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Changes in appetite and body weight in response to long-term oral administration of the ghrelin agonist GHRP-2 in growth hormone deficient children.

GHRP-2 (GPA-748, Wyeth-Ayerst) is an orally active peptide growth hormone (GH) secretagogue which acts through a G-protein coupled receptor for which the natural ligand--an acylated 28 amino acid peptide, ghrelin--was recently isolated. Ghrelin and its analogs have potent GH-releasing activities, but in animal studies ghrelin also causes weight gain. As part of a study examining the effect of GHRP-2 on GH secretory dynamics and growth, we evaluated its effects on appetite and body weight. Ten prepubertal children with GH deficiency (growth velocity < or = 4 cm/year in association with a GH response to two provocative stimuli < 10 ng/ml) were included in the study. At the beginning of the study their age was 10.4 +/- 2 years (mean +/- SD), with a height of -3.8 +/- 0.1 SDS. Body mass index (BMI) was 17.9 +/- 3.6 kg/m2, and the BMI Z score 0.21 +/- 1.51 SDS. GHRP-2 was administered orally at a dose of 900 microg/kg b.i.d. for 12 months. Seven out of ten patients reported a significant increase in appetite during the first 6 months of the study. There was a tendency for the BMI SDS to increase during the study, but this increase did not reach statistical significance (0.21 +/- 1.5 vs 0.25 +/- 1.5 SDS). These results suggest that at a dose of 900 microg/kg b.i.d., GHRP-2 appears to have a transient stimulatory effect on appetite, but does not have a chronic clinically significant effect on BMI in children with GH deficiency.

Adolescent↗

Aldosterone target neurons in the nucleus tractus solitarius drive sodium appetite.

Sodium appetite can be enhanced by the adrenal steroid aldosterone via an unknown brain mechanism. A novel group of neurons in the nucleus tractus solitarius expresses the enzyme 11-beta-hydroxysteroid dehydrogenase type 2, which makes them selectively responsive to aldosterone. Their activation parallels sodium appetite in different paradigms of salt loss even in the absence of aldosterone. These unique aldosterone target neurons may represent a previously unrecognized central convergence point at which hormonal and neural signals can be integrated to drive sodium appetite.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗

Chronic excitotoxic lesion of the dorsal raphe nucleus induces sodium appetite.

We determined if the dorsal raphe nucleus (DRN) exerts tonic control of basal and stimulated sodium and water intake. Male Wistar rats weighing 300-350 g were microinjected with phosphate buffer (PB-DRN, N = 11) or 1 microg/0.2 microl, in a single dose, ibotenic acid (IBO-DRN, N = 9 to 10) through a guide cannula into the DRN and were observed for 21 days in order to measure basal sodium appetite and water intake and in the following situations: furosemide-induced sodium depletion (20 mg/kg, sc, 24 h before the experiment) and a low dose of dietary captopril (1 mg/g chow). From the 6th day after ibotenic acid injection IBO-DRN rats showed an increase in sodium appetite (12.0 +/- 2.3 to 22.3 +/- 4.6 ml 0.3 M NaCl intake) whereas PB-DRN did not exceed 2 ml (P < 0.001). Water intake was comparable in both groups. In addition to a higher dipsogenic response, sodium-depleted IBO-DRN animals displayed an increase of 0.3 M NaCl intake compared to PB-DRN (37.4 +/- 3.8 vs 21.6 +/- 3.9 ml 300 min after fluid offer, P < 0.001). Captopril added to chow caused an increase of 0.3 M NaCl intake during the first 2 days (IBO-DRN, 33.8 +/- 4.3 and 32.5 +/- 3.4 ml on day 1 and day 2, respectively, vs 20.2 +/- 2.8 ml on day 0, P < 0.001). These data support the view that DRN, probably via ascending serotonergic system, tonically modulates sodium appetite under basal and sodium depletion conditions and/or after an increase in peripheral or brain angiotensin II.

Angiotensin-Converting Enzyme Inhibitors↗

Evidence of a role for neuropeptide Y and monoamines in mediating the appetite-suppressive effect of GH.

