The effects of naltrexone, an oral beta-endorphin antagonist, in children with the Prader-Willi syndrome

Obesity in Prader-Willi syndrome: physiopathological mechanisms, nutritional and pharmacological approaches

Prader-Willi syndrome (PWS) is a genetic disorder caused by the lack of expression of genes on the paternally inherited chromosome 15q11.2-q13 region. The three main genetic subtypes are represented by paternal 15q11-q13 deletion, maternal uniparental disomy 15, and imprinting defect. Clinical picture of PWS changes across life stages. The main clinical characteristics are represented by short stature, developmental delay, cognitive disability and behavioral diseases. Hypotonia and poor suck resulting in failure to thrive are typical of infancy. As the subjects with PWS age, clinical manifestations such as hyperphagia, temperature instability, high pain threshold, hypersomnia and multiple endocrine abnormalities including growth hormone and thyroid-stimulating hormone deficiencies, hypogonadism and central adrenal insufficiency due to hypothalamic dysfunction occur. Obesity and its complications are the most common causes of morbidity and mortality in PWS. Several mechanisms for the aetiology of obesity in PWS have been hypothesized, which include aberration in hypothalamic pathways of satiety control resulting in hyperphagia, disruption in hormones regulating appetite and satiety and reduced energy expenditure. However, despite the advancement in the research field of the genetic basis of obesity in PWS, there are contradictory data on the management. Although it is mandatory to adopt obesity strategy prevention from infancy, there is promising evidence regarding the management of obesity in adulthood with current obesity drugs along with lifestyle interventions, although the data are limited. Therefore, the current manuscript provides a review of the current evidence on obesity and PWS, covering physiopathological aspects, obesity-related complications and conservative management.

Developmental Considerations for the Use of Naltrexone in Children and Adolescents

Naltrexone (NTX) is a well-tolerated drug with a wide safety margin and mechanism of action that affords use across a wide variety of indications in adults and children. By antagonizing the opioid reward system, NTX can modulate behaviors that involve compulsivity or impulsivity, such as substance use, obesity, and eating disorders. Evidence regarding the disposition and efficacy of NTX is mainly derived from adult studies of substance use disorders and considerable variability exists. Developmental changes, plausible disease-specific alterations and genetic polymorphisms in NTX disposition, and pharmacodynamic pathways should be taken into consideration when optimizing the use of NTX in the pediatric population. This review highlights the current state of the evidence and gaps in knowledge regarding NTX to facilitate evidence-based pharmacotherapy of mental health conditions, for which few pharmacologic options exist.

Obesity management in Prader-Willi syndrome: current perspectives

Prader-Willi syndrome (PWS) is a complex multisystem disorder due to the absent expression of the paternally active genes in the PWS critical region on chromosome 15 (15q11.2-q13). The syndrome is considered the most common genetic cause of obesity, occurring in 1:10,000-1:30,000 live births. Its main characteristics include neonatal hypotonia, poor feeding, and lack of appetite in infancy, followed by weight gain, lack of satiety, and uncontrolled appetite, frequently after the age of 2-3 years. The clinical picture includes short stature, multiple endocrine abnormalities (hypogonadism, growth hormone/insulin-like growth factor-I axis dysfunction, hypothyroidism, central adrenal insufficiency), dysmorphic features, scoliosis, osteoporosis, mental retardation, and behavioral and psychiatric problems. Subjects with PWS will become severely obese unless their food intake is strictly controlled. Constant and obsessive food seeking behavior can make life very difficult for both the family and caretakers. Prevention of obesity is mandatory in these patients from the first years of life, because once obesity develops it is difficult to maintain the control of food intake. In fact, PWS subjects die prematurely from complications conventionally related to obesity, including diabetes mellitus, metabolic syndrome, sleep apnea, respiratory insufficiency, and cardiovascular disease. The mechanisms underlying hyperphagia in PWS are not completely known, and to date no drugs have proven their efficacy in controlling appetite. Consequently, dietary restriction, physical activity, and behavior management are fundamental in the prevention and management of obesity in PWS. In spite of all available therapeutic tools, however, successful weight loss and maintenance are hardly accomplished. In this context, clinical trials with new drugs have been initiated in order to find new possibilities of a therapy for obesity in these patients. The preliminary results of these studies seem to be encouraging. On the other hand, until well-proven medical treatments are available, bariatric surgery can be taken into consideration, especially in PWS patients with life-threatening comorbidities.

