EN
Orexin-A and orexin-B, also named hypocretin-1 and hypocretin-2, are hypothalamic neuropeptides which are important regulators of sleep-wake cycles, reward-seeking, and body energy balance. These neuropeptides bind to two specific, membranebound receptors: OX1R and OX2R, members of the GPCR superfamily. A potent proapoptotic activity of orexins has recently been demonstrated in colon cancer cell lines and human colorectal tumor. In our studies we investigated effects of orexins on survival of rat C6 glioma cells, an experimental model for studies on glioblastoma multiforme, and compared them with those exerted on cultured astocytes from rat cerebral cortex. Orexins A and B decreased the number of surviving C6 glioma cells after 48 h of treatment (MTT test), and reduced [3H]thymidine incorporation into proliferating C6 cells. On the contrary, 48 h incubation of cultured astrocytes with orexins increased astrocyte viability and moderately stimulated their proliferation. Taken together, our results suggest that effects of orexins on cell survival depend on the cell type (normal versus cancer). It can be speculated that orexins may serve as potential anticancer factors in therapy of brain tumors. Supported by MNiSW (grant No 4254/B/PO1/2010/38) and InterMolMed (grant No POIG.01.01.02-10-107/09).