Orexins (hypocretins) actions on the GHRH/somatostatin-GH axis.
The secretion of growth hormone (GH) is regulated through a complex neuroendocrine control system that includes two major hypothalamic regulators, namely GH-releasing hormone (GHRH) and somatostatin (SST) that stimulate and inhibit, respectively, GH release. Classical experiments involving damage and electrical stimulation suggested that the lateral hypothalamic area (LHA) modulated the somatotropic axis, but the responsible molecular mechanisms were unclear. Evidence obtained during the last decade has demonstrated that orexins/hypocretins, a family of peptides expressed in the LHA controlling feeding and sleep, play an important regulatory role on GH, by inhibiting its secretion modulating GHRH and SST neurones. Considering that GH release is closely linked to the sleep-wake cycle and feeding state, understanding orexin/hypocretin physiology could open new therapeutic possibilities in the treatment of sleep, energy homeostasis and GH-related pathologies, such as GH deficiency.
López
M
M
Department of Physiology, School of Medicine, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela, Spain. m.lopez@usc.es
Nogueiras
R
R
Tena-Sempere
M
M
Diéguez
C
C
D000818:Animals; D001835:Body Weight / Q000502:physiology; D004435:Eating / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D013006:Growth Hormone / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000378:metabolism*; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D007031:Hypothalamus / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism; D009479:Neuropeptides / Q000378:metabolism*; D009490:Neurosecretory Systems / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D000068797:Orexins; D010902:Pituitary Gland / Q000378:metabolism; D012890:Sleep / Q000502:physiology; D013004:Somatostatin / Q000378:metabolism*; D014851:Wakefulness / Q000502:physiology
D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D018377:Neurotransmitter Agents; D000068797:Orexins; D013004:Somatostatin; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone