Somatotropic axis in hypocretin-deficient narcoleptic humans: altered circadian distribution of GH-secretory events.
Am J Physiol Endocrinol Metab
; 284(3): E641-7, 2003 Mar.
Article
em En
| MEDLINE
| ID: mdl-12453828
ABSTRACT
Narcolepsy is a sleep disorder caused by impaired hypocretin (orexin) neurotransmission. Growth hormone (GH) secretion may be altered in narcolepsy for various reasons. Slow-wave sleep episodes, which are closely associated with GH-secretory events, are more randomly dispersed over 24 h in narcoleptics. Furthermore, hypocretins may inhibit pituitary GH release. We assessed the function of the somatotropic axis in narcolepsy by deconvolving 24-h (10-min sampling interval) plasma GH concentration profiles in seven hypocretin-deficient narcoleptic patients and in seven healthy controls matched for age, sex, and body weight. Both basal and pulsatile GH secretion rate and secretagogue-induced GH release were similar in patients and controls. However, narcoleptics secreted approximately 50% of their total production during the daytime, whereas controls secreted only 25% during the day. Also, the GH output pattern of narcoleptics was significantly less regular. We propose that hypocretin deficiency disrupts the circadian distribution of hypothalamic GH-releasing hormone release in narcoleptic patients to simultaneously cause daytime GH release and promote their propensity to fall asleep during the day.
Buscar no Google
Base de dados:
MEDLINE
Assunto principal:
Neuropeptídeos
/
Hormônio do Crescimento
/
Ritmo Circadiano
/
Peptídeos e Proteínas de Sinalização Intracelular
/
Narcolepsia
Idioma:
En
Ano de publicação:
2003
Tipo de documento:
Article