Prader-Willi syndrome

Prader-Willi syndrome is a multi system disorder characterized by neonatal hypotonia, later obesity, hyperphagia and mental retardation. It occurs sporadically, either as a result of microdeletion of chromosome 15p (70%) or as a result of maternal disomy of chromosome 15 (30%). The major problems encountered by parents are those of hyperphagia, food-seeking and obesity, and conduct disorder, particularly tantrums or oppositional behaviour.

Behavioural management of Prader-Willi syndrome

Prader-Willi syndrome is a genetic illness associated with a defect on chromosome 15. It presents with hypotonicity in infancy followed by voracious appetite and gross obesity from early childhood and with a range of other clinical and behavioural sequelae. This case report is of an adolescent boy who was admitted to a psychiatric unit for an intensive behavioural programme to control his weight gain and deal with associated behavioural problems, and demonstrates that an inpatient programme can lead to sustainable improvements in weight control and other indicators of well-being in PWS patients.

Naltrexone and fluoxetine in Prader-Willi syndrome

The case discussed is of a 9-year-old boy with a diagnosis of Prader-Willi, compulsive eating, severe skin picking, mild mental retardation, and behavioral problems. Prehospital, hospital, and posthospital course is reviewed. An approach using fluoxetine and naltrexone shows a marked improvement in weight control, skin picking, and behavior. Obesity and self-mutilation are discussed with regard to the use of fluoxetine and naltrexone.

Psychopharmacogenetic aspects of Prader-Willi syndrome

The study of genes, drugs, and behavior in three male adolescents with Prader-Willi syndrome (PWS) revealed a clinical profile that raises questions about the indications for neuroleptic and appetite-suppressing medications in this condition. Evidence of the inadvisability of neuroleptic medication and of the pathophysiology of PWS has led to a remarkable control of violent outbursts and hyperphagia by carbamazepine in one patient afflicted with both PWS and Klinefelter's syndrome. Testosterone and behavioral therapy proved to be useful in the management of two patients. The present observations, which are supported by recent advances in the pathophysiology of satiety, suggest that PWS should be understood as a metabolic disorder and subjected to psychopharmacogenetic study.

Opioids and the developing organism: a comprehensive bibliography, 1984-1988

A comprehensive bibliography of the literature concerned with opioids and the developing organism for 1984-1988 is presented. Utilized with companion papers (Neurosci. Biobehav. Rev. 6:439-479; 1982; 8:387-403; 1984), these articles cover the clinical and laboratory references beginning in 1875. For the years 1984, 1985, 1986, 1987, and 1988, a total of 877 citations were recorded. A series of indexes accompanies the citations in order to make the literature more accessible. These indexes are divided into clinical and laboratory topics, and subdivided into such topics as the type of opioid explored and the general area of biological interest (e.g., physiology).

Cerebral beta-endorphin levels in a woman with Prader-Labhart-Willi syndrome

By means of a specific two-site immunoradiometric assay, we explored the beta-endorphin levels in various brain regions of a patient affected by Prader-Labhart-Willi Syndrome. The rank of the beta-endorphin levels of five cerebral zones (hypothalamus, substantia grisea centralis, pons dorsalis, medulla oblongata dorsalis medialis, thalamus medialis) of the patient was homologous to that of subjects without the syndrome, except for the medulla oblongata dorsalis medialis. In patient with the Prader-Labhart-Willi Syndrome this region had a higher ranking level than in subjects without it. However, a functional meaning cannot be attributed to such difference because the patient of this study did not exhibit neurological disturbances relating to elevated beta-endorphin levels in the medullary region investigated.

Endogenous opiates: 1986

This is the ninth installment of our annual review of research involving the endogenous opiate peptides. It is restricted to the non-analgesic and behavioral studies of the opiate peptides published in 1986. The specific topics this year include stress; tolerance and dependence; eating; drinking; gastrointestinal, renal, and hepatic processes; mental illness; learning, memory, and reward; cardiovascular responses; respiration and thermoregulation; seizures and other neurological disorders; activity; sex, pregnancy, and development; and some other behaviors.