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Calpain Inhibitors Protect Against Depolarization‐induced Neurofilament Protein Loss of Septo‐hippocampal Neurons in Culture
Author(s) -
Kampfl A.,
Zhao X.,
Whitson J. S.,
Posmantur R.,
Dixon C. E.,
Yang K.,
Clifton G. L.,
Hayes R. L.
Publication year - 1996
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.1460-9568.1996.tb01218.x
Subject(s) - calpain , neurofilament , depolarization , western blot , extracellular , calcium , chemistry , hippocampal formation , microbiology and biotechnology , spectrin , cytoskeleton , biology , biochemistry , biophysics , neuroscience , immunology , immunohistochemistry , cell , organic chemistry , gene , enzyme
Abstract We examined the effect of a 6 min depolarization with 60 mM KCl and 1.8, 2.8 or 5.8 mM extracellular CaCl 2 on neurofilament proteins of high (NF‐H), medium (NF‐M) and low (NF‐L) molecular weight in primary septo‐hippocampal cultures. One day after depolarization, Western blot analyses revealed losses of all three neurofilament proteins. Increasing the extracellular calcium concentration from 1.8 to 5.8 mM CaCl 2 in the presence of 60 mM KCl produced increased losses of all three neurofilament proteins to ˜80% of control values in the absence of cell death. Calcium‐dependent losses of the neurofilament proteins correlated with calcium‐dependent increases in calpain 1‐mediated breakdown products of alpha‐spectrin. Calpain inhibitors 1 and 2, applied immediately after depolarization and made available to cultures for 24 h, reduced losses of all three neurofilament proteins to ˜14% of control values. The protective effects of calpain inhibitors 1 and 2 were influenced by different levels of extracellular calcium. Qualitative immunohistochemical evaluations confirmed semiquantitative Western blot data on neurofilament loss and protection by calpain inhibitors 1 and 2. We propose that brief depolarization causes loss of neurofilament proteins, possibly due to calpain activation. Thus, calpain inhibitors could represent a viable strategy for preserving the cytoskeletal structure of injured neurons.