Orexins/hypocretins and aminergic systems

  title={Orexins/hypocretins and aminergic systems},
  author={Krister S. Eriksson and Olga A. Sergeeva and H. L. Haas and Oliver Selbach},
  journal={Acta Physiologica},
Orexin/hypocretin neurones in the posterior hypothalamus are mutually connected with noradrenergic, serotonergic, dopaminergic, histaminergic, and cholinergic neurone systems. They activate these targets by direct post‐synaptic and indirect pre‐synaptic mechanisms and in turn receive inhibitory feedback and excitatory feed forward control. With respect to behavioural state control, orexin/hypocretin neurones are conducting the orchestra of biogenic amines. This review highlights the role of… 

Orexins Excite Neurons of the Rat Cerebellar Nucleus Interpositus Via Orexin 2 Receptors In Vitro

It is demonstrated that orexins excite the cerebellar IN neurons through OX2R and suggest that the central orexinergic nervous system may actively participate in motor control through its modulation on one of the final outputs of the spinocerebellum.

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Orexin predominantly suppresses mouse SCN Period1 (Per1)-EGFP-expressing clock cells and augments the SCN clock-resetting effects of neuropeptide Y (NPY), another neurochemical correlate of arousal, and potentiates NPY's inhibition of SCN Per1-EGFP cells.



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It is proposed that wakefulness and associated energy expenditure thus depend on that property, which allows the hypocretin–orexin neurons to maintain a tonic excitatory influence on the central arousal and peripheral sympathetic systems.

Orexin A activates locus coeruleus cell firing and increases arousal in the rat.

  • J. HaganR. Leslie N. Upton
  • Biology, Psychology
    Proceedings of the National Academy of Sciences of the United States of America
  • 1999
It is shown that the brain region receiving the densest innervation from orexinergic nerves is the locus coeruleus, a key modulator of attentional state, where application of orexIn A increases cell firing of intrinsic noradrenergic neurones and modulates neuroendocrine function.

Orexin (hypocretin)/dynorphin neurons control GABAergic inputs to tuberomammillary neurons

Orexins excite TM neurons directly and by disinhibition, gated by dynorphin, which might explain some of the neuropathology of narcolepsy.

Orexin/Hypocretin Excites the Histaminergic Neurons of the Tuberomammillary Nucleus

A functional connection between the two populations of hypothalamic neurons is suggested and that they may cooperate in the regulation of rapid-eye-movement sleep and feeding.

Functions of the orexinergic/hypocretinergic system.

The present review focuses on the physiological properties of the cells that secrete or respond to orexins, which appear to be controlled by feeding- and sleep-related signals via a variety of neurotransmitters/hormones from the brain and other tissues.

Orexin Excites GABAergic Neurons of the Arcuate Nucleus by Activating the Sodium—Calcium Exchanger

By combining patch-clamp and RT-multiplex PCR analysis of individual neurons in mouse brain slices, it is shown that an electrophysiologically distinct subset of ARC neurons coexpress orexin receptors and glutamate decarboxylase-67 and are excited by Orexin.

Excitation of Ventral Tegmental Area Dopaminergic and Nondopaminergic Neurons by Orexins/Hypocretins

Dysfunction of the orexin modulation of VTA neurons may be important in triggering attacks of cataplexy in narcolepsy, in which the Orexin system is disrupted.