Role of the Orexin System on the Hypothalamus-Pituitary-Thyroid Axis.
Hypocretin/orexin (ORX) are two hypothalamic neuropeptides discovered in 1998. Since their discovery, they have been one of the most studied neuropeptide systems because of their projecting fields innervating various brain areas. The orexinergic system is tied to sleep-wakefulness cycle, and narcolepsy is a consequence of their system hypofunction. Orexinergic system is also involved in many other autonomic functions such as feeding, thermoregulation, cardiovascular and neuroendocrine regulation. The main aim of this mini review article is to investigate the relationship between ORX and thyroid system regulation. Although knowledge about the ORX system is evolving, its putative effects on hypothalamic-pituitary-thyroid (HPT) axis still appear unclear. We analyzed some studies about ORX control of HPT axis to know better the relationship between them. The studies that were analyzed suggest Hypocretin/ORX to modulate the thyroid regulation, but the nature (excitatory or inhibitory) of this possible interaction remains actually unclear and needs to be confirmed.
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of Naples Naples, Italy.
Antonietta
A
Messina
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of Naples Naples, Italy.
Carolina
C
De Fusco
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of Naples Naples, Italy.
Vincenzo
V
Monda
Neapolitan Brain Group (NBG), Clinic of Child and Adolescent Neuropsychiatry, Department of Mental, Physical Health and Preventive Medicine, Second University of Naples Naples, Italy.
Maria
M
Esposito
Department of Clinical and Experimental Medicine, University of Foggia Foggia, Italy.
Fiorenzo
F
Moscatelli
Department of Clinical and Experimental Medicine, University of Foggia Foggia, Italy.
Anna
A
Valenzano
Neapolitan Brain Group (NBG), Clinic of Child and Adolescent Neuropsychiatry, Department of Mental, Physical Health and Preventive Medicine, Second University of Naples Naples, Italy.
Marco
M
Carotenuto
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of Naples Naples, Italy.
Emanuela
E
Viggiano
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of Naples Naples, Italy.
Sergio
S
Chieffi
Department of Psychiatry, University of Toronto Toronto, ON, Canada.
Vincenzo
V
De Luca
Department of Clinical and Experimental Medicine, University of Foggia Foggia, Italy.
Giuseppe
G
Cibelli
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of Naples Naples, Italy.
Marcellino
M
Monda
Department of Experimental Medicine, Section of Human Physiology and Unit of Dietetic and Sport Medicine, Second University of NaplesNaples, Italy; Department of Clinical and Experimental Medicine, University of FoggiaFoggia, Italy.
Giovanni
G
Messina
D000818:Animals; D001341:Autonomic Nervous System / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D007030:Hypothalamo-Hypophyseal System / Q000378:metabolism / Q000502:physiology*; D000068797:Orexins / Q000378:metabolism / Q000502:physiology*; D013961:Thyroid Gland / Q000378:metabolism / Q000502:physiology*
D000068797:Orexins
HPT axis; autonomic functions; neuroendocrine control; orexin; posterior lateral hypothalamic area