Non-ergot-type dopamine receptor agonists such as ropinirole are used for the treatment of Parkinson disease, but they occasionally show serious side effects including sleep attacks and daytime sleepiness. These symptoms are reminiscent of narcolepsy, a major sleep disorder. Because narcolepsy is thought to result from deficiency of a hypothalamic neuropeptide orexin, we examined whether ropini...

Orexin is a neuropeptide produced by a specific subset of neurones located in the lateral hypothalamic area. Mice lacking either prepro-orexin or orexin receptor 2, as well as those in which orexin-producing neurones (orexin neurones) are deleted, share a common phenotype: altered sleep-wake regulation and the sudden onset of muscle atonia. These symptoms are similar to the human sleep disorder...

It is well known that olfaction influences food intake, and conversely, that an individual's nutritional status modulates olfactory sensitivity. However, what is still poorly understood is the neuronal correlate of this relationship, as well as the connections between the olfactory bulb and the hypothalamus. The goal of this report is to analyze the relationship between the olfactory bulb and h...

objective(s): intracerebroventricular injection of orexin-a (hypocretin-1) antagonist has been shown to inhibit stress-induced analgesia. however the locations of central sites that may mediate these effects have not been totally demonstrated. this study was performed to investigate the role of rostral ventromedial medulla (rvm) orexin receptor 1 in stress-induced analgesia (sia). materials and...

The orexin neurones play an essential role in driving arousal and in maintaining normal wakefulness. Lack of orexin neurotransmission produces a chronic state of hypoarousal characterized by excessive sleepiness, frequent transitions between wake and sleep, and episodes of cataplexy. A growing body of research now suggests that the basal forebrain (BF) may be a key site through which the orexin...

Hypocretin (orexin) and dynorphin are neuropeptides with opposing actions on motivated behavior. Orexin is implicated in states of arousal and reward, whereas dynorphin is implicated in depressive-like states. We show that, despite their opposing actions, these peptides are packaged in the same synaptic vesicles within the hypothalamus. Disruption of orexin function blunts the rewarding effects...

The absence of orexin results in narcolepsy-cataplexy. While the function of the central orexinergic system in sleep regulation has been well studied, the role of orexin in motor control is largely unknown. Here, we show that orexin-A acts via OX(1) and OX(2) receptors to directly depolarize neurons in the rat lateral vestibular nucleus (LVN), a subcortical motor center, and enhance their sensi...

Orexin A and orexin B are hypothalamic neuropeptides that play critical roles in the regulation of sleep/wakefulness, as well as in a variety of physiological functions such as emotion, reward, and energy homeostasis. The actions of orexins are mediated by two receptors, orexin 1 (OX1R) and orexin 2 (OX2R) receptors. OX1R and OX2R show partly overlapping but distinct distributions throughout th...

Introduction: Ghrelin and Orexin A exert inhibitory effects on gonadotropins secretion. Aromatase is a key enzyme in the steroidogenesis pathway which converts testosterone to the estradiol. Treatment of neonatal female rats with testosterone propionate (TP) alters gonadotropin secretion patterns in the adulthood. In the present study the effects of central injection of ghrelin or orexin A o...

BACKGROUND Narcolepsy with cataplexy is associated with a loss of orexin/hypocretin. It is speculated that an autoimmune process kills the orexin-producing neurons, but these cells may survive yet fail to produce orexin. OBJECTIVE To examine whether other markers of the orexin neurons are lost in narcolepsy with cataplexy. METHODS We used immunohistochemistry and in situ hybridization to ex...