期刊
BRAIN RESEARCH
卷 1704, 期 -, 页码 137-149出版社
ELSEVIER
DOI: 10.1016/j.brainres.2018.10.005
关键词
Subfornical organs; Angiotensin II; Ca2+ imaging
资金
- Ministry of Education, Science, Sports and Culture of Japan [09470020, 16K08073]
- JSPS fellowship [S-96368]
- Grants-in-Aid for Scientific Research [09470020, 16K08073] Funding Source: KAKEN
Characteristics of subfornical organ (SFO) neurons were examined by measuring the cytosolic Ca2+ concentration ([Ca2+](i)) in acutely dissociated neurons of the rat. SFO neurons, defined by the responsiveness to 50 mM K+ (n = 67) responded to glutamate (86%), angiotensin II (All) (50%), arginine vasopressin (AVP) (66%) and/or carbachol (CCh) (61%), at their maximal concentrations, with marked increases in [Ca2+](i). More than a half (174/307) of SFO neurons examined exhibited spontaneous Ca2+ oscillations, while the remainder showed a relatively stable baseline under unstimulated conditions. Spontaneous Ca2+ oscillations were suppressed when extracellular Ca2+ was removed and were inhibited when extracellular Na+ was replaced with equimolar N-methyl-D-glucamine. Ca2+ oscillations were unaffected by the inhibitor of Ca2+-dependent ATPases cyclopiazonic acid, the N-type Ca2+ channel blocker omega-conotoxin GVIA and the P/Q-type Ca2+ channel blocker omega-agatoxin IVA, but significantly inhibited by the high-voltage-activated Ca2+ channel blacker Cd2+ and the L-type Ca2+ channel blocker nicardipine. Ca2+ oscillations were also completely arrested by the voltage-gated Na+ channel blocker tetrodotoxin in 50% of SFO neurons but only partially in the remaining neurons. These results suggest that SFO neurons exhibit spontaneous membrane Ca2+ oscillations that are dependent in part on Ca2+ entry through L-type Ca2+ channels, whose activation may result from burst firing. Moreover, All at picomolar concentrations induced Ca2+ oscillations in neurons showing no spontaneous Ca2+ oscillations, while spontaneous Ca2+ oscillations were arrested by gamma-aminobutyric acid (10 mu M), suggesting that rises in [Ca2+](i) during Ca2+ oscillations may play an important role in the modulation of SFO neuron function.
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