Ischaemic brain damage: the role of excitatory activity and of calcium entry.

The pattern of selective vulnerability occurring after cerebral ischaemia is similar to that after status epilepticus (Brierley, 1976; Corsellis and Meldrum 1976). In the hippocampus, the pyramidal neurones in the CA1 and CA3 zones and the hilar polymorphic neurones are particularly vulnerable and the dentate granule cells are relatively resistant. During status epilepticus induced experimentally in rats by the i. v. administration of bicuculline, allylglycine or kainic acid (Evans, Griffiths and Meldrum, 1983, 1984; Griffiths, Evans and Meldrum, 1983, 1984), selectively vulnerable neurones show condensation of perikaryal cytoplasm and swelling of mitochondria. The changes are evident after 30-90 min of continuous seizure activity. Severe condensation with a pyknotic nucleus and multiple, small, structureless vacuoles occur in a minority of vulnerable neurones after 90-150 min (Evans, Griffiths and Meldrum, 1984; Griffiths, Evans and Meldrum, 1984).