Orexin neurons hypothalamus

Overall, however, secondary cataplexies are associated with specific lesions located in the lateral and posterior hypothalamus, involving the HCRT/orexin neurons. 

Hakansson M, de Lecea L. Sutcliffe. TG. Yanagisawa M, Meister B. Leptin receptor- and STAT3-immunore-activities in hypocretin/orexin neurones of the lateral hypothalamus. J Neuroendocrinol 1999 11 653-663. 

In the mammalian brain orexins are almost exclusively expressed in a small group of neurons located in the lateral hypothalamus (LH) andperifornical area (PEA)... 

Narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and cataplexy, may be caused by the lack of hypocretin mRNA and peptides in humans (Peyron et al., 2000) or a disruption of the hypocretin receptor 2 or its ligand in dogs and mice (Lin et al., 1999 Chemelli et al., 1999). Hypocretin-containing neurons are located exclusively in the dorsomedial, lateral, and perifornical hypothalamic areas (Peyron et al., 1998). Two hypocretin sequences, Hcrt-1 (orexin-A) and Hcrt-2 (orexin-B), are generated from a single preprohypocretin (De Lecea et al., 1998 Peyron et al, 1998 Sakurai et al, 1998). Axons from these neurons are found in the hypothalamus, locus coeruleus (LC), raphe nuclei, tuberomamillary nucleus, midline thalamus, all levels of spinal cord, sympathetic and parasympathetic centers, and many other brain regions... 

Guan, J. L., Uehara, K., Lu, S. et at (2002). Reciprocal synaptic relationships between orexin- and melanin-concentrating hormone-containing neurons in the rat lateral hypothalamus a novel circuit implicated in feeding regulation. Int. J. Obes. Relat. Metab. Disord. 26, 1523-32. 

Backberg, M., Hervieu, G., Wilson, S. Meister, B. (2002). Orexin receptor-1 (OX-R1) immunoreactivity in chemically identified neurons of the hypothalamus focus on orexin targets involved in control of food and water intake. Eur. J. Neurosci. 

Orexins (also known as hypocretins) and presynaptic receptors activated by orex-ins were first described in 1998 (Figure 1). Orexin-A (hypocretin-1) and orexin-B (hypocretin-2) consist of 33 and 28 amino acid residues, respectively, and are derived from a common precursor molecule (prepro-orexin). They act on two receptors, OXi and OX2. Orexinergic neurones have their perikarya in the lateral and posterior part of the hypothalamus and project to many parts of the brain, including the cerebral cortex, thalamus, limbic system, locus coeruleus and raphe nuclei, and to the spinal cord. Orexin-like immunoreactive neurones also occur in the small intestine (for review, see Smart and Jerman 2002). 

The neurons containing orexin/hypocretin are located in the dorsolateral and posterior hypothalamus and have widespread projections in the brain and in the spinal cord (Peyron et al., 1998), indicating that they may be involved in multiple functions (see the reviews by Kilduff and Peyron, 2000 Sutcliffe and de Lecea, 2002). In particular, the orexin/ hypocretin system has been implicated in neuroendocrine and autonomic functions, in addition to food intake regulation. The hypocretin/orexin peptides are excitatory. 

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