. A statistically significant difference was detected between groups control and IDef (P<0.01), control and IDA, IDec and IDA, IDef and IDA (P<0.001).

CONCLUSIONS

A significant positive correlation was demonstrated between iron status of the body and levels of ghrelin. Decrease in ghrelin levels in IDA can lead to loss of appetite, desire to eat diverse foods with resultant delay in growth and development.

Therapeutic approaches for muscle wasting disorders

Muscle wasting and weakness are common in many disease states and conditions including aging, cancer cachexia, sepsis, denervation, disuse, inactivity, burns, HIV-acquired immunodeficiency syndrome (AIDS), chronic kidney or heart failure, unloading/microgravity, and muscular dystrophies. Although the maintenance of muscle mass is generally regarded as a simple balance between protein synthesis and protein degradation, these mechanisms are not strictly independent, but in fact they are coordinated by a number of different and sometimes complementary signaling pathways. Clearer details are now emerging about these different molecular pathways and the extent to which these pathways contribute to the etiology of various muscle wasting disorders. Therapeutic strategies for attenuating muscle wasting and improving muscle function vary in efficacy. Exercise and nutritional interventions have merit for slowing the rate of muscle atrophy in some muscle wasting conditions, but in most cases they cannot halt or reverse the wasting process. Hormonal and/or other drug strategies that can target key steps in the molecular pathways that regulate protein synthesis and protein degradation are needed. This review describes the signaling pathways that maintain muscle mass and provides an overview of some of the major conditions where muscle wasting and weakness are indicated. The review provides details on some therapeutic strategies that could potentially attenuate muscle atrophy, promote muscle growth, and ultimately improve muscle function. The emphasis is on therapies that can increase muscle mass and improve functional outcomes that will ultimately lead to improvement in the quality of life for affected patients.

Early satiety in cancer patients: a common and important but underrecognized symptom

INTRODUCTION

The severity of anorexia correlates with the presence of early satiety. The sense of fullness limits nutritional intake. The symptom is poorly understood because most assessment questionnaires do not include early satiety.

METHODS

Patients rarely volunteer early satiety. Central and peripheral mechanisms may be involved in the genesis of early satiety. These would include central sensory specific satiety, food aversions, diurnal changes in intake, gastric motility and accommodation and as gastrointestinal hormones.

CONCLUSIONS

Prokinetic medications, such as metoclopramide are used to treat early satiety. However, other medications which influence gastric accommodation such as clonidine, sumatriptan, or sildenafil, or diminish enteric afferent output such as kappa opioid receptor agonists, may favorably influence early satiety and should be subject to future research. Translational research is needed to understand the relationship of early satiety to gastric motility and accommodation.