Among the many responses to GH administration is suppression of voluntary feed intake (FI) in some species, attributed to improvement in the efficiency of nutrient utilization and, therefore, reduced need for ingested substrates. Commercial broiler chickens have been genetically selected for generations for rapid growth, realized largely via the major correlated response of increased voluntary feed consumption. Neuropeptide Y (NPY) and monoamines play very important roles in the central regulation of feeding. Preliminary studies from our laboratory suggest that the appetite-suppressive effect of GH may be independent of its actions as a repartitioning agent, and may involve alterations in NPY expression at the pre-translational level. The purpose of this investigation was to explore the dose-response nature of the appetite-suppressive effect of GH in juvenile broilers, and the possible involvement of NPY and monoamines in this process. A GH dose-response study was conducted using 8-week-old female broilers infused i.v. with GH in a pulsatile pattern for 7 days at 0, 10, 50, 100 or 200 microgram/kg body weight per day. Hypothalamic NPY and epinephrine (EP) concentrations decreased in a dose-related manner with GH. At the highest dosage, voluntary FI decreased 19% (P<0.05) and hypothalamic NPY mRNA decreased approximately 50% in the infundibular nuclei and midline region (P<0.0001). In contrast, birds pairfed to the high-GH dosage group did not differ from controls, verifying that changes in NPY and monoamines were not secondary to reduced FI. We conclude that hypothalamic NPY and EP are likely candidates to explore further as mediators of the appetite-suppressive effect of GH.

Animals↗

Effects of nutritional status and gonadal steroids on expression of appetite-regulatory genes in the hypothalamic arcuate nucleus of sheep.

Sheep exhibit photoperiod-driven seasonal changes in appetite and body weight so that nutritional status increases in long days (LD) and decreases in short days (SD); additionally, they are reproductively active in SD and inactive in LD. We addressed the hypothesis that appetite-regulatory genes in the hypothalamus respond differently to changes in nutritional feedback induced by photoperiod as opposed to food restriction, and that responses would be influenced by gonadal steroid status. Castrated oestradiol-implanted male sheep were kept in SD (8 h light/day) or LD (16 h light/day) for 11 weeks, with ad libitum or restricted food (experiment 1; n=8/group). Rams were kept in SD or LD for 12 weeks with ad libitum or restricted food (experiment 2; n=6/group). Gene expression (by in situ hybridisation) in the hypothalamic arcuate nucleus for leptin receptor (OB-Rb), neuropeptide Y (NPY), pro-opiomelanocortin (POMC) and agouti-related peptide (AGRP) was unaffected by photoperiod treatment, but food restriction increased NPY and AGRP mRNAs, in experiment 1. In experiment 2, mRNAs for POMC and cocaine- and amphetamine-regulated transcript (CART) were up-regulated and AGRP down-regulated in SD, while food restriction increased OB-Rb mRNA, increased NPY and AGRP mRNAs only in LD and decreased POMC mRNA only in SD. Thus, gene expression responded differently to photoperiod and food restriction, and the melanocortin pathway was up-regulated in SD in reproductively activated rams but not in oestradiol-implanted castrates. These data support the hypothesis that hypothalamic appetite-regulatory pathways respond differently to changes in nutritional feedback induced by photoperiod as opposed to food restriction, with gonadal steroid feedback additionally influencing the responses.

Androgens↗

Hormonal regulation of appetite and food intake.

Several clinical disorders are strongly influenced by hormones involved in appetite and weight regulation. Obesity and eating disorders are of major importance, because they are associated with severe morbidity and considered to be among the greatest health problems in the Western world today. This review describes recent findings in hormonal regulation of food intake by substances acting both centrally, such as corticotropin-releasing factor, neuropeptide Y and leptin, and peripherally, such as cholecystokinin and somatostatin. Sex hormones and glucocorticoids play an important role in long-term regulation of metabolism. The role of these hormones in appetite and weight changes during life as well as during pregnancy and lactation is discussed. Furthermore, the development of obesity and eating disorders is influenced, in particular, by steroid hormones. Treatment with sex hormones, as in hormone replacement therapy, affects appetite and weight and may have beneficial effects in preventing android obesity. Currently, there is great effort in developing endogenous neurohumoral substances into effective drugs for the treatment of obesity and eating disorders. Leptin and neuropeptide Y analogues are of interest as potential antiobesity agents.

Appetite↗

Cellular analysis of appetitive learning in invertebrates.

