Evaluation of beta-amyloid peptide 25-35 on calcium homeostasis in cultured rat dorsal root ganglion neurons.
Accumulation of beta-amyloid (Abeta) protein in brain is an important characteristic for the etiology of Alzheimer's disease. Of all the possible processes generating the neurotoxic effects by Abeta, disruption of intracellular Ca(2+) homeostasis is the primary event. In this process, various intracellular Ca(2+) regulatory mechanisms are reported to be involved. Using patch-clamp techniques, both low and high voltage activated Ca(2+) channel currents were recorded in the cultured dorsal root ganglion (DRG) neurons. Application of Abeta protein fragment, Abeta(25-35) (2 microM), for 30 s increased the amplitude in both currents. The Abeta-triggered facilitation effect of Ca(2+) channel was found in all the depolarized potentials tested, as shown in the current-voltage relationship. Furthermore, after applying single cell Ca(2+) microfluorometric method, it was found that Abeta(25-35) alone could trigger elevations of intracellular Ca(2+) concentration ([Ca(2+)](i)) level in 90% of the cells tested. The elevation diminished completely by cumulatively adding CdCl(2), NiCl(2), thapsigargin (TG), FCCP and Zn(2+) in the normal bath solution. Combining pharmacological approaches, we found that voltage-dependent Ca(2+) channels, Ca(2+) stores and a putative Zn(2+)-sensitive extracellular Ca(2+) entry, respectively, makes 61.0, 25.1, and 13.9% contribution to the [Ca(2+)](i) increase caused by Abeta. When tested in a Ca(2+)-free buffer, mitochondria was found to contribute 41.3% of Abeta produced [Ca(2+)](i) elevation and the remaining 58.7% was attributed to endoplasmic reticulum (ER) release.
He
L-M
LM
Institute of Biophysics and Biochemistry, Huazhong University of Science and Technology, Wuhan 430074, PR China.
Chen
L-Y
LY
Lou
X-L
XL
Qu
A-L
AL
Zhou
Z
Z
Xu
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T
D016229:Amyloid beta-Peptides / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / Q000494:pharmacology; D018929:Cell Culture Techniques; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000187:drug effects* / Q000378:metabolism*; D006706:Homeostasis / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D019284:Thapsigargin / Q000494:pharmacology; D014475:Uncoupling Agents / Q000494:pharmacology
D016229:Amyloid beta-Peptides; D015220:Calcium Channels; D004791:Enzyme Inhibitors; D010446:Peptide Fragments; D014475:Uncoupling Agents; C074636:amyloid beta-protein (25-35); D002259:Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone; D019284:Thapsigargin; D002118:Calcium