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Transient Brain Ischaemia Provokes Ca 2+ , PIP 2 and Calpain Responses Prior to Delayed Neuronal Death in Monkeys
Author(s) -
Yamashima Tetsumori,
Saido Takaomi C.,
Takita Masatoshi,
Miyazawa Atsuo,
Yamano Jun,
Miyakawa Atsuo,
Nishijyo Hisashi,
Yamashita Junkoh,
Kawashima Seiichi,
Ono Taketoshi,
Yoshioka Tohru
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.tb01337.x
Subject(s) - calpain , hippocampal formation , immunostaining , endoplasmic reticulum , ischemia , biology , hippocampus , microbiology and biotechnology , endocrinology , medicine , chemistry , immunohistochemistry , biochemistry , immunology , enzyme
To clarify the mechanism of postischaemic delayed cornu Ammonis (CA)‐1 neuronal death, we studied correlations among calpain activation and its subcellular localization, the immunoreactivity of phosphatidylinositol 4,5‐bisphosphate (PIP 2 ) and Ca 2+ mobilization in the monkey hippocampus by two independent experimental approaches: in vivo transient brain ischaemia and in vitro hypoxia‐hypoglycaemia of hippocampal acute slices. The CA‐1 sector undergoing 20 min of ischaemia in vivo showed microscopically a small number of neuronal deaths on day 1 and almost global neuronal loss on day 5 after ischaemia. Immediately after ischaemia, CA‐1 neurons ultrastructurally showed vacuolation and/or disruption of the lysosomes. Western blotting using antibodies against inactivated or activated μ‐calpain demonstrated μ‐calpain activation specifically in the CA‐1 sector immediately after ischaemia. This finding was confirmed in the perikarya of CA‐1 neurons by immunohistochemistry. CA‐1 neurons on day 1 showed sustained activation of μ‐calpain, and increased immunostaining for inactivated and activated forms of μ‐ and m‐calpains and for PIP 2 . Activated μ‐calpain and PIP 2 were found to be localized at the vacuolated lysosomal membrane or endoplasmic reticulum and mitochondrial membrane respectively, by immunoelectron microscopy. Calcium imaging data using hippocampal acute slices showed that hypoxia‐hypoglycaemia in vitro provoked intense Ca 2+ mobilization with increased PIP 2 immunostaining specifically in CA‐1 neurons. These data suggest that transient brain ischaemia increases intracellular Ca 2+ and PIP 2 breakdown, which will activate calpain proteolytic activity. Therefore, we suggest that activated calpain at the lysosomal membrane, with the possible release of biodegrading enzyme, will cause postischaemic CA‐1 neuronal death.