In recent years significant progress has been made in the analysis of the cellular mechanisms underlying appetitive learning in two invertebrate species, the pond snail Lymnaea stagnalis and the honeybee Apis mellifera. In Lymnaea, both chemical (taste) and tactile appetitive conditioning paradigms were used and cellular traces of behavioural classical conditioning were recorded at several specific sites in the nervous system. These sites included sensory pathways, central pattern generator and modulatory interneurones as well as motoneurones of the feeding network. In the honeybee, a chemical (odour) appetitive conditioning paradigm resulted in cellular changes at different sites in the nervous system. In both the pond snail and the honeybee the activation of identified modulatory interneurones could substitute for the use of the chemical unconditioned stimulus, making these paradigms even more amenable to more detailed cellular and molecular analysis.

Animals↗

[Standards, Options and Recommendations (SOR) for the use of appetite stimulants in oncology. Work group. Federation of the French Cancer Centres (FNCLCC)].

CONTEXT: The "Standards, Options and Recommendations" (SOR) project, started in 1993, is a collaboration between the Federation of the French Cancer Centres (FNCLCC), the 20 French Cancer Centres and specialists from French Public Universities, General Hospitals and Private Clinics. The main objective is the development of clinical practice guidelines to improve the quality of health care and outcome for cancer patients. The methodology is based on literature review and critical appraisal by a multidisciplinary group of experts, with feedback from specialists in cancer care delivery. OBJECTIVES: To develop clinical practice guidelines according to the definitions of the Standards, Options and Recommendations project for the use of appetite stimulants in oncology. METHODS: Data were identified by searching Medline and the personal reference lists of members of the expert groups. Once the guidelines were defined, the document was submitted for review to 55 independent reviewers, and to the medical committees of the 20 French Cancer Centres. RESULTS: The main recommendations for the use of appetite stimulants in oncology are: 1) Corticosteroids and the synthetic progestogens (megestrol acetate and medroxyprogesterone acetate) are appetite stimulants. 2) They can be useful in managing anorexia and weight loss in cancer patients, especially in the palliative setting, despite the potential side-effects of these agents. 3) The most effective way of using these drugs is not known. Inclusion in clinical trials is recommended. 4) Cyproheptadine, metoclopramide, nandrolone and pentoxif line should not be used outside prospective clinical trials. 5) Hydrazine sulfate should not be used.

Adrenal Cortex Hormones↗

[Appetite and regulation of food intake in uremia].

Anorexia, nausea and vomiting are common symptoms in patients with severe renal failure. Abnormalities in body fluids volume, serum electrolytes concentrations and acid-base balance and accumulations of uremic toxic substances might be primarily contributing to the suppression of appetite. However, the detailed mechanisms that cause appetite suppression in uremia are poorly understood. Impaired gastric emptying, constituents of peritoneal dialysate, plasma high leptin, high cholecystokinin and low neuropeptide Y are also considered to be contributing to appetite suppression in uremia.

Animals↗

Supportive role of a micronutrient appetite normaliser in convalescing patients.

A total of 722 patients recruited from various clinics across Western India, particularly in Western Maharashtra and South Gujarat, recovering from a variety of clinical conditions such as infections of the respiratory tract, malaria, enteric fever, jaundice, surgical procedures and so on were administered a micronutrient appetite normaliser formulation (neogadine) for periods up to 30 days. There was a significant and steady increase in the scores of appetite and well-being during the study period. Very good to good response were reported in 83% of patients. Neogadine was well tolerated with no significant adverse effects on any patients. Based on past experience with this micronutrient formulation as well as the findings of the present study, it is reasonable to conclude that neogadine plays a useful supportive role in the restoration of appetite and well-being in conditions that apply to private practice situations in India.

Adult↗

Orexins (hypocretins): their role in appetite and arousal.

Serendipity and hypothesis-driven research both contributed to the discovery and characterization of two recently identified neuropeptides thought to be involved in the control of appetite and arousal. These two peptides, named hypocretin-1 and -2, or orexin-A and -B, originated from a common precursor, prepro-hypocretin or prepro-orexin, encoded by a gene localized to human chromosome 17q21. Orexin/hypocretin neuropetides are produced by a small set of neurons in the lateral hypothalamic and perifornical areas, classically involved in the control of feeding behavior, blood pressure and central regulation of immune function. Orexin-/hypocretin-containing neurons project widely to the CNS, and orexin receptors have been found in areas known to participate in the control of feeding, sleep, wakefulness, neuroendocrine homeostasis and autonomic regulation. Initially, a role in appetite control was suggested as the main action of the two hypothalamic neuropetides, as their site of synthesis and incretion, the lateral hypothalamus, is primarily involved in the control of food ingestion. Destruction of lateral hypothalamic areas results in underfeeding, and orexins were thought to be the substances mediating appetite-stimulating drives. Further studies indicate a more complex array of functions and effects. The orexin signaling pathway is now thought to participate in a complex cycle of energy homeostasis, including the control of food intake, waking time, motor activity, metabolic rate, heart rate and blood pressure.

Animals↗

[Activity of neurons in the pedunculopontine nucleus in conditioned instrumental appetitive reflex].

Activity of 91 neurons in the compact and diffuse parts of the pedunculopontine tegmental nucleus (PPTg) was recorded in freely moving rabbits during execution of instrumental appetitive conditioning. Of the recorded neurons, 37.4% changed their activity in response to a conditioned stimulus, which is the evidence for the PPTg involvement in instrumental conditioning. Excitatory conditioned neuronal responses to the conditioned stimulus and food reinforcement significantly prevailed over inhibitory reactions. Neuronal responses to the conditioned stimulus were classified in several basic patterns reflecting stimulus effects, structure of the behavioral act, and reinforcement properties. These reactions indicate the involvement of the PPTg in attention, motor learning, and reinforcement. The revealed differences in associative reactive properties of the compact and diffuse parts of the PPTg to the conditioned stimulus and reinforcement point to the functional heterogeneity of this structure and suggest the leading role of the cholinergic part of the PPTg in instrumental appetitive conditioning and reinforcement as well as the essential contribution of the diffuse part into classical appetitive conditioning.

Animals↗

The amphetamine appetite suppressant saga.

(1) In 1999, all amphetamine derivatives still sold in France as appetite suppressants were withdrawn from the market because of serious cardiovascular adverse effects. Sibutramine, marketed in France since 2001, is closely related to this group of drugs. (2) The adverse effects shared by these drugs are mainly neuropsychiatric (due to a psychostimulant action) and cardiovascular (arterial hypertension and tachycardia). (3) More specific cardiovascular adverse effects, such as pulmonary hypertension and severe cardiac valve damage, emerged after several years of use. The first reports date back to the 1960s. (4) The pulmonary hypertension associated with appetite suppressants can be fatal or necessitate transplantation. (5) Cardiac valve damage due to appetite suppressants is generally irreversible and sometimes requires surgery.

Amphetamine-Related Disorders↗

Ghrelin plasma levels and appetite in peritoneal dialysis patients.

Anorexia-associated malnutrition is a severe complication that increases mortality in peritoneal dialysis (PD) patients. Ghrelin is a recently-discovered orexigenic hormone with actions in brain and stomach. We analyzed, in 42 PD patients, the possible relationship between ghrelin and appetite regulation with regard to other orexigens [neuropeptide Y (NPY), NO3] and anorexigens [cholecystokinin (CCK), leptin, glucose-dependent insulinotropic peptide (GIP), tumor necrosis factor alpha (TNFalpha)]. All orexigens and anorexigens were determined in plasma. Eating motivation was evaluated using a visual analog scale (VAS). The patients were divided into three groups: those with anorexia (n = 12), those with obesity associated with high intake (n = 12), and those with no eating behavior disorders (n = 18). A control group of 10 healthy volunteers was also evaluated. Mean plasma levels of ghrelin were high (3618.6 +/- 1533 mg/mL), with 36 patients showing values above the normal range (< 2600 mg/mL). Patients with anorexia had lower ghrelin and NPY levels and higher peptide-C, CCK, interleukin-1 (IL-1), TNFalpha, and GIP levels than did the other patients. Patients with anorexia also had an early satiety score and low desire and pleasure in eating on the VAS and diet survey. We observed significant positive linear correlations between ghrelin and albumin (r = 0.43, p < 0.05), prealbumin (r = 0.51, p < 0.05), transferrin (r = 0.4, p < 0.05), growth hormone (r = 0.66, p < 0.01), NO3 (r = 0.36, p < 0.05), and eating motivation (VAS). At the same time, negative relationships were observed between blood ghrelin and GIP (r = -0.42, p < 0.05), insulin (r = -0.4, p < 0.05), leptin (r = -0.45, p < 0.05), and creatinine clearance [r = -0.33, p = 0.08 (nonsignificant)]. Ghrelin levels were not related to Kt/V or to levels of CCK and cytokines. Ghrelin plasma levels are elevated in PD patients. Uremic patients with anorexia show relatively lower ghrelin plasma levels than the levels seen in obese patients or in patients with normal appetite. The role of ghrelin in appetite modulation is altered in uremic PD patients, and that alteration is possibly associated with disorders in insulin and growth hormone metabolism.

Adult↗

Delayed gastric emptying in children with poor appetite.

BACKGROUND: In this study we aimed to evaluate gastric emptying time in children with poor appetite. METHODS: Anthropometrical measurements, daily energy intakes and gastric emptying times were determined in 36 children with poor appetite. The children were grouped as those with normal and delayed gastric emptying. These groups were then compared with respect to age and nutritional status. RESULTS: Malnutrition was found in 63.9% and gastric emptying was delayed in 58.3% of all cases. Children with delayed gastric emptying were significantly older and malnutrition was significantly higher in this group (7.2 +/- 3.1 vs 3.9 +/- 1.5 years, P: 0.001 and 81.0% vs 40.0%, P: 0.017, respectively). Daily mean energy intake was significantly lower than daily mean energy requirement in children with delayed and normal gastric emptying (P = 0.002 and 0.026 respectively). CONCLUSION: In children with poor appetite, probability of gastric motility disorders should be taken into consideration. Especially in children with failure to thrive at preschool and early school years gastric motility studies should be undertaken.

Adolescent↗

[Orexin, sleep and appetite regulation: a review].

Since 1998, two research groups independently reported the discovery of two novel hypothalamic neuropeptides, called hypocretin-1 and hypocretin-2, respectively many studies have been carried out about their possible functions. One group named these new peptides orexins (A and B) after the Greek word for appetite, since they found that central administration of orexins potently increased food intake in rats. However hypocretins/ orexins are involved in various hypothalamic mechanisms, such as energy homeostasis, neuroendocrine functions, appetite and satiety regulation, vigilance and defence behaviour, sleep and wake regulation. Here is a review of the recent literature, showing some recent discoveries about the link between orexin system, sleep regulation and appetite regulation.

Animals↗

Salt appetite, body sodium, handling of a NaCl load, renin, and aldosterone in genetically and spontaneously hypertensive rats.

Salt appetite, body sodium, handling of a NaCl load, plasma renin activity (PRA), and plasma aldosterone concentration (PAC) were compared in New Zealand genetically hypertensive (GH) and Japanese spontaneously hypertensive rats (SHRs) and their respective normotensive controls [normal Wistar (N) and Wistar-Kyoto (WKY) rats]. Salt appetite was increased in SHRs compared with GH, N, and WKY rats when rats were on salt-free chow and given a choice of distilled water and NaCl solution. Body sodium, measured by whole body counting, was higher in SHRs than in the other strains but did not differ among GH, N, and WKY rats. The rate of excretion of a NaCl load was not increased in GH rats and was slightly increased in SHRs only when on a very low NaCl intake. PRA and PAC (radioimmunoassay) were lower in SHRs than in GH, N, and WKY rats. PAC had a significant negative correlation with body sodium across the four strains. There is no evidence of any abnormality in sodium regulation in GH rats. However, the SHRs have an increased salt appetite and an increased body sodium even when sodium intake is limited; PRA and PAC appear to have responded appropriately to the increased body sodium.

Aldosterone↗

Sensitivity of the appetite control system in obese subjects to nutritional and serotoninergic challenges.

The sensitivity of the appetite system of a group of obese individuals was assessed in response to two challenges known to reduce hunger and enhance satiety in lean people. The challenges were the presentation of a caloric (high protein) load and the activation of serotonin systems. Eight obese female adults (BMI = 38) received 2 X 15 mg d-fenfluramine or placebo daily for 3 days, the study conforming to a 2 X 2 factor (drug X lunch type), double blind, repeated measures design. Three hours after dosing on day 3 they ate either a high carbohydrate (63 percent of total energy) or high protein (54 percent) lunchtime meal (the caloric load). These fixed meal challenges were equal in energy (475 kcal), weight and fat content. Ratings of hunger motivation and food preferences were tracked over the course of lunch and for a further 3 hours, at which point subjects returned for a self-selection test meal. Intakes from this second open meal revealed significant main effects of both caloric load and drug on energy intake, with the high protein d-fenfluramine combination being the most potent anorectic pairing. These findings were supported by the profiles of hunger motivation. This study has confirmed that the appetite system of these subjects was responsive to these biologically relevant challenges. The results suggest that the combination of an appetite modulating drug with specific dietary intervention may represent an effective strategy for the management of hunger arising from caloric restriction.

Adult↗