期刊
FRONTIERS IN CELLULAR NEUROSCIENCE
卷 9, 期 -, 页码 -出版社
FRONTIERS MEDIA SA
DOI: 10.3389/fncel.2015.00061
关键词
astrocytes; fluoxetine; pH; NHE1; ERK1/2; AKT
资金
- National Natural Science Foundation of China [31440048, 31400925]
- Ministry of Education and Science of the Russian Federation and Lobachevsky State University of Nizhny Novgorod [02.B.49.21.0003]
- Russian Scientific Foundation [14-15-00633]
- Russian Science Foundation [14-15-00633] Funding Source: Russian Science Foundation
Clinical evidence suggest astrocytic abnormality in major depression (MD) while treatment with anti-psychotic drugs affects astroglial functions. Astroglial cells are involved in pH homeostasis of the brain by transporting protons (through sodium-proton transporter 1, NHE1, glutamate transporters EAAT1/2 and proton-lactate co-transporter MCT1) and bicarbonate (through the sodium bicarbonate co-transporter NBC or the chloride bicarbonate exchanger AE). Here we show that chronic treatment with fluoxetine increases astroglial pH i by stimulating NHE1-mediated proton extrusion. At a clinically relevant concentration of 1 mu M, fluoxetine significantly increased astroglial pH i from 705 to 7.34 after 3 weeks and from 718 to 758 after 4 weeks of drug treatment. Stimulation of NHE1 is a result of transporter phosphorylation mediated by several intracellular signaling cascades that include MAPK/ERK1/2, PI3K/AKT and ribosomal S6 kinase (RSK). Fluoxetine stimulated phosphorylation of ERK1/2, AKT and RSK in a concentration dependent manner. Positive crosstalk exists between two signal pathways, MAPK/ERK1/2 and PI3K/AKT activated by fluoxetine since ERK1/2 phosphrylation could be abolished by inhibitors of PI3K, LY294002 and AKT, triciribine, and AKT phosphorylation by inhibitor of MARK, U0126. As a result, RSK phosphorylation was not only inhibited by U0126 but also by inhibitor of LY294002. The NHE1 phoshorylation resulted in stimulation of NHE1 activity as revealed by the NH4CI-prepulse technique; the increase of NHE1 activity was dependent on fluoxetine concentration, and could be inhibited by both U0126 and LY294002. Our findings suggest that regulation of astrocytic pH i and brain pH may be one of the mechanisms underlying fluoxetine action.
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