Stroke, Vol 21, 771-776, Copyright © 1990 by American Heart Association
H Onodera and K Kogure
The protective roles of Ca2+ channel blockers against ischemic hippocampal
damage are still debated. We used autoradiography to study postischemic
L-type Ca2+ channels (1,4-dihydropyridine Ca2+ channel blocker binding),
adenosine A1 receptors, and muscarinic cholinergic receptors in the rat
hippocampus using [3H]PN200-110 (PN), [3H]cyclohexyladenosine (CHA), and
[3H]quinuclidinyl benzilate (QNB), respectively, in 49 rats subjected to 20
minutes of forebrain ischemia. The rats were decapitated after 1 (n = 7), 3
(n = 7), 6 (n = 8), 12 (n = 7), 24 (n = 6), 48 (n = 6), or 168 (n = 8)
hours of recirculation; eight control rats were sham-operated but
experienced no cerebral ischemia. Reduced receptor binding preceding the
delayed death of CA1 pyramidal cells was first observed in the stratum
oriens of the CA1 subfield. Significant reductions in [3H]PN, [3H]CHA, and
[3H]QNB bindings of this stratum compared with control were noticed after 3
(35%, p less than 0.01), 12 (31%, p less than 0.01), and 1 (10%, p less
than 0.05) hours of recirculation, respectively. By 168 hours after
ischemia (when the populations of CA1 pyramidal cells were depleted) all
strata in the CA1 subfield had lost most of their receptor sites, and
[3H]PN, [3H]CHA, and [3H]QNB bindings in the stratum oriens were decreased
to 23%, 30%, and 63% of control (p less than 0.01). Although [3H]PN binding
in the CA3 subfield did not change significantly during 168 hours after
ischemia, the histologically intact dentate gyrus exhibited a 31% loss of
binding sites compared with control (p less than 0.05).(ABSTRACT TRUNCATED
AT 250 WORDS)
ARTICLES
Calcium antagonist, adenosine A1, and muscarinic bindings in rat hippocampus after transient ischemia
Department of Neurology, Tohoku University School of Medicine, Sendai, Japan.
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