Mechanisms of orexin A-evoked changes of intracellular calcium in primary cultured cortical neurons.
We have investigated the effect of orexin A on the intracellular free calcium concentration ([Ca2+]i) in primary cultured cortical neurons and explored the exact mechanisms of orexin A-evoked changes of [Ca2+]i. In the present study, changes of [Ca2+]i induced by orexin A in primary cultured cortical neurons were first detected by confocal laser scanning microscopy using Ca2+-sensitive dye fluo-4 as a novel calcium fluorescent probe. Our results showed that 1-0.1 microM orexin A induced the increase in [Ca2+]i in cortical neurons. The increase in [Ca2+]i by acute application of orexin A occurred in a dose-dependent manner. Orexin A-induced increase in [Ca2+]i was not observed under the condition of Ca2+-free Dulbecco's modified Eagle's medium. Pretreatment on the cells with 1 microM thapsigargin did not block orexin A-evoked response. These findings first illuminated the fact that orexin A-induced increase in [Ca2+]i may be mainly from extracellular calcium influx in cortical neurons.
Xia
Jian-Xia
JX
Department of Neurobiology, Third Military Medical University, Chongqing 400038, China.
Chen
Xiao-Wei
XW
Cheng
Sai-Yu
SY
Hu
Zhi-An
ZA
D000814:Aniline Compounds; D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D005456:Fluorescent Dyes; D047908:Intracellular Signaling Peptides and Proteins / Q000494:pharmacology*; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D009479:Neuropeptides / Q000494:pharmacology*; D000068797:Orexins; D051381:Rats; D017208:Rats, Wistar; D014851:Wakefulness / Q000502:physiology; D014966:Xanthenes
D000814:Aniline Compounds; C409648:Fluo 4; D005456:Fluorescent Dyes; D047908:Intracellular Signaling Peptides and Proteins; D009479:Neuropeptides; D000068797:Orexins; D014966:Xanthenes; D002118:Calcium