@article {N{\"a}sman10658, author = {Johnny N{\"a}sman and Genevieve Bart and Kim Larsson and Lauri Louhivuori and Hanna Peltonen and Karl E. O. {\r A}kerman}, title = {The Orexin OX1 Receptor Regulates Ca2+ Entry via Diacylglycerol-Activated Channels in Differentiated Neuroblastoma Cells}, volume = {26}, number = {42}, pages = {10658--10666}, year = {2006}, doi = {10.1523/JNEUROSCI.2609-06.2006}, publisher = {Society for Neuroscience}, abstract = {We studied the cellular response to orexin type 1 receptor (OX1R) stimulation in differentiated IMR-32 neuroblastoma cells. In vitro differentiation of IMR-32 cells with 5-bromo-2'-deoxyuridine leads to a neuronal phenotype with long neurite extensions and an upregulation of mainly N-type voltage-gated calcium channels. Transduction of differentiated IMR-32 cells with baculovirus harboring an OX1R{\textendash}green fluorescent protein cDNA fusion construct resulted in appearance of fluorescence that was confined mainly to the plasma membrane in the cell body and to neurites. Application of orexin-A to fluorescent cells led to an increase in intracellular free Ca2+ concentration, [Ca2+]i. At low nanomolar concentrations of orexin-A, the response was reversibly attenuated by removal of extracellular Ca2+, by application of a high concentration (10 mm) of Mg2+, and by the pharmacological channel blocker dextromethorphan. A diacylglycerol, dioctanoylglycerol, but not thapsigargin or depolarization with potassium, mimicked the OX1R response with regard to Mg2+ sensitivity. A reverse transcription-PCR screening identified mRNAs for all transient receptor potential canonical (TRPC) channels, including TRPC3, TRPC6, and TRPC7, which are known to be activated by diacylglycerol. Expression of a dominant-negative TRPC6 channel subunit blunted the responses to both dioctanoylglycerol and OX1R stimulation. The results suggest that the OX1R activates a Ca2+ entry pathway that involves diacylglycerol-activated TRPC channels in neuronal cells.}, issn = {0270-6474}, URL = {https://www.jneurosci.org/content/26/42/10658}, eprint = {https://www.jneurosci.org/content/26/42/10658.full.pdf}, journal = {Journal of Neuroscience} }