Chloride efflux is known to be involved in the progression of apoptosis in various cell types. We have recently shown that the volume-sensitive outwardly rectifying (VSOR)
anion channel serves as the pathway for apoptotic
chloride efflux in some cells. In the present study, we tested the
neuroprotective effects of drugs that can block the VSOR
anion channel, on delayed neuronal death (DND) induced by transient forebrain
ischemia. The functional expression of the VSOR
anion channel was first examined in hippocampal neurons in both primary culture and hippocampal slice preparations, by the whole-cell patch-clamp technique. We then tested the channel's sensitivity to an
anion channel blocker, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic
acid (
DIDS), and a
tyrosine kinase blocker,
genistein. By histological examinations and
cytochrome c release assessments, the protective effects of these drugs on the DND of hippocampal CA1 neurons in mice subjected to transient
ischemia were examined. Drugs were administered via the jugular vein prior to ischemic treatment and into the peritoneal cavity after reperfusion. Hippocampal neurons were found to express the volume-sensitive Cl(-) channel, which exhibits outward rectification and is sensitive to
DIDS and
genistein. Administration of
DIDS or
genistein reduced
cytochrome c release and the number of damaged neurons in the CA1 region after transient forebrain
ischemia. This fact suggests that the DND induction mechanism involves the activity of the VSOR
anion channel and that this channel may provide a therapeutic target for the treatment of
stroke.