H2O2 mobilizes Ca2+ from agonist- and thapsigargin-sensitive and insensitive intracellular stores and stimulates glutamate secretion in rat hippocampal astrocytes.
The effect of hydrogen peroxide (H2O2) on cytosolic free calcium concentration ([Ca2+]c) as well as its effect on glutamate secretion in rat hippocampal astrocytes have been the aim of the present research. Our results show that 100 microM H2O2 induces an increase in [Ca2+]c, that remains at an elevated level while the oxidant is present in the perfusion medium, due to its release from intracellular stores as it was observed in the absence of extracellular Ca2+, followed by a significant increase in glutamate secretion. Ca2+-mobilization in response to the oxidant could only be reduced by thapsigargin plus FCCP, indicating that the Ca2+-mobilizable pool by H2O2 includes both endoplasmic reticulum and mitochondria. We conclude that ROS in hippocampal astrocytes might contribute to an elevation of resting [Ca2+]c which, in turn, could lead to a maintained secretion of the excitatory neurotransmitter glutamate, which has been considered a situation potentially leading to neurotoxicity in the hippocampus.
González
Antonio
A
Department of Physiology, University of Extremadura, Avenida Universidad s/n, E-10071 Cáceres, Spain. agmateos@unex.es
Granados
María P
MP
Pariente
José A
JA
Salido
Ginés M
GM
D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013050:Spectrometry, Fluorescence; D019284:Thapsigargin / Q000494:pharmacology*
D018698:Glutamic Acid; D019284:Thapsigargin; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D002118:Calcium