Hypocretins/orexins act through two receptor subtypes: OX(1) and OX(2). Outside the brain, orexin receptors are expressed in adrenal glands, where orexins stimulate the release of glucocorticoids. To further address the regulation of steroidogenesis, we analyzed the effect of orexins on the expression of steroidogenic enzymes in human adrenocortical National Cancer Institute (NCI) H295R cells b...

Neurons in the lateral hypothalamus (LH) that contain hypocretin/orexin have been established as important promoters of arousal. Deficiencies in the hypocretin/orexin system lead to narcolepsy. The inhibition of hypocretin/orexin neurons by sleep-promoting neurotransmitters has been suggested as one part of the sleep regulation machinery. Adenosine has been identified as a sleep promoter and it...

OBJECTIVE Patients with Parkinson's disease frequently complain of sleep disturbances and loss of muscle atonia during rapid-eye-movement (REM) sleep is not rare. The orexin-A (hypocretin-1) hypothalamic system plays a central role in controlling REM sleep. Loss of orexin neurons results in narcolepsy-cataplexy, a condition characterized by diurnal sleepiness and REM sleep without atonia. Alter...

Avoiding danger and finding food, which are life-sustaining activities that are regulated by emotion, reward and energy balance, require proper wakefulness. The orexin system controls sleep and wakefulness through interactions with systems that regulate emotion, reward and energy homeostasis. Recent findings have brought about the possibility of novel therapies targeting the orexin system for s...

Release of the neuropeptides corticotropin-releasing factor (CRF) and orexin-A in the ventral tegmental area (VTA) play an important role in stress-induced cocaine-seeking behavior. We provide evidence for pharmacologically significant interactions between CRF and orexin-A that depend on oligomerization of CRF1 receptor (CRF1R) and orexin OX1 receptors (OX1R). CRF1R-OX1R heteromers are the cond...

Obesity is a public health disease and its incidence is steadily increasing both in adults and in children especially in the Western World. It is important to understand the underlying mechanisms of obesity and possible treatments as the orexin system with its receptors, which are involved in different physiological processes. In fact, the aim of this mini-review is to consider the importance o...

Food intake is stimulated following administration of orexin-A into the perifornical region of the lateral hypothalamus (LH/PFA). Orexin neurons originating in the LH/PFA interact with a number of hypothalamic systems known to influence food intake, including glutamatergic neurons. Glutamatergic systems in the LH/PFA were demonstrated to initiate feeding through N-methyl-d-aspartic acid (NMDA) ...

Hypothalamic orexin/hypocretin neurons recently emerged as key orchestrators of brain states and adaptive behaviors. They are critical for normal stimulation of wakefulness and breathing: Orexin loss causes narcolepsy and compromises vital ventilatory adaptations. However, it is unclear how orexin neurons generate appropriate adjustments in their activity during changes in physiological circums...

This study sought to explore the degree of orexin levels in Chinese opiate and methamphetamine addicts and the differences between them. The cross-sectional study was conducted among detoxified drug addicts from Mandatory Detoxification Center (MDC) in five Chinese cities. Orexin levels were assayed with radioimmunoassay (RIA). Mann-Whitney U test and Kruskal-Wallis test were used to detect dif...

Increasing evidence has indicated that brain orexin plays a vital role in the regulation of gastrointestinal physiology such as gastric secretion, gastric motility and pancreatic secretion. However, little is known whether orexin in the brain is involved in the physiology of the lower gastrointestinal tract. The aim of this study was therefore to elucidate whether orexin-A in the brain is invol...