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Hypocretins, also known as orexins, are hypothalamic peptides that have been implicated in a variety of behaviors, e.g. food-seeking and feeding, arousal and sleep, reaction to stress. Disturbances in the central hypocretin neurotransmission are believed to underlie narcolepsy. It has also been postulated that hypocretins play an important role in the regulation of hypothalamus-pituitary-adrenal (HPA) axis, energy homeostasis, acquisition and learning of reward system-stimulating signals. Hypocretins exert their numerous actions by interacting with two membrane-bound, G protein-coupled receptors: Hcrtr-1 and Hcrtr-2 (OX and OX ). This review summarizes experimental data on structure and localization of hypocretins and hypocretin receptors, and signal transduction pathways triggered by their stimulation. Special emphasis is given to the proapoptotic activity of hypocretins in cancer cells, and the novel mechanisms whereby they trigger apoptosis.

The Editorial Board
Andrzej Łukaszyk - przewodniczący, Zofia Bielańska-Osuchowska, Szczepan Biliński, Mieczysław Chorąży, Aleksander Koj, Włodzimierz Korochoda, Leszek Kuźnicki, Aleksandra Stojałowska, Lech Wojtczak

Editorial address:
Katedra i Zakład Histologii i Embriologii Uniwersytetu Medycznego w Poznaniu, ul. Święcickiego 6, 60-781 Poznań, tel. +48 61 8546453, fax. +48 61 8546440, email:

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