The orexin-induced release of cytokines in primary microglial cell cultures
Orexin A and B (hypocretin 1 and 2) are hypothalamic neuropeptides that have been implicated in a variety of physiological functions, including sleep and arousal, reaction to stress, regulation of energy homeostasis and hypothalamo-pituitary-adrenal axis. The neuropeptides exert their numerous actions by interacting with two specific, membrane-bound, G-protein-coupled receptors, OX1R and OX2R. We have recently demonstrated that orexin receptors are expressed in rat astrocytes and modify their function. Thus, searching for new orexins roles, in this work we investigated whether these peptides can affect the production of cytokines by microglial cells. Studies were performed on primary microglial cultures from rat cerebral cortex. Orexin A and orexin B stimulated the release of IL-6 as well as TNF-α from microglial cells, as measured by rat IL-6 and TNF-α immunoassay ELISA kits. Interestingly, orexins did not affect the release of IL-1. The obtained results might be important in the aspect of interaction between microglia and neurons/astrocytes in the central nervous system. Supported by MNiSW (grant No 4254/B/PO1/2010/38) and InterMolMed (grant No POIG.01.01.02-10-107/09